U.S. study affirms prior research linking high-flavonoid diets to reduced risk in post-menopausal women
The antioxidants in vegetables, fruits, tea, and cocoa show anti-cancer effects in hundreds of cell and animal studies, and in many, albeit not all, epidemiologic (population) studies.
But until recently, few epidemiological studies had looked for links between intakes of flavonoids — polyphenol-type antioxidants that abound in most plant foods, as well as in tea, wine, and coffee — and the risk of breast cancer.
Three years ago, a Greek-British team conducted a case-control study in 2,358 Greek women — 820 with breast cancer and 1,548 free of the disease, who completed diet questionnaires designed to determine their flavonoid intakes.
And the results showed that the women free of breast cancer typically ate more of a certain class of flavonoids — called flavones — that abounds in leafy vegetables (Peterson J et al 2003).
A follow up study by the same team, this time in Italy, followed 5,157 cancer patients and healthy control subjects, and came to an identical conclusion: higher intakes of flavone-type flavonoids were substantially linked to a lower risk of breast cancer (Bosetti C et al. 2005).
U.S. study confirms flavonoid benefits
Researchers led by Dr. Brian Fink of the University of North Carolina conducted a case-control study among women on Long Island, New York: 1,434 breast cancer patients and 1,440 healthy controls.
The women were interviewed about known and suspected risk factors and asked to complete a diet survey, as the basis for estimating their average flavonoid intake in the year prior.
This time, all flavonoids were found protective, to varying extents, but flavones remained the champs, reducing risk by 39 percent.
And the protection was seen at readily achievable intake levels that approximate America's “5-A-Day” (servings of fruits and vegetables) dietary guidelines.
As the study authors said, “A decrease in breast cancer risk was associated with flavonoid intake; the decrease was most pronounced among postmenopausal women for flavonols [a subgroup of flavonoids] … These results suggest that U.S. women can consume sufficient levels of flavonoids to benefit from their potential chemopreventive effects.”
Interestingly, dietary flavonoids may prevent cancer and vascular disease despite an inability to act as direct antioxidants in the human body. For more on that, see Food-Borne Antioxidants Mostly Act Indirectly.
And rather than attempting to skew your diet toward any one group of antioxidants, it makes sense to enjoy a wide range of fruits and vegetables, and quaff coffee, tea, and natural, non-alkalized (non-Dutched) cocoa.
- Fink BN, Steck SE, Wolff MS, Kabat GC, Gammon MD. Construction of a flavonoid database for assessing intake in a population-based sample of women on Long Island, New York. Nutr Cancer. 2006;56(1):57-66.
- Fink BN, Steck SE, Wolff MS, Britton JA, Kabat GC, Schroeder JC, Teitelbaum SL, Neugut AI, Gammon MD. Dietary flavonoid intake and breast cancer risk among women on Long Island. Am J Epidemiol. 2007 Mar 1;165(5):514-23. Epub 2006 Dec 11.
- 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.
- Bosetti C, Spertini L, Parpinel M, Gnagnarella P, Lagiou P, Negri E, Franceschi S, Montella M, Peterson J, Dwyer J, Giacosa A, La Vecchia C. Flavonoids and breast cancer risk in Italy. Cancer Epidemiol Biomarkers Prev. 2005 Apr;14(4):805-8. Review.
- Peterson J, Lagiou P, Samoli E, Lagiou A, Katsouyanni K, La Vecchia C, Dwyer J, Trichopoulos D. Flavonoid intake and breast cancer risk: a case--control study in Greece. Br J Cancer. 2003 Oct 6;89(7):1255-9.
- Nettleton JA, Harnack LJ, Scrafford CG, Mink PJ, Barraj LM, Jacobs DR Jr. Dietary flavonoids and flavonoid-rich foods are not associated with risk of type 2 diabetes in postmenopausal women. J Nutr. 2006 Dec;136(12):3039-45.
- Sesso HD, Gaziano JM, Liu S, Buring JE. Flavonoid intake and the risk of cardiovascular disease in women. Am J Clin Nutr. 2003 Jun;77(6):1400-8.
- Yochum L, Kushi LH, Meyer K, Folsom AR. Dietary flavonoid intake and risk of cardiovascular disease in postmenopausal women. Am J Epidemiol. 1999 May 15;149(10):943-9. Erratum in: Am J Epidemiol 1999 Aug 15;150(4):432.