(Second in a series)

MANILA, Philippines ? Animal protein is being attributed as the cause of bone loss and fractures as indicated in several studies. And if you think cow?s milk is synonymous to stronger bones and calcium, better think twice.

A study conducted by Yale University School of Medicine in New Haven, Connecticut, cited that age-adjusted female hip fracture incidence has been noted to be higher in industrialized countries.

A possible explanation that has received little attention is that elevated metabolic acid production associated with a high animal protein diet might lead to chronic bone buffering and bone dissolution.

Female fracture rates

In an attempt to examine this hypothesis, cross-cultural variations in animal protein consumption and hip fracture incidence were examined. When female fracture rates derived from 34 published studies in 16 countries were regressed against estimates of dietary animal protein, a strong, positive association was found.

The authors of The China Study: Startling Implications for Diet, Weight Loss and Long Term Health? cited this report that summed up data on protein intake and fracture rates, saying these were published in 29 peer-reviewed research publications.

?All the subjects in these surveys were women 50 years and older. It found that a very impressive 70 percent of the fracture rate was attributable to the consumption of animal protein,? stressed T. Collin Campbell and co-author Thomas Campbell. T. Collin Campbell is the Jacob Gould Schurman professor emeritus of Nutritional Biochemistry at Cornell University.

The study said this association (fractures and animal protein) could not be plausibly explained by either dietary calcium or total caloric intake. Recent studies suggest that the animal protein-hip fracture association could have a biologically tenable basis. ?We conclude that further study of the metabolic acid-osteoporosis hypothesis is warranted.?

Scientist Jane Plant, author of the ?No Dairy Breast Cancer Prevention Program,? cited calcium loss from the body as a result of ingesting animal-based proteins:

Buffering mechanism

?A diet high in animal-based proteins increases the amount of acid in the body. This triggers a buffering mechanism, which releases stored calcium from the bones. The body would normally reabsorb the calcium released, but the animal protein inhibits the para-thyroid function that controls this re-absorption. The body then excretes the calcium, causing bone loss.?

Plant then cited research suggesting that ?a diet high in vegetable protein might actually be somewhat protective against osteoporosis.?

The Campbell authors also cited numerous studies showing countries that consumed the most cow?s milk and its products also had the highest fracture rates and the worst bone health among its populace.

Campbell cited a Lancet study (1968) that explained animal protein, unlike plant protein, increased acid load in the body.

?An increased acid load means that our blood and tissues become more acidic. The body does not like this acidic environment and begins to fight it. To neutralize the acid, the body uses calcium, which acts as a very effective base. This calcium, however, must come from somewhere. It ends up being pulled from the bones, and the calcium loss weakens them, putting them at greater risk for fracture,? Campbell said.

He added: ?We have evidence for well over a hundred years that animal protein decreases bone health,? citing ?Acid Loading and Osteoporosis? at the Journal of the American Geriatric Soc 30 in 1982.

The explanation of animal protein causing excess metabolic acid, for example, was first suggested in the 1880s and was documented as long ago as 1920.