There is nothing happier than a coffee drinker with his first cup in the morning. But coffee has a historic reputation of being blamed for many ills, from stunting growth to causing heart disease and cancer. 

Over the last 20 years, medical research debunked any connection between coffee and an increased risk of cancer or heart disease. Most studies found coffee consumption was associated with increased life expectancy. New research from Harvard University Department of Nutrition published in Diabetologia, Journal of the European Association for the Study of Diabetes, reveals coffee may be curative. Increasing coffee consumption by one and half cups per day, 12 fluid ounces, over a four year period actually reduces the risk of type 2 diabetes by 11%.

Dr. Frank Hu and Dr. Shilpa Bhupathiraju of the Department of Nutrition at Harvard University examined the associations between four-year changes in coffee and tea consumption and risk of type 2 diabetes in the subsequent four years. The researchers used observational data from three large prospective, US-based studies in their analysis: the Nurses’ Health Study (NHS) that followed female nurses aged 30-55 years between 1986-2006, the NHS II that followed younger female nurses aged 25-42 years between 1991-2007, and the Health Professionals Follow-up Study that followed male healthcare professionals 40-75 years between 1986-2006. Each of these studies detailed information on diet, lifestyle, medical conditions, and other chronic diseases was collected every two to four years for over twenty years.

The availability of these repeated measures and the long duration of followup allowed the authors to evaluate four-year changes in coffee and tea intake in relation to risk of type 2 diabetes in each of the following four year segments. Researchers examined whether the association with diabetes incidence differed between changes in caffeinated and decaffeinated coffee. Diet was assessed every four years using a food frequency questionnaire. Self-reported incident type 2 diabetes cases were validated by supplementary questionnaires. The final analysis included over 95,000 women and almost 28,000 men.

The authors documented 7,269 incident type 2 diabetes cases. They found that participants who increased their coffee consumption by more than one cup/day, median change = 1.69 cups/day, over a four-year period, had a 11% lower risk of type 2 diabetes in the subsequent four years compared to those who made no changes in consumption. Participants who decreased their coffee intake by one cup a day or more, median change = -2 cups/day, had a 17% higher risk for type 2 diabetes.

Those with highest coffee consumption and who maintained that consumption — referred to as “high-stable consumers” since they consumed three cups or more per day — had the lowest risk of type 2 diabetes, 37% lower than the “low-stable consumers” who consumed one cup or less per day.

While baseline decaffeinated coffee consumption was associated with a lower type 2 diabetes risk, the changes in decaffeinated coffee consumption did not change this risk.

The researchers determined: “In these three large prospective cohorts with more than 1.6 million person-years of followup, we observed that increasing coffee, but not tea, intake over a four-year period was associated with a lower type 2 diabetes risk in the next four 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 four-year changes in other dietary and lifestyle factors.”

They add: “Changes in coffee consumption habits appear to affect diabetes risk in a relatively short amount of time. Our findings confirm that higher coffee consumption is associated with a lower type 2 diabetes risks and provides novel evidence that changes in coffee consumption habits are related to diabetes risk.”

So the next time you want to hold that personal fireplace in your hand and smell the aroma of a good cup of Joe, get a bigger cup to increase your happiness and health!

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