Nail Problems
Nail problems refer to changes in the appearance of the finger and/or toenails, such as thickening or curving, as well as fungus or bacterial overgrowth in and around the nails (often associated with acrylic nails for cosmetic purposes), or bacteria (tinea and candidiasis), Such changes are usually indications of an underlying metabolic or nutritional dysfunction within the body or a sign of skin disease or general illness.

Symptoms and Causes
Thickened and curved nails most often affect the big toes of older people and are often due to poor circulation, cardiovascular problems, and/or thyroid disease. Pitting in the nails can be a sign of anemia. Pitting and thickening together can be a sign of psoriasis. Brittle, ridged, and curved nails can signify anemia and iron deficiency while brittle nails alone can indicate thyroid problems, iron deficiency, kidney disorders, poor circulation, and/or omega-3 fatty acid deficiency. Vertical lines in nails usually signify poor nutrient absorption, iron deficiency, decreased overall health, or poor protein metabolism, while horizontal lines can indicate severe stress caused by unresolved emotional issues or from disease and/or infection. Flat nails can be due to poor circulation from Raynaud's disease while nail beading (bumps) may suggest arthritis. Nails that easily chip, crack, peel, and break are usually due to food allergies, mineral deficiencies and/or and need for digestive enzymes.

Fungal or bacterial overgrowth around the nails suggests a yeast infection (candidiasis) and in women can also be due to the use of acrylic nail polish.

Red skin around the cuticles can be a sign of poor essential fatty acid metabolism while darkening of the overall nail bed may be due to vitamin B12 deficiency, and white spots can signify zinc deficiency.

Note: Despite the above indications a medical diagnosis should never be based on a person's nail condition alone.