Vitamin A

Vitamin A is a family of fat-soluble compounds that play an important role in vision, bone growth, reproduction, cell division, and cell differentiation. Along with vitamins D, E and vitamin K, Vitamin A is stored in your body in small amounts to ensure that your cells have access to it at all times. Vitamin A is essential to maintain intact epithelial tissues as a physical barrier to infection; it is also involved in maintaining a number of immune cell types from both the innate and acquired immune systems.

Deficiency of vitamin A is found among malnourished, elderly, and chronically sick populations in the United States, but it is more prevalent in developing countries where foods are either grown from nutrient-depleted soils. Deficiency symptoms include night blindness, hyperkeratinosis of the skin, and xerophthalmia, an eye condition which if untreated can lead to permanent blindness.  While deficiency is considered rare in the Western world, in the third world it is expected to affect 100 million children.

Vitamin A is used to treat vitamin A deficiency. There is no drug available that replaces the need for a nutrient.

Vegetables such as carrots and sweet potatoes, aswell as dark green vegetables, contain large amounts of carotenoids, especially beta-carotene.  Vegetables are not a good direct source of vitamin A, but the carotenoids they do provide, can be transformed into retinol in the body. This is then converted into Vitamin A.

Your RDA of vitamin A could be achieved by eating two or three carrot sticks, one tablespoon of cooked carrots, two tablespoons of cooked winter squash, sweet potatoes or pumpkin, 1/4 cup of dark green leafy vegetables (spinach, beet greens or Swiss chard), 4 asparagus spears, 1/4 cup broccoli, one apricot, 1/2 peach or 1/4 cup cantaloupe.

While there is no RDA for beta-carotene, the National Institutes of Health (NIH) Office of Dietary Supplements recommends eating five or more servings of fruits and vegetables per day, including dark green and leafy vegetables and deep yellow/orange fruits to get appropriate amounts of beta-carotene.  Serve fruits and vegetables raw whenever possible as cooking significantly depletes nutrient stores. Vitamin A is lost in the fat during frying making it the least beneficial form of cooking.

Supplements that contain 25,000 International Units (IU) or more of vitamin A per capsule are available as over-the-counter preparations in many areas.  Supplements are readily available, and are a good choice for people who are concerned about not getting enough vitamin A from their diets, or for those who may think they are somehow losing part of what they take in. Dietary supplements should be based on natural food sources and not chemically synthesized for maximum bioavailability and potential benefit.

Eggs and whole milk are also good sources of vitamin A.  Vitamin A can be found in many animal sources, such as eggs, meat, milk, cheese, cream, liver, kidney, cod, and halibut fish oil.

A deficiency can occur when vitamin A is lost through chronic diarrhea and through an overall inadequate intake, as is often seen with protein-energy malnutrition.  People with Crohn's disease often experience diarrhea, fat malabsorption, and malnutrition [29].  The control of vitamin A deficiency in many areas of the world will lead to substantial and lasting improvement in childhood survival as well as preventing the scandal of irreversible blindness due to malnutrition.

Vitamin A is an essential human nutrient and cannot not be replaced with any other nutrient or by any drug. By understanding its need, you can take steps to ensure it is included in your good diet.