bone up on puppy food

See, it's like two sets of workers inside your bones.  One crew is taking down anything that looks weak or corrupt, the other crew is putting up new arch ways and a strong honeycomb structure.
Human bones are made up of connecting rods and stalagtite looking structures and arches.  If we don't get enough nutrition and calcium, and as we enter old age, the crew that puts up the new stuff falls behind.  Bone density goes down, breaks may occur.
Doctors love to push Fosamax and other drugs to fix this.  They increase bone density, partially by laying off the crew that tears out the faulty old material.  The bone is not always stronger as a result of this adding new bone over rotten bone, it's heavier, denser, but not always stronger, breaks may still occur.  The drug industry however profits, so it's considered a net good.

The best prevention and treatment is to keep both bone crews on the job: 1) exercise, walking and weight bearing.  Swimming and biking have little impact.  2) phylates, a nutrient in seeds, whole grains, beans, greens, nuts.  You need to eat a few servings of these every day.  Added benefit, all of these also reduce weight, cut diabetes, heart disease, blood pressure and they have lots of calcium.

In 1949 phylates got a bad rap, a test on puppies indicated they caused bone loss.  Finally someone decided to study humans to addresses this issue, so the results are astonishing, it turns out don't feed puppies walnuts and pinto beans, instead eat them yourself and you both avoid osteoporosis.