Serum Micronutrient Levels In Premature Canities: A Systematic Review and Meta-analysis.

Background: Premature canities, also known as premature graying of hair, is the graying of hair before 20 years old in Caucasians, before 25 years old in Asians, and before 30 years old in African–Americans. The risk factors for premature canities are multifactorial. The role of micronutrient deficiency has long been suggested to be involved in the etiopathogenesis of premature canities. The management of premature canities remains limited and far from satisfactory; hence, knowing what vitamins and minerals can help in treating premature canities is vital. Aim: This study aims to analyze serum vitamin B12, iron, ferritin, copper, calcium, and zinc levels in premature canities. Methods: The MEDLINE/PubMed electronic database, Cochrane library, ClinicalTrials.gov, EBSCO, Scopus, ProQuest, Cambridge Core, reference lists, conference proceedings, and researchers in fields of eligible studies were searched. Twelve studies (n = 1791 subjects) were included in qualitative analysis of which nine studies (n = 1381 subjects) were included in meta-analysis. Serum levels of micronutrients (vitamin B12, iron, ferritin, copper, calcium, and zinc) were compared in the premature canities and nonpremature canities groups. Result: Pooling of data using fixed-effects model found the overall effect mean difference serum vitamin B12 level was −0.697 ± 0.105 (95% CI = −0.904 to −0.490), p < 0.001. The overall mean difference serum iron level was 0.146 ± 0.105 (95% CI = −0.058 to 0.350), p = 0.161. The overall mean difference serum ferritin level was 0.720 ± 0.071 (95% CI = 0.585 to 0.854), p < 0.001. The overall mean difference serum copper level was 0.230 ± 0.118 (95% CI = −0.003 to 0.463, p = 0.053. The overall mean difference serum calcium level was −0.443 ± 0.114 (95% CI = −0.655 to −0.212), p < 0.001. The overall mean difference serum zinc level was −0.104 ± 0.138 (95% CI = 0.377 to 0.170, p = 0.457. Qualitative analysis showed that vitamin B12 plays an important role in DNA synthesis in the proliferation of hair follicle cells and in melanogenesis. Iron, ferritin, copper, calcium, and zinc also play important roles in stabilizing and increasing tyrosinase activity in several stages of the melanogenesis process. Conclusion: The meta-analysis showed that serum levels of vitamin B12, ferritin, and calcium were significantly lower in premature canities. Although the lower serum iron, copper, and zinc levels were not significantly different in premature canities compared with nonpremature canities. Qualitative analysis found that deficiency of vitamin B12, iron, ferritin, zinc, copper, and calcium can affect the physiology of hair melanogenesis that causing premature canities.