Vitamin A is actually a group of compounds that include retinol and beta-carotene among others. The science behind it dates back to 1816 when scientists noticed nutrition deprived dogs developed corneal ulcers. It was later found to be a fat soluble vitamin (as opposed to water-soluble) meaning it is stored in the fat (along with vitamins D, E, and K).
Vitamin A is indeed important in maintaining good vision. It is also important for cell growth and differentiation, skin health, and the immune system. For women the recommended daily allowance (RDA) is 700 mcg and 900 for men. The widely considered upper safe limit is considered to be 3000 mcg.
Animal sources of vitamin A include cheddar cheese, eggs, butter, and liver. Plant source include carrots, broccoli, kale and spinach. Dandelion greens have a particularly high amount of vitamin A and are used in natural medicine.
Worldwide Vitamin A deficiency is a huge problem. Approximately…
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