by Michael O’Leary

Sometimes it seems as if scientific research is a little like the childhood daisy rhyme, “she loves me, she loves me not,” repeated as petals of the daisy are picked off. So many things are first thought to be good for you, then a new study shows not so much.

That has been the history of research into coffee and health, some studies show health benefits of coffee consumption and just as you pour that second cup, another study shows the opposite. Part of the reason for this, as Harvard nutrition researcher Dr. Rob van Dam explains, is that a simple cup of coffee is anything but simple.

So it is not surprising that people greeted the news about a Chinese study showing coffee consumption might reduce the incidence of type 2 diabetes with a bit of skepticism.

Still, the study published in the Euroean Journal of Nutrition is worth a look. The researchers from the Department of Epidemiology and Health Statistics, Medical College, Qingdao University, analyzed data from 42 studies involving nearly 2 million participants.

Twenty-six of the studies examined the levels of coffee intake. Another 10 studies looked at decaffeinated coffee intake, and six studies looked at caffeine intake.

What they found was that coffee intake was associated with a lower incidence of type 2 diabetes, especially among non-smokers and people who were not overweight (BMI less than 25).

When they did a dose-response analysis, they found that the beneficial effect increased with increased caffeine consumption. They wrote that type 2 diabetes decreased by 12 percent for every two cups of coffee per day, and that incidence of type 2 diabetes declined by 11 percent for every 2 cups of decaf consumed, but declined by 14 percent for every 200 mg/day of caffeine intake.

The amount of caffeine in coffee varies widely, but your average 16 oz. Starbucks contains 150 mg to 300 mg.

While the biological mechanism for caffeine’s beneficial effect on type 2 diabetes is unknown, a Singapore study last year showed that a compound called chlorogenic acid (CGA) may be part of the answer.

You can bet more coffee and type 2 diabetes studies are underway, so you might as well enjoy another cup of coffee until the next study is published.