Several at-risk subpopulations for poor vitamin D status have been identified. Except for migrant populations, these groups have already been mentioned previously.
Elderly individuals prefer to stay indoors and many are actually 'shut-ins' who have little opportunity for direct sun exposure (UV-B does not penetrate glass windows in rooms or solaria). The shut-ins are most likely to be deficient in vitamin D and calcium and at increased risk for fractures of the hip, especially with increasing age. They need supplementation on a daily basis with a calcium salt (—1000 mg of elemental calcium) plus vitamin D (400 IU or more) to counter not only hypovitamino-sis D but also secondary hyperparathyroidism and possibly osteoporosis. Two large prospective trials have demonstrated efficacy of such therapy in reducing hip and other nonverteabral fractures.
Vegans are at risk of low serum 25(OH)D3 and the pathologic changes mentioned above for the elderly unless they consume a supplement of vitamin D and calcium because plant foods are typically low in each nutrient. Fortification of plant foods, such as of soy milk, may overcome this concern.
Long-Term Breast-Fed Infants and Young Children of Dark Skin
Although breast-feeding is strongly recommended and lauded, the switching of infants from breast-milk to other beverages does not always include cows' milk or other calcium-rich drinks. In the southern US, this switching has led to a modest epidemic of rickets, which should not occur with our established knowledge about causation. Dark pigmentation reduces the efficiency of the skin to produce vitamin D and because many children with such skin coloration do not tolerate milk (lactose) well, they consume too little vitamin D and calcium. Supplementation and/or alternate food sources should easily correct these nutrient deficits.
Migration of dark-skinned people, especially Muslims, from the Middle East and other Asian nations to the UK and other Northern European nations has led to decreased skin production of vitamin D, especially in the winter months, and to reported cases of rickets and osteomalacia. Cultural practices, i.e., limited food selections and clothing that covers the bodies of women and children, contribute to the etiology of these diseases. Supplementation with calcium and vitamin D should prove effective in promoting bone health of affected individuals.
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