New research, published in the International Journal of Cancer, reports that increased intake of the flavonoid kaempferol, found in spinach and some cabbages, was associated with a 40 per cent reduced risk of ovarian cancer.
Ovarian cancer accounts for 4 per cent of all cancers diagnosed in women globally, with 190,000 new cases every year.
In Europe there are 61,000 new cases each year, with the highest incidence rates found in the Northern European countries of the UK, Ireland, Denmark and Finland.
The new study, led by Margaret Gates from Brigham and Women's Hospital and Harvard Medical School, fills a gap in our knowledge since no prospective study has previously examined the association between flavonoid intake and ovarian cancer risk.
Gates and co-workers calculated intake of the flavonoids myricetin, kaempferol, quercetin, luteolin and apigenin among 66,940 women enrolled in the Nurses' Health Study.
Between 1984 and 2002 347 cases of epithelial ovarian cancer were diagnosed.
While total intake of the five flavonoids together was not found to provide a benefit, a significant 40 per cent reduction in ovarian cancer incidence was observed between the women with the highest kaempferol intake, compared to women with the lowest intake.
A significant 34 per cent reduction in ovarian cancer incidence was also observed between the women with the highest intake of the flavone luteolin (found in citrus, for example), compared to women with the lowest intake.
"There was evidence of an inverse association with consumption of tea (nonherbal) and broccoli, the primary contributors to kaempferol intake in our population," added Gates.
"These data suggest that dietary intake of certain flavonoids may reduce ovarian cancer risk, although additional prospective studies are needed to further evaluate this association," concluded the researchers.
"If confirmed, these results would provide an important target for ovarian cancer prevention."
Interest in flavonoids is growing rapidly and a mounting body of science, including epidemiological, laboratory-based and randomised clinical trials, continues to report the cancer-fighting potential of a number of different flavonoids, such as isoflavones, anthocyanidins and flavonols.
According to Business Insights, the market potential for flavonoids in the dietetic and nutritional supplement market is in excess of €670m ($862m) for 2007, with annual increases of 12 per cent.
Source: International Journal of Cancer Early view - published on-line ahead of print, doi: 10.1002/ijc.22790 "A prospective study of dietary flavonoid intake and incidence of epithelial ovarian cancer" Authors: M.A. Gates, S.S. Tworoger, J.L. Hecht, I. De Vivo, B. Rosner, S.E. Hankinson