Leukonychia on finger nails as a marker of calcium and/or zinc deficiency
Popular lay media claim that the aetiology of leukonychia (white spots) on finger nails is due to calcium and/or zinc (McKeith, 2008; Holford, 1998) deficiency. No studies are available in scientific literature to support or refute these claims. Cited causes in dermatology journals include, trophic disturbances, gender, hand dominance, nail trauma and orange stick usage (Mitchell, 1953) although this is dated. This small scale study aimed to establish if there is a correlation between calcium and/or zinc intakes and the presence or absence of leukonychia on finger nails. Methods:
A cross sectional survey was completed by 82 university undergraduate students. The study was approved by the University ethics panel. A convenience sample was taken from students enrolled on courses within the School of Health Science. A self administered questionnaire collected data on the number of leukonychia present on participant's finger nails, participant's opinions on leukonychia's aetiology, calcium and zinc intakes, age, gender, handedness, supplement usage, activities and orange stick usage. A food frequency questionnaire, adapted from the tool used in the European Prospective Investigation into Cancer (EPIC) (Day et al., 2001), was developed to allot participants calcium and zinc intake scores. Data was coded and analysed using the Statistical Package for Social Sciences (SPSS) version 17. Spearmans Correlation was used to assess the relationship between calcium and zinc intake scores and the number of leukonychia present. Results:
The majority of participants thought that leukonychia was a result of a singular or multiple nutrient deficiency (51%), mainly either calcium or zinc. Leukonychia was present in 46% of the sample. It was not significantly associated with calcium intake (P = 0.681), zinc intake (P = 0.604), age (P = 0.715), gender (P = 0.089), hand dominance (P = 0.151), multivitamin/mineral usage (n = 62, P = 0.655) or orange stick usage (n = 12, P = 0.961). The majority (63%) of participants reported to take part in activities that knock their hands frequently. A correlation was found between activities that knock participants hands frequently and the number of leukonychia present on finger nails (P = 0.000, t = −4.902, df = 77). Discussion:
The results showed there was no correlation between calcium or zinc intake scores and leukonychia. Participant's intakes scores followed similar patterns to the actual intakes observed in a survey of the UK general population (Henderson et al., 2003). For both nutrients male intake score where higher than females and intake scores for calcium increased with age. However a limitation of this study is that nutrient intake was estimated using a non-validated tool which provided an arbitrary intake score that could not be quantitatively compared to the National Diet and Nutrition Surveys (Henderson et al., 2003) data. Another limitation was that the number of leukonychia was also gathered using a non-validated tool and all results were self-reported. Conclusion:
This study suggested that there is no correlation between the presences of leukonychia and calcium or zinc intake scores. Although it would be beneficial if this study was repeated using more robust measures of calcium and zinc intake and leukonychia, and within a larger population known to have low calcium and zinc intakes. References:
Day, N., McKeown, N., Wong, M., Welch, A. & Bingham, S. (2001) Epidemiology assessment of diet: a comparison of a 7-day diary with a food frequency questionnaire using urinary markers of nitrogen, potassium and sodium. Int. J. Epidemiol. 30, 309–317.
Henderson, L., Irving, K., Gregory, J., Bates, C.J., Prentice, A., Perks, J., Swan, G. & Farron, M. (2003) National Diet and Nutrition Survey: Adults aged 19–64 years. Vol 3:Vitamin and mineral intake and urinary analytes. London: TSO.
Holford, P. (1998) The Optimum Nutrition Bible: The Book You Have to Read if You Care About Your Health. London: Piatkus Books.
McKeith, G. (2008) Food Bible: The Complete A-Z Guide to a Healthy Life. London: Michael Joseph.
Mitchell, J.C. (1953) A clinical study of leukonychia. Br. J. Dermatol. 65, 121–130.