Type 2 Diabetes continued...
More recently, Australian researchers looked at 18 studies of nearly 458,000 people. They found a 7% drop in the odds of having type 2 diabetes for every additional cup of coffee drunk daily. There were similar risk reductions for decaf coffee drinkers and tea drinkers. But the researchers cautioned that data from some of the smaller studies they reviewed may be less reliable. So it's possible that they overestimated the strength of the link between heavy coffee drinking and diabetes.
How might coffee keep diabetes at bay?
“It’s the whole package,” Hu says. He points to antioxidants -- nutrients that help prevent tissue damage caused by molecules called oxygen-free radicals. “We know that coffee has a very strong antioxidant capacity," Hu says.
Coffee also contains minerals such as magnesium and chromium, which help the body use the hormone insulin, which controls blood sugar (glucose). In type 2 diabetes, the body loses its ability to use insulin and regulate blood sugar effectively.
It's probably not the caffeine, though. Based on studies of decaf coffee, “I think we can safely say that the benefits are not likely to be due to caffeine," Hu says.
Hold the Caffeine?
The fact that coffee contains good stuff does not necessarily mean that it’s good for us, says James D. Lane, PhD, professor of medical psychology and behavioral medicine at Duke University Medical Center in Durham, N.C.
“It has not really been shown that coffee drinking leads to an increase in antioxidants in the body,” Lane tells WebMD. “We know that there are antioxidants in large quantities in coffee itself, especially when it’s freshly brewed, but we don’t know whether those antioxidants appear in the bloodstream and in the body when the person drinks it. Those studies have not been done.”
Regular coffee, of course, also contains caffeine. Caffeine can raise blood pressure, as well as blood levels of the fight-or-flight chemical epinephrine (also called adrenaline), Lane says.
Heart Disease and Stroke
Coffee may counter several risk factors for heart attack and stroke.