"While the World Health Organization had considered six units of beta-carotene to be equal to one unit of vitamin A, the US Institute of Medicine revised this downward in 2002, considering 12 units of carotene in foods on a mixed diet to be equal to one unit of vitamin A. However, even this revision was criticized by a review in the Journal of Nutrition, which reported field studies suggesting that it took 21 units of beta-carotene to equal one unit of vitamin A.50 While the Institute of Medicine's figure considered half of the carotene in oils to be converted to vitamin A, a much higher conversion rate than that for solid foods, a more recent study found that even when carotene is provided as a concentrated dose in the form of an oil, conversion factors range from a minimum of 2.4 to a maximum of 20.2.51 Additionally, several medical conditions interfere with the conversion of carotenes to vitamin A, children have lower conversion rates than adults, and infants cannot make this conversion at all, requiring an animal source of vitamin A.36"
Dioxins in Animal Foods:
A Case for Vegetarianism?
By Chris Masterjohn
www.westonaprice.org



Saying children can't convert carotenes into vit A... very interesting.
Certainly worth trying to prove wrong if you feed your kid vegan.