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, “Dietary protein: an essential nutrient for bone health.”
“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 contained a large amount of meat, 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?
