Vitamin A has never basked in the limelight or topped the list of popular nutrients, but its benefits to the body have a substantial impact on health. Vitamin A deficiency is a perpetual problem in many countries. By knowing the pros of this nutrient, as well as its sources, patients can successfully maintain healthy eyes, bones and skin.
Good eyesight and this nutrient go hand-in-hand. Poor night vision is strongly associated with a lack of vitamin A, as is dry eye [Source: Johnson, Rengstorff]. This nutrient in the form of beta-carotene has been shown to benefit patients with macular degeneration as part of a multivitamin containing 500 mg of vitamin C, 400 IU of vitamin E, 15 mg of beta-carotene, 80 mg of zinc and 2 mg copper [Source: AREDS].
Acne and scaliness of the skin is associated with vitamin A deficiency [Source: Guyton and Hall]. The benefits of this vitamin in relation to the skin extend to prevention of infections. The World Health Organization has included vitamin A supplementation in the management of measles infection, as it significantly lowers the risk of death from the condition [Source: WHO]. One trial also demonstrated a benefit of vitamin A supplementation for patients with heavy menstruation [Source: Lithgow]. Those who have undergone a gallbladder removal may have trouble absorbing fat-soluble vitamins, including A, D, E and K. Poor digestion, absorption and dietary choices can heighten the need for general supplementation.
Beneficial elements are best obtained through food sources high in beta-carotene, a carotenoid. Carotenoids, of which there are more than five hundred known, are chemicals derived from plants. They give fruits and vegetables their pigment and, as they are studied more, are found to contain respectable levels of antioxidants. Beta-carotene is very closely related in structure to vitamin A and is one of the few carotenoids that can be converted to vitamin A in the liver.
Vitamin A is found in animal products such as liver, eggs and cow milk, while beta-carotene is in many fruits and vegetables, like carrots, apricots, spinach, kale and cabbage. As they contain a buffet of nutrients, eggs, spinach and cabbage should be a regular component of your diet.
As a supplement, both vitamin A and beta-carotene are acceptable. Most multivitamins already include one of these forms. Dosing for vitamin A commonly ranges from 5,000-15,000 IU (international units). Those who eat more varieties, specifically colors, of vegetables have less need for supplementation, as do the elderly. An excess of vitamin A has been linked to birth defects in some animals. To be safe, when supplementing during pregnancy don’t ingest more than 10,000 IU a day [Source: Mills]. Prenatal vitamins typically provide less than this to allow for vitamin A and beta-carotene in the diet.
There’s a very high rate of tolerance for vitamin A. Clinically, doctors have used up to 100,000 IU a day to treat infections. Dosages such as this should only be done under a doctor’s supervision and for brief periods of time (days). Any female who has even the slightest inclination of pregnancy should not consume this high level of vitamin A. Signs of vitamin A toxicity include joint pain, muscle aches and dry skin. Toxicity from a daily multivitamin is rare. Some data suggests a link of excessive amounts of this nutrient to osteoporosis [Source: Melhus].