Vitamin D Therapy Dosage

The recommended daily intake level of vitamin D was set in 1997. The U.S. food and Nutrition Board, a branch of the Department of Agriculture, is revising the level, based on research showing that vitamin D may help prevent cancer and other diseases. Currently, most Americans get their vitamin D from fortified foods, such as milk and cereals. But sunlight is still the best source of vitamin D, with no risk of toxicity.

Food Sources of Vitamin D

• Cod liver oil and the skin of fish such as salmon, tuna and mackerel contain high levels of vitamin D. One tablespoon of cod liver oil contains 340 percent of the recommended daily value of vitamin D, while one serving of cooked salmon contains 90 percent of the recommended daily value. Vitamin D-enriched mushrooms contain 100 percent of the daily value. Most foods, however, do not naturally contain vitamin D. Some foods are supplemented with vitamin D, such as milk, breakfast cereals and some types of cheese and yogurt. For people who are at risk of vitamin D deficiency, supplementation is possible.

Recommended Daily Intake

• Vitamin D supplements come in two forms: vitamin D2 and vitamin D3. The two were considered equivalent in their abilities to prevent rickets, but recent studies have shown that vitamin D3 is more efficiently assimilated by the body. The American Academy of Pediatrics suggests that children up to 13 take 400 IU of vitamin D daily. Current recommendations specify that adults 50 and younger should take 200 IU daily, adults from 50 years old to 70 should take 400 IU, and adults older than 71 years should take 600 IU.

Therapeutic Dosages

• According to a November 2007 Canadian Broadcasting Corp. report, therapeutic dosages of vitamin D, aimed at treating disease or severe insufficiencies, can range from 1,000 IU per day to 4,000 IU per day. The Canadian Cancer Society recommends 1,000 IU per day, and the Canadian Association of Naturopathic Doctors recommends 2,000 IU to 4,000 IU per day. According to Health Canada, the maximum safe daily dosage for vitamin D is 2,000 IU. Others disagrees. Dr. David Lescheid, a naturopathic doctor in Toronto, recommends up to 10,000 IU per day.

People at Risk for Deficiency

• Vitamin D supplementation started in the 1930s, when the United States began to fortify milk and cereal products to combat rickets, which was a major health problem. Subsequently, rickets disappeared, and now fortified foods provide most Americans with their vitamin D. Several groups are at risk for vitamin D deficiency, including exclusively breast-fed infants, people with dark skin, people who are obese, people with fat malabsorption, older people and those with limited sun exposure. Generally speaking, people living above 42 north latitude, or from northern California to Boston, do not get enough sunlight from about November to February. People living from Los Angeles to Columbia, S.C., get enough sunlight. But exposure to sunlight through a window blocks vitamin D absorption, so the exposure must be outdoors. Sunscreen also blocks vitamin D. It is not possible to absorb toxic levels of vitamin D through exposure to sunlight.