|Tang, Guangwen -|
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: April 20, 2009
Publication Date: November 20, 2009
Citation: Tang, G. 2009. Spinach and carrots: vitamin A and health. In: Watson, R., Preedy, V., editors. Bioactive Foods in Promoting Health: Fruits and Vegetables. London, UK: Elsevier. p.381-391. Technical Abstract: Vitamin A is an essential nutrient for the promotion of general growth, maintenance of visual function, regulation of the differentiation of epithelial tissues and immune function, and embryonic development. Vitamin A can only be supplied naturally, either as preformed vitamin A from foods of animal origin (e.g. liver, dairy products, eggs, etc.) or as provitamin A carotenoids from plants such as carrots, spinach, red yams, pumpkins, cantaloupes, etc. Spinach and carrots are major vegetables rich in provitamin A carotenoids and are commonly consumed. They represent dark green and yellow vegetables. Both spinach and carrots are good sources of vitamin A and can supply significant amounts of vitamin A for our daily needs, even though their vitamin A equivalencies are different. Spinach and carrots are safe sources of vitamin A because provitamin A carotenoids are not associated with specific adverse health effects. Spinach and carrots provide about 20-30% of the vitamin A in the average American diet. Vitamin A is produced in human metabolism by the breakdown of the pigments in spinach leaf (dark green leafy vegetables) and carrot roots (yellow colored vegetables). With condensed contents of provitamin A pigments, dietary spinach and carrots can supply significant amounts of vitamin A for our daily needs. Over-consumption of vitamin A can be toxic to humans, but over-consumption of provitamin A carotenoids is never toxic since the breakdown of carotenoids to vitamin A is well controlled. Even though overconsumption of provitamin A pigment rich foods such as carrots is not harmful, it is not encouraged.