Flavonol and Flavone Intakes in US Health Professionals
Section snippets
Food Collection and Analysis
We collected foods that are known to be important sources of flavonols and flavones (11), (12). Three samples of the following fresh product were purchased at local Boston area supermarkets: Macintosh, Granny Smith and Red Delicious apples; Spanish, white, and all-purpose yellow onions; avocado; cantaloupe; watermelon; alfalfa sprouts; and green pepper. Mixed fresh and frozen samples were used for blueberries and yellow squash. Corn and green beans consisted of a mix of fresh, frozen, and
Results
Flavonoid content of foods Values in US foods were similar to those previously reported by us in European foods (Table 1). By far the highest amounts of quercetin (when expressed on a weight basis) were in yellow and Spanish onions. Considering realistic serving sizes, however, the amounts in tea and apples were also high. Apple juice and wine contained modest amounts of quercetin. Few foods except tea contained appreciable amounts of kaempferol and myricetin; and no apigenin or luteolin was
Discussion
We found that the mean intake of quercetin plus related flavonols and flavones in two US adult populations was approximately 20 to 22 mg per day. These figures are based largely on new chemical analyses of US foods; these newly analyzed foods contributed approximately 74% of the men's and 69% of the women's summed flavonol and flavone intake. Spices and herbs in the amounts normally added to food probably only increase flavonoid intake marginally as only chili powder contains a high quantity of
Applications
Flavonoids can function as antioxidants and are hypothesized to be important determinants of diseases related to oxidative stress. Studies of flavonoid intake in relation to hypertension, plasma low-density lipoprotein cholesterol, coronary artery disease, stroke, gastric cancer, chronic obstructive pulmonary disease, and dementia have been published. Results have been inconsistent and are hampered by lack of comprehensive data on the flavonoid content of foods. We have therefore analyzed US
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