Osteoporosis and Vitamin D
You need to make sure you are getting enough vitamin D, in addition to calcium. Vitamin D helps your body absorb the calcium in your diet and any supplements you take. Our skin actually makes vitamin D when we are exposed to sunlight.
Taking too much vitamin D can be dangerous, so be sure to discuss vitamin D supplements with your doctor before you start taking them. People aged 19 to 50 years should take 200 IU (international units) a day. People aged 51 to 70 years need 400 IU a day and people over 70 years of age should take 600 IU a day. Some experts believe that 800 to 1,000 IU per day is even better at reducing the risk of fractures.
While there are limited amounts of vitamin D in foods, you can get vitamin D from fortified milk, fish and fish liver oils. Fortified foods such as milk are the best source for vitamin D.
With respect to sunlight that helps us make vitamin D, there are a few factors to keep in mind. Northern latitudes, season, time of day, cloud cover, smog, skin color, and sunscreen can affect the amount of vitamin D your skin can make. If you live north of a line running from Boston to the northern edge of the state of California, you will not be able to make enough vitamin D during the winter months of November through February. Complete cloud cover can reduce the energy of the sun's rays by 50%. Shade and severe smog reduce it by 60%. Also, the UV rays in sunlight that are necessary for vitamin D production cannot penetrate glass. Sunscreen also blocks UV rays and can reduce the amount of vitamin D that skin makes. People with lighter skin color tend to absorb more UV rays and produce more vitamin D. African Americans have fewer osteoporotic fractures than whites, however, which appears to be due to several other factors.
Despite the importance of sun exposure in producing vitamin D, it is important to limit the amount of exposure you have to the sun. Exposure to too much sunlight and its UV rays can lead to skin cancer. It is estimated that excess exposure to UV light causes 1.5 million skin cancers and 8,000 deaths due to melanoma, an aggressive form of skin cancer, each year in the United States. Taking vitamin D supplements may be a safer way to get enough vitamin D. Discuss the use of supplements with your doctor.
There is evidence that vitamin D has important benefits beyond strengthening bones. It may help prevent both type 1 and 2 diabetes, hypertension, glucose intolerance (related to diabetes), multiple sclerosis and other health conditions. Vitamin D may also be protective against certain forms of cancer such as cancer of the colon, prostate and breast.
You need to be careful that you don't take too much vitamin D. Excess vitamin D can cause nausea, vomiting, loss of appetite, constipation, weakness and weight loss. Excess vitamin D can also increase the amount of calcium in the blood and cause mental confusion and heart rhythm problems. The combination of calcium and vitamin D supplements may increase your risk for kidney stones. It is important to discuss calcium and vitamin D supplements with your doctor before you start taking them.