DEAR DR. BLONZ: My hairstylist recommended I get a biotin supplement to help strengthen my hair. I would like some insight as to whether this makes sense, and if so, why I hadn't heard of this until now. -- V.H., Oakland, Calif.
DEAR S.F.: Biotin is a vitamin that plays a role in the metabolism and synthesis of fats, amino acids and carbohydrates. As such, it is important that we have this nutrient in our diet. Biotin, however, is only needed in small amounts, and deficiencies are rare. An adequate intake of biotin for adults is 30 micrograms per day (one microgram is one millionth of a gram). Symptoms of a biotin deficiency include hair loss and skin rashes, but if there's no deficiency to start with, there is no evidence that taking amounts above normal body requirements can solve hair, skin or nail problems.
Foods that contain biotin include organ meat, oatmeal, egg yolks, milk, soybeans, peanuts, whole grains, fruits and vegetables. It is also known that biotin can be synthesized by the bacteria that live in our large intestine, though it's unclear how much of this biotin we actually absorb.
While we are on this topic, here is an interesting side note about biotin and eggs. While egg yolks are a good source of biotin, there is a compound in raw egg whites, called avidin, that prevents biotin from being absorbed. Biotin deficiencies have been found in individuals who consume large quantities of raw egg whites. Perhaps this was nature's way of keeping the fox out of the hen house.
DEAR DR. BLONZ: Can vitamin K creams help remove spider veins? -- C.S., Berkeley, Calif.
DEAR C.S.: Spider veins are small red blood vessels usually found on the legs near the skin surface. They fan out from a small branch of a blood vessel near the surface. Treatment involves locating and disrupting the blood supply. Spider veins are not a sign of poor health in and of themselves, but they can be a source of embarrassment.
Vitamin K plays a role in blood coagulation (clotting), and current treatments of spider veins involve coagulation, or blocking the blood flow to the visible vessels. One medical technique uses a laser to "photo-coagulate" the master vessel feeding the veins, while another uses a saline injection to bring about the desired blockage.
The idea that an externally applied vitamin K cream might clear up spider veins seems straightforward, but there is little in the way of evidence to support this use. It is also not advisable to take vitamin K by mouth in the hopes that it can eliminate spider veins. As a caution, individuals with a blood-clotting disorder, or those taking anticoagulants, should speak with their physician before using any product containing vitamin K.
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