Biotin

Daily Value: 300 micrograms

Good Food Sources: Brewer's yeast, corn, barley, soybeans, walnuts, peanuts, molasses, cauliflower, milk, egg yolks, fortified cereals

Your nails are a disaster. They've been clipped, filed and buffed, then coated with polish. And they still look thin, brittle and pathetic.

They will never appear in Vogue. But they do happen to be just about the first thing folks notice when you shake hands or pet their dogs. So what are you gonna do?

Well, you may want to take a tip--no pun intended--from some of the men and women who went to a nail doctor in New York City. In a study conducted by Columbia University College of Physicians and Surgeons in New York City and Thomas Jefferson University Hospital in Philadelphia, these people took an average of two milligrams (2,000 micrograms) a day of biotin, a B-complex vitamin that is necessary for your body to process the fat and protein that you eat.

Except for those of us who have brittle nails or a genetic inability to absorb biotin, most people really don't need to worry about whether or not they're getting enough. That's because unless you have a genetic defect that alters the way your body uses this nutrient, either you get enough of it through the eggs, milk and cereals in your diet or your body will manufacture what you need.

People with Type II (non-insulin-dependent) diabetes may prove to be a different story. When Japanese researchers studied the biotin and blood sugar levels of people with diabetes, they found that the higher someone's blood sugar, the lower his level of biotin. They also noted that people with diabetes have significantly lower biotin levels than people who don't have the disease.

Nobody knew quite what this meant, but the researchers wanted to see what would happen if they raised biotin levels in those with diabetes. So they gave nine milligrams (9,000 micrograms) of biotin to 18 people with diabetes every day for a month.

The result? After 30 days, the participants' blood sugar levels fell to nearly half of their original levels. For the full details on using nutrients to treat diabetes, see page 211.

Using Biotin Safely

Biotin may be one of the safest of all vitamins. There are no reports of toxicity, even when it's taken in high doses above the Daily Value of 300 micrograms.

Biotin is destroyed by certain food-processing techniques such as canning and heat curing. So it's always better to choose fresh fruits, vegetables and meats over canned or cured foods.