Since it is clear that vitamin D deficiency is a public health concern (at least in regard to bone health), how does one ensure adequate vitamin D intake (from Holick MF. NEJM 2007;357:266-81)?
1. Food – fish, cod liver oil, shitake mushrooms – one can usually take in about 300-500 IU vitamin D from a serving of each of these items. Many dairy products and breakfast cereals are fortified with vitamin D (usually D3) but a standard serving usually only provides about 50-100 IU of vitamin D.
2. Sunlight – exposure to direct sunlight (depending on time of day, season etc.) to just the arms and legs for as little as 10 min can provide up to 3000 IU of D3. Obviously, excessive exposure to sun and sunburn should be avoided because of the increased risk of melanoma and other skin disease.
A. Over the counter: Most contain D3and are provided in a variety of strengths (discussed later).
B. Prescription: These contain D2and are available in 8000 IU/ml liquid (for children) and 50,000 IU gelcaps.