MEAT DIETS AND FRAGILE BONES: INFERENCES ABOUT OSTEOPOROSIS

Authors: Klevay, Leslie; WILDMAN, R - UNIVERSITY OF LOUISIANA

Submitted to: Journal of Trace Elements in Medicine and Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2003
Publication Date: 5/1/2003
Citation: Klevay, L.M., Wildman, R.E. 2002. Meat diets and fragile bones: inferences about osteoporosis. Journal of Trace Elements in Medicine and Biology. 16:149-154.

Interpretive Summary: Diets very high in meat have been known to be harmful to bones for nearly 150 years. Data first were gathered on leopards and lions at the London Zoo. Osteoporosis in people tends to be highest in nations that consume the most protein per capita. The characteristic of these diets that is responsible for this association is unknown as is the amount of protein or meat needed to produce the effect. Bones from an experiment with mice fed only on sirloin were carefully broken and breaking strength was recorded. Bones were stronger if the mice also ate liver with the sirloin. Similarities were noted between these results and those from experiments on copper deficiency; it was inferred that lack of copper, rather than too much protein, was responsible for the weakness. The Western diet so closely associated with osteoporosis often is low in copper.

Technical Abstract: Mice fed sirloin are hypercholesterolemic in comparison to mice fed meat and beef liver because of a relative deficiency of copper compared to zinc. Because women supplemented with copper have improved bone density and femurs of rats deficient in copper have decreased mechanical strength, the hypothesis that mice fed meat would have fragile bones was tested. Male, albino, Swiss mice were fed trimmed sirloin or sirloin supplemented with beef liver (3/1 by weight). After 62 days, when hypercholesterolemia was detected, mice were killed and femurs were removed, cleaned and dried. Breaking strength was measured carefully at room temperature. The meat diet produced femurs 23% weaker (8.8 +/- 0.70 N/mgx100 vs 11.4 +/- 0.92, mean +/- SE, p < 0.04) in comparison to meat plus liver. Calcium, copper and phosphorus concentrations were unaffected but zinc was mildly elevated in the weak bones (426 +/- 17.5 ug/g vs 355 +/- 9.23, p < 0.002). These elements generally are unaltered in osteoporotic bones. Because copper deficiency produces osteoporosis in animals and people and because the Western diet often is low in copper, further tests of the hypothesis that diets low in copper contribute to osteoporosis are warranted.