Harvard advises on foods to help prevent diabetes

Havard Medical School’s report Healthy Eating for Type 2 Diabetes, ​explains how food choices, as well as weight control, can help manage and "even prevent"​ diabetes.

The authors of the paper, which is designed as guidance to consumers, say that research into the relationship between eating specific types of foods and diabetes risk is “limited and the results somewhat controversial.”​

They drew their conclusions from studies that required people to report what they ate or drank, and pointed out these were considered less rigorous than those in which people are assigned to follow different diets.

Fiber, grains and nuts​

Both men and women who eat plenty of whole grains had a roughly 40 percent lower risk of diabetes than those who eat little, with cereals, breads, and grains apparently the most beneficial.

“Fiber slows the digestion of food, so glucose is released into the bloodstream more gradually, and you feel full longer,”​ writes the paper. “This can help you avoid overeating and becoming overweight, thus reducing your risk of diabetes. Soluble fiber in particular appears to improve both blood sugar and insulin sensitivity, and high-fiber diets may even lower the need for insulin.”​

Women who eat nuts or peanut butter at least five times a week have a 20 to 30 percent lower risk of diabetes than those who rarely eat them.

'Not wonder foods'​

However the authors stressed that “these are not wonder foods that will magically ward off diabetes.”​

They said there is no specific ‘diabetes diet’ that prohibits sugar and lists other ingredients to avoid, but said people with diabetes should follow the same dietary advice as most people, but with extra emphasis on controlling weight and keeping blood sugar, blood pressure, and cholesterol values as close to normal as possible.

The authors recommended a well-balanced diet that emphasizes fruit, vegetables, whole grains, and lean protein, while watching calorie intake and getting regular exercise.

Raising the risk​

Among the high risk foods, women who drink two or more sugary soft drinks have a 24 percent higher risk of developing diabetes compared to those who consume less than one per month, and two or more daily fruit drinks (with little real fruit juice) lead to a 31 percent higher risk.

Women who eat around one serving of red meat a day have about a 20 percent higher risk of diabetes than those who eat at least one serving a week, and men who eat processed meats five times a week are nearly twice as likely to develop diabetes as men who eat such foods just twice a month.

One study documented a 30 percent increased risk of diabetes among women who ate the most trans fats compared to those who ate the least

The report quoted American Heart Association findings that the incidence of hypertension is twice as common among people with diabetes as it is among the general public. It recommended the equivalent of approximately one teaspoon of table salt, saying that most Americans consume much more.

It also warned that too many refined carbohydrates, from which valuable nutrients, fiber, and vitamins are removed during the refinement process, can cause a significant spike in blood sugar and increase insulin requirements if eaten in large quantities.

It's not all about functional foods​

The report also highlighted the potential benefits of some products not traditionally considered to be 'healthy'. It noted that one cup of coffee a day could lower diabetes risk by 13 percent and two cups a day could cut the risk by 42 percent, compared to people who drink none.

While warning that alcohol can be a double-edged sword because of its detrimental effect on heart health, the report reveals that men who have two to four drinks per week had a 25 percent lower risk than teetotalers. Five to six drinks per week drops the risk by 33 percent and one drink a day cut risk by 43 percent.

“There’s some evidence that light to moderate alcohol intake can lower insulin resistance and enhance glucose metabolism in people with diabetes,”​ wrote the authors. “It’s also well documented that alcohol improves insulin sensitivity only when people drink light to moderate amounts.”​ Heavy consumption has the opposite effect, they said.