Health problems? Look to your fingernails.

If our eyes are the windows to our souls, our nails are the screen doors to our bodies. More than just cosmetic annoyances, brittle, ridged, or yellow fingernails and toenails can indicate nutrient deficiencies and health problems ranging from anemia to thyroid disease. “Nails suffer the most when we don’t treat our bodies well,” says Lisa Petty, a holistic nutritionist in Canada and author of Living Beauty. “When nutrients go into our bodies, the skin, hair, and nails get them last. So a nail problem can signal a problem in our bodies.”

Made of keratin protein, fingernails and toenails protect the ultra-sensitive skin at the end of our fingers and toes, known as the nail bed. Our nails are formed by nail matrices, which are collections of nerves, lymph vessels, and blood vessels protected by cuticles. Nails can grow in a variety of shapes based on individual genetics, but healthy nails share similar characteristics: They are smooth, not easily breakable, and translucent (the pink color comes from the network of tiny blood vessels underneath the nail plate). But if our nail matrices don’t get enough nutrients, the actual nail can become damaged, discolored, or just plain unsightly.

Fortunately, you can fix most nail problems with diet changes, vitamins, supplements, and simple maintenance. Here’s how to combat common nail woes and make your tattered talons healthy and strong.

Problem: Brittle or split nails

Causes: Lack of moisture or not enough of the B vitamin biotin

Solutions: Take 2,000 mcg of biotin daily, says Richard Eisen, MD, a dermatologist at South Shore Skin Center in Massachusetts, or nosh on biotin-rich cauliflower, lentils, and peanuts. Moisturize nails from the inside with 1,000 mg of fish oil per day that contains eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Keep them hydrated on the outside with twice-daily applications of a natural oil, like almond, and wear gloves when washing dishes to keep nails from drying out.

Problem: Soft or upward-curving nails

Cause: Iron deficiency

Solution: If tests confirm low iron, take 325 mg of iron sulfate three times a day, Eisen recommends.

Problem: Vertical ridges

Cause: Age (think of vertical ridges as wrinkles on your nails)

Solutions: To smooth out ridges, polish nails with a few drops of almond oil and a chamois buffer. Because buffing removes a thin layer of nail, take only three or four swipes per nail per week, says Rachel Gower, founder of The Upper Hand salons in Houston. Avoid conventional ridge fillers, which use synthetic chemicals, like noxious polyester resin, to fill in grooves.

Problem: Horizontal ridges or dents

Causes: Trauma, caused by picking at your cuticle or continually hitting the front edge of your nail on a paper-towel dispenser, can create ridges. Dents indicate that some condition—a high fever, nutritional deficiencies, psoriasis, or trauma from surgery—has actually affected nail growth.

Solutions: Eat enough protein (the recommended daily allowance is 55 grams). Petty advises supplementing with up to 10,000 IU of vitamin A daily to help your nails metabolize the protein, along with
3 mg of choline-stabilized orthosilicic acid (dietary silicon) to strengthen nails.

Problem: Yellow nails

Causes: Lack of vitamin E or not giving nails enough time to breathe between polishes

Solutions: Eisen recommends 400 IU of vitamin E twice a day. Almonds, hazelnuts, peanuts, sweet potatoes, and wheat germ oil are also good sources of this antioxidant.

Problem: Fungus

Causes: Yeast or bacteria that grow when the nail matrix and cuticle are continually exposed to warmth and moisture. Fungal infections can spread rapidly, especially under toenails. Signs include yellow, greenish, or dirty-looking nails; thickness; or separation of the nail from the nail bed.

Solutions: Soak nails in antibacterial pure tea tree oil for 15 minutes a day until the fungus clears. Or take one 200 mg capsule of the antifungal herb myrrh three times a day, says Norma Pasekoff Weinberg, author of Natural Hand Care (Storey Publishing, 1998). Note that topical and oral fungal medications are not a sure fix and may cause liver problems, says Elizabeth K. Hale, MD, clinical associate professor of dermatology at New York University.

Problem: White spots

Causes: Nail trauma (the most common culprit) or zinc deficiency

Solutions: Petty recommends 50 mg of zinc daily. You can also get zinc from red meat, sesame seeds, pumpkinseeds, and peas. White spots caused by trauma will disappear as the nail grows.

When to Worry

The following nail blights accompanied by disease symptoms, such as shortness of breath or fatigue, could indicate these far-more-serious conditions.

• Upward-curving nails: thyroid disease
• Brittle nails: hyper- or hypothyroidism
• Yellow nails: chronic bronchitis
• Blue nail beds: circulation problems
• Red nail beds: heart disease
• White nail beds: liver disease

By Vicky Uhland