"I base that hypothesis on the fact that their bone turnover markers are normal, vitamin D is higher than normal and inflammation is low," he says. "We think it's possible these people don't have increased risk of fracture but that their low bone mass is related to the fact that they are lighter because they take in fewer calories."
Fontana says more study is needed to prove that raw food vegans have light-but-healthy bones. One study could involve following large groups of them for years to look at fracture rates. Other, more imminent studies will involve using micro MRI to get a 3-D look at bone architecture and structure. Those studies could begin soon.
In the meantime, Fontana isn't telling people to follow such an extreme diet.
"I think over the long term, a strict raw food vegan diet could pose some health problems," he says. "But it's not my role to tell them to eat differently. I'm simply interested in learning about the positive and/or detrimental health effects of this diet.
"However," he concludes, "if someone wishes to improve their health and reduce their risk of cardiovascular disease and cancer, I would definitely suggest that they get away from the refined and processed foods that Americans usually eat and try to eat a wide variety of nutrient-dense foods, such as vegetables, fruits, whole grains, legumes and fish."