What Your Patients’ Nails Reveal About Their Nutrition

Sometimes the smallest details visible on human anatomy can provide the most fascinating clues into patient pathology. Take the nails, for example. Examining finger- and toenails can help clinicians detect any number of general and specific factors, including overall vitality, nutritional status, cardiovascular functions, rheumatic conditions, and dermatologic problems.

Although the nail structure may be easily overlooked, disorders of the nails make up approximately 10% of all dermatologic conditions.1 Virtually every nutritional deficiency can affect the growth of the nails in some manner.1 These indications provide rapid insights into patient history and pathology, and can help clinicians focus diagnostic considerations and subsequent testing. For example, brittle nail syndrome appears to abate with supplementation of a 2.5 mg dose of biotin daily or a 10 mg dose of silicon daily, a useful form of which is choline-stabilized orthosilicic acid.2

If nutrient deficiencies are suspected, physical signs like ridging, white spots, spooning, vertical lines, and others will help focus diagnostic considerations. Nails renew every six months or so, meaning patients have a living six-month medical record that’s unique in all of the physical exam components.

Kara Fitzgerald, ND, is an educator at IFM and an IFM Certified Practitioner. She received her Doctor of Naturopathic Medicine degree from the National College of Natural Medicine in Portland, Oregon. Her clinical practice is in Sandy Hook, Connecticut.

Koilonychia, also known as spoon nails, is a nail disease that can be a sign of hypochromic anemia, especially iron deficiency anemia.3 It refers to abnormally thin nails (usually of the hand) which have lost their convexity, becoming flat or even concave in shape. Koilonychia may result from a variety of causes, such as malnutrition, gastrointestinal blood loss, gastrointestinal malignancy, and celiac disease.3

Most nutrient deficiencies, autoimmune diseases, and systemic diseases will present on the nails before they show up in any other clinical or laboratory findings. One fascinating 2017 study showed that the toenails of older women who were physically active contained higher levels of Ca and Fe and lower levels of Hg.4 The trace elements of men’s toenails in this study were not markedly influenced by physical activity.4

Learn more with IFM’s free educational resource


  1. Cashman MW, Sloan SB. Nutrition and nail disease. Clin Dermatol. 2010;28(4):420-425. doi:10.1016/j.clindermatol.2010.03.037.
  2. Scheinfeld N, Dahdah MJ, Scher R. Vitamins and minerals: their role in nail health and disease. J Drugs Dermatol. 2007;6(8):782-787.
  3. Kumar V, Aggarwal S, Sharma A, Sharma V. Nailing the diagnosis: koilonychia. Perm J. 2012;16(3):65.
  4. 4. Sureda A, Bibiloni M, Julibert A, et al. Trace element contents in toenails are related to regular physical activity in older adults. PLoS One. 2017;12(10):e0185318. doi:10.1371/journal.pone.0185318.

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