> Food and Nutrition > Vitamins > vitamin A

I am constantly amazed at how scientific studies can bemisused to create confusion.

The latest in “Gullible’s Travels” is a report out of Sweden (published in The New England Journal of Medicine and aired on North American news networks Jan. 22, 2003) that consuming 1.5 milligrams of vitamin A per day causes brittle bones.

If that were true, all liver, vitamin A and beta-carotene supplements and vegetables with vitamin A and beta-carotene content in excess of 1.5 mg should, like toxic drugs, be made available by prescription only.

Beta-carotene is a pro-vitamin or precursor to vitamin A and is found in vegetables and fruit in varying amounts. Vitamin A is synthesized in the livers of all mammal sand fish.

Three-and-a-half ounces of fried beef liver contains 35,000 to 40,000 international units (IU) of vitamin A. That is the same form of vitamin A in that yucky tablespoon of cod liver oil your mother may have given you as an infant. That amount of vitamin A is equivalent to 21 to 24 mg of beta-carotene, since one IU of vitamin A equals 0.6 micrograms of beta-carotene.

One medium-size carrot (a rich source) contains 10,000 IU of vitamin A, the equivalent to six mg of beta-carotene. The true sweet potato–commonly and erroneously referred to as a yam–is extremely high in beta-carotene, which can be well in excess of 30,000 IU of vitamin A in an average serving. Beets, pumpkin, squash, broccoli and leafy greens are all rich in beta-carotene.

Unfortunately, the news reports did not specify if the Swedish men in the above study were supplementing with synthetic or natural beta-carotene, or natural vitamin A from fish liver oil or synthetic A from palmitates. A previous study also out of Scandinavia suggested a synthetic beta-carotene may be a carcinogen.

The current study compared blood levels of both beta-carotene and retinol (vitamin A). There was no mention of calcium, magnesium or vitamin D intakes. Vitamin D status in northern latitudes is critical since summer exposure may not be enough to store sufficient vitamin D to carry bone health through the winter. Good magnesium intake also gives bones tensile strength and makes them less brittle.

It would be more appropriate to assess calcium, magnesium and vitamin D status before scaring the general population away from beta-carotene and vitamin A.

A simple check with the human nutrition branch of the US Department of Agriculture would confirm that vitamin A deficiency among the US population is prevalent. Canada is no different in this respect, according to Nutrition Canada surveys. Too many people are not eating enough carotenoid-rich vegetables, and liver is not exactly a favourite on most people’s menus.

When one has an infection, the body’s requirement for vitamin A increases. If there is inflammation and fever, the need for this vitamin increases dramatically. Requirements for nutritional factors that work with vitamin A, such as zinc and vitamin B₆, also increase the need for vitamin A.

Despite this study, evidence in the medical literature underscores the importance of dietary vitamin A. One of the most significant long-term studies in the International Journal of Vitamin Research conclusively demonstrated that dentists and their spouses who consumed 10,000 IU or more daily of vitamin A were found to be healthier than those who consumed less.

References: International Journal of Vitamin Research 1970; 40(2): 125-130. Croft Woodruff, a vitamin retailer and health activist for EDTA chelation therapy, founded and currently co-hosts the longest-running alternative health radio program in Vancouver on Oldies Radio CISL 650. Phone: 604-324-2121.

Source: alive #247, May 2003