Tl;dr The very short version of this can be found at this link. For the juicy details, stay here!
Let’s start with an enticing tidbit from a paper in no less than the Journal of the American College of Nutrition, with the wonderful title, “”
“In agreement with both experimental and clinical intervention studies, large prospective epidemiologic observations indicate that relatively high protein intakes, including those from animal sources are associated with increased bone mineral mass and reduced incidence of osteoporotic fractures.”
Let’s not be guilty of the same sloppy epidemiological science we accuse other nutrition camps of, though. Epidemiology can generate hypotheses, and give us ideas to think about that then need to actually be tested. Epidemiology can’t prove cause and effect, but it can generally disprove it. For example, in the case of dietary protein, if epidemiological findings suggest that higher protein intakes—including animal protein—are “associated with” better bone health, we can’t conclude that the protein itself is directly responsible for the stronger bones, but we can safely assume that protein isn’t harmful for bones. And in the case of protein and bone mass, we do have pretty good clinical and experimental evidence showing that indeed, higher protein intakes do induce positive changes in bone tissue. Not in cultured bone cells. Not in mice. In actual living, breathing humans.
It’s hard to believe that in certain circles, protein has gotten a reputation as being harmful for bone health. After all, Paleolithic hunter-gatherer diets typically , yet anthropologists can sometimes distinguish the remains of hunter-gatherers from those of agriculturalists solely by examining the bones: the high-protein eating hunter-gatherers typically had bones that were larger, stronger and denser, and showed fewer signs of chronic disease.
Scientists believe the differences in physical activity between the two civilizations played a bigger role than any dietary changes, and sure, hunting and gathering no doubt required a lot of time on one’s feet, but ask any farmer: farming isn’t exactly sedentary work! Even if a heavy physical workload was responsible for Paleolithic peoples’ stronger bones, we can still conclude that a high intake of animal protein didn’t work against building bone mass.
So how did some people come to think that protein—animal protein, in particular—is harmful for bones?