Tl;dr Read the very short version of this here.
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?
