Dietary Flavonoid Sources in Australian Adults
Evidence from laboratory-based in vitro studies provides compelling evidence supporting the involvement of dietary flavonoid intake in human cancer risk. Associations between intakes of individual flavonoids and disease outcomes at the population level are emerging from recent epidemiological studies. As an important step in the development of methods to assess flavonoid intakes across populations, the major sources of dietary flavonoids in the adult Australian population were identified. Data from a 24-h diet recall questionnaire used in a national nutrition survey (NNS95-comprising a sample of 10,851 subjects aged 19 yr and over) were combined with U.S. Department of Agriculture data on flavonoid content of foods to identify key sources. Black and green teas clearly were the dominant sources of the flavonols kaempferol, myricetin, and quercetin. Other significant flavonol sources included onion (isorhamnetin and quercetin), broccoli (kaempferol and quercetin), apple (quercetin), grape (quercetin), coffee (myrcetin), and beans (quercetin). Black and green teas also were dominant sources of flavon-3-ols, with wine, apples, and pears contributing somewhat. In terms of flavanone consumption, oranges (hesperetin and naringenin), lemon (eriodictyol), mandarin (hesperetin), and grapefruit (naringenin) were the major sources. Parsley (apigenin), celery (apigenin and luteolin), and English spinach (luteolin) were the major flavone sources. Wine was the major anthocyanadin source (delphinidin, malvidin, peonidin and petunidin), with smaller amounts fromcherry (peonidin) and blueberry (delphinidin, malvidin, peonidin and petunidin). It is suggested that the relatively small number of aforementioned key foods form the basis of food frequency questionnaires to assess flavonoid intake.
Nutrition and Cancer