"Let food be thy medicine, and medicine be thy food." - Hippocrates

Like or Tweet this post by clicking the star on the right

Foreword:

Remember, this blog is targeting healthy individuals seeking optimum health through diet and lifestyle who are ideally already following the Paleolithic/primal lifestyle.

Table of Contents

1. Introduction & Summary
1.1 Author’s Note
2. Cancer
3. Insulin Sensitivity & Glucose Tolerance
4. Type 2 Diabetes Mellitus
5. Heart Health & Hypertension
6. Pregnancy
7. Antioxidants & Inflammation
8. Mental Health
9. Liver Health
10. Oral Health
11. Bone Health
12. Gout
13. Fitness Performance
14. Metabolic Syndrome
15. Gallstone Disease
16. Additives & Nutrient Uptake
17. Variation Among Types of Coffee
18. Sleep
19. Future Topics of Interest
21. References (Annotated Bibliography)
22. Acknowledgements

1. Introduction & Summary

Over half of all American adults drink some form of coffee on a daily basis. But is it good for you? There are a plethora of ways to drink it: iced, with skim, 1%, 2%, whole, cream, half and half, with soy, a dash of cinnamon, nutmeg, sugar, artificial sweetener, non-dairy creamer, as espresso, etc. Ask around and you’ll get just as many different opinions as to whether or not it’s good for you: it cures cancer, it causes cancer, it is hard on your heart, or it lowers blood pressure. What the hell is going on here? So, I decided to kick off my first EBP article by boiling down all the research I could find on coffee into a coherent, science-based recommendation.

What follows this introduction is a lot of summarization of research articles, so I will briefly give my recommendation on coffee. If you are currently healthy and enjoy coffee, drink it – but drink it black, and no more than six 6-ounce “cups” (or about 1 liter total) per day. Habitual drinking of four or five “cups” spread throughout each day is encouraged, but drink it before 5 pm. It is important you get ample calcium and occasionally lift heavy things to maintain bone health. Drink decaf all you want.

I say no more than one liter per day because it seems practical to hedge your bets: 4 or 5 cups will get you the vast majority of the benefits, while minimizing any potential risks associated with such a large volume of coffee consumption. What are the benefits of habitual coffee consumption? Coffee seems to protect against many types of cancer, including oral, pharyngeal, liver, pancreatic, colon, prostate, endometrial, brain and potentially others. It also appears that habitual consumption leads to improved insulin sensitivity, reduced risk of type 2 diabetes, reduced risk of heart disease and other heart problems, reduced oxidative stress and inflammation, better oral health, better mental health, better liver health, reduced risk of gout and gallstone disease, and couple cups of coffee before some high-intensity endurance exercise can boost performance. And it has practically no calories40! One major downside I have seen is that coffee reduces the body’s ability to metabolize calcium, so it is very important to ensure you are getting your calcium. Also, caffeinated coffee may be related to birth defects and should probably be avoided by pregnant women, especially during the first trimester. It seems that decaffeinated coffee can give you a fair amount of benefits without any apparent risk, but you will miss out on many of the great benefits of caffeinated coffee.

Coffee

As an important note, this recommendation is not a permission slip to enjoy other types of caffeinated beverages like energy drinks or diet sodas! There are many components of coffee that all seem to interact to produce these effects, so you cannot generalize its benefits to other things. Also, it’s psychologically unhealthful to think of coffee as a need, so if you’re at a stage of psychological addiction that you simply cannot go without your coffee, you need to try to go thirty days without it to give yourself a little “reboot”. If you don’t want to drink four or five cups of coffee that is just fine, but don’t expect the benefits that come with that level of coffee consumption. If you already drink much more than five cups of coffee a day, you should consider lowering your intake to reduce your risk of unhealthful side effects.
Top

1.1 Author’s Note

I spent a lot of time on this research and writing this up, so I really hope you enjoy it. If you want to get a glimpse at how coffee affects each topic, simply look at the overviews. “The Research” sections are a lot more rigid and detailed.

Please don’t hesitate to leave a comment if you want me to research an unmentioned topic or critique my writing or reasoning. Every comment helps! Thanks for reading. I intend to keep this updated as new research comes to light.
Top


2. Cancer

Overview: You might find some big claims around the ‘net about coffee and it’s protective effects on certain types of cancer, and in fact the claims are mostly true! Studies show an inverse association between caffeinated coffee drinking and oral, pharyngeal, liver, pancreatic, colon, prostate, endometrial and even brain cancer. These associations are weaker or non-existent for decaf, depending on which type of cancer you are talking about. Finally, it seems that while coffee may help protect against acquiring cancer, it does not significantly affect cancer mortality in any broad sense.

Hepatocellular Carcinoma

The Research: A recent study in Evidence Based Dentistry3 found an inverse association of caffeinated coffee with the risk cancer of the oral cavity and pharynx, decreasing combined risk by 39%. Data on decaf was too sparse for detailed analysis. Another major study60 showed that there was a 60% risk decrease for aggressive prostate cancers in those who drank six or more cups of coffee – decaf or caffeinated - per day, but there was no such association for non-advanced or low-grade prostate cancers. It also seems that24 coffee consumption may be associated with decreased risk of endometrial cancer, especially among overweight women. Several studies35,56,58,75,78 found that coffee drinking has a strong protective effect against the most common type of liver cancer, called hepatocellular carcinoma. This is likely due to the fact that colon, liver and pancreatic cancers are related to insulin resistance, which coffee helps protect against58. Multiple studies32,44 have found an inverse association between total caffeinated coffee consumption and risk of glioma, or brain cancer. No association between coffee and breast cancer has been found22. No association between coffee consumption and total cancer mortality among men was found, although a possible weak association was found for women54. From all of this research, it seems that caffeinated coffee is definitively superior to decaffeinated coffee with respect to its protective effects against cancers.
Top


3. Insulin Sensitivity & Glucose Tolerance

Overview: Coffee’s role in insulin sensitivity and glucose tolerance is paradoxical and very puzzling to researchers – hey, I’ll admit, I was close to banging my head on my desk as I was working on this. On one hand, long-term habitual use of caffeinated coffee is associated with better insulin sensitivity and glucose tolerance, while acute administration of seems to decrease insulin sensitivity in certain conditions but not others. There appears to be an interactive group of events that goes on in the digestive tract after coffee consumption, with polyphenols, beneficial acids, and caffeine all following different pathways. My suspicion is that we have not yet come up with an appropriate method of testing in testing in order to see what is really going on.

The take-home message is this: habitual, long-term caffeinated coffee drinking improves insulin sensitivity. As for the acute effects, it seems that decaffeinated coffee or coffee extracts quickly lower blood glucose levels and insulin levels, while caffeinated coffee does not. I’m not too worried about the acute effects, however, as they appear to have no long-term negative effects, and if you’re already eating paleo/primal then you have relative little carbohydrate intake which will help minimize any of the acute effects of coffee on glucose tolerance.

The Research: Acute administration of caffeinated coffee produces a myriad of puzzling results. Researchers46 found that caffeinated coffee elicits acute insulin insensitivity when ingested before a carbohydrate load, and if co-ingested with one meal it results in insulin insensitivity after another meal. After a second dose of caffeinated coffee, insulin sensitivity was decreased. Another study8 found that caffeinated coffee and lipids additively decrease glucose tolerance.

Consumption of polyphenols, which are abundant in coffee, attenuate postprandial (“after-meal”) glycemic responses and fasting hyperglycemia and improve insulin secretion and sensitivity, but the mechanism of their action is not yet known30. A study34 analyzing the extract of decaffeinated green coffee beans found that a dose of the extract reduced plasma glucose compared to control, but without affecting insulin. This indicates that the extract works by inhibiting amylolytic enzymes, which break down sugars, and attenuating intestinal glucose absorption. Additionally, researchers63 found that chlorogenic acid and trigonelline, which are two major components of coffee, significantly reduced early glucose and insulin concentrations following an oral glucose tolerance test when compared with placebo. It has been suggested that this is mediated through incretin hormones, which help stimulates insulin release and inhibits glucagon release to lower blood glucose, but research49 does not support this. Another study42 suggests that polyphenol content in coffee may protect beta cells from oxidative stress, which helps in response to a glucose load, while caffeine in caffeinated coffee may counteract these positive effects and instead act through a different pathway.

Long-term consumption of coffee appears to be quite beneficial for insulin sensitivity and glucose tolerance. A long-term study5 found that men who had impaired fasting glucose or impaired glucose tolerance and reverted to normal glucose tolerance had statistically higher coffee consumption compared to their non-reverting counterparts. This is consistent with other research41 that has shown that average fasting glucose levels have been found to decrease as coffee consumption increases61. Additionally, habitual coffee consumption seems to help lower insulin resistance in postmenopausal women, especially in overweight women14.

Researchers43 sought to resolve the coffee-insulin paradox by testing coffee along with co-consumption of sugar. Out of coffee, decaf, black tea, straight sucrose (10g), hot water, or coffee+sucrose (10g), only the coffee+sucrose reduced postprandial glycemia, which they thought may explain paradoxical findings of studies relating coffee to reduced risk of diabetes. However, it is unclear whether or not this is associated with long-term insulin regulation, as other studies11 have found that drinking coffee with additives like cream and sugar is correlated with obesity. In a review9 of research, scientists saw strong evidence that caffeine reduces insulin sensitivity in skeletal muscle, but it is unclear whether or not this is acute or long-term or whether or not it even applies to caffeinated coffee.
Top


4. Type 2 Diabetes Mellitus

Insulin Pump

Overview: All studies point to the conclusion that habitual caffeinated coffee consumption significantly reduces the risk of type 2 diabetes mellitus. The association is not so clear for decaf or coffee with various additives like cream and sugar.

The Research: Studies41 show that there is a strong inverse relationship between caffeinated coffee consumption and type 2 diabetes, reducing the risk from 38-46%. This applies across ethnicity10,25 and gender27. There is a dose-response effect, meaning that higher coffee consumption leads to lower risk of type 2 diabetes41, and this relationship holds for all types of coffee analyzed to date, not just filtered31. This relationship may be enhanced by the idea that coffee drinkers are simply replacing their more sugary drinks with coffee, and one study62 showed that replacing one sugar-sweetened beverage with 1 cup of coffee was associated with a risk reduction of 17%.
Top


5. Heart Health & Hypertension

Overview: Contrary to popular belief among physicians and patients, coffee use is not associated with heart problems. In fact, it has been shown to be loosely associated with a reduced risk of cardiovascular disease, coronary heart disease mortality and reduced blood pressure; at worst, there is no association. Heart problems should not be a worry for healthy coffee drinkers, but may pose problems for those who already have heart disease.

The Research: A recent review50 looked at the evidence surrounding coffee use and cerebrovascular disease (CVD) as well as coronary heart disease (CHD). Recent large studies have suggested that coffee probably decreases the rate of CVD events. Results from the massive Nurses’ Health Study of 85,747 women found no association between coffee consumption and CVD occurrence; a recent Swedish study found no association between coffee consumption and CHD and a meta-analysis also reported these same results80. A study of 2,975 men reported the risk of a first cardiovascular event was decreased by 67% for those who drank more than 8 cups of coffee per day. The NHANES prospective study found a strong protective association of coffee in elders without high blood pressure, and the Framingham Study found a 43% inverse relation between caffeinated coffee use and CHD mortality. It appears that caffeinated coffee use has a protective relationship with the onset of heart valve disease, as shown by a recent study demonstrating habitual coffee use’s inverse relationship with a measure of arterial stiffness57.

Echocardiogram

Contrary to popular belief among physicians and patients, they50 also found that drinking more than 4 cups of coffee a day resulted in an 18% reduction in hospitalizations for cardiac rhythm disturbances, while decaf offered no protection. It is important to note that this protective association may appear because people who are susceptible to atrial fibrillation may have already reduced their coffee intake. Other studies found no association between coffee intake and risk of atrial fibrillation in normal persons28 or patients with known heart problems69. Additionally, it appears that coffee bean extract reduces high blood pressure, so long-term coffee consumption may protect against hypertension53; another study68 found no association between hypertension and consuming more than 3 or less than 1 cup of coffee per day, with a slight increase in risk for those consuming 1 to 3 cups. A meta-analysis on the subject found a very slight (1.22 mmHg systolic and 0.49 mmHg diastolic) increase in blood pressure in regular coffee drinkers79.

Taking caffeine before high-intensity exercise does result in a higher average heart rate compared to placebo33, but this is coupled with a significant performance increase. Another study70, showed that caffeine administrations totaling an equivalent 5 or 6 cups of coffee resulted in a modest average increased in blood pressure (2.7% to 3.6% for a “normal” subject) and a reduced average heart rate of 2 bpm, with amplified blood pressures and epinephrine levels elevated until around bedtime. Although these effects do not seem significant for those who are healthy, individuals who already have heart problems should use caution before drinking caffeine, especially before exercise, for these reasons.


Top


6. Pregnancy

Overview: It is not quite clear whether or not coffee is beneficial or harmful to an unborn fetus. It seems that there are both good and bad effects, but I would strongly caution against drinking coffee while pregnant, especially during the first trimester, because of the sheer fragility of infants during such a critical time of development. If you simply refuse to give up coffee while pregnant, keep it to a minimum.

The Research: One study59 found that maternal consumption of coffee was inversely associated with advanced β-cell autoimmunity in the offspring; β-cell autoimmunity is responsible for type 1 diabetes. A study12 on maternal caffeine intake and the risk of certain birth defects found small elevations in odds ratios for total maternal coffee/caffeine intake for certain birth defects. Another study45 found that maternal coffee and/or tea consumption seems to be associated with a type of childhood acute lymphoblastic leukemia. In a review of the benefits and risks of coffee consumption13, researchers suggested the pregnant women should avoid coffee because of its potential interference with oral contraceptives or hormones. Research1 seems to show that risks are higher during the first third of pregnancy, but that neonates may actually benefit from caffeine therapy for certain conditions.
Top


7. Antioxidants & Inflammation

Overview: Sustained consumption of coffee can be an important part of an anti-inflammatory diet, protecting against oxidative stress and reducing markers of inflammation. It appears that the long-term beneficial effects of coffee outweigh the cortisol increases found in acute doses of caffeine.

The Research: A study61 on some unhealthy mice found that drinking coffee (as opposed to water) for five weeks ameliorated the development of hyperglycemia, improved insulin sensitivity, decreased levels of inflammatory cytokines, and improved fatty liver. Another study7 found that during a four-week period of coffee ingestion, oxidative DNA damage was markedly reduced and glutathione (antioxidant) and glutathione reductase (makes glutathione) activity were elevated. Researchers38 have also observed that coffee is also significantly inversely correlated to a marker of inflammation called serum C-reactive protein.

Chlorogenic acid is the ester of caffeic acid and quinic acid. A study52 found that, in vitro, caffeic acid has a stronger antioxidant activity than chlorogenic acid. Both had beneficial effects on intestinal ischemia-reperfusion injury, which is tissue damage caused when blood supply returns to tissue after ischemia (lack of blood supply). The absence of ischemia creates conditions where the recirculation of blood in the area causes inflammation and oxidative stress, and it seems that caffeic acid is a major player in chlorogenic acid’s protective effects against ischemia-reperfusion injury.

Some research26 has shown that a cup of coffee increases the circulating cortisol concentrations in healthy men. On the contrary, another study64 demonstrated that caffeinated coffee decreases salivary cortisol concentrations in pregnant women. More research needs to be done in this area before any conclusions can be drawn on the long-term effects of coffee on cortisol, and the importance of that relationship.

Several pathways have been suggested for the protective and anti-inflammatory effects of coffee. Improved brain performance and mental health as a result of the coffee in polyphenols (a type of antioxidant) may be due to the fact that they inhibit DNA methyltransferase 3, which has been associated with development, cancer and brain function51. It appears13 that coffee is able to ameliorate oxidative stress because it can induce mRNA and protein expression and stimulate the Nrf2-ARE pathway, a well-studied biochemical pathway which helps reduce inflammation.
Top


8. Mental Health

Studies13,55,77 have shown a clear inverse dose-response relationship between coffee intake and the risk of Parkinson’s Disease. Other studies13,21 indicate that drinking coffee decreases risk of dementia/Alzheimer’s Disease by about 65% for those who drink 3-5 cups per day at midlife. It appears that the protective effect on Alzheimer’s Disease is the result of a synergistic effect of caffeine on some other component of coffee76.

Mental Health

Also, research13 shows that caffeine and its metabolites help in proper cognitive functionality. It is well-documented and well-known that caffeine can increase concentration and performance on sustained attention tasks.
Top


9. Liver Health

Overview: Caffeinated coffee seems to be important for improving fatty liver and protecting liver health, some of which may be due to its beneficial effects on insulin sensitivity.

The Research: A study61 on mice found that after five weeks of drinking either coffee or water, fatty liver was improved in the coffee-drinking group. A study15 on non-alcoholic fatty liver disease found that coffee drinkers have lower fatty liver involvement and a less severe ultrasound bright liver score (BLS), which if higher is associated with obesity, higher insulin resistance, lower HDL cholesterol, older age and arterial hypertension. Another study found that in a group of participants with advanced hepatitis C-related liver disease, regular coffee consumption was associated with lower rates of decrease progression, with relative risks declining for increasing coffee intake23.
Top


10. Oral Health

Overview: Coffee seems to be effective at supporting the health of your teeth. Certain compounds in coffee have antibacterial effects against those bacteria that cause cavities, and coffee extract has also shown to protect against demineralization.

The Research: A study4 on the antibacterial effects of coffee found that the individual chemicals in coffee – specifically caffeine, trigonelline, caffeic acid, protocatachuic acid and chlorogenic acid – showed similar antimicrobial activity, and when added together appeared to have a synergistic effect. Two other studies6,71 found that coffee extract was active against Streptococcus mutans but not S. sobrinus, both of which cause tooth caries, and was also effective as an antidemineralization agent.
Top


11. Bone Health

Overview: Coffee is bad for bone health, slightly decreasing bone mineral density and increasing risk of fractures and osteoporosis. Coffee drinkers need to ensure they are getting an ample supply of calcium, and periodically lifting heavy things to increase bone quality.

Osteoporosis

The Research: One study36 found that high coffee consumption was a significant predictor of trochanteric hip fractures, and another study20 found it was associated with osteoporotic status. Drinking coffee has also been shown to be associated with low back pain in older women2 and decreased bone mineral density in men29. A study39 on rats found that coffee intake had serious adverse effects on calcium metabolism, including increased levels of calcium in the urine and plasma, decreased bone mineral density and lower volume of bone, thus delaying the bone repair process.
Top


12. Gout

Long-term coffee consumption may help protect against gout, which is arthritis caused by build up of uric acid in the joints17.
Top


13. Fitness Performance

Fitness

A study on the effects of caffeine on high-intensity endurance cycling performance33 found that performance time was quite significantly improved following acute caffeine ingestion, regardless of whether or not that followed a withdrawal period. However, it did result in increased average heart rate.
Top


14. Metabolic Syndrome

One study16 found no clear association between coffee and incident of the metabolic syndrome.
Top


15. Gallstone Disease

Multiple studies65,66,67 have shown that habitual caffeinated coffee consumption is associated with a reduced risk of gallstone disease in both men and women, with increasing coffee consumption leading to decreased risk. Decaffeinated coffee does not seem to have this association.
Top


16. Additives & Nutrient Uptake

Overview: Learn to like your black coffee, as additives are associated with obesity and decreased uptake of beneficial components of coffee. Water would not be good for you if you dump a bunch of sugar and a cup of soy creamer in it, so don’t do it with your coffee! Ditch the sugar-substitutes as well, as they will at best keep your sweet cravings up. Lastly, and there’s no way around it: coffee makes you poop. It does so by inhibiting pancreatic lipase – and therefore inhibiting lipid degradation – which decreases lipid absorption and caloric intake slightly. In large amounts, coffee can result in oily or loose stools. Interesting fact: the drug Orlistat functions by inhibiting pancreatic lipase and is well-known for it’s effects on those who eat a high fat diet. Let’s just say, it’s recommended those who take the drug “bring a change of clothes with you to work.” Yikes.

The Research: Researchers15 have observed an opposing/antagonizing role of coffee with regards to overweightness, which is probably related to the other benefits of coffee, namely increased insulin sensitivity. Another study11 found that additive use explains the association between coffee/tea consumption and obesity and men, finding that artificial sweetener use was associated with higher BMI. Coffee does not seem to be an effective way of reducing appetite or energy intake26. It seems that the extract of decaffeinated green coffee beans are fairly effective at inhibiting pancreatic lipase37, which is responsible for lipid degradation; this decreases lipid absorption and reduces caloric intake, and also explains the subjective digestive effects of coffee consumption. This result is consistent with another study which showed that a period of coffee consumption led to reduced weight/body fat and reduced energy/nutrient intake7

In a review of literature13, researchers found that coffee lipid fraction containing cafestol and kahweol act as a safeguard against some malignant cells (ie. it’s anticarcinogenic) by modulating the detoxifying enzymes, but do raise serum cholesterol – which is not necessarily bad, depending on who you ask! Cafestol may have other potential health benefits as well.
Top


17. Variation Among Types of Coffee

Overview: It doesn’t really matter which way you brew coffee if you’re after the beneficial compounds, but if you have had stomach irritation after drinking then try a darker roast.

The Research: Studies31,48,65,66 show that many - and maybe all – types of coffee (green, broth boiled, French press, filtered) have beneficial effects on different medical problems and comparable bioavailability of beneficial components of coffee. However, another study18 demonstrated that dark roasted brews have lower concentrations of N-methylpyridinium, which lowers gastric acid secretion and helps with stomach irritation.
Top


18. Sleep

Overview: Although this will not come as a shock to many of you, coffee drunk after 5 pm will probably impair your ability to sleep. Research does support that coffee is helpful if you are trying to stay up late and/or drive while sleep deprived.

The Research: Studies72,73 have shown that drinking coffee at night – or after 5 pm – is associated with a shortened sleep duration in both adolescents and people aged 25-45 years old, and this is probably generalizable to people of all ages. Another study74 showed that a cup of coffee was able to restore nighttime driving performance to normal levels without altering subsequent sleep.
Top


19. Future Areas of Interest

Once I get the time I will be looking at coffee’s association with the following areas and updating this page accordingly. Feel free to suggest other topics in the comments!

  • Fibrocystic Disease
  • Breast Cysts
  • Hypoglycemia
  • Stomach Irritation
  • Fat Oxidation

20. References


  1. Adén, U. (2011). Methylxanthines during pregnancy and early postnatal life. Handbook of experimental pharmacology, 200, 373-89. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/20859804

    The evidence base for adverse effects of caffeine in first third of pregnancy are stronger than for later parts of pregnancy and there is currently insufficient evidence to advise women to restrict caffeine intake after the first trimester. In fact, several studies have suggested that neonates can benefit from methylxanthine (eg. caffeine) therapy for apneas or situations of hypoxia/ischemia, but much more research needs to be done before something like this could be *recommended*.

  2. Ahn, S., & Song, R. (2009). Bone mineral density and perceived menopausal symptoms: factors influencing low back pain in postmenopausal women. Journal of Advanced Nursing, 65(6), 1228-36. Retrieved June 9, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/19374677

    Drinking coffee was statistically significantly associated with low back pain.

  3. Al-Dakkak, I. (2011). Tea, coffee and oral cancer risk. Evidence Based Dentistry, 12(1), 23-4. Retrieved June 4, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/21436863

    Meta-analysis of nine case-control studies supports an inverse association of caffeinated coffee with the risk of cancer of the oral cavity and pharynx, decreasing combined risk by 39 percent. No association was found with caffeinated coffee and laryngeal cancer. Data on decaffeinated coffee was too sparse for detailed analysis, but indicated no increased risk. Tea intake was not associated with head and neck cancer risk.

  4. Almeida, A., Naghetini, C., Santos, V., Farah, A., & Glória, M. (2010). The antibacterial effect of coffee against Streptococcus mutans is enhanced by the addition of caffeine and other coffee natural compounds. Association for Science and Information on Coffee, N/A. Retrieved June 4, 2011, from http://www.asic-cafe.org/pdf/abstract/H406_ALMEIDA_2010.pdf

    Investigated inhibition of Streptococcus mutans by coffee chemical compounds and by these compounds added separately to Coffea arabica extract. All tested coffee extracts showed antibacterial activity. Plain caffeine, trigonelline, caffeic, protocatachuic and chlorogenic acids at 2.0 mg/mL showed similar antimicrobial activity. Caffeine at concentrations found in the beverage (.5 to 1.0 mg/mL) inhibited S. mutans temporarily, but higher concentrations obtained a stronger and longer lasting inhibition. When the individual chemicals were added separately to Coffea arabica, an improvement to its antibacterial effect was observed, suggesting a synergistic effect.

  5. Alvarsson, M., Hilding, A., & Ostenson, C. (2009). Factors determining normalization of . Diabetic Medicine, 26(4), 345-53. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/19388963

    Men who reverted to normal glucose tolerance - from having impaired fasting glucose (IFG) or impaired glucose tolerance (IGT) at baseline - had higher coffee consumption.

  6. Antonio, A., Iorio, N., Farah, A., Santos, K. D., & Maia, L. (2010). In Vitro antibacterial and antidemineralizant activity. Association for Science and Information on Coffee, N/A. Retrieved June 5, 2011, from http://www.asic-cafe.org/pdf/abstract/PH902_ANTONIO_2010.pdf

    Coffea canephora extract was active against S. mutans, although it had no significant effect on S. sobrinus. Difference among control and coffee plaque pH (~4.8) was not statistically significant after 7 days of treatment. The demineralization in fragments subjected to the coffee extract was lower than in the negative and blank controls. C. canephora seems beneficial as an anticariogenic agent (helps protect against tooth decay) and as an antidemineralization agent (helps keep minerals in tooth enamel).

  7. Bakuradze, T., Boehm, N., Baum, M., Eisenbrand, G., Janzowski, C., Lang, R., et al. (2011). Antioxidant-rich coffee reduces DNA damage, elevates glutathione status and contributes to weight control: results from an intervention study. Molecular nutrition & food research, 55(5), 793-7. Retrieved June 3, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/21462335

    Four weeks of wash-out, four weeks of coffee intake, then four weeks of wash-out, drinking 3-4 cups per day during coffee intake phase. During the coffee ingestion period, oxidative DNA damage was markedly reduced, and Glutathione level and GSR activity were elevated, while body weight/body fat and energy/nutrient intake were reduced.

  8. Beaudoin, M., Robinson, L., & Graham, T. (2011). An oral lipid challenge and acute intake of caffeinated coffee additively decrease glucose tolerance in healthy men. Journal of Nutrition, 141(4), 574-81.

    At T=0, ten males underwent an oral-fat tolerance test or consumed water; 5 hours later they consumed caffeinated coffee, decaffeinated coffee, or water. At T=6h, they underwent an oral glucose tolerance test. At 7h, caffeinated coffee produced the highest glucose concentrations. Caffeinated and decaffeinated coffee produced the highest glucagon-like peptide-1, which stimulates insulin release in euglycemia and is about 3x as potent as GIP for stimulating insulin release in hyperglycemia (http://www.ncbi.nlm.nih.gov/pubmed/8036284). Caffeinated coffee increased glucose-dependent insulinotropic polypeptide (GIP), which induces insulin secretion in healthy subjects in hyperglycemic conditions, but not in euglycemia (http://www.ncbi.nlm.nih.gov/pubmed/8036284). Both oral lipids and caffeinated coffee independently and additively decrease glucose tolerance, and this can be explained at least in pair by impaired glucose homeostasis.

  9. Beaudoin, M., & Graham, T. (2011). Methylxanthines and human health: epidemiological and experimental evidence.. Handbook of experimental pharmacology, 200, 509-48. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/20859811

    With the exception of bone mineral, there is little evidence that caffeine impacts negatively on other health issues. There is strong evidence that caffeine reduces insulin sensitivity in skeletal muscle, but this may not apply for coffee in particular because of its demonstrated benefits for insulin sensitivity in habitual coffee drinkers.

  10. Boggs, D., Rosenberg, L., Ruiz-Narvaez, E., & Palmer, J. (2010). Coffee, tea, and alcohol intake in relation to risk of type 2 diabetes in African American women. American Journal of Clinical Nutrition, 92(4), 960-6. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/20826625

    African American women who drink moderate amounts of caffeinated coffee have a reduced risk of type 2 diabetes, while decaf and tea was not associated with risk of diabetes.

  11. Bouchard, D., Ross, R., & Janssen, I. (2010). Coffee, tea and their additives: association with BMI and waist circumference. Obesity Facts, 3(6), 345-52. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/21196787

    Frequency of coffee/tea consumption was NOT association with measures of obesity as *additive* use explained the association between tea consumption and obesity in men. Also, artificial sweetener use within coffee/tea was associated with higher BMI.

  12. Browne, M., Hoyt, A., Feldkamp, M., Rasmussen, S., Marshall, E., Druschel, C., et al. (2011). Maternal caffeine intake and risk of selected birth defects in the National Birth Defects Prevention Study. Birth Defects Research Part A: Clinical and Molecular Teratology, 91(2), 93-101. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/21254365

    Small but statistically significant elevations in adjusted odds ratios for total maternal dietary caffeine intake or specific types of caffeinated beverages, but dose-response patterns were absent. This was observed for the following defects: anotia/microtia, esophageal atresia, small intestinal atresia, and craniosynostosis. The Researchers were not convinced of the association, but it definitely does not rule out that caffeinated beverages do NOT cause birth defects, however minor. I would recommend against it, at least for the first trimester.

  13. Butt, M., & Sultan, M. (2011). Coffee and its consumption: benefits and risks. Critical Reviews in Food Science & Nutrition, 51(4), 363-73. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/21432699

    Unfortunately could only access the abstract: Many research investigations, epidemiological studies, and meta-analyses regarding coffee consumption revealed its inverse correlation with that of diabetes mellitus, various cancer lines, Parkinsonism, and Alzheimer’s disease. Moreover, it ameliorates oxidative stress because of its ability to induce mRNA and protein expression, and mediates Nrf2-ARE pathway stimulation. Furthermore, caffeine and its metabolites help in proper cognitive functionality. Coffee lipid fraction containing cafestol and kahweol act as a safeguard against some malignant cells by modulating the detoxifying enzymes, but do raise serum cholesterol - which is not necessarily bad, depending on who you ask! Caffeine also affects adenosine receptors and its withdrawal is accompanied with muscle fatigue and allied problems… so if you decide to stop, it can create minor temporary problems. An array of evidence showed that pregnant women or those with postmenopausal problems should avoid excessive consumption of coffee because of its interference with oral contraceptives or postmenopausal hormones.

  14. Catalano, D., Trovato, G., Spadaro, D., Martines, G., Garufi, G., Tonzuso, A., et al. (2008). Insulin resistance in postmenopausal women: concurrent effects of hormone replacement therapy and coffee. Climacteric, 11(5), 373-82. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/18781481

    The combination of coffee consumption and hormone replacement therapy (HRT) could lower insulin resistance in postmenopausal women. In overweight women, greater insulin sensitivity is associated with intake of espresso coffee and not with HRT; in normal weight women, only HRT is associated with lower insulin resistance.

  15. Catalano, D., Martines, G., Tonzuso, A., Pirri, C., Trovato, F., & Trovato, G. (2010). Protective role of coffee in non-alcoholic fatty liver disease (NAFLD). Digestive Diseases and Sciences, 55(11), 3200-6. Retrieved June 1, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/20165979

    There appears to be an opposing/antagonizing role of coffee with regard to overweightness and insulin resistance that decreases fatty liver involvement in coffee drinkers, and leads to a less severe ultrasound bright liver score (BLS) which is associated with obesity, higher insulin resistance, lower HDL cholesterol, older age and arterial hypertension.

  16. Cherniack, E. (2011). Polyphenols: Planting the seeds of treatment for the metabolic syndrome. Nutrition, 27(6), 617-23. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/21367579

    There is not yet a clear association (ie. the results are mixed) between coffee and incidence of metabolic syndrome.

  17. Choi, H., & Curhan, G. (2010). Coffee consumption and risk of incident gout in women: the Nurses’ Health Study. American Journal of Clinical Nutrition, 94(2), 922-7. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/20739424

    Long-term coffee consumption is associated with lower risk of incident gout (arthritis caused by build up of uric acid in the joints) in women. Caffeine from all sources seems to have this protective effect.

  18. Dossin, E., Leloup, V., & Blank, I. (2010). Quantification of compounds in coffee involved in gastic acid regulation. Association for Science and Information on Coffee, N/A. Retrieved June 5, 2011, from http://www.asic-cafe.org/pdf/abstract/PH904_LELOUP_2010.pdf

    Dark roasted brews have lower concentrations of N-methylpyridinium, which shows a protective effect toward gastic acid secretion (lowers it). Green coffee brews have greater beta-N-alkanoyl-5-hydroxytryptamide concentrations. You can expect less stomach irritation with dark roasted brews.

  19. Duarte, G., & Farah, A. (2010). The human urinary excretion of chlorogenic acids and metabolites after coffee consumption may be affected by the simultaneous consumption of milk. Association for Science and Information on Coffee, N/A. Retrieved June 4, 2011, from http://www.asic-cafe.org/pdf/abstract/H409_DUARTE_2010.pdf
    In vitro studies have shown that milk proteins may bind chlorogenic acids (CGA) and decrease their absorption. Total urinary excretion of total urinary CGA and metabolites consistently lower in after coffee-milk consumption compared to coffee, with an average decrease of 33 ± 15%. After coffee consumption, 68 ± 12% of total CGA ingested was recovered in urine, in cinnamic and quinic acids moieties derivatives, while after coffee-milk consumption only 40 ± 8% was recovered.

  20. Maghraoui, A. E., Ghazi, M., Gassim, S., Ghozlani, I., Mounach, A., Rezqi, A., et al. (2010). Risk factors of osteoporosis in healthy Moroccan men. BMC Musculoskeletal Disorders, 11, 148. Retrieved June 9, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/20602777

    High coffee consumption was related to osteoporotic status.

  21. Eskelinen, M., & Kivipelto, M. (2010). Caffeine as a protective factor in dementia and Alzheimer’s disease. Journal of Alzheimers Disease, 20(Suppl 1), S167-74. Retrieved June 1, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/20182054

    In one study, coffee drinking of 3-5 cups per day at midlife was associated with a decreased risk of dementia/AD by about 65% at late-life. Most studies support this conclusion, although there is some inconsistency which can probably be explained by analyzing the combined effects of coffee and tea, while the protective effects against cognitive decline/dementia are less evident for tea drinking.

  22. Fagherazzi, G., Touillard, M., Boutron-Ruault, M., Clavel-Chapelon, F., & Romieu, I. (2011). No association between coffee, tea or caffeine consumption and breast cancer risk in a prospective cohort study. Public Health Nutrition, [Epub ahead of print], 1-6. Retrieved June 3, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/21466740

    No association was found between coffee, tea or caffeine and breast cancer risk. Median intake was 2.2 cups/day for coffee and 1.7 cups/day for tea, or a median of 164 mg/d of caffeine.

  23. Freedman, N., Everhart, J., Hoefs, J., Dienstag, J., Morishima, C., Abnet, C., et al. (2009). Coffee intake is associated with lower rates of liver disease progression in chronic hepatitis C. Hepatology, 50(5), 1360-9. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/19676128

    Higher coffee consumption has been associated inversely with the incidence of chronic liver disease in population studies. In a large prospective study of participants with advanced hepatitis C-related liver disease, regular coffee consumption was associated with lower rates of disease progression, with relative risks declining for increasing coffee intake.

  24. Friberg, E., Orsini, N., Mantzoros, C., & Wolk, A. (2009). Coffee drinking and risk of endometrial cancer - a population-based cohort study. International Journal of Cancer, 125(10), 2413-7. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/19585497

    These data indicate that coffee consumption may be associated with decreased risk of endometrial cancer, especially among women with excessive body weight.

  25. Fuhrman, B., Smit, E., Crespo, C., & Garcia-Palmieri, M. (2009). Coffee intake and risk of incident diabetes in Puerto Rican men: results from the Puerto Rico Heart Health Program. Public Health Nutrition, 12(6), 842-8. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/18775084

    Study findings support a protective effect of coffee intake on diabetes risk, while also suggesting that abstainers may be at reduced risk.

  26. Gavrieli, A., Yannakoulia, M., Fragopoulou, E., Margaritopoulos, D., Chamberland, J., Kaisari, P., et al. (2011). Caffeinated coffee does not acutely affect energy intake, appetite, or inflammation but prevents serum cortisol concentrations from falling in healthy men.. Journal of Nutrition, 141(4), 703-7. Retrieved June 1, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/21346100

    A normal amount of caffeinated (3 mg caffeine/kg body weight) coffee (200 mL) does not have short-term effects on appetite, energy intake, glucose metabolism or inflammatory markers, but does increase circulating cortisol concentrations in healthy men.

  27. Goto, A., Song, Y., Chen, B., Manson, J., Buring, J., & Liu, S. (2011). Coffee and caffeine consumption in relation to sex hormone-binding globulin and risk of type 2 diabetes in postmenopausal women. Diabetes, 60(1), 269-75. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/21030499

    Sex hormone-binding may account for the inverse association between caffeinated coffee consumption and type 2 diabetes risk among postmenopausal women, as the levels of the two are associated.

  28. Gronroos, N., & Alonso, A. (2010). Diet and risk of atrial fibrillation - epidemiologic and clinical evidence. Circulation Journal, 74(10), 2029-38. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/20838006

    High coffee intake was not clearly associated with an increased risk of atrial fibrillation.

  29. Hallström, H., Melhus, H., Glynn, A., Lind, L., Syvänen, A., & Michaëlsson, K. (2010). Coffee consumption and CYP1A2 genotype in relation to bone mineral density of the proximal femur in elderly men and women: a cohort study. Nutrition and Metabolism, 7, 12. Retrieved June 9, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/20175915

    High coffee consumption of coffee was associated with a 4% lower bone mineral density in men, but not in women.

  30. Hanhineva, K., Törrönen, R., Bondia-Pons, I., Pekkinen, J., Kolehmainen, M., Mykkänen, H., et al. (2010). Impact of dietary polyphenols on carbohydrate metabolism. International Journal of Molecular Sciences, 11(4), 1365-402.

    In animal models and a limited number of human studies carried out so far, polyphenols and foods or beverages rich in polyphenols have attenuated postprandial glycemic responses and fasting hyperglycemia, and improved acute insulin secretion and insulin sensitivity. Unsure of the mechanism by which they act, but there are several posited in the article. Polyphenol consumption appears to help prevent insulin resistance, metabolic syndrome and type 2 diabetes.

  31. Hjellvik, V., Tverdal, A., & Strøm, H. (2011). Boiled coffee intake and subsequent risk for type 2 diabetes. Epidemiology, 22(3), 418-21. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/21317784

    A moderate inverse association was found between consumption of broth boiled and other types of coffee at the age of 40-45 years and the risk of being prescribed oral antidiabetic drugs 5-20 years later), so it is not just filtered coffee that has a protective effect against type 2 diabetes.

  32. Holick, C., Smith, S., Giovannucci, E., & Michaud, D. (2010). Coffee, tea, caffeine intake, and risk of adult glioma in three prospective cohort studies. Cancer Epidemiology Biomarkers & Prevention , 19(1), 39-47. Retrieved June 8, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/20056621

    Consumption of caffeinated beverages, including coffee and tea, may reduce the risk of adult glioma. Consumption of five or more cups of coffee/tea daily compared with no consumption was associated with a decreased risk of glioma. No association was observed between decaf coffee and glioma risk. For men, a statistically significant inverse association was observed between caffeine consumption and risk of glioma, but this was weaker for women.

  33. Irwin, C., Desbrow, B., Ellis, A., O’Keeffe, B., Grant, G., & Leveritt, M. (2011). Caffeine withdrawal and high-intensity endurance cycling performance. Journal of Sports Science, 29(5), 509-15. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/21279864

    Performance time was significantly improved after acute caffeine ingestion (3mg/kg) following a withdrawal period and following the non-withdrawal period, with no significant differences between the two. Average heart rate throughout exercise was significantly higher following acute caffeine administration compared with placebo.

  34. Iwai, K., Fukunaga, T., Nakagiri, O., Hirano, M., & Ikeguchi, M. (2010). Extract of decaffeinated green coffee beans improves postprandial hyperglycemia in rats and humans. Association for Science and Information on Coffee, N/A. Retrieved June 4, 2011, from http://www.asic-cafe.org/pdf/abstract/H408_IWAI_2010.pdf

    Meals of 200g plus one dose of extract (either 100 or 300 mg) of decaffeinated green coffee beans (EDGCB) or control. Plasma glucose after 30 min was significantly lower after EDGCB-containing beverages (300 mg) than control. Reduction of plasma glucose level was also seen in high glycemic response group. No significant differences were seen in plasma insulin profiles, indicating EDGCB operates by inhibiting amylolytic enzymes and attenuating intestinal glucose absorption. Sponsored by a coffee company.

  35. Johnson, S., Koh, W., Wang, R., Gobindarajan, S., Yu, M., & Yuan, J. (2011). Coffee consumption and reduced risk of hepatocellular carcinoma: findings from the Singapore Chinese Health Study. Cancer Causes & Control, 22(3), 503-10. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/21258859

    Compared with non-drinkers of coffee, individuals who consumed three or more cups of coffee per day experienced a 44% reduction in risk of hepatocellular carcinoma after adjustment for potential confounders and tea consumption.

  36. Jokinen, H., Pulkkinen, P., Korpelainen, J., Heikkinen, J., Keinänen-Kiukaanniemi, S., Jämsä, T., et al. (2010). Risk factors for cervical and trochanteric hip fractures in elderly women: a population-based 10-year follow-up study. Calcified Tissue International, 87(1), 44-51. Retrieved June 9, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/20526588

    Found that high coffee consumption was a significant predictor of trochanteric hip fractures.

  37. Kitaura, K., Iwai, K., Fukunaga, T., Kimura, R., & Nakagiri, O. (2010). Evaluation of the in Vitro inhibitory effects of an extract of decaffeinated green coffee beans on lipid degradation. Association for Science and Information on Coffee, N/A. Retrieved June 4, 2011, from http://www.asic-cafe.org/pdf/abstract/PH905_KITAURA_2010.pdf

    Sponsored by a coffee company. Examined the biochemical activities of extracts of decaffeinated green coffee beans (EDGCB). Compared to catechins (like those found in tea), EDGCB and polyphenolic chlorogenic acids (CGAs) had little effect on micelle particle size distribution, which are lipid molecules arranged in a spherical form that occur spontaneously in water. EDGCB and CGA-positive fractions inhibited pancreatic lipase, while the CGA-negative fractions did not. Half-maximal inhibitory concentration (IC50) values for the different quinic acids (diCQA less than CQA less than FQA) were found. The results suggest that EDGCB inhibits lipid degradation by inhibiting the CGA component of pancreatic lipase.Inhibiting lipid degradation decreases lipid absorption and reduces caloric intake, but can result in oily or loose stools. The drug Orlistat functions by inhibiting pancreatic lipase and is well-known for it’s effects on those who eat a high fat diet. It’s recommended those who take the drug “bring a change of clothes with you to work.”

  38. Kotani, K., Tsuzaki, K., Sano, Y., Maekawa, M., Fujiwara, S., Hamada, T., et al. (2008). The relationship between usual coffee consumption and serum C-reactive protein level in a Japanese female population. Critical Chemistry & Laboratory Medicine, 46(10), 1434-7. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/18844498

    Coffee consumption is significantly, independently and inversely correlated to a market of inflammation (serum C-reactive protein), indicating that coffee has anti-inflammatory effects.

  39. Lacerda, S., Matuoka, R., Macedo, R., Petenusci, S., Campos, A., & Brentegani, L. (2010). Bone quality associated with daily intake of coffee: a biochemical, radiographic and histometric study. Brazilian Dental Journal, 21(3), 199-204.

    Study investigated the effects of coffee on bone metabolism in rats. Coffee intake caused serious adverse effects on calcium metabolism in rats, including increased levels of calcium in the urine and plasma, decreased bone mineral density and lower volume of bone, thus delaying the bone repair process.

  40. Leloup, V., Derff, F. L., & Blank, I. (2010). Energy Value of Soluble Coffee for Nutrition Labeling. Association for Science and Information on Coffee, N/A. Retrieved June 4, 2010, from http://www.asic-cafe.org/pdf/abstract/PH903_LELOUP_2010.pdf
    At a dosage of 2g/100mL, a cup of soluble coffee provides 0.0 g fat, 0.2 g proteins, 0.1 g carbohydrates, and 0.4-0.7 f fibers. Energy values vary in the range of 1-4 kCal/cup.

  41. Lin, W., Pi-Sunyer, F. X., Chen, C., Davidson, L., Liu, C., Li, T., et al. (2011). Coffee consumption is inversely associated with type 2 diabetes in Chinese. European Journal of Clinical Investigation, 41(6), 659-666. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/21226707

    Habitual coffee drinkers had a 38-46% lower risk of type 2 diabetes mellitus than nondrinkers. There are decreasing adjusted odd ratios with increasing consumption, indicating a dose-response effect of coffee consumption on the likelihood of having T2DM. Adjusted mean fasting glucose levels decreased as frequency of coffee consumption increased.

  42. Loopstra-Masters, R., Liese, A., Haffner, S., Wagenknecht, L., & Hanley, A. (2011). Associations between the intake of caffeinated and decaffeinated coffee and measures of insulin sensitivity and beta cell function. Diabetologia, 54(2), 320-8. Retrieved June 1, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/21046357

    Cross-sectional study suggesting caffeinated coffee (CC) as positively related to measures of insulin sensitivity, and decaffeinated coffee (DC) as favorably related to measures of beta cell function.; both CC and DC were inversely related to 2 h postload glucose. DC was positively related to acute insulin response, while CC was not associated with acute insulin response or proinsulin ratios.May provide pathophysiological insight into how coffee impacts risk of type 2 diabetes mellitus. Insulin resistance and impaired beta cell function are known to contribute to an impaired response to a glucose load. Polyphenol content in coffee (esp. chlorogenic acid) may protect beta cells from oxidative stress, and caffeine in CC may somewhat counteract these positive effects and instead act through a different pathway.

  43. Louie, J., Atkinson, F., Petocz, P., & Brand-Miller, J. (2008). Delayed effects of coffee, tea and sucrose on postprandial glycemia in lean, young, healthy adults. Asia Pacific Journal of Clinical Nutrition, 17(4), 657-62. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/19114405

    Out of coffee, decaf, black tea, straight sucrose (10g), hot water, or coffee+sucrose (10g), only the coffee+sucrose reduced postprandial glycemia, which may explain paradoxical findings of studies relating coffee to reduced risk of diabetes.

  44. Michaud, D., Gallo, V., Schütze, M., Schlehofer, B., Tjønneland, A., Olsen, A., et al. (2010). Coffee and tea intake and risk of brain tumors in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort study. American Journal of Clinical Nutrition, 92(5), 1145-50. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/20844074

    In this large cohort study, researchers observed an inverse association between total coffee and tea consumption and risk of glioma (brain/spine tumor that arises from glial cells).

  45. Milne, E., Royle, J., Armstrong, B., Bennett, L., Klerk, N. d., Bailey, H., et al. (2011). Maternal consumption of coffee and tea during pregnancy and risk of childhood ALL: results from an Australian case-control study. Cancer Causes and Control, 22(2), 207-18. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/21113653

    Maternal coffee and/or tea consumption seems to be associated to childhood acute lymphoblastic leukemia with translocations, which is where part of the chromosome swaps with another part. This association needs further study.

  46. Moisey, L., Robinson, L., & Graham, T. (2010). Consumption of caffeinated coffee and a high carbohydrate meal affects postprandial metabolism of a subsequent oral glucose tolerance test in young, healthy males. British Journal of Nutrition, 103(6), 833-41. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/19889241

    Caffeine and caffeinated coffee (CC) elicit acute insulin insensitivity when ingested before a carbohydrate load. Co-ingestion of CC with one meal resulted in insulin insensitivity during the postprandial phase of a second meal in the absence of further CC ingestion. Thus, CC may play a role in daily glycaemic management. After the second dose, although glycemic insulin response was greater for CC, glucose area under curve (AUC) was higher, implying decreased insulin sensitivity.So, it seems that coffee/caffeine acutely decreases insulin sensitivity, but improves insulin sensitivity in the long term (http://jama.ama-assn.org/content/291/10/1199.2.full).

  47. Monteiro, M., Duarte, G., Felberg, I., & Farah, A. (2010). The bioavailability of chlorogenic acids from coffee is not affected by the simultaneous consumption of soybean extract. Association for Science and Information on Coffee, N/A. Retrieved June 5, 2010, from http://www.asic-cafe.org/pdf/abstract/PH907_MONTEIRO_2010.pdf

    Simultaneous consumption of soybean extract and coffee does not affect bioavailability of CGA in humans. However, this is just soybean extract and not soy milk or any large-volume additive. Another study showed that milk reduces bioavailability of beneficial chemicals from coffee, and it’s possible soy milk has the same affect.

  48. Monteiro, M., Marques, V., & Farah, A. (2010). Urinary excretion of chlorogenic acids and metabolites in humans after green and roasted coffees consumption. Association for Science and Information on Coffee, N/A. Retrieved June 7, 2011, from http://www.asic-cafe.org/pdf/abstract/PH906_MONTEIRO_2010.pdf

    After 10h fasting and 48h phenolic free diet. Three caffeoylquinic acids, three dicaffeoylquinic acids and thirteen metabolites were identified and quantified in urine samples. Average total urinary excretion of phenolic compounds after green (2.4±0.9 mmol) or roasted (2.3±0.6 mmol) coffee was significantly higher than after placebo (1.3±0.6 mmol). CGA from green and roasted coffees are similarly bioavailable in humans, but isomerization of some compounds may occur in the digestive tract.

  49. Olthof, M., Dijk, A. v., Deacon, C., Heine, R., & Dam, R. v. (2011). Acute effects of decaffeinated coffee and the major coffee components chlorogenic acid and trigonelline on incretin hormones. Nutrition & Metabolism, 8, 10. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/21299855

    Treated with decaffeinated coffee, chlorogenic acid, trigonelline or placebo. No treatment significantly affected overall GLP-1 or GIP secretion pattern relatively to placebo *following* OGTT. Decaffeinated coffee did slightly, but this did not correspond with changes in glucose or insulin secretion. The other study (http://www.ncbi.nlm.nih.gov/pubmed/21346110) had coffee/lipid intake *before* the OGTT, so that may be relevant. However, this study does not support the idea that the secretion of incretin hormones explain how coffee acutely improves glucose tolerance (which is contradicted in that other study). The chronic effects of coffee needs to be examined, obviously.

  50. Pryde, M., & Kannel, W. (2011). Efficacy of dietary behavior modification for preserving cardiovascular health and longevity. Cardiology Research and Practice, 2011, 820457. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/21253499

    *Review* In 1989 there was a massive prospective study that reported a trivial increased in CVD risk for persons who consume 4 cups of coffee per day, with a strong positive correlation between decaf and CHD.More recent large studies have suggested that coffee probably decreased the rate of CVD events. The Nurses’ Health Study of 85,747 women found no association between coffee consumption and CVD occurrence.A Swedish study found no association between coffee consumption and CHD.A study of 2,975 men reported the risk of a first cardiovascular event was decreased by 67% for those who drank more than 8 cups of coffee per day.NHANES prospective study found a strong protective association of coffee in elders without high blood pressure.The Framingham Study found a 43% inverse relation between caffeinated coffee use and CHD mortality for subjects without HBP, and appears to be primarily attributable to a protective relationship between caffeinated coffee use and onset of heart valve disease.Contrary to popular belief among physicians and patients, investigators found that drinking more than 4 cups of coffee daily resulted in an 18% reduction in hospitalizations for cardiac rhythm disturbances across groups, while decaffeinated coffee resulted in no protection.

  51. Rajavelu, A., Tulyasheva, Z., Jaiswal, R., Jeltsch, A., & Kuhnert, N. (2011). The inhibition of the mammalian DNA methyltransferase 3a (Dnmt3a) by dietary black tea and coffee polyphenols.. BioMedCentral Biochemistry, 12, 16.

    Dietary polyphenols, such as the ones found in coffee (chlorogenic acid), inhibit DNA methyltransferase 3a. Dnnmt3a has been associated with development, cancer and brain function, and may be a possible biochemical mechanism for the improvement of brain performance and mental health by dietary polyphenols.

  52. Sato, Y., Itagaki, S., Kurokawa, T., Ogura, J., Kobayashi, M., Hirano, T., et al. (2011). In vitro and in vivo antioxidant properties of chlorogenic acid and caffeic acid. International Journal of Pharmacy, 403(1-2), 136-8. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/20933071

    Chlorogenic acid is the ester of caffeic acid and quinic acid.In vitro, caffeic acid had a stronger antioxidant activity than chlorogenic acid, and the uptake of chlorogenic acid in Caco-2 (which resemble the cells lining the small intestine) cells was much less than that of caffeic acid.Both chlorogenic acid and caffeic acid had effects on intestinal ischemia-reperfusion injury, which is tissue damage caused when blood supply returns to tissue after ischemia, or lack of blood supply. Absence of oxygen and nutrients during ischemia creates conditions where the recirculation of blood in the area causes inflammation and oxidative stress. It is possible that caffeic acid is a major player in chlorogenic acid’s protective effects against ischemia-reperfusion injury.

  53. Savica, V., Bellinghieri, G., & Kopple, J. (2010). The effect of nutrition on blood pressure. Annual Review of Nutrition, 30, 365-401.

    Although not entirely conclusive, coffee bean extract has been shown to help reduce blood pressure, so long-term coffee consumption may protect against hypertension.

  54. Tamakoshi, A., Lin, Y., Kawado, M., Yagyu, K., Kikuchi, S., & Iso, H. (2011). Effect of coffee consumption on all-cause and total cancer mortality: findings from the JACC study. European Journal of Epidemiology, 26(4), 285-93. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/21298466

    All-cause mortality risk decreased with increasing coffee consumption in both men and women, with a risk elevation at the highest coffee consumption level compared with the second highest in women, although this likely involves error. No association was found between coffee consumption and total cancer mortality among men, with a weak inverse association among women.

  55. Tanaka, K., Miyake, Y., Sakae, N., Fukuyama, H., Hirota, Y., Nagai, M., et al. (2011). Intake of Japanese and Chinese teas reduces risk of Parkinson’s disease. Parkinsonism & Related Disorders, [Epub ahead of print]. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/21458354

    A clear inverse dose-response relationship between total caffeine intake and PD risk was observed; demonstrating that intake of coffee and caffeine reduced the risk of PD.

  56. Tornai, I. (2010). Role of environmental factors in the etiology of hepatocellular carcinoma. Orv Hetil, 151(28), 1132-6. Retrieved June 1, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/20570793

    Coffee drinking and dietary antioxidants (eg. in coffee) have protective effect against hepatocellular carcinoma (AKA malignant hepatoma), the most common type of liver cancer.

  57. Trovato, G., Pirri, C., Martines, G., Trovato, F., & Catalano, D. (2010). Coffee, nutritional status, and renal artery resistive index. Renal Failure, 32(10), 1137-47. Retrieved June 1, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/20954972

    Coffee use is inversely associated with renal resistive index (RRI), which is used to detect arterial stiffness (AS), which is associated with an increased risk of cardiovascular events. Lower serum albumin, insulin resistance, and renal insufficiency are associated with greater RRI - against which habitual coffee drinkers are risk-protected.

  58. Tsugane, S., & Inoue, M. (2010). Insulin resistance and cancer: epidemiological evidence. Cancer Science, 101(5), 1073-9. Retrieved June 1, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/20345478

    Colon, liver and pancreatic cancer are inversely associated with physical activity and coffee consumption. These cancers are associated with insulin resistance, which can be prevented by increasing physical activity, and possibly coffee consumption.

  59. Virtanen, S., Uusitalo, L., Ahonen, S., Simell, O., Ilonen, J., Veijola, R., et al. (2011). Maternal food consumption during pregnancy and risk of advanced β-cell autoimmunity in the offspring. Pediatric Diabetes, 12(2), 95-9.

    Maternal consumption of butter, low-fat margarines, berries, and coffee were inversely associated with the development of advanced β-cell autoimmunity in the offspring, adjusted for genetic risk group, familial diabetes, sociodemographic, perinatal, and dietary factors. Anutoimmune destruction of pancreatic beta cells is responsible for type 1 diabetes (http://www.ncbi.nlm.nih.gov/pubmed/16280652).

  60. Wilson, K., Kasperzyk, J., Rider, J., Kenfield, S., Dam, R. v., Stampfer, M., et al. (2011). Coffee consumption and prostate cancer risk and progression in the health professionals follow-up study. Journal of the National Cancer Institute, [Epub ahead of print]. Retrieved June 3, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/21586702

    Men who consumed six or more cups per day had a lower adjusted relative risk for overall prostate cancer compared with nondrinkers, and the association was strong for lethal/aggressive (60%) prostate cancer. Coffee consumption wasn’t associated with nonadvancedor low-grade cancers and was weakly inversely associated with high grade cancer, with similar associations for caffeinated and decaffeinated coffee. The association appears to be unrelated to caffeine content.

  61. Yamauchi, R., Kobayashi, M., Horio, F., Matsuda, Y., Ojika, M., Shigeoka, S., et al. (2010). Coffee and caffeine ameliorate hyperglycemia, fatty liver, and inflammatory adipocytokine expression in spontaneously diabetic KK-Ay mice. Journal of Agricultural and Food Chemistry, 58(9), 5597-603.

    Mice were given coffee or water for five weeks. Coffee ameliorated the development of hyperglycemia and improved insulin sensitivity, decreased levels of inflammatory cytokines, and improved fatty liver. Caffeine may be one of the effective antidiabetic compounds in coffee.

  62. Koning, L. d., Malik, V., Rimm, E., Willett, W., & Hu, F. (2011). Sugar-sweetened nutrition and artificially sweetened beverage consumption and risk of type 2 diabetes in men. American Journal of Clinical Nutrition, 93(6), 1321-7.

    The replacement of one serving of sugar-sweetened beverage with 1 cup (about 237 mL) of (presumably black) coffee was associated with a type 2 diabetes risk reduction of 17%. Sugar-sweetened beverage consumption is associated with a significantly elevated risk of type 2 diabetes, but these beverages included sodas, fruit punches, lemonades and fruit drinks, not sweetened coffee or tea.

  63. Dijk, A. v., Olthof, M., Meeuse, J., Seebus, E., Heine, R., & Dam, R. v. (2009). Acute effects of decaffeinated coffee and the major coffee components chlorogenic acid and trigonelline on glucose tolerance. Diabetes Care, 32(6), 1023-5. Retrieved June 7, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/19324944

    Chlorogenic and trigonelline - two major components of coffee - significantly reduced early glucose and insulin concentrations following an oral glucose tolerance test when compared with placebo.

  64. Tsubouchi, H, K Shimoya, S Hayashi, M Toda, K Morimoto, and Y Murata. “Effect of coffee intake on blood flow and maternal stress during the third trimester of pregnancy.” International Journal of Gynaecology & Obstetrics 92.1 (2006): 19-22. PubMed. Web. 10 June 2011.

    The reduced salivary cortisol levels suggest that coffee intake decreases maternal stress during pregnancy.

  65. Leitzmann, M, W Willett, E Rimm, M Stampfer, D Spiegelman, G Colditz, and E Giovannucci. “A prospective study of coffee consumption and the risk of symptomatic gallstone disease in men..” Journal of the American Medical Association 281.22 (1999): 2106-2112. JAMA. Web. 10 June 2011.

    Coffee consumption may help prevent symptomatic gallstone disease (study on men), showing benefits for all coffee brewing methods and greater risk reduction for increasing coffee intake. Decaffeinated coffee wasn’t associated with a decreased risk.

  66. Leitzmann, MF, MJ Stampfer, WC Willett, D Spiegelman, GA Colditz, and EL Giovannucci. “Coffee intake is associated with lower risk of symptomatic gallstone disease in women.” Gastroenterology 123.6 (2002): 1823-30. PubMed. Web. 10 June 2011.

    Coffee consumption may help prevent symptomatic gallstone disease (study on women), showing benefits for all coffee brewing methods and greater risk reduction for increasing coffee intake. Decaffeinated coffee wasn’t associated with a decreased risk.

  67. Shaffer, EA. “Gallstone disease: Epidemiology of gallbladder stone disease.” Best Practice & Research Clinical Gastroenterology 20.6 (2006): 981-96. PubMed. Web. 10 June 2011.

    Coffee is a protective factor against the risk of gallbladder stone disease.

  68. Zhang, Z., Hu, G., Caballero, B., Appel, L., & Chen, L. (2011). Habitual coffee consumption and risk of hypertension: a systematic review and meta-analysis of prospective observational studies. American Journal of Clinical Nutrition, 93(6), 1212-9. Retrieved June 11, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/21450934

    Habitual coffee consumption of more than 3 cups per day was not associated with an increased risk of hypertension compared to the group consuming less than 1 cup per day. There was a slightly elevated risk in the group consuming a moderate amount of coffee, or 1 to 3 cups per day.

  69. Myers, M. (1991). Caffeine and cardiac arrhythmias. Annals of Internal Medicine,114(2), 147-50. Retrieved June 11, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/1984393

    In five placebo-controlled trials, caffeine in doses equivalent to 5 or 6 cups of coffee did not increase frequency or severity of ventricular arrhythmias in normal persons, patients with ischemic heart disease, or those with pre-existing serious ventricular ectopy.

  70. Lane, J., Pieper, C., Phillips-Bute, B., Bryant, J., & Kuhn, C. (2002). Caffeine affects cardiovascular and neuroendocrine activation at work and home. Psychosomatic Medicine, 64, 595-603. Retrieved June 11, 2011, from http://www.psychosomaticmedicine.org/content/64/4/595.full.pdf

    Caffeine administration of 500 mg (5 or 6 cups of coffee) - half at breakfast, half at lunchtime - resulted in an increase in blood pressure of 2.7% to 3.6% for a “normal” (112/64 mm Hg) subject, and reduced average heart rate by 2 bpm, or 3.3% for a “normal” of 60 bpm. The doses of caffeine amplified blood pressures and epinephrine levels were statistically significantly higher until bedtime. The elimination half-life of caffeine is 3 to 5 hours in healthy adults. These results don’t seem to be significant for healthy adults, but should be taken into consideration by hypertensive patients who want to avoid pressing, nerdy pun intended, their luck.

  71. Antonio, A., Iorio, N., Pierro, V., Candreva, M., Farah, A., Santos, K. D., et al. (2011). Inhibitory properties of Coffea canephora extract against oral bacteria and its effect on demineralisation of deciduous teeth. Archives of Oral Biology, 56(6), 556-64. Retrieved June 11, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/21185010

    Coffea canephora extract was tested in vitro against two strains of cariogenic bacteria, Streptococcus mutans and S. sobrinus. The researchers found “minimum inhibitory concentration” (MIC), which is the lowest concentration of antimicrobial that will inhibit the visible growth of a microorganism after overnight incubation, and “minimum bactericidal concentration” (MBC), which is the lowest concentration of antibiotic required to kill the germ, in order to determine the antibiotic activity of the extract. The extract was active and effective against S. mutans but showed no activity against S. sobrinus, while maintaining the same pH as controls but increasing enamel hardness. The researchers concluded that C. canephora extract is beneficial as an anticariogenic substance.

  72. Léger, D., Roscoat, E., Bayon, V., Guignard, R., Pâquereau, J., & Beck, F. (2011). Short sleep in young adults: Insomnia or sleep debt? Prevalence and clinical description of short sleep in a representative sample of 1004 young adults from France. . Sleep Medicine, 12(5), 454-62. Retrieved June 11, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/21474376

    Drinking coffee after 5 p.m. was significantly associated with short sleep in adults aged 25-45 years old.

  73. Yen, C., Ko, C., Yen, J., & Cheng, C. (2008). The multidimensional correlates associated with short nocturnal sleep duration and subjective insomnia among Taiwanese adolescents. Sleep, 31(11), 1515-25. Retrieved June 11, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/19014071

    Drinking coffee at night was significantly associated with short nocturnal sleep duration in adolescence.

  74. Philip, P., Taillard, J., Moore, N., Delord, S., Valtat, C., Sagaspe, P., et al. (2006). The effects of coffee and napping on nighttime highway driving: a randomized trial. . Annals of Internal Medicine, 144(11), 785-91. Retrieved June 11, 2011, from http://www.ncbi.nlm.nih.gov/pubmed/16754920

    Nighttime driving performance was similar to daytime performance for 75% of participants after one cup of coffee, 66% after an hour and a half nap, and only 13% for placebo. Drinking coffee statistically significantly reduces driving impairment without altering subsequent sleep.

21. Acknowledgements

  • Kevin G. for bringing up important points on the acute effects of coffee on blood pressure and insomnia.
  • Redditor zenon for pointing out another causal interpretation of a study regarding coffee and atrial fibrillation.
  • Redditor katertot for listening to me ramble on about coffee for a week.
  • Redditor mountaindrew_ for giving me additional meta-analyses for the article.
  • Fitocracy user betaPhase for pointing out the distinction between bone density and bone quality.

Top
Images from Flickr - click images to find original artist

Copyright © 2011 Ryan Town. All rights reserved.
Work may be used freely if credit is given.

  1. teeth-bleaching-kit reblogged this from primalmd
  2. lewesde reblogged this from primalmd
  3. pamo reblogged this from primalmd
  4. primaltoad reblogged this from primalmd
  5. shotzombies reblogged this from primalmd and added:
    Pretty comprehensive overview of the health risks/rewards of coffee.
  6. toniferous reblogged this from primalmd and added:
    internetboner
  7. thesamjam reblogged this from primalmd
  8. johnnythehack reblogged this from primalmd
  9. primalmd posted this