According to a new study, overweight and obese adults who eat a diet rich in slowly digested carbohydrates, such as whole grains, legumes and other high-fiber foods, have significantly lower levels of inflammation markers associated with chronic disease.
Such a "low-glycemic-load" diet, which does not cause blood-glucose levels to spike, also increases a hormone that helps regulate the metabolism of fat and sugar.
The controlled, randomized feeding study, conducted at the Fred Hutchinson Cancer Research Center, involved 80 healthy Seattle-area men and women -- half of normal weight and half overweight or obese.
Among overweight and obese study participants, a low-glycemic-load diet reduced a biomarker of inflammation called C-reactive protein by about 22 percent. C-reactive protein is associated with an increased risk for many cancers as well as cardiovascular disease. Lowering inflammatory factors is important for reducing a broad range of health risks.
The researchers also found that among overweight and obese study participants, a low-glycemic-load diet modestly increased -- by about 5 percent -- blood levels of a protein hormone called adiponectin. This hormone plays a key role in protecting against several cancers, including breast cancer, as well as metabolic disorders such as type-2 diabetes, nonalcoholic fatty liver disease and hardening of the arteries.
"Glycemic load" refers to how the intake of carbohydrates, adjusted for total grams of carbohydrate, affects blood-sugar levels. Lentils or pinto beans have a glycemic load that is approximately three times lower than instant mashed potatoes, for example, and therefore won't cause blood-sugar levels to rise as quickly.
Study participants completed two 28-day feeding periods in random order -- one featuring high-glycemic-load carbohydrates, which typically are low-fiber, highly processed carbs such as white sugar, fruit in canned syrup and white flour; and the other featuring low-glycemic-load carbohydrates, which are typically higher in fiber, such as whole-grain breads and cereals.
The diets were identical in carbohydrate content, calories and macronutrients. All food was provided by the Hutchinson Center's Human Nutrition Laboratory, and study participants maintained weight and physical activity throughout.
The bottom line: when it comes to reducing markers of chronic-disease risk, not all carbohydrates are created equal. Quality matters.
Whenever possible, choose low glycemic carbohydrates that are less likely to cause rapid spikes in blood glucose. These foods include whole grains, legumes such as kidney beans, soy beans, pinto beans and lentils, milk, and fruits such as apples, oranges, grapefruit and pears.
Avoid high-glycemic-load carbohydrates that quickly raise blood glucose. These include highly processed foods that are full of white sugar and white flour, and sugar-sweetened beverages and breakfast cereals.
Source: Journal of Nutrition, online February 2012
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