Grains consist of three layers: the fiber- and nutrient-containing bran and germ layers and the starchy kernel layer. Refined grains, like white flour, are largely stripped of the bran and germ; whole grains — such as oatmeal, brown rice, barley and breads made from whole wheat — retain more of those components.
Studies suggest that the fiber, antioxidants and other nutrients in whole grains may help lower cholesterol, blood sugar and insulin levels, as well as improve blood vessel functioning and reduce inflammation in the circulatory system.
In the new study, Qi and his colleagues at Harvard Medical School in Boston found that among 7,800 U.S. women followed for 26 years, those with the highest bran intake were 28 percent less likely to die during the study period than those who consumed the least bran.
Similarly, they were 35 percent less likely to die of cardiovascular disease (heart disease or stroke) specifically.
The findings, published in the journal Circulation, do not prove that bran-heavy diets were the reason for the lower risks.
However, the connection was not explained by generally healthier lifestyles among the bran lovers. When the researchers accounted for other diet habits — like fat intake and total calories — as well as the women's weight, exercise levels, smoking history and drinking habits, the link between higher bran intake and lower death rates remained.
This suggests that bran intake itself may help lower diabetics' risk of premature death, according to Qi.
He suggested that women and men with diabetes try to replace refined grains in their diets with bran-rich whole grains.
That said, the researcher pointed out that the risk reductions in this study were seen across a large population — with bran lovers showing a relatively lower risk of death than those who ate little bran. That does not mean that for any one person with diabetes, boosting bran intake would have a substantial effect on longevity.
The findings are based on 7,822 women with type 2 diabetes who were part of the Nurses' Health Study, a long-term study of U.S. female nurses begun in 1976. Every two years, the women answered the questions about their lifestyle, medical history and any disease diagnoses.
Over 26 years of follow-up, 852 study participants died, including 295 women who died of heart disease or stroke.
Overall, Qi's team found, women in the top 20 percent for bran intake had a 28 percent lower risk of dying from any cause during the study period, compared with women in the lowest 20 percent. Their risk of death from cardiovascular disease was 35 percent lower.
SOURCE: http://circ.ahajournals.org/cgi/content/abstract/CIRCULATIONA HA.109.907360v1 Circulation, online May 10, 2010.More