Vitamin D plays an important role in calcium absorption and in bone health. The relationship between calcium and vitamin D is similar to that of a locked door and a key. Vitamin D is the key that unlocks and opens the door, allowing calcium to leave the intestine and enter the bloodstream. Your body needs vitamin D to use calcium to build healthy bones and prevent osteoporosis. The Institute of Medicine updated the Recommended Dietary Allowances for calcium and Vitamin D in December 2010. The Recommended Dietary Allowance for vitamin D is 600 International Units per day from age 1 to 70 years old, including pregnant or lactating women. For people over 70, 800 International Units is recommended.

Vitamin D supplements are often not necessary because vitamin D is available from foods such as fortified milk, fish, and egg yolks. Your skin also produces Vitamin D from exposure to sunlight. In general, here in Arizona you only need need 10-15 minutes of sunlight daily on your face and arms at midday to maintain an adequate level of vitamin D.

However, although many people are able to get enough vitamin D naturally, studies show that vitamin D production decreases in the elderly and in people who stay indoors, for example, people in nursing homes. These individuals may need to consume more foods that contain vitamin D or take a supplement. Taking more than 4000 International Units of vitamin D per day is not recommended over the age of 9 years or 3000 International Units from age 4 to 8 or 2500 International Units for ages 1 to 3. Massive doses of vitamin D may be toxic and are not recommended unless prescribed by your doctor.