If you have been paying attention to the headlines over the last couple of days, you may be familiar with the recently published study about vitamin A. According to the January 2nd issue of the Journal of the American Medical Association, too much vitamin A may increase the risk for hip fractures in postmenopausal women. With this new information, you should be questioning its relevancy to your own life and wondering whether you should take heed, right? This question cannot be easily answered until we have more information about its application to men and young adults. Nevertheless, this study does show that women beyond their childbearing years should be cautious about their consumption of vitamin A above the recommended daily allowance (RDA). 

It is relatively easy to consume adequate levels of vitamin A through the diet. However, supplements contribute significantly to the intake in the U.S. In fact, according to the Third National Health and Nutrition Survey, the mean intake of vitamin A from supplements alone is 1,338 mcg a day. Compare this estimate to 700 mcg, the current RDA. Most of these supplements are composed of retinol, which seems to be the major contributor to the risk of osteoporotic hip fractures. Nevertheless, vitamin A plays an important role in the proper functioning of our bodies; therefore, it is important to have a good understanding of the nutrient and how different forms of it are metabolized and used by our system.

What is retinol?
Vitamin A includes a family of fat-soluble vitamins and occurs in two forms: retinol and provitamin A (carotene). It is essential for an efficient immune system and is important in maintaining the health of your eyesight, skin, teeth, bones, and mucous membranes. It is easy to confuse retinol with the provitamin A, beta carotene, but it is essential to understand the difference between the two. Retinol is one of the most active, or usable, forms of vitamin A, and is found in animal foods such as liver and eggs. Retinol is often called preformed vitamin A and can be toxic. This condition, called hypervitaminosis A can cause birth defects, liver abnormalities, and reduced bone mineral density that may result in osteoporosis. When toxic symptoms arise suddenly, which can happen after consuming very large amounts of preformed vitamin A over a short period of time, signs of toxicity include nausea and vomiting, headache, dizziness, blurred vision, and muscular uncoordination. For this reason, it is important to check your multivitamins to make sure that the source of vitamin A is not retinol or palmitate. All vitamin supplement products that contain any form of vitamin A must list vitamin A as the main ingredient on the label, even if it is all in the form of beta carotene, so do not be alarmed. Some multivitamins like Cooper Complete have labels that list the ingredient as "Vitamin A (as natural mixed carotenoids)". In such cases, you will have no need to worry. However, in some cases you may have to look at the "other ingredient" section of the label to determine what the product includes. 

What is beta carotene?
Beta carotene, as well as the other members of the carotenoid family, are precursors to vitamin A, meaning that they are transformed into the vitamin after entering the body. The metabolism of beta carotene is much different than that of retinol because the body can convert it into as much or as little of vitamin A as it needs. For this reason, you cannot ingest toxic levels of beta carotene. However, eating high levels of it may actually turn your skin an orange color! This provitamin A has been linked to a lower risk of cataracts, heart disease, and cancers, such as rectal cancer, melanoma, and bladder cancer. The November 4,1994 issue of the Journal of the American Medical Association, stated that the natural carotenoids, including beta carotene (5000 IU) but also lutein and zeaxanthin, have been shown to be effective in decreasing the risk and even reversing the development of age-related macular degeneration, the leading cause of blindness in Americans over 65 years of age. 

Carotenoids, including beta carotene, come in several different forms and are actually better absorbed in a supplement form than from foods. The carotenoids in foods are locked in a fibrous matrix that is difficult for the body to break down. Cooking the foods helps to break down the matrix, which helps to increase absorption, but overcooking could actually break down the nutrients in the carotenoids themselves. Carotenoid supplements, because they do not contain this matrix, are very well absorbed. The natural form of beta carotene comes from a type of algae, usually Dunaliella salina. The natural form of beta carotene has a different composition than the synthetic form. It actually contains a chemical, which is the primary antioxidant part of the vitamin. The synthetic beta carotene, which is water dispersible (acetate and palmitate), does not contain this important element and has much weaker antioxidant properties. 

How is excess vitamin A related to hip fractures?
Vitamin A has long been known to have adverse skeletal affects and now this newly published study provides additional evidence. What we know is that this vitamin can interfere with vitamin D's ability to maintain normal calcium levels, which can contribute to the acceleration of bone resorption and fractures. What we may not realize is how much vitamin A we consume from enriched foods. For example, a tablespoon of fortified margarine contains 150 mcg and many breakfast cereals contain up to 375 mcg per serving. Also, because of the loss of vitamin A from the removal of fat, skim and lowfat milk are also fortified with 150 mcg per cup. It is easy to see how the vitamin A that we consume can add up. This new study is so compelling that it may actually result in a reassessment of the amounts of retinol in fortified foods and vitamin supplements because they add significantly to total retinol consumption in the United States.

For more information about Cooper Complete^® nutritional supplements, go to:  http://www.cooperaerobics.com/supplements