While diets rich in whole-grains have been shown to improve the cardiovascular health of the general population, a new study from the Harvard School of Public Health shows that they may be particularly beneficial to diabetics. The authors say that their results are important because diabetics are known to be at a 2-3 times higher risk for deaths from heart attack and stroke than the general population.

The team found that deaths from all causes were reduced by 20% in the women who were in the top fifth of whole grain consumption, compared to those in the lowest fifth.

Lu Qi and his team studied the effects of whole grains on the cardiovascular health and death rate of over 7,800 women who took part in the Nurses’ Health Study, with a follow-up period of up to 26 years. All women suffered from type 2 diabetes. The team looked at the whole grain component of the women’s diets over the years, as well as their overall death rate and death risk from heart-related problems alone. Over the study period, 852 deaths from general causes and 295 from cardiovascular causes were recorded.

The team found that deaths from all causes were reduced by 20% in the women who were in the top fifth of whole grain consumption, compared to those in the lowest fifth. Deaths from cardiovascular-related problems were reduced by 35% in the top fifth versus the lowest fifth of whole-grain consumption. When the researchers looked separately at the components of the whole grains (like bran, germ, and fiber), after controlling for certain lifestyle variables, they found that bran alone was strongly associated with reduced death risk. Women in the top fifth of bran consumption had a 55% reduced risk of death from any cause and a 64% reduced risk of death from cardiovascular causes (compared again to women in the lowest fifth of bran consumption).

The authors suggest that there may be several reasons underlying the healthy effects of whole grains, and of bran in particular. Some of these, they say, include the “reduction in serum lipids and blood pressure, improvement of glucose and insulin metabolism, and endothelial [blood vessel] function, and alleviation of oxidative stress and inflammation.”

The authors also say that “[h]igher intake of whole grain is part of a cluster of healthier dietary and lifestyle habits (eg, less smoking, more physical activity, and lower BMI).” So it is important to include multiple healthy habits as part of the effort to stay in good cardiovascular health. Qi and his team do point out that the study was limited to white women, and the effect will need to be “examined in men and other ethnic groups” to determine whether it will also hold true for other demographics.

The study is published in the May 10, 2010 issue of Circulation.