A team of Dutch and Swiss researchers recently reported that vitamin-D deficiency is widespread in
Europe. They found that 36 per cent of elderly men and 47 per cent of elderly women suffer from a lack
of vitamin-D during the winter months(1). Researchers from the Johns Hopkins School of Medicine in
Boston report similar findings(2).
Why a deficiency?
Lack of exposure to sunlight is the main cause of vitamin D deficiency. In recent years medical authorities have exhorted us to avoid the sun and apply sunscreen before we venture outside. This advice is aimed at reducing the astronomical increase in the incidence of skin cancer and melanoma. Recent research, however, has shown that relying on sunscreens to prevent skin cancer and melanoma is counterproductive(6). Research has also shown that regular use of sunscreens completely eliminates the body's synthesis of vitamin D and can lead to a serious vitamin D deficiency(7,8).
Sun avoidance by itself leads to vitamin D deficiency. Windowpanes effectively screen out UVB rays(9). Clothing, whether it be a light cotton shirt or a heavy jogging suit, eliminates or seriously reduces the synthesis of vitamin D(10). Air pollution (ozone and sulfur dioxide) cuts out a large portion of the sunlight needed for vitamin D synthesis and many medications (anticonvulsants, steroids) also interfere with vitamin D formation(2,5,8,9). Vegetarians are at particular risk for vitamin D deficiency because of their high fiber intake and lack of dairy products in the diet(11).
Health authorities have attempted to ensure that people get enough vitamin D through the diet by fortifying milk. This approach, however, is ineffective. Recent research studies have shown that the vitamin D content of milk is highly erractic and many of the samples tested in two recent surveys done in Canada and the United States contained no vitamin D at all(12,13).
Consequences of vitamin D deficiency
Vitamin D deficiencies have also been implicated in the development of breast cancer, melanoma, ovarian cancer, prostate cancer, and of course, osteoporosis and hip fractures(2,3,16,17,18,19,20,21,22,23,24,25,26).
Breast cancer rates in the northeastern part of the United States are almost twice as high as in the south and southwest(3). The incidence of ovarian cancer among women aged 45 to 54 years is five times higher in Indiana than in North Carolina. Researchers ascribe this difference to a vitamin D deficiency in northern states caused by a lack of sunlight(18).
Osteoporosis affects about 24 million people in the United States alone and costs about 10 billion dollars a year to treat. One third of postmenopausal women suffer from osteoporosis and, as a result, experience a total of about 1.3 million bone fractures a year(19). Deficiencies in calcium and vitamin D intake have both been implicated in the development of osteoporosis(19,20,21). Recent research has shown that elderly people receiving a single, large, oral dose of vitamin D (100,000 IU) at the start of the winter had 20 per cent fewer bone fractures than a control group(27).