Calcium intake in a normal diet is about 200mgs per day. That is fine but what matters most is absorption. You can consume all the calcium you want but you will not take it into your body without vitamin D. Vitamin D comes in several forms. It needs to be pre-activated by healthy kidneys and then it needs to be activated by the skin and the eyes. While we are rightfully concerned about skin cancer, we overdo it with sunglasses, hats, and sunscreen which precipitates widespread vitamin D deficiency. For instance, if you spend about 20 minutes in the sun without a shirt on, you will absorb 10,000 international units of vitamin D. Up until recently the recommended daily intake of vitamin D was 200 international units and has recently been increased to 400 international units. I would propose that if our skin is capable of giving us 10,000 international units of vitamin D in 20 minutes, there is a very high likelihood that we need more than 400 international units of vitamin D to be healthy. There is increasing evidence that vitamin D deficiency is increasing rapidly in our population. In the early 20th century, we artificially added vitamin D to milk in order to treat a skeletal disorder known as rickets that was occurring disproportionately in the central part of the country where there was little or no fresh fish consumption. Since that part of the country was dairy country, the best way to get vitamin D in the population to treat rickets was to add it to milk. Currently we should probably consider adding vitamin D to soft drinks as its consumption eclipses milk. Vitamin D is essential to absorbing calcium.
How to build bone? The best answer is to get outside and do weight bearing exercise over the course of your life. Walking and weight training are good for your skeleton. The bone is a living organ. We make it and we dissolve it over and over again. We can modify the process of bone loss which goes along with aging. If we can interfere with the back side of the process, resorbing it, then theoretically we can build up bone. To go back to the bone bank analogy, think of the difference between a checking account and a certificate of deposit. With a certificate of deposit, you put the money in but it’s more difficult to take it out. That’s what happens with medications like Fosamax and Boniva. We make the bone difficult to resorb and therefore make withdrawals from the bone bank more difficult. This works to some extent but only for about 2 years. The problem is the bone that is built up is not properly repaired and then you can end up with a new kind of fracture. There are other ways of messing with your physiology but many of them have significant side effects as well. For instance, we take from the world of cancer treatment medications and apply them in lesser doses for osteoporosis. Virtually all of cancer treatment severely decimates the skeleton and so most cancer regimens use very powerful bone building chemicals to undo the damage of the poison. Unfortunately, chemotherapy is extremely destructive to healthy tissue as well as cancer including the skeleton.