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Dr Russ Blog - Multivitamin Report Card: A-minus?
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Multivitamin Report Card: A-minus?
Created on 5/13/2008
Vitamin A is important to health, including the proper functioning of our bones and eyes (in fact, vitamin A is often referred to as retinol because it is so important to the retina of our eyes). You may have also heard about one of the carotenes called beta carotene, sometimes called provitamin A, because in our bodies it can be turned into vitamin A. The two are related but very different, both are frequently found in multivitamins, and therein lies a potential problem.
Vitamin A and carotenes from dietary sources are safe because the amounts present in foods are relatively low, yet adequate to prevent deficiency states. On the other hand, the concentrations of vitamin A and beta carotene typically contained in multivitamins are very high. Though vitamins are natural, remember that what is natural is not synonymous with what is safe, especially when the dosage is high.
Moderately high intakes of vitamin A over time can contribute to bone weakening, or osteoporosis, in both women and men. Very high intakes of vitamin A (more than 25,000 IU each day) can cause significant illness / toxicity. Supplemental beta carotene is also not completely safe, especially for those of us who smoke or who have smoked in the past. High intakes of beta carotene (typically greater than 20,000 IU per day) in smokers have been linked to an increased risk of lung and colon cancer.
To be honest, most people in developed countries don't need supplemental vitamin A because our access to healthy food sources is plentiful. The best way to get adequate levels of vitamin A into your body is to enjoy a well-balanced diet that includes low fat dairy products, eggs, fish, and meat in moderation. Carotenes, including beta carotene, are best obtained by enjoying many different colored fruits and vegetables each day.
If you intend to take a multivitamin, use one that doesn't contain any vitamin A or provides you with less than 4,000 IU per day when taken properly. Keep beta carotene levels from supplements, including your multivitamin, at or below 10,000 IU per day. If you smoke or have a history of smoking in the past, avoid supplemental beta carotene altogether, but regularly enjoy eating the full range of fruits and vegetables. Again, eating foods that are high in vitamin A and carotenes appears to be good for us; it's the much higher dosages found in supplements we need to be careful about.
Be well.
Dr. Russ
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