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Chapter 071. Vitamin and Trace Mineral Deficiency and Excess (Part 8)

Flavonoids Flavonoids constitute a large family of polyphenols that contribute to the aroma, taste, and color of fruits and vegetables. Major groups of dietary flavonoids include anthocyanidins in berries; catechins in green tea and chocolate; flavonols (e.g., quercitin) in broccoli, kale, leeks, onion, and the skins of grapes and apples; and isoflavones (e.g., genistein) in legumes. Isoflavones have a low bioavailability and are partially metabolized by the intestinal flora. The dietary intake of flavonoids is estimated to be between 10 and 100 mg/d, although this is almost certainly an underestimate due to the lack of knowledge of their concentrations in. | Chapter 071. Vitamin and Trace Mineral Deficiency and Excess Part 8 Flavonoids Flavonoids constitute a large family of polyphenols that contribute to the aroma taste and color of fruits and vegetables. Major groups of dietary flavonoids include anthocyanidins in berries catechins in green tea and chocolate flavonols e.g. quercitin in broccoli kale leeks onion and the skins of grapes and apples and isoflavones e.g. genistein in legumes. Isoflavones have a low bioavailability and are partially metabolized by the intestinal flora. The dietary intake of flavonoids is estimated to be between 10 and 100 mg d although this is almost certainly an underestimate due to the lack of knowledge of their concentrations in many foods. Several flavonoids have been shown to have antioxidant activity and to affect cell signaling. From observational epidemiologic studies and from limited clinical human and animal studies flavonoids have been postulated to play a role in the prevention of several chronic diseases including neurodegenerative disease diabetes and osteoporosis. The ultimate importance and usefulness of their compounds against human disease have yet to be demonstrated. Vitamin A Vitamin A in the strictest sense refers to retinol. However the oxidized metabolites retinaldehyde and retinoic acid are also biologically active compounds. The term retinoids includes all molecules including synthetic molecules that are chemically related to retinol. Retinaldehyde 11-cis is the essential form of vitamin A that is required for normal vision whereas retinoic acid is necessary for normal morphogenesis growth and cell differentiation. Retinoic acid does not function in vision and in contrast to retinol is not involved in reproduction. Vitamin A also plays a role in iron utilization humoral immunity T cell-mediated immunity natural killer cell activity and phagocytosis. Vitamin A is commercially available in esterified forms e.g. acetate palmitate since it is more stable as an ester. .