Remember the ads: milk - it does a body good. Those must've been scientifically based, right? There is no possible way that lobbying groups played a role in that ad campaign. Also, it's just sensible that bones have calcium; therefore, we have to pummel the body with piles of calcium-rich foods, right?
Well, it turns out that milk is not the densest calcium-rich food. Various green veggies are. Whoops.
It also turns out that osteoporosis and hip fracture rates are highest in the developed world with the highest intakes of calcium: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3004072/. Hmm. That's weird, huh?
It also turns out that very high calcium intake appears to be causal in cardiac event risk and arterial plaques: https://www.sciencedaily.com/releases/2017/08/170808145454.htm. The National Institutes of Health was loathe to admit this connection, but finally has, even though they long ago took to supporting the eat-lots-of-calcium mythology. Oops.
Fat soluble vitamins (which we long ago removed from dairy in our low fat and no fat efforts) are actually responsible for how your body lays down bone matrix: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5494092/.
Intense physical activity tells your body to build strong bones. This is probably at least a small part of the reason females have a higher propensity toward bone mass loss than males. We now know that perfectly healthy astronauts get osteoporosis within just a few weeks of weightlessness. So, again, loading the skeleton is of paramount importance.
But then, there's this cute little piece of the puzzle that somehow everyone missed. Well, everyone in the mainstream medical and scientific communities missed it (and some still aren't up to date). Now, expert consensus agrees that higher dietary protein intake has a vital role in skeletal health: https://www.iofbonehealth.org/news/expert-consensus-finds-higher-protein-intake-benefits-adult-bone-health. The rest of us in the health and fitness fields who've long emphasized legitimately beneficlal and effective training and nutrition were talking about this while we were being readily naysaid ten, fifteen, twenty years ago. Protein. It's been known forever to make up the vast majority of bone by volume. Yet, we strength coaches and trainers who recommended moderate to high protein were considered irresonsible, bro-science touting, and playing with fire with regards to kidney pressures and acid load. Whoopsie! I guess television commercials weren't infallable founts of perfect nutritional information.