Nutritional deficiencies are almost never a cause of hair loss.
In situations where hair loss is in fact the result of a nutritional deficiency, many other far more serious symptoms are usually evident as well. Nutritional treatments for hair loss are only effective in the rare situations where a nutritional deficiency actually exists. Anemic people generally appear pale and weak. Women with heavy menstrual flows lose iron contained in their menses. If their diets do not supply adequate iron to replace the iron lost each month, an iron deficiency and thinning hair can result.