Coffee and doughnuts: double-trouble for diabetes risk

Mysterious protective effects of coffee against diabetes have been reported in the past.  A 2010 meta-analysis analyzing data from 18 studies reported that each additional cup of coffee consumed per day was associated with a 7% reduction in risk of diabetes.1  This was surprising, especially because coffee consumption has been shown to raise glucose levels after a meal so you would expect it to worsen diabetes, not help it.  However, this is true of both decaffeinated and regular coffee, although regular coffee raises blood glucose more than decaf.2 

The reason for the decreased diabetes risk remains uncertain, but since coffee comes from a darkly colored bean, it is likely that antioxidants, minerals, or other phytochemicals present in coffee may be responsible for the long term benefits seen in the observational studies.3 With this in mind, we must also remember that almost all of the subjects in the observational studies were eating the standard American diet and therefore starving for antioxidants and phytochemicals. 

Is the standard American diet so nutrient-poor that a significant portion of people’s phytochemical intake comes from their morning coffee? 

It’s likely. Additional studies support this possibility. One observational study of 28,000 postmenopausal women actually found that decaffeinated coffee was more protective than regular coffee – which suggests that the caffeine in coffee might be increasing risk, while the phytochemicals decrease risk.4 Chlorogenic acid and trigonelline, two of the major phytochemicals in coffee, have been shown to decrease blood glucose and insulin concentrations in the blood compared to placebo after ingesting sugar, so these phytochemicals likely increase insulin sensitivity.5  It is doubtful that coffee would offer any additional protection on top of a nutrient dense diet - the responsible phytochemicals can be obtained from other plant foods and the diet would not be so lacking in antioxidants.  For example, blueberries contain the antioxidant chlorogenic acid, and the phytoestrogen trigonelline is also found in peas, lentils, soybeans, and sunflower seeds. 6-8  The only reason coffee is beneficial is because of the severe deficiencies in the plant-derived phytochemicals in the diet of most Americans, and coffee at least supplies something.  

Research has found something that makes the insulin desensitizing effects of caffeine even worse - ingesting caffeine with a high-fat meal.

High-fat meals are another factor known to impair glucose tolerance, and saturated fat consumption causes the body to produce inflammatory molecules that contribute to insulin resistance.9  This study demonstrated caffeine consumption and a high-fat meal had additive insulin desensitizing effects, and this did  not merely raise the blood glucose - but also when the insulin doesn’t work well the body has to make more of it, and higher insulin causes weight gain and increases cancer risk.10-12 When subjects ingested a high-fat meal followed by a sugary drink, and blood glucose levels were 32% higher compared to subjects who had water in place of the high-fat meal.  In the second part of the study, subjects were given two cups of caffeinated coffee in addition to the high-fat meal and sugary beverage – this time, blood glucose was even higher – 65% higher than the subjects who had only water before the sugary drink.13  Apparently, coffee can have good or bad effects on insulin depending on whether it is consumed with high fat animal products or not.

The message here is that coffee can be both good and bad, but its powerful addictive qualities, with the potential for withdrawal headaches and to increase blood pressure should make people cautious;14-16 the most likely risks are almost never mentioned in news reports.  I do not think anyone should rely on coffee to protect themselves against diabetes.  If you do choose to drink coffee, stick to water-processed (non-chemical) decaf, and of course skip the doughnuts!



1. Huxley R, Lee CM, Barzi F, et al: Coffee, decaffeinated coffee, and tea consumption in relation to incident type 2 diabetes mellitus: a systematic review with meta-analysis. Arch Intern Med 2009;169:2053-2063.

2. Greenberg JA, Owen DR, Geliebter A: Decaffeinated coffee and glucose metabolism in young men. Diabetes Care 2010;33:278-280.

3. Tunnicliffe JM, Shearer J: Coffee, glucose homeostasis, and insulin resistance: physiological mechanisms and mediators. Appl Physiol Nutr Metab 2008;33:1290-1300.

4. Pereira MA, Parker ED, Folsom AR: Coffee consumption and risk of type 2 diabetes mellitus: an 11-year prospective study of 28 812 postmenopausal women. Arch Intern Med 2006;166:1311-1316.

5. van Dijk AE, Olthof MR, Meeuse JC, et al: Acute effects of decaffeinated coffee and the major coffee components chlorogenic acid and trigonelline on glucose tolerance. Diabetes Care 2009;32:1023-1025.

6. Zheng W, Wang SY: Oxygen radical absorbing capacity of phenolics in blueberries, cranberries, chokeberries, and lingonberries. Journal of Agricultural and Food Chemis ry 2003;51:502-509.

7. Rozan P, Kuo YH, Lambein F: Nonprotein amino acids in edible lentil and garden pea seedlings. Amino Acids 2001;20:319-324.

8. Sanchez-Hernandez L, Puchalska P, Garcia-Ruiz C, et al: Determination of trigonelline in seeds and vegetable oils by capillary electrophoresis as a novel marker for the detection of adulterations in olive oils. Journal of Agricultural and Food Chemis ry 2010;58:7489-7496.

9. Wen H, Gris D, Lei Y, et al: Fatty acid-induced NLRP3-ASC inflammasome activation interferes with insulin signaling. Nat Immunol 2011.

10. Bowker SL, Majumdar SR, Veugelers P, et al: Increased cancer-related mortality for patients with type 2 diabetes who use sulfonylureas or insulin. Diabetes Care 2006;29:254-258.

11. Davies M, Gupta S, Goldspink G, et al: The insulin-like growth factor system and colorectal cancer: clinical and experimental evidence. Int J Colorectal Dis 2006;21:201-208.

12. Harish K, Dharmalingam M, Himanshu M: Study Protocol: insulin and its role in cancer. BMC endocrine disorders 2007;7:10.

13. Beaudoin MS, Robinson LE, Graham TE: An oral lipid challenge and acute intake of caffeinated coffee additively decrease glucose tolerance in healthy men. J Nutr 2011;141:574-581.

14. Giggey PP, Wendell CR, Zonderman AB, et al: Greater Coffee Intake in Men Is Associated With Steeper Age-Related Increases in Blood Pressure. Am J Hypertens 2010.

15. Noordzij M, Uiterwaal CS, Arends LR, et al: Blood pressure response to chronic intake of coffee and caffeine: a meta-analysis of randomized controlled trials. J Hypertens 2005;23:921-928.

16. James JE: Critical review of dietary caffeine and blood pressure: a relationship that should be taken more seriously. Psychosom Med 2004;66:63-71.


Eat fiber-rich foods now, not later!

There are a few different classifications of fiber, and their common characteristic is resistance to digestion in the human small intestine.   Eating fiber-rich foods is associated with a number of health benefits:

  • Fiber promotes weight maintenance by slowing gastric emptying; and adding volume to food, promoting satiety
  • Fiber helps to prevent diabetes by slowing entrance of glucose into the bloodstream, curbing glucose (and insulin) spikes after meals
  • Soluble fiber (a type of fiber abundant in oats and beans) has cholesterol-lowering effects.
  • Cardiovascular health – a pooled analysis of 10 prospective studies found that an increase of 10 grams of dietary fiber per day was associated with a 24% decrease in deaths from coronary heart disease.1
  • Digestive health – fiber adds bulk and acts as a stool softener, making bowel movements faster and easier, and preventing constipation and diverticular disease.
  • Fermentation of fiber and resistant starch by bacteria in the large intestine helps to prevent colorectal cancers 2

Fiber vs. fiber-rich foods: Fiber can be isolated and taken as a supplement or added to a processed food, but these are not the recommended ways to get your fiber.  Although fiber itself has beneficial properties, fiber-rich whole foods come packaged with disease-fighting phytochemicals.  There have been inconsistencies in the results of studies on fiber and colorectal cancer, probably because it appears to be high-fiber foods, not fiber alone that reduces risk. 3-8

The American Heart Association recommends consuming 25 grams of fiber each day –a nutritarian diet far exceeds that recommendation, providing about 60-80 grams of fiber each day, since the vast majority of my recommended food pyramid is made up of fiber-rich foods like vegetables, fruits, seeds and beans.  

A study relating dietary fiber intake to lifetime risk of cardiovascular disease was once presented at the American Heart Association’s Nutrition, Physical Activity, and Metabolism conference. Data from the 2003-2008 U.S. National Health and Nutrition Examination Surveys were analyzed. The researchers used a mathematical algorithm to predict lifetime risk for cardiovascular disease, based on diet, blood pressure, cholesterol, smoking, and history of diabetes.  All of the participants were free of cardiovascular disease at the start.  

The algorithm placed participants in groups of either high or low lifetime risk of cardiovascular disease.  Then they were arranged into four groups according to the ratio of their intake of dietary fiber to calories - dietary fiber only, no fiber supplements were included.  The lowest fiber intake was 0.1g/1000 calories, and the highest was on par with a nutritarian diet, 49.1g/1000 calories.

Individuals aged 20-39 in the highest quartile of fiber intake were almost twice as likely to be in the low risk category than those in the lowest quartile. Middle aged individuals in the highest quartile were about 50% more likely to be in the low risk category. Interestingly though, a similar association was not seen in 60-79 year olds.  The researchers theorized that many older adults with high fiber intake may have already developed significant risk for heart disease before they added more high-fiber foods to their diet.   They concluded that starting to increase fiber intake at a younger age helps to decrease the risk of cardiovascular disease later in life.9,10

It is important to eat healthfully your entire life to get maximum benefits, however once you have not eaten properly for the first 60 years, then to get the disease-protective benefits to dramatically reduce heart attack, stroke and cancer risk from a plant-based diet (vegan or flexitarian) later in life, it is not good enough to just be good, you have to be great.  In other words, a nutritarian diet with attention to the most nutritionally powerful and protective plant foods is necessary, not just the dietary mediocrity practiced by most vegans and vegetarians.

Eating to Live is a lifetime commitment – just like it takes years for heart disease to develop, it takes years to build up protection against heart disease.  No matter what your age, you can benefit from improving your diet – but the point is, the time to start is right now and the place to start is with a nutritarian diet that pays attention to the disease-fighting nutrients in foods. Once you are past middle age, the way to start is not with some wishy-washy low fat, high fiber diet.  That is not good enough, you have to do better than that and pay attention to the micronutrient-richness of your meals and achieve comprehensive nutritional adequacy, which is the core of my message.  



1. Pereira MA, O'Reilly E, Augustsson K, et al: Dietary fiber and risk of coronary heart disease: a pooled analysis of cohort studies. Arch Intern Med 2004, 164:370-376.

2. O'Keefe SJ, Ou J, Aufreiter S, et al: Products of the colonic microbiota mediate the effects of diet on colon cancer risk. J Nutr 2009, 139:2044-2048.

3. Singh PN, Fraser GE: Dietary risk factors for colon cancer in a low-risk population. Am J Epidemiol 1998, 148:761-774.

4. Uchida K, Kono S, Yin G, et al: Dietary fiber, source foods and colorectal cancer risk: the Fukuoka Colorectal Cancer Study. Scand J Gastroenterol 2010, 45:1223-1231.

5. Park Y, Hunter DJ, Spiegelman D, et al: Dietary fiber intake and risk of colorectal cancer: a pooled analysis of prospective cohort studies. JAMA : the journal of the American Medical Association 2005, 294:2849-2857.

6. Michels KB, Fuchs CS, Giovannucci E, et al: Fiber intake and incidence of colorectal cancer among 76,947 women and 47,279 men. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology 2005, 14:842-849.

7. Terry P, Giovannucci E, Michels KB, et al: Fruit, vegetables, dietary fiber, and risk of colorectal cancer. J Natl Cancer Inst 2001, 93:525-533.

8. Wakai K, Date C, Fukui M, et al: Dietary fiber and risk of colorectal cancer in the Japan collaborative cohort study. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology 2007, 16:668-675.

9. Northwestern University (2011, March 23). Load up on fiber now, avoid heart disease later. . In ScienceDaily; 2011.

10. Ning H, Van Horn L, Shay CM, et al: Dietary Fiber Intake and Long Term Cardiovascular Risk: Findings from the National Health and Nutrition Examination Surveys (NHANES) 2003-2008. In American Heart Association: Nutrition, Physical Activity, and Metabolism 2011.