What You Should Know About Vitamin A
I've been writing and lecturing about the benefits of vitamin D for over four years. The mainstream media also is presenting vitamin D news on a regular basis. The “sunshine vitamin” and vitamin D supplements have many benefits in boosting bone, muscle and eye health. Vitamin D also may prevent a number of types of cancer, including breast and colon cancer. Vitamin D also significantly reduces risk of stroke and heart disease. The more we address this global deficiency in vitamin D, we reduce much mortality, suffering and disease.
But there is another “old standby” inexpensive vitamin that has not gotten the same media exposure as that of vitamin D, that is vitamin A. Vitamin A is required for eye health, including night vision and macular degeneration. It is important in immune health, including allergies, autoimmune disease and proneness to infection. Vitamin A is also important for skin and hair health. It also regulates bone health and protection from lung, colon, breast and prostate cancers, and aids in the synthesis of testosterone, estrogen and growth hormone.
Vitamin A deficiency is a significant health problem in many developing countries, causing blindness, eye impairment and death from infectious diseases like measles and diarrhea. Subclinical deficiencies in this country are more common than we think.
There are currently no blood tests that reveal vitamin A status. It is widely assumed that a “good diet” provides enough vitamin A. What are the dietary sources of vitamin A? Liver is the best, but how many of us eat liver? Egg yolks, butter, cream, and very small amounts in meat and fish, are the only sources of pre-formed vitamin A. But wait a minute — don't carrots have vitamin A? or yams? No. There are no plant sources of vitamin A. None. Carrots, and other vegetables have beta carotene, a plant carotenoid, but that is not vitamin A. Our bodies do have some ability to convert beta carotene, and other carotenoids to vitamin A, but this is not an automatic one to one conversion. No more than one tenth of beta carotene is converted to true vitamin A.
There are a number of factors that prevent beta carotene from becoming vitamin A. One is subclinical hypothyroidism. We need T3 to convert carotenes to vitamin A, and widespread deficiencies in iodine, as well as the presence of chlorine and fluoride in drinking water contribute greatly to subclinical hypothyroidism. Aging and some genetic variabilities also effect the conversion to vitamin A.
Other factors that inhibit this conversion are gluten sensitivities, food allergies, abnormal gut microorganisms, fat malabsorption, low fat diets, pancreatic insufficiency, and lack of zinc and B vitamins.
Most people will benefit from taking pre-formed vitamin A, especially if you have any of the above conditions, or suffer recurring infections, have any eye issues, or want extra protection from cancer.
Is vitamin A safe? How much should I take? Giving newborn infants one 50,000 IU dose in Indonesia significantly lowered the death rate at age one. Teenage girls taking 300,000 IU and boys taking 400,000 to 500,000 IU daily for acne all showed significant improvement and no signs of toxicity.
The biggest caution is with pregnancy. Some studies have indicated increased risk of birth defects with doses over 15,000 IU. Other studies, however, have shown decreased risk of birth defects at these levels. Until we have more evidence, it is wise to limit the intake of pre-formed vitamin A to no more than 10,000 IU for pregnant women, and for that matter for any sexually active woman of childbearing age.
Many people avoid dairy products for health reasons, and avoid egg yolks, mistakenly thinking they will raise cholesterol. Because the conversion of beta carotene to vitamin A is much less efficient than we thought, it is likely that many of us would benefit from taking pre-formed vitamin A.
Any adult or child can safely take 5,000 to 10,000 IU daily. Taking other fat soluable vitamins along with A will reduce any potential toxicity. For example, 5,000 IU of vitamin D and 90 mcg of vitamin K2 will reduce risk and increases the benefit.