Fingernail strength -- like hair thickness, skin tone, and shoe size -- is subject to a lot of normal variation. If you're a healthy person with no obvious nutritional deficiencies, research suggests that vitamins are unlikely to help strengthen your nails. This doesn't mean you are without options if you want to strengthen your nails.
For Most People, Vitamins Won't Help
Many supplements are sold with the promise of strengthening nails, but the available scientific research doesn't back up most of those claims. For example, one set of researchers published an article in the August 2007 edition of "The Journal of Drugs in Dermatology," in which they examined all the available research with regard to vitamins and nail strength. They found no evidence to support the use of vitamin C, vitamin E, vitamin B12, vitamin A, retinoids, retinol or retinal. And they didn't look only at vitamins -- their study found no evidence to support using zinc, iron, copper or selenium, either. An exception was the use of biotin, which appeared to help in some cases of brittle nail syndrome.
What You Can Do Instead
The American College of Osteopathic Dermatology offers many tips for preventing nails from becoming brittle, split or overly soft. For example, avoid repeatedly getting hands wet and dry by wearing gloves when doing housework. They also recommend lotions containing lanolin if dryness is a problem. If, on the other hand, overly soft nails are the problem, household cleaners, nail polish removers and other household chemicals can add to the problem, so limiting your exposure can help. The American Academy of Dermatology emphasizes the importance of being gentle with your nails to prevent additional breaking or splitting. For example, you should avoid using your nails as a tool to pry open the back of a cell phone case. Of course, if you have naturally weak nails, these measures won't cause you to have strong nails, but they might help reduce the problem.
Biotin Might Help in Some Cases
Biotin, also called vitamin H, appears to be one possible exception to the rule: It may help some people with brittle nails, but the evidence is not very strong. In a study published December 1999 in the "Journal of the American Academy of Dermatology," biotin appeared to increase nail thickness and decrease splitting in some individuals with brittle nails. More studies are needed, however, to support possible benefits.
Nutritional Deficiencies Are Rare
If you have a severe problem with your nails -- beyond wishing they were as strong as your friend's or neighbor's -- see your doctor for advice. Although true nutritional deficiencies are extremely rare these days, it's still possible that a vitamin or mineral deficiency could cause problems with your nails. Many diseases or infections can also cause changes in the nails. Getting the appropriate diagnosis is key to knowing how to treat your problem nails, so it's wise to see your doctor before taking biotin or any other supplement.