Low Serum Vitamin D, Zinc Shown to be Risk Factor for Alopecia Areata

Lower serum vitamin D and zinc levels may be considered risk factors for alopecia areata, new findings suggest, suggesting that their measurement can serve as an indicator for alopecia risk and disease severity.1

These findings resulted from new research conducted for the purposes of making a thorough and systematic evaluation of any connections between alopecia areata and serum trace element levels.

Ruiying Wu, from the school of clinical medicine at Beijing University of Chinese Medicine, led a team of investigators in this analysis. Wu et al. noted that only 1 other study had used a meta-analysis to examine the link between serum trace elements and patients’ alopecia areata risk, though they added that this analysis had not looked into vitamin D.2

“At the same time, the publication of numerous new clinical studies in recent years prompted us to conduct a systematic review and meta-analysis of existing research,” Wu and colleagues wrote. “Our goal was to comprehensively and systematically assess the relationship between serum trace element levels (zinc, copper, and VD) and the risk of developing [alopecia areata].”1

Study Design and Details

The research team conducted their comprehensive meta-analysis during which an extensive search was carried out using a variety of major databases. Some examples of databases implemented by the team include Web of Science, EMBASE, PubMed, and the Cochrane Library, with studies they highlighted having been published from the inception of each of these databases through May 2024.

The investigators restricted their meta-analysis to human studies that had no language limitations, seeking to evaluate any associations between trace element levels and alopecia areata. Several different keywords were used for the investigators’ database search strategy, some of which included phrases like "zinc/Zn," "copper," "vitamin D/cholecalciferol/calciferol/25-hydroxy vitamin D/25-hydroxy cholecalciferol," "trace element," and "alopecia areata/alopecia totalis/alopecia universalis.”

An independent screening was conducted among 2 of the meta-analysis’s investigators to determine which studies to include. They would resolve any disagreements through consultation with a third researcher for the purposes of consistency in their results.

The team decided that research designs deemed as eligible would include cross-sectional, case–control, or cohort studies. In terms of other inclusion criteria, they determined that they would need participants of included clinical research to be either patients diagnosed with alopecia areata or healthy controls. Clinical trials were also required to have evaluated serum levels of trace elements and be published in English.

To combine effect estimates, the research team applied either a fixed-effects or random-effects model. Their decision was dependent on the degree of heterogeneity evaluated using the I² statistic.

Notable Findings

There were 34 studies in total included in the investigators’ final meta-analysis, all of which had assessed 4,931 subjects from 16 countries. Their evaluation of these studies led to the conclusion that individuals with alopecia areata were shown to have significantly lower serum levels of zinc (SMD = −0.69 μg/dL, 95% CI = −0.99 to −0.39, P < .05) and vitamin D (SMD = −0.93 ng/mL, 95% CI = 0.168–0.747, P < .05) compared to levels observed in the control groups.

Additionally, the research team highlighted an association they found with a deficiency in vitamin D and an increased risk of alopecia areata, noting an odds ratio of 2.48 (95% CI = 1.47–4.17, P < .05). However, the team found no such difference in serum copper levels between those with alopecia areata and healthy controls.

“In conclusion, our analysis provides the latest and most comprehensive evidence on the relationship between serum trace element levels and [alopecia areata],” they wrote. “...This suggests that measuring serum [vitamin D] and zinc levels in [alopecia areata] patients can serve as indicators for assessing disease risk and severity, aiding in early identification and intervention.”1

References

1. Wu, R., Li, Y., Peng, H., Yang, Z., Wang, Y., Lv, S. and Yang, D. (2025), Association Between Serum Trace Elements Level and Alopecia Areata: A Systematic Review and Meta-Analysis. J Cosmet Dermatol, 24: e16740. https://doi.org/10.1111/jocd.16740.
2. W. Jin, H. Zheng, B. Shan, and Y. Wu, “Changes of Serum Trace Elements Level in Patients With Alopecia Areata: A Meta-Analysis,” Journal of Dermatology 44, no. 5 (2017): 588–591, https://doi.org/10.1111/1346-8138.13705.