What Vitamins Are Needed for Strong Nails?

Strong, well-groomed fingernails don't just look good — they're also an indicator of good health. Any type of nutrient deficiency can result in nails that are weak, brittle or malformed, but the vitamins for nails that are most important are the B vitamins and vitamin C.

Chances are that you've seen hair, nail and skin supplements claiming to help you grow stronger, longer nails. Most of these include the B vitamin biotin, sometimes in very large amounts.

Biotin is a water-soluble nutrient that aids the metabolism of fatty acids, glucose and amino acids, which are crucial for healthy body tissues, including nails. A telltale sign of a biotin deficiency is brittle nails, as well as thinning hair and skin rashes. But, according to the National Institutes of Health, biotin deficiency is rare.

In the absence of a biotin deficiency, NIH reports that there is no solid evidence that biotin for nails can improve nail strength. If you have a biotin deficiency, however, your doctor may recommend a biotin supplement. When the deficiency is repaired, you should notice stronger nails.

To prevent a deficiency, meet the Adequate Intake (AI) levels of biotin set by the Food and Nutrition Board of the National Academies of Medicine of 30 micrograms daily for men, women and pregnant women, and 35 micrograms for women who are breastfeeding. According to the NIH, biotin-rich foods include:

• Beef liver: 30.8 micrograms per serving
• Egg: 10 micrograms per one whole egg
• Canned salmon: 5 micrograms in 3 ounces
• Pork chop: 3.8 micrograms in 3 ounces
• Roasted sunflower seeds: 2.6 micrograms in one-fourth cup
• Sweet potato: 2.4 micrograms in one-half cup

Supplements with biotin vitamins for fingernails often contain thousands of times the AI. There is no evidence that taking megadoses of vitamins, in the absence of a deficiency, will have any added benefit. Although biotin is a water-soluble nutrient with no risk of toxicity, taking large amounts can cause other problems.

The NIH reports that high biotin intakes may cause false high or low laboratory test results that could potentially lead to poor management or misdiagnosis of a health condition. If you are taking biotin, be sure to tell your doctor.

Read more: The 10 Best Supplements

Vitamin B12, or cobalamin, is a water-soluble vitamin that also plays a role in the metabolism of fat and protein. It's involved in the creation of red blood cells, neurological function and the production of DNA. Additionally, B12 is associated with skin health, and low levels may manifest in alterations in the nails, according to a review published in the American Journal of Clinical Dermatology in February 2015.

B12 deficiency is more common than biotin deficiency, and certain groups have a higher risk of low B12 levels. These include the elderly, vegans and vegetarians, people with pernicious anemia and individuals who have gastrointestinal problems or who have had gastrointestinal surgery.

B12 deficiency results in a condition called megaloblastic anemia. In addition to nail and skin changes, symptoms include fatigue, weakness, constipation, loss of appetite, weight loss, numbness and tingling in the hands and feet, poor balance, depression, confusion, dementia and a sore mouth and tongue.

The recommended daily intake of B12 is 2.4 micrograms for men and women, 2.6 micrograms for pregnant women and 2.8 micrograms for breastfeeding women. Vegans and vegetarians have trouble getting enough of the vitamin because there are no plant foods that are reliable sources. However, some plant foods are fortified with the nutrient. According to NIH, the best sources of B12 include:

• Clams: 84.1 micrograms per 3-ounce serving
• Beef liver: 70.7 micrograms in 3 ounces
• Fortified nutritional yeasts: 6 micrograms per serving
• Rainbow trout: 3.5 micrograms in 3 ounces
• Light canned tuna fish: 2.5 micrograms in 3 ounces
• Fortified breakfast cereals: 1.5 micrograms per serving

Folate is another B vitamin for nails that plays a role in the metabolism of fats and proteins that contribute to tissue integrity. Also called folic acid, it's crucial for healthy cell growth and cell division as well as DNA creation. Nail abnormalities are one of many manifestations of folate deficiency, and may appear as central ridges, according to a research article published by the Indian Dermatology Online Journal in March 2015.

Like B12 deficiency, folate deficiency also results in anemia, causing weakness, fatigue, irritability, poor concentration, headache, shortness of breath and heart palpitations.

To protect your nails and avoid the other uncomfortable symptoms of folate deficiency, be sure to meet the daily recommended intake of 400 micrograms each day, recommended by the National Academies of Medicine. Pregnant women have increased folate needs of 600 micrograms per day, and breastfeeding women need 500 micrograms daily.

Folate is abundant in plant foods. The NIH reports these food sources high in folate, for example:

• Spinach, boiled: 131 micrograms per one-half cup
• Black-eyed peas, boiled: 105 micrograms in one-half cup
• Fortified breakfast cereals: 100 micrograms per serving
• Asparagus: 89 micrograms in four spears
• Brussels sprouts, boiled: 78 micrograms in one-half cup
• Romaine lettuce, shredded: 64 micrograms in 1 cup

Like biotin, large doses of B12 have not been shown to cause adverse effects. Large doses of folate aren't toxic, but they may mask a B12 deficiency, increase the risk of colon and other cancers in some people, and increase the risk of impaired cognitive development in children whose mothers took high doses of folate before becoming pregnant and during early pregnancy, according to the NIH.

For these reasons, the National Academies of Medicine has set an upper tolerable intake level (UL) for folate of 1,000 micrograms per day for all adults.

Read more: What Foods Are High in B Vitamins?

Vitamin C is critical for the creation of healthy collagen, the main component of hair, nails and skin. While vitamin C deficiency is rare in developed countries, reports NIH, certain populations are at risk:

• Smokers and those exposed to second-hand smoke
• People who don't eat many fruits and vegetables
• Individuals with chronic diseases and malabsorption disorders

Another risk of low vitamin C is iron deficiency anemia. Vitamin C aids the absorption of non-heme iron from plant foods that have poor bioavailability. For people who don't eat animal foods, which contain the readily absorbed heme iron, not getting enough vitamin C could lead to poor iron status. According to MedlinePlus, iron deficiency anemia can cause a nail abnormality called koilonychia, which results in thin nails with raised ridges that curve inward.

The National Academies of Medicine has set the recommended daily intake for vitamin C at 90 milligrams for men, 75 milligrams for women, 85 milligrams for pregnant women and 120 milligrams for breastfeeding women. The NIH reports that fresh fruits and vegetables are the best sources of vitamin C, including:

• Red bell peppers: 95 milligrams per one-half cup
• Oranges: 70 milligrams per medium fruit
• Kiwis: 64 milligrams per medium fruit
• Green bell pepper: 60 milligrams per one-half cup
• Broccoli: 51 milligrams per one-half cup, cooked