It is a partially fictitious claim that consuming carrots enhances night vision. One of the primary nutrients found in carrots is beta-carotene, which gives this root vegetable its characteristic orange color. Beta-carotene serves as a precursor to vitamin A and aids in the adjustment of our eyes in dim lighting conditions. Nonetheless, vitamin A cannot grant superhuman night vision abilities or eliminate the need for corrective eyewear. Nevertheless, consuming an adequate amount of vitamin A supports eye health.
Furthermore, vitamin A stimulates the production and activity of white blood cells, participates in bone remodeling, preserves healthy endothelial cells that line internal surfaces in the body, and regulates cell growth and division necessary for reproduction.
The human diet consists of two primary forms of vitamin A: preformed vitamin A (retinol, retinyl esters) and provitamin A carotenoids, such as alpha-carotene and beta-carotene, which convert to retinol. Preformed vitamin A is derived from animal products, fortified foods, and vitamin supplements, whereas carotenoids occur naturally in plant-based foods. Additionally, certain carotenoids found in food possess health-promoting properties, including lycopene, lutein, and zeaxanthin, though they do not convert into vitamin A.
The current measurement unit for vitamin A on the Nutrition Facts label is international units (IU). However, the Institute of Medicine provides Recommended Dietary Allowances (RDA) for vitamin A, which are expressed in micrograms (mcg) of retinol activity equivalents (RAE) to account for different absorption rates of preformed vitamin A and provitamin A carotenoids. As of July 2018, large companies, following the new food and dietary supplement labeling regulations by the Food and Drug Administration (FDA), are required to list vitamin A as "mcg RAE" rather than IU.
For adults aged 19 years and older, the Recommended Dietary Allowance (RDA) for vitamin A is 900 mcg RAE for men (equivalent to 3,000 IU) and 700 mcg RAE for women (equivalent to 2,333 IU). The Tolerable Upper Intake Level (UL) represents the maximum daily intake that is unlikely to have harmful effects on health. For vitamin A derived from retinol, the UL is set at 3,000 micrograms of preformed vitamin A.
The evidence suggests that consuming a variety of vitamin A-rich foods, particularly fruits and vegetables, offers protection against certain diseases. However, the health benefits of vitamin A supplements are less conclusive.
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