Does Vitamin A Really Cause Osteoporosis?

Recently, the Journal of the American Medical Association reported a conclusion reached by the 1980 Nurses' Health Study (of 72,337 postmenopausal women over eighteen years): women with the highest vitamin A intake have an 89% higher risk of hip fracture (osteoporosis). (1)

Almost all previous research with vitamin A had shown a benefit to bone health. For example, a study giving rats with bone fractures a dosage of vitamin A equivalent to 10 million IU daily for five weeks reported accelerated fracture healing.(2) But until further investigation of this Nurses' Health Study I decided to reduce vitamin A supplementation in my practice.

We now have the further investigation.(3) The study measured vitamin A intake in the food the nurses were eating. Their main food sources were A-fortified milk, A-fortified breakfast cereals, A-fortified margarine, and liver. Milk has calcium alright (many more nutrients are crucial to bone health besides calcium, by the way), but it also has high phosphorous and too much phosphorous can lead to bone loss. (4) Most margarines and milk contain artery-destructive trans-fatty acids that deplete your body's essential fatty acids which are necessary for good bone health.(5, 6) Most breakfast cereals are very high in sugar. High sugar increases calcium in your urine (7) and causes bone loss at least in animals.(8) The liver of any animal accumulates toxic chemicals, two of which are lead and cadmium (9) and both cause osteoporosis.

So was it really the vitamin A that increased the hip fracture risk? Previous research has shown that it was more likely the dairy products, sugar, liver and trans-fatty acids. In my practice I have gone back to full supplementation of vitamin A and the recommendations for good bone development and maintenance that I have always had: weight-bearing exercise at least three times a week; decrease of animal protein in the diet, especially milk products; and a vitamin and mineral supplement tailor-made from research that showed many nutrients as well as calcium were important for good bone health.

References
1. Feskanich, D. et al. Vitamin A intake and hip fractures among postmenopausal women. JAMA 2002; 287: 47-54

2. Udupa, K.N. et al. Role of vitamin A in the repair of fracture. Indian Journal of Medical Research 1966; 54: 1122-1130

3. Gaby, A.R. Does vitamin A cause osteoporosis? Townsend Letter for Doctors and Patients. 2002: 225 (April): 132-133

4. Calvo M.S. et al. Changing phosphorous content of the U.S. diet: potential for adverse effects on bone. Journ Nutrition 1996; 126: 1168S-1180S

5. Holman, R.T. et al. Effects of trans-fatty isomers upon essential fatty acid deficiency in rats. Proc Soc Exp Biol Med 1956; 93: 175-179

6. Odutuga, A.A., Effects of low zinc status and essential fatty acid deficiency on bone development and mineralization. Comp Biochem Physiol 1982; 71A: 383-388.

7. Lemann, J. Jr. et al. Possible role of carbohydrate-induced calciuria in calcium oxalate kidney stone formation. New Eng Journ Medicine 1969: 280: 233-237

8. Saffar, J.L. et al. Osteoporotic effect of a high carbohydrate diet (Keyes 2000) in golden hamsters. Archives Oral Biology 1981; 26: 393-397

9. Boyer, K.W. et al. Trace element levels in tissues from cattle fed a sewage sludge-amended diet. Journ Toxicology Environmental Health 1981; 8: 281-295

Bruce Lofting, N.D.
April 2002