July 18, 2017
One very important mistakeBy Marilyn Goebel on March 22, 2009
I found one very important mistake. On page 154 in the chapter about osteoporosis and kidney stones, in a box labeled “Supplements for Osteoporosis” she lists “Vitamin A 20,000 IU daily (forms bone matrix)”. There are several studies about vitamin A and bone density that show that vitamin A above 5,000 IU daily is bad for the bones. Since many foods, such as low fat milk and margarine are fortified with vitamin A, it is very easy to get a toxic amount of vitamin A, even if you take only a multivitamin. Some multi-vitamins or cod liver oil can put you in the toxic range. Beta carotene, a precursor to vitamin A, does not harm the bones, so look for a supplement with mostly beta carotene, rather than retinol.
Gregory Bravo 8 years ago
Marilyn is right and wrong in her review. While she is accurate in that there are a few studies showing that vitamin A above 5000 IU have been correlated with lower bone density, those studies are VERY LIMITED in their conclusions. The real reason those studies showed a correlation between vitamin A intake and bone density was NOT because of the vitamin A itself, but rather because of the VITAMIN D DEFICIENCY in the participants!!!!
Most Americans are already borderline or deficient in vitamin D intake. It has been shown that an adult male’s body consumes 4000 IU of vitamin D a day. If you are only getting the USRDA of 400 IU a day, you will end up with vitamin D deficiency quite quickly. Since vitamins A and D use some of the same transporters in the body, having a low D intake while increasing your vitamin A intake will cause vitamin D deficiency symptoms to increase.
HOWEVER, if you have adequate vitamin D intake, you can take massive amounts of vitamin A without any toxicity symptoms at all. This has been shown in NUMEROUS studies with rats. In fact, if the rats have adequate vitamin D intake, this prevents vitamin A toxicity entirely.
So, it is not the intake of vitamin A that causes the loss in bone density… it is ACTUALLY the vitamin D deficiency!!!If you’d like some scientific references, you can check these websites:
http://www.westonaprice.org/basicnutrition/vitamina-osteo.html
http://www.westonaprice.org/basicnutrition/vitaminasaga.html