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Effect of nutrition

Biotin-rich foods and supplements may help strengthen brittle fingernails.

Vitamin A is an essential micronutrient for vision, reproduction, cell and tissue differentiation, and immune function. Vitamin D and calcium work together in cases of maintaining homeostasis, creating muscle contraction, transmission of nerve pulses, blood clotting, and membrane structure. A lack of vitamin A, vitamin D, or calcium can cause dryness and brittleness.

Insufficient vitamin B12 can lead to excessive dryness, darkened nails, and rounded or curved nail ends. Insufficient intake of both vitamin A and B results in fragile nails with horizontal and vertical ridges. Some over-the-counter vitamin supplements such as certain multivitamins and biotin may help in growth of strong nails, although this is quite subjective. Both vitamin B12 and folate play a role in red blood cell production and oxygen transportation to nail cells. Inadequacies can result in discoloration of the nails.

Diminished dietary intake of omega-3 fatty acids may contribute to dry and brittle nails.

Protein is a building material for new nails; therefore, low dietary protein intake may cause anemia and the resultant reduced hemoglobin in the blood filling the capillaries of the nail bed reflects varying amounts of light incident on the nail matrix resulting in lighter shades of pink ultimately resulting in white nail beds when the hemoglobin is very low. When hemoglobin is close to 15 or 16 grams, most of the spectrum of light is absorbed and only the pink color is reflected back and the nails look pink.

Essential fatty acids play a large role in healthy skin as well as nails. Splitting and flaking of nails may be due to a lack of linoleic acid.

Iron-deficiency anemia can lead to a pale color along with a thin, brittle, ridged texture. Iron deficiency in general may cause the nails to become flat or concave, rather than convex. As oxygen is needed for healthy nails, an iron deficiency or anemia can lead to vertical ridges or concavity in the nails. RDAs for iron vary considerably depending on age and gender. The recommendation for men is 8 mg per day, while that of women aged 19–50 is 18 mg per day. After women hit age 50 or go through menopause, their iron needs drop to 8 mg daily.