Drinking three to four cups of delicious coffee each day may help prevent type 2 diabetes, according to research published by the Institute for Scientific Information on Coffee (ISIC). Really, that is an actual organization dedicated to promoting the health benefits of coffee. Some skepticism might ordinarily be warranted but since this is about coffee, it is okay to just accept the science.
New evidence linking moderate coffee consumption with a possible reduced risk of developing type 2 diabetes was presented during a session at the 2012 World Congress on Prevention of Diabetes and Its Complications (WCPD) and is also included in the report, which outlines the epidemiological evidence linking coffee consumption to diabetes prevention, compared to consuming none or less than two cups per day (1). Another study also found an inverse dose dependent response effect with each additional cup of coffee reducing the relative risk by 7-8 percent (2).
Whilst these epidemiological studies suggest an association between moderate coffee consumption and reduced risk of developing diabetes, they are unable to infer a causal effect. As such, clinical intervention trails are required to study the effect in a controlled setting. One prospective randomized controlled trial (3), tested glucose and insulin after an oral glucose tolerance test with 12g decaffeinated coffee, 1g chlorogenic acid, 500 mg trigonelline, or placebo. This study demonstrated that chlorogenic acid, and trigonelline reduced early glucose and insulin responses, and contribute to the putative beneficial effect of coffee.
The report notes that the association between coffee consumption a reduced risk of type 2 diabetes could be seen as counter intuitive, as drinking coffee is often linked to unhealthier habits, such as smoking and low levels of physical activity.
Furthermore, studies have illustrated that moderate coffee consumption is not associated with an increased risk of hypertension, stroke or coronary heart disease (4 ,5, 6). Research with patients with CVD has also shown that moderate coffee consumption is inversely associated with risk of heart failure, with a J-shaped relationship (7).
Finally, the report puts forward some of the key mechanistic theories that underlie the possible relationship between coffee consumption and the reduced risk of diabetes. These included the 'Energy Expenditure Hypothesis', which suggests that the caffeine in coffee stimulates metabolism and increases energy expenditure and the 'Carbohydrate Metabolic Hypothesis', whereby it is thought that coffee components play a key role by influencing the glucose balance within the body. There is also a subset of theories that suggest coffee contains components that may improve insulin sensitivity though mechanisms such as modulating inflammatory pathways, mediating the oxidative stress of cells, hormonal effects or by reducing iron stores.
Dr. Pilar Riobó Serván, Associate Chief of Endocrinology and Nutrition, Jiménez Díaz-Capio Hospital of Madrid and a speaker at the WCPD session concludes the report, commenting: "A dose-dependent inverse association between coffee drinking and total mortality has been demonstrated in general population and it persists among diabetics. Although more research on the effect of coffee in health is yet needed, current information suggests that coffee is not as bad as previously considered!"
1 van Dam RM et al. (2002) Coffee consumption and risk of type 2 diabetes mellitus. Lancet . 360:1477-8
2 Huxley R et al. (2009) Coffee, Decaffeinated Coffee, and Tea Consumption in Relation to Incident Type 2 Diabetes Mellitus. Arch Intern Med 169:2053-63
3 Olthof MR et al. (2011) Acute effects of decaffeinated coffee and the major coffee components chlorogenic acid and trigonelline on incretin hormones. Nutrition&Metabolism. 8:10
4 Lopez E et al (2011) Coffee consumption and mortality in women with cardiovascular disease. Am J Clin Nutr. 94(1): 218–224.
5 Zhang WH et al. (2009) Coffee consumption and risk of cardiovascular events and all-cause mortality among women with type 2 diabetes. Diabetologia. 52(5):810-817
6 Ahmed H et al. (2009) Coffee Consumption and Risk of Heart Failure in Men: an Analysis from the Cohort of Swedish Men Am Heart J. 158(4):667–672
7 Mostofsky E. (2012) Habitual coffee consumption and risk of heart failure: a dose-response meta-analysis. Circ Heart Fail. 5(4): 401-5