Previously, such as here, here and here, I have written about the potential health benefits of coffee, and specifically its relationship with a reduced risk of cardiovascular disease and diabetes. I was therefore interested to read a recently published study that, once again, assessed the relationship between coffee and health. The focus of this study was the relationship between coffee, as well as tea and green tea, on risk of diabetes . The population being studied was made up of almost 37,000 Singaporean Chinese men and women, who were followed for a period of almost 6 years on average.
After adjusting for ‘confounding factors’ such as age, body mass index, and physical activity, there was no significant relationship between tea (including green tea) drinking and diabetes, but there was for coffee. In individuals drinking’s four or more cups of coffee per day, risk of diabetes was reduced by 30 per cent.
The authors of this paper cite other evidence from epidemiological studies which have found coffee consumption to be associated with a reduced risk of diabetes, including a meta-analysis  that found that at the highest levels of coffee consumption (6/7 or more cups of coffee per day), risk of diabetes was reduced by 35 per cent.
The authors of this most recent study also speculate regarding the explanation for the relationship between coffee drinking and diabetes. They suggest that individuals drinking more coffee are less sensitive to caffeine (a substance which has been found to reduce insulin sensitivity and would be expected to increase diabetes risk). However, the authors note that in the meta-analysis mentioned above , decaffeinated coffee was associated with a reduced risk of diabetes, and this association was even stronger than for caffeinated coffee. This evidence suggests that it might be something about the coffee itself which provides some protection against diabetes.
If it is something in the coffee, then what is it? Well, there’s no shortage of candidates here. For example, coffee is rich in magnesium, a nutrient that in studies has been linked with protection from diabetes. Also, coffee is rich in substances that have high antioxidant activity. This may help to protect the cells in the pancreas from that make insulin from damage from free radicals, helping to preserve insulin levels in the body. Their antioxidant action may also help insulin do its job in the tissues.
This study adds to the already sizeable body of evidence, which suggests that far from being something to be avoided, coffee may have some positive benefits for health. And as a lifelong coffee drinker myself, I’ll drink to that.
1. Odegaard AO, et al. Coffee, tea, and incident type 2 diabetes: the Singapore Chinese Health Study. Am J Clin Nutr. 2008;88(4):979-85.
2. van Dam RM, et al. Coffee consumption and risk of type 2 diabetes: a systematic review. JAMA. 2005 Jul 6;294(1):97-104.