For most of us, life without coffee would be…rough. But does coffee have any benefit other than getting our eyes open in the morning? Surprisingly, several epidemiological studies over the past three years found a lower risk for type 2 diabetes in people who drank higher amounts of coffee. (Journal of the American Medical Association, July 6, 2005).
Specifically, data pooled from several studies found that people who drank 4 to 6 cups of coffee per day had a 28% lower risk of diabetes when compared with people who drank less than two cups a day. Those who drank more than 6 cups of coffee a day had a 35% lower risk. Moreover, the association held true for men and women, obese and normal weight persons. Confounding factors such as smoking history, physical activity and alcohol consumption were not related to the results in several studies.
How can this be? Caffeine alone can increase blood sugar levels and worsen insulin sensitivity—risk factors for type 2 diabetes. Coffee contains more than caffeine, however. Other substances in coffee may be the grounds for its positive effect:
Chlorogenic acid: an antioxidant substance shown to reduce blood glucose levels in animal studies.
Quinides: by-products of chlorogenic acid that improve insulin sensitivity in animal studies.
Magnesium: a nutrient that helps the body use carbohydrates for energy. Magnesium deficiency has been linked to insulin resistance and increased risk for type 2 diabetes in children and adults. (Diabetes Care, Volume 28, Number 5, May 2005.)
Still, we still have more questions than answers:
What’s “a cup”? A standard cup of coffee in the United States is 8 ounces, double the size of a typical serving in Europe (which is generally twice as strong).
Regular or decaf? Although most studies looked at the intake of caffeinated coffee, two studies on decaffeinated coffee found the same association between higher intakes and lower risk of type 2 diabetes.
Filtered or boiled? Drip-filtered coffee (versus boiled) appears to be most beneficial on LDL cholesterol levels and risk for type 2 diabetes.
Cream or sugar? Cream or milk added to coffee or tea was not associated with the risk for type 2 diabetes. One study did find an association between sugar in coffee and lower insulin sensitivity—a risk factor for type 2 diabetes.
A word of caution: Studies that look at “associations” do not prove cause and effect. People in prison, for example, tend to have more tattoos. That does not mean everyone with a tattoo will end up in prison. Until human intervention studies give us more information, don’t rely too strongly on your Starbuck’s to lower your risk for type 2 diabetes.