It starts with getting adequate calcium in your first 30 years of life.

There are a number of lifestyle factors that can help with the latter:

  • Getting regular exercise, especially weight-bearing and muscle strengthening exercise.
  • Getting adequate vitamin D, whether through diet, exposure to sunshine, or supplements. Look for a multivitamin that supplies 800 to 1,000 IU of vitamin D per day. If your multi only has 400 IU of vitamin D, consider taking an extra supplement. Many people may need 2,000 IU per day (or more) of vitamin D for adequate blood levels, particularly if they have darker skin, spend winters at higher latitudes (such as the northern U.S.), or spend little time in the sun. If you fall into one of these groups, which would include most of the U.S. population, taking 2,000 IU is reasonable and well within the safe range. As always, it’s a good idea to discuss use of supplements with your doctor, and he or she may want to order a vitamin D blood test.
  • Consuming enough calcium to reduce the amount the body has to borrow from bone.
  • Consuming adequate vitamin K, found in green, leafy vegetables. Data from the Framingham Heart Study also shows an association between high vitamin K intake and reduced risk of hip fracture in men and women, and increased bone mineral density in women. (10, 11) Getting one or more servings per day of broccoli, Brussels sprouts, dark green lettuce, collard greens, or kale should be enough to meet the daily recommended target of 120 micrograms per day for men and 90 micrograms per day for women.
  • Not getting too much preformed vitamin A.
  • Reduce your consumption of  caffeine and cola. Although the votes aren’t all in, there is some evidence that drinking a lot of coffee—about four or more cups per day—can increase the risk of fracture. Caffeine tends to promote calcium excretion in urine. Meanwhile, the Framingham Osteoporosis Study has found that older women who drink cola every day have lower bone mineral density than those who drink it less than once a month. (12) This may be due to cola’s high levels of phosphorous, which may alter the dietary balance between calcium and phosphorous and thereby weaken bones.
  • Get enough protein, but not too much. The body needs protein to build healthy bones. But as your body digests protein, it releases acids into the bloodstream, which the body neutralizes by drawing calcium from the bones. Following a high-protein diet for a few weeks probably won’t have much effect on bone strength. Doing it for a long time, though, could weaken bone. In the Nurses’ Health Study, for example, women who ate more than 95 grams of protein a day were 20 percent more likely to have broken a wrist over a 12-year period when compared to those who ate an average amount of protein (less than 68 grams a day). (13) But this area of research is still controversial, and findings have not been consistent. Some studies suggest increasing protein increases risk of fractures; others associate high-protein diets with increased bone mineral density. It is still unclear what level of protein intake provides the best protection against osteoporosis, and more research is needed.
  • Get enough vitamin A, but not too much. Long associated with good vision, vitamin A has also been found to direct the process of borrowing and redepositing calcium in bone. However, too much preformed vitamin A (also known as retinol) can promote fractures. Choose a multivitamin supplement that has all or the majority of its vitamin A in the form of beta-carotene, a vitamin A precursor, since beta-carotene does not increase one’s fracture risk. Many multivitamin manufacturers have already reduced the amount of preformed vitamin A in their products.