Coffee may help keep diabetes at bay

Leslie Beck

Published on Friday, Mar. 26, 2010, Globe and Mail

To defend against Type 2 diabetes, you may consider drinking more coffee, especially at lunch. And it doesn’t seem to matter if it’s regular, decaf or sweetened with sugar.

According to a study to be published in the April issue of the American Journal of Clinical Nutrition, women who drank at least three cups of coffee a day – compared with those who drank none – lowered their risk of developing Type 2 diabetes by 23 per cent.

This isn’t the first time coffee-loving Canadians have received good news. Findings from previous research have suggested that, if you drink enough coffee, you’ll lower the risk of developing heart disease, asthma, gallstones, Parkinson’s disease, liver cancer and possibly colon cancer.

But the most promising evidence for coffee’s health benefits come from studies on diabetes. So far, more than 17 large studies have linked coffee drinking with protection from Type 2 diabetes.

What’s new about the current study is the notion that when you drink coffee may be more important than how much of it you drink all day.

Type 2 diabetes occurs when the body’s pancreas does not secrete enough insulin, the hormone that removes sugar (glucose) from the bloodstream, or when cells don’t use insulin properly, or both.

In the study, researchers studied 69,532 French women, aged 41 to 72, to investigate the long-term effect of drinking coffee, tea and chicory (a caffeine-free coffee substitute) on Type 2 diabetes risk. They also examined whether coffee consumed at various times of day, and whether adding milk or sugar, made a difference.

After 11 years of follow-up, 1,415 women developed Type 2 diabetes. Women who drank at least three cups (375 ml) of coffee a day were 23 per cent less likely to be diagnosed with diabetes than women who did not drink coffee. Tea and chicory consumption did not alter diabetes risk.

Drinking coffee at lunch, but not breakfast or dinner, was linked with protection from diabetes. Women who drank more than 1.1 cups (more than 125 ml) had a 34 per cent lower risk of type 2 diabetes than non-coffee drinkers. Both caffeinated and decaffeinated coffee at lunch significantly reduced diabetes risk.

Filtered coffee, but not instant, defended against Type 2 diabetes whether it was sweetened with sugar or not. Black coffee, but not coffee with milk, was also associated with protection from the disease. (Milk is thought to inactivate some of coffee’s protective compounds.) Note that “one cup” of coffee in this study, defined as 125 ml (1/2 cup), is a considerably smaller serving than what’s poured in coffee shops. A Starbuck’s grande, for instance, serves up 16 ounces or 473 ml.

Researchers suspect that some of coffee’s benefits are linked to an antioxidant called chlorogenic acid. This natural compound has been shown to dampen inflammation in the body, reduce glucose (sugar) absorption and improve how the body uses insulin. Coffee also contains magnesium, a mineral linked to blood sugar regulation.

Interestingly, another study to be published in the same journal next month revealed that coffee consumption significantly reduced blood levels of interleukin-18, an inflammatory compound linked with a greater risk of diabetes and heart disease. Drinking coffee also had favourable effects on antioxidant capacity and it increased blood levels of adiponectin, a hormone produced by fat cells that promotes insulin sensitivity. (Lower levels of adiponectin are linked with Type 2 diabetes.)

What’s original about the French study is the finding that coffee’s beneficial effects may be influenced by your meal. The data suggest that only having coffee at lunch was enough to lower diabetes risk. In this study, lunch was the largest meal of the day, accounting for more calories and more carbohydrate intake than breakfast or dinner. The protective effect of coffee at a larger meal could be due to the ability of chlorogenic acid to reduce how much glucose is absorbed into the bloodstream.

While drinking coffee may help lower the odds of diabetes, you’d be foolhardy to rely on this strategy alone. ...