Vitamin D is also produced by exposure to moderate direct sunlight, although such exposure can have photoaging and carcinogenic effects on the skin. Synthetic forms of vitamin D are under study. Vitamin E is a common supplement. This high dose also acts as an anticoagulant, which may lower the risk of myocardial infarction. Whether the high dose increases the risk of bleeding remains unclear.
Vitamin E improves cellular immune function, which potentially lowers the risk of infection.
Vitamin E complex, which contains various subtypes of vitamin E, may be more beneficial than -tocopherol alone. Thiamine deficiency usually occurs with deficiency of the other B vitamins. Symptoms of deficiency, which are vague, include anorexia, weight loss, confusion, apathy, and weakness. Isolated thiamine deficiency can lead to beriberi, causing heart failure and peripheral nerve damage. Deficiency is very rare in developed countries but can occur with psychiatric eating disorders.