One of the major factors in bone loss, besides normal aging, is simply inactivity due to a sedentary lifestyle. Astronauts who spend a significant amount of time in low gravity environments suffer rapid decreases in bone density.
There is anecdotal evidence to suggest that eating and drinking large amounts of low pH foods and drinks (like Coke and Pepsi) cause the body to deplete its calcium reserves to maintain proper internal pH balance. Perhaps the soft drink industry would like to fund a study on that?
Protein deficiency is a non-issue. You literally have to be starving yourself to experience protein deficiency. Protein quality, with a few notable exceptions, is a non-issue. Food combining is not necessary for vegans to get adequate protein. The food combining myth was disproven decades ago. There is no basis for the notion that animal proteins are better absorbed by the body. Certain animal proteins, like casein, have been linked to disease in humans.
Studies like the one cited by Outlaw irritate me because I have attempted to make healthy lifestyle changes many, many times over the past decade or so. It takes a lot of will power to overcome long time eating habits. On top of that, I love the taste of foods that are supposed to be unhealthy. So, in the past I would start trying out a new diet and exercise routine. Then I would come across some "study" that suggested I was wasting my time. Finally, I would relapse into old habits, thinking that all the foods I loved weren't so bad after all.
It appears to me that for every bit of good research out there that challenges the dominant, well funded food industry, there's a lot of public relations and marketing designed to minimize or circumvent that research. Large studies cost a lot of money to implement, and researchers have to pay their bills just like everyone else. So, I have to wonder when I read the results of a study that appears to confirm the dominant paradigm, where did the funding for that research come from? Instead of focusing on general measures of health and well-being, why does that research narrow its focus to a single factor? Did the study in question actually deal with osteoporosis, or was mention of that disability added by a public relations team? Why?
Of course, it's not just this study. There seems to be a push to market omega-3 fatty acids and the fish that contain them. Why is that? Eating a lot of oily fish won't overcome the effects of bad lifestyle choices, just like popping vitamin pills won't make someone who eats a lot of junk food healthy.
Dave