Q. My doctor says I have a low vitamin D level and recommended I take supplements. What does this mean?

Jianming Han, MD, PhD

A. Vitamin D is very important for bone health, as it is essential for promoting calcium absorption in the stomach. Typical diseases caused by vitamin D deficiency are Rickets in children and osteomalacia (soft bones) in adults.

Vitamin D deficiency is associated with increased risk for cancer (particularly colon, prostate, and breast); hypertension, and autoimmune diseases (e.g., multiple sclerosis and type I diabetes). It is also related to depression, fatigue, muscle weakness, and chronic pain syndrome. A study in older patients showed that vitamin D3 supplements (700 IU-1000 IU/day) lowered the risk of falls by 19%. The protective effect of vitamin D appears to be linear: as vitamin D3 levels increase (within the therapeutic range), there is an associated decrease in morbidity. In other words, Vitamin D enhances overall wellness.

What causes Vitamin D deficiency or insufficiency? Lack of dietary intake, insufficient sunlight (especially since concerns about skin cancer result in avoidance of sun exposure and/or use of sunblock), malabsorption diseases (such as celiac disease and short bowel syndrome), use of some medications, and end stage liver disease are all risk factors for vitamin D deficiency or insufficiency.

The simple and effective way to correct vitamin D is oral vitamin D3 supplement. For prevention of vitamin D deficiency, the American Academy of Pediatrics currently recommends 400 IU/day for breast-fed infants; for children and adolescents at risk of vitamin D deficiency (dark skin or inadequate sun exposure), a daily supplement of 400-1000 IU/day of vitamin D3 is recommended; for adults at risk (older than 50, pregnant, or lactating), 800-1000 IU/day is recommended.

Casual sun exposure should meet vitamin-D needs. Approximately 5-30 minutes of sun exposure between 10:00pm and 3:00pm at least twice a week to the face, arms, legs, or back without sunscreen usually leads to sufficient vitamin D synthesis.