Nearly Half of Women are Vitamin A Deficient
A newly discovered genetic variation may be the reason why nearly half of women in the United Kingdom are vitamin A deficient. This previously unknown variation appears to reduce the ability to produce sufficient amounts of vitamin A from beta-carotene, according to researchers.
Retinol, or preformed vitamin A, is found only in animal foods, while fruits and vegetables contain carotenoids that also provide vitamin A activity. The body can convert certain carotenoids (e.g., beta-carotene, alpha-carotene) into vitamin A. These carotenoids are sometimes called “provitamin A,” while retinol is “preformed vitamin A.”
Vitamin A is essential for strengthening the immune system, which is critical for fighting infections such as flu and other respiratory conditions. This vitamin is also important for maintaining healthy skin and the mucus membranes inside the lungs and nose, and for preserving eyesight.
A study published in the New England Journal of Medicine in 1995 found that excessive intake of vitamin A during pregnancy could cause certain birth defects. Provitamin A, or beta-carotene, however, was determined to be safe, and this finding resulted in a general consensus that people should eat more beta-carotene and let the body do the conversion as needed.
The new discovery of the genetic variation by investigators at Newcastle University indicates that for many women, beta-carotene is not an effective substitute for vitamin A. Dr. Georg Lietz, who led the research team, noted in the University’s news release that “many women are simply not getting enough of this vital nutrient because their bodies are not able to convert the beta-carotene.”
This conclusion was reached after the study team evaluated a group of 62 women and discovered that 29 of them (47%) had a genetic variation that prevented them from effectively converting beta-carotene into vitamin A. The study also showed that all the women were consuming only about one-third of their recommended intake of preformed vitamin A, which made them vitamin A deficient. Foods that contain preformed vitamin A include dairy products such as eggs and milk, as well as liver. These are foods that younger women are less likely to eat than are older women. Therefore younger women may be at greater risk of vitamin A deficiency.
For now, researchers will attempt to determine whether this genetic variation also occurs in men and whether body composition has an impact on the ability to absorb and transform beta-carotene into vitamin A. Women, however, should be aware that they may be vitamin A deficient and take steps to ensure they get an adequate amount of this important nutrient.
Newcastle University news release, Nov. 17
Rothman KJ et al. New England Journal of Medicine 1995 Nov 23; 333(21): 1369-73