VITAMIN A: A VITAL NUTRIENT

by STEPHEN BYRNES, PhD

Published originally in A & U Magazine, April 2001    

Vitamin A earned its name from the fact that it was the first vitamin discovered. Researchers in the 1930s described vitamin A as the "anti-infective vitamin" as it is intimately involved in the health of the mucous membranes and in fighting off infections.

Since its discovery, vitamin A has been shown to be pivotal in several bodily functions: formation of "visual purple" which allows us to see partially in low light; maintenance of healthy vision and proper eye function; repair and maintenance of epithelial tissues, especially those of the skin and mucous membranes; maintenance of the endocrine system, especially the thyroid gland; proper utilization of dietary proteins; protecting and fighting against cancers of various types; and stimulation of the thymus gland, a major part of the immune system. Vitamin A is also an antioxidant that helps to neutralize tissue-damaging free radicals.

The body's stores of vitamin A are rapidly depleted under stress of any type as the nutrient is needed to convert cholesterol into the various stress hormones. Its important to remember that "stress" includes not only psychological factors, but physical, chemical, biological, and nutritional ones as well. Physical stressors can include heavy exercise, "burning the candle at both ends," and lack of sleep. Chemical stressors can include drugs of any type and various compounds that are not natural to the body, e.g., pollution and cigarette smoke. Nutritional stressors would include a poor diet, malnutrition, and subclinical nutrient deficiencies. Biological stressors include infections. Studies have shown that HIV+ individuals tend to have lower levels of vitamin A and deficiency is associated with faster disease progression (along with several other key antioxidant nutrients). Taking care to avoid as many of the stressors listed above can go a long way to maintaining one's health and protecting your bank of vitamin A that is mostly stored in your liver. Including vitamin A-rich foods in your diet and supplementation are also good ideas.

When approaching supplementation, a couple of things need to be kept in mind:

1. Supplements of beta-carotene (or foods containing it such as orange and yellow plant foods) are NOT the same as those with vitamin A. Beta-carotene is the metabolic precursor of vitamin A; it must be converted into real vitamin A in the intestines along with the help of bile salts, thyroid hormone, and dietary fat. Infants, and those with diabetes, alcoholism, hypothyroidism, and/or liver or gall bladder problems cannot make this conversion or do so very poorly. Additionally, the body=s conversion of beta-carotene to active vitamin A is very poor: it takes roughly 6 units of beta-carotene to make just one unit of vitamin A. Fish liver oils, especially cod liver oil, are preferred as supplemental sources. Avoid all synthetic sources of vitamin A. (It should be noted that betacarotene has other uses besides being a vitamin A precursor.)

2. Consumers are often warned that vitamin A can be toxic if taken to excess. Such warnings are overblown. Though vitamin A can produce toxicity symptoms if taken to excess, it takes a huge and massive amount to generate them. There have been studies done of people who have taken 300,000 units of vitamin A a day for over a year with NO adverse effects. Additionally, the toxicity symptoms of excess vitamin A disappear quickly once supplementation is stopped.

Foods rich in vitamin A include liver, eggs, butter, whole milk dairy products, shellfish, fish roe, and cod liver oil. It should be noted here that low or non-fat dairy products contain very little to no vitamin A. Because vitamin A is required for protein utilization by the body, whole milk dairy products are better nutritional choices.

Supplementing with vitamin A could be a wise choice for those of you facing immune dysfunction, vision problems, poor thyroid function, and infections of the respiratory or urinary tracts, in combination with a nutrient-dense diet that eliminates refined sugars, margarine, vegetable oils, processed foods, and drugs. I suggest to my HIV+ clients 1-2 teaspoons of cod liver oil each day (its easy to take with a little water) as a good source for vitamins A and D, and EPA and DHA, two omega-3 fatty acids intimately involved in the health of the immune and nervous systems. If an infection occurs, its best to avoid large doses of cod liver oil in favor of isolated vitamin A supplements derived from fish liver oil. Amounts to take will vary according to the person, but a safe amount would be 50,000 IUs a day until the infection is gone or under control.