# Fingernail Mineral Profiling as a Non‐Invasive Tool to Assess Dietary and Lifestyle Factors: Results From the Cross‐Sectional Fulda NutriNAIL Study

## TL;DR

This study shows that analyzing minerals in fingernails can reveal information about diet, lifestyle, and health without invasive methods.

## Contribution

The study introduces fingernail mineral profiling as a non-invasive tool to assess dietary and lifestyle factors.

## Key findings

- Sodium and potassium levels in fingernails were strongly correlated (r = 0.89).
- Selenium levels were 21% higher in individuals who used selenium supplements.
- Nail surface features like brittleness and white spots were linked to specific mineral differences.

## Abstract

In the past, fingernail and toenail analyses were mainly used for toxicological investigations on heavy metals and only a few studies used mineral content as a biomarker for assessing lifestyle or dietary habits. The Fulda NutriNAIL study examined associations between lifestyle, dietary habits, supplement use, and fingernail mineral composition in 184 participants (18–81 years) from Fulda, Germany. Mineral concentrations were quantified via Inductively Coupled Plasma Mass Spectrometry (ICP‐MS), and questionnaire data were analyzed for lifestyle correlations. Positive mineral‐to‐mineral correlations were observed between sodium (Na) and potassium (K) (r = 0.89), calcium (Ca) and magnesium (Mg) (r = 0.57), and iron (Fe) and cobalt (Co) (r = 0.66). We detected 21% higher selenium levels in the fingernails of selenium supplement users than for non‐users. Omnivores showed higher Se levels than vegans and slightly higher levels than vegetarians and participants with thyroid disorders had significantly higher nail selenium levels. In addition, nail surface features were linked to specific mineral differences: potassium in brittle nails, reduced sodium and potassium in longitudinal ridges, and reduced chromium (Cr) in white spots. These findings demonstrate that fingernail mineral profiling is a non‐invasive method for assessing lifestyle‐ and diet‐related micronutrient status.

ICP‐MS profiling of fingernails and assessment of the dietary habits and lifestyle of 184 adults revealed correlations between Na–K, Ca–Mg and Fe–Co, as well as significant differences in selenium content based on the participants' diets. In addition, nail surface characteristics were associated with mineral differences. The study supports non‐invasive health monitoring.