Vitamin D deficiency is common in the developed world, and according to at least one study, people with very pale skin are most likely to be seriously deficient. Researchers at the University of Leeds in the United Kingdom took the vitamin D levels of about 1,200 people. They found that 730 had lower than optimal levels, and those with fair skin had significantly lower levels. The possible reason? People with very fair skin tend to avoid the sun because they burn easily, making it difficult for their bodies to make sufficient “D” from sun exposure. This suggests that if you have fair skin and tend to avoid direct sunlight, supplementing may be especially important for you. Dr. Weil recommends 2,000 IU of vitamin D daily in the form of D3 (cholecalciferol) rather than D2 (ergocalciferol).