A new study by the Havard School of Public Health, published in the journal of Diabetologia, revealed that increasing coffee consumption over a four year period reduces the risk of diabetes by 11%, by drinking one and a half cups of coffee and by 37% if three or more cups are consumed.The population studied included people from the Nurses’ Health Study (NHS) (female nurses aged 30-55 years, 1986-2006), the NHS II (younger female nurses aged 25-42 years 1991-2007), and the Health Professionals Follow-up Study (HPFS) (male professionals 40-75 years, 1986-2006). The final analysis included 48,464 women in NHS, 47,510 women in the NHS II, and 27,759 men in HPFS. The researchers collected detailed information on diet, lifestyle and health conditions every 2-4 years for over 20 years, allowing them to evaluate 4 year changes in coffee and tea intake relative to type 2 diabetes.
They also examined whether the risk of diabetes differed between caffeinated and decaffeinated coffee. Diet was assessed every 4 years using a validated food frequency questionnaire. Self-reported incident type 2 diabetes cases were validated by supplementary questionnaires.
The authors documented 7,269 incident type 2 diabetes cases, and found that participants who increased their coffee consumption by more than 1 cup/day (median change=1.69 cups/day) over a 4-year period had a 11% lower risk of type 2 diabetes in the subsequent 4-years compared to those who made no changes in consumption. Participants who decreased their coffee intake by 1 cup a day or more (median change=-2 cups/day) had a 17% higher risk for type 2 diabetes. Changes in tea consumption were not associated with type 2 diabetes risk. People who drank three or more cups per day had the lowest risk of type 2 diabetes at 37%.
The study states: “In these 3 large prospective cohorts with more than 1.6 million person-years of follow-up, we observed that increasing coffee, but not tea, intake over a 4-year period was associated with a lower type 2 diabetes risk in the next 4 years. Decreasing coffee intake was associated with a higher type 2 diabetes risk. These changes in risk were observed for caffeinated, but not decaffeinated coffee, and were independent of initial coffee consumption and 4-year changes in other dietary and lifestyle factors.”
“Changes in coffee consumption habits appear to affect diabetes risk in a relatively short amount of time. Our findings confirm those of prospective studies that higher coffee consumption is associated with a lower type 2 diabetes risk and provide novel evidence that changes in coffee consumption habits are related to diabetes risk.”
Shilpa Bhupathiraju et al. Changes in coffee intake and subsequent risk of type 2 diabetes: three large cohorts of US men and women. Diabetologia, April 2014 DOI: 10.1007/s00125-014-3235-7