Vitamin D is necessary for absorption of calcium, which makes it essential for bone health. It has also been investigated for the treatment and prevention of numerous diseases. An article published in Alternative Medicine Review (2005;10(2):94-111) reviewed the requirements and benefits of vitamin D throughout life, in terms of promotion of optimal health. Vitamin D can be made in the skin from a precursor of vitamin D, when there is exposure to the sun. It can also be found in the diet in foods such as dairy products, which are fortified with this vitamin, and in fatty ocean fish. However, most people do not consume optimal levels of vitamin D in their diet.
The earliest requirement of vitamin D for life is during pregnancy and lactation, when vitamin D is essential for bone development. In childhood, vitamin D is necessary to prevent rickets. In adulthood, we still require vitamin D for bone health, but also for its protective effect against muscle weakness, internal cancers, type I diabetes and multiple sclerosis. The exact amount of vitamin D required depends on exposure to UVB light from the sun which can vary in intensity based on latitude, time of day and season. As well, the amount of vitamin D made in the body is also dependent on amount of body fat, skin pigmentation and the fraction of skin exposed to sunlight. The authors state that vitamin D blood levels are the most reliable indicator of vitamin D status, and should be in the range of 30-50ng/mL for optimal health.
The current US recommendation for intake to prevent deficiency related to bone density is 200 IU per day for children and younger adults, 400 IU/d for people aged 51-70 and 600/d for those over 70. However, this article suggests that based on the amount required for health and the prevention of other diseases, the recommendation should be raised to 1000 IU for children and younger adults when sun exposure is limited. Supplementation is inexpensive and a convenient way to achieve optimal levels of vitamin D.
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