In our last issue, we reviewed three studies, each of which linked higher intake of flavonoids from vegetables and fruits to reduced risk of breast cancer (See "Food-Borne Antioxidants May Curb Breast Cancer").
Now we have the results of a similar study that looked for links between flavonoid intake and risk of death from cardiovascular disease, coronary heart disease, or stroke.
After analyzing data from 34,489 post-menopausal participants in the Iowa Women’s Health Study, researchers at the University of Minnesota and the University of Oslo, Norway determined that the women with the highest intake of certain classes of flavonoids had less risk of death from heart disease and all other causes.
Flavonoids appear to act as antioxidants—either directly or indirectly—thereby helping to foil a key cardiovascular risk factor: oxidation of LDL cholesterol (See accompanying article “Food-borne Antioxidants May Act Indirectly”).
Flavonoids also inhibit inflammation in the blood and arteries, improve the performance of our artery lining (endothelial tissue), and keep blood from becoming sticky and overly clot-prone (i.e., they inhibit platelet aggregation).
The people in the Iowa Women’s Health Study were free of cardiovascular disease at its outset, and their flavonoid intake was estimated from dietary surveys submitted at the beginning of the study.
The women’s intake of total flavonoids and of each of seven flavonoid subgroups were recorded, and they were then grouped into five flavonoid-intake categories called "quintiles."
The flavonoid subgroups for which the women's intake was estimated were flavonols, flavones, flavanones, flavan-3-ols, anthocyanidins, proanthocyanidins, and soy isoflavones.
Deaths from cardiovascular disease (CVD), coronary heart disease (CHD), stroke, and all causes were recorded over the study’s 16-year period.
The scientists then compared the rates of heart-related deaths among women in the highest-intake quintiles with death rates among women in the lowest-intake quintile.
They reported finding significant inverse associations in two instances:
- Anthocyanidins (berries and cocoa/chocolate): Eating any amount, compared to none, reduced a woman’s risk of CHD, CVD, and total mortality by 12 percent, nine percent, and 10 percent, respectively.
- Flavonones (citrus fruits and peppermint): Women consuming the most of these flavonoids reduced their risk of CHD and death by 22 percent.
Certain flavonoid-rich foods were associated with significant reductions in risk of heart-related deaths:
- Strawberries reduced the risk of death from CVD.
- Chocolate reduced the risk of death from CVD.
- Bran (added to foods) reduced the risk of death from stroke and CVD.
- Apples or pears or both and red wine reduced the risk death from of CHD and CVD.
- Grapefruit reduced the risk of death from CHD.
No associations were found between flavonoid intake and risk of death from stroke.
- Mink PJ, Scrafford CG, Barraj LM, Harnack L, Hong CP, Nettleton JA, Jacobs DR Jr. Flavonoid intake and cardiovascular disease mortality: a prospective study in postmenopausal women. Am J Clin Nutr. 2007 Mar;85(3):895-909.