New US study affirms prior research linking high-flavonoid diets to reduced risk in post-menopausal women
by Craig Weatherby
The flavonoid-type antioxidants in vegetables, fruits, tea, and cocoa show anti-cancer effects in hundreds of cell and animal studies, and in some epidemiologic studies in large populations.
But few epidemiologic studies have looked for links between flavonoid intake and breast cancer.
Three years ago, a Greek-British study in 2,358 breast-cancer patients and health controls in Greece found a lower risk of breast cancer among who ate more of a certain type of flavonoids (flavone) found primarily 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 health controls, and came to an identical conclusion: higher intake of flavone-type flavonoids was associated with a lower risk of breast cancer.
(Oddly, new research indicates that dietary flavonoids may prevent cancer and vascular disease despite an inability to act as direct antioxidants in the human body. We’ll cover this news in our next issue,)
New 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 food frequency questionnaire regarding their average intake in the year prior.
This time, all flavonoids were found protective, to varying extents, with flavones remaining 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 they said, “A decrease in breast cancer risk was associated with flavonoid intake; the decrease was most pronounced among postmenopausal women for flavonols… These results suggest that US women can consume sufficient levels of flavonoids to benefit from their potential chemopreventive effects.”
Rather than attempting to skew your diet toward any one class of flavonoids, it makes sense to enjoy a wide range of fruits and vegetables, and quaff tea and 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.