Vitamin D

Vitamin D is a fat-soluble vitamin that plays a role in many important body functions. It is best known for working with calcium in your body to help build and maintain strong bones. Vitamin D is also involved in regulating the immune system and cells, where it may help prevent cancer.

Your body stores vitamin D and can make it when your skin is exposed to sunlight. Vitamin D is also found in some foods, mostly ones like milk that have been fortified with vitamin D. There are two forms of vitamin D: ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). Some research suggests that cholecalciferol is better at raising levels of vitamin D in the blood.

In children, a vitamin D deficiency can cause rickets, a disease that results in soft, weak bones. In adults, many people may not be getting enough vitamin D, especially those who live in northern areas (like the northern half of the U.S.) and the elderly. People with dark skin do not absorb sunlight as easily as those with light skin, so their risk of low vitamin D is even higher. One study of childbearing women in the Northern U.S. found that 54% of African-American women and 42% of white women had low levels of vitamin D.

That’s important because researchers are beginning to find that low levels of vitamin D may be linked to other diseases, including breast and colon cancer, prostate cancer, high blood pressure, depression, and obesity. The evidence doesn’t prove that too little vitamin D causes these conditions, but that people with higher levels of vitamin D are less likely to get these diseases.

Uses

Getting the proper amount of vitamin D may help prevent several serious health conditions.

Osteoporosis

Vitamin D helps your body absorb and use calcium, which you need for strong bones. Getting enough vitamin D throughout your life is important, since most bone is formed when you are young. For post-menopausal women who are at higher risk of osteoporosis, taking vitamin D along with calcium supplements can reduce the rate of bone loss, help prevent osteoporosis, and may reduce the risk of fractures.

Other Bone Disorders

Vitamin D protects against rickets and osteomalacia, softening of the bones in adults. Seniors who live in northern areas and people who do not get direct sunlight for at least 45 minutes per week should make sure they get enough vitamin D through fortified milk and dairy products. Or they can take a vitamin D supplement or a multivitamin with vitamin D.

Prevention of Falls

People who have low levels of vitamin D are at greater risk of falling, and studies have found that taking a vitamin D supplement (700 - 1000 IU daily) may reduce that risk. In seniors, vitamin D may reduce falls by 22%.