Frequently, proponents of a raw food vegetarian diet claim that it is the ideal diet for human health. This is not the case for bone health according to the results of a study conducted by Dr. Luigi Fontana from the Instituto Superiore di Sanita in Rome in collaboration with researchers at the Washington University School of Medicine in St. Louis. Their study compared 18 people who had been eating raw food vegetarian diets for an average of 3.6 years to 18 individuals who consumed typical American diets. The raw food group had significantly lower bone mineral content and bone mineral density in comparison to those eating standard fare.

The average bone mineral density T scores for both female and male vegetarians were about –2.0 at the lumbar spine and approximately –1.8 for women and –1.5 for men when measured at the hip. These T scores are diagnostic of osteopenia (T scores from –1 to –2.5) and are reason for concern and taking serious measures for osteoporosis prevention.

Due to the small number of participants in this study and the fact that the researchers can’t be sure that the low bone mineral density did not exist in these people before they started eating a raw vegetarian diet, additional research is needed to confirm their results. However, the results make sense because the diets of these vegetarians were low in calcium, vitamin D, and protein. This would be expected to result in a loss of bone mass with any type of diet - raw, cooked, vegetarian, or otherwise. Read more about osteoporosis prevention.

Source
Fontana, Luigi, et al. “Low bone mass in subjects on a long-term raw vegetarian diet.” Archives of Internal Medicine 165 (2005): 684-9. (See article abstract)