Issues with the health of your nails can be from nutritional deficiency, nutritional toxicity or other causes (such as liver disease and chronic kidney disease).
Nutritional deficiency:
Long standing iron deficiency can result in spoon-shaped nails (koilonychia). Recommended dietary intake (RDI) is 8-18ug/day.
Vitamin B12 deficiency has been associated with changes in nail pigments. RDI is 2.4ug/day.
Protein deficiency or protein energy malnutrition can result with transverse ridges on nails. RDI is 0.75-0.84g/kg body weight. Recent studies have recommended higher intakes of 1.0-1.2g/kg body weight for elderly (65yo+).
Selenium deficiency can result in white fingernail beds. RDI is 60-70ug/day.
Nutritional toxicity:
Vitamin A toxicity can result in nail brittleness such as above 20,000ug/day. RDI is 700-900ug/day.
Selenium toxicity can result in nail brittleness, nail discolouration and nail loss such as above 850ug/day.
If you are experiencing these symptoms see a healthcare professional and conduct tests such as blood tests to determine whether you are deficient. Supplement only if necessary as excess vitamins/minerals can be toxic! It’s best to obtain nutrients from a balanced diet. See a dietitian to ensure you are eating healthily every day!
Source: