Melanin levels in relation to vitamin D among first-generation immigrants from different ethnic groups and origins: A comparative national Canadian cross-sectional study

Said Yousef; Manny Papadimitropoulos; MoezAlIslam Faris; Hayder Hasan; Alomgir Hossain; Ian Colman; Douglas Manuel; George A Wells

doi:10.3389/fmed.2022.992554

Melanin levels in relation to vitamin D among first-generation immigrants from different ethnic groups and origins: A comparative national Canadian cross-sectional study

Front Med (Lausanne). 2023 Jan 9:9:992554. doi: 10.3389/fmed.2022.992554. eCollection 2022.

Authors

Said Yousef^{1

2}, Manny Papadimitropoulos^{3

4}, MoezAlIslam Faris⁵, Hayder Hasan⁵, Alomgir Hossain^{1

6}, Ian Colman¹, Douglas Manuel^{6

7

8}, George A Wells^{1

2}

Affiliations

¹ School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada.
² Cardiovascular Research Methods Centre, University of Ottawa Heart Institute, Ottawa, ON, Canada.
³ Eli Lilly Canada Inc., Toronto, ON, Canada.
⁴ Faculty of Pharmacy, University of Toronto, Toronto, ON, Canada.
⁵ Department of Clinical Nutrition and Dietetics, College of Health Sciences, Research Institute of Medical and Health Sciences, University of Sharjah, Sharjah, United Arab Emirates.
⁶ Institute for Clinical Evaluative Sciences, Toronto, ON, Canada.
⁷ Ottawa Hospital Research Institute, Ottawa, ON, Canada.
⁸ Department of Family Medicine, University of Ottawa, Ottawa, ON, Canada.

Abstract

Introduction: Immigrants to Western countries tend to have darker skin than native-born populations. We examined the relationship between skin melanin and serum vitamin D (vitD) [S-25(OH)D] levels and explored whether melanin levels explained S-25(OH)D variations between immigrants and native-born Canadians. This study offers novel findings as no such study has been conducted.

Methods: We used a national cross-sectional population-based design with data from the Canadian Health Measures Survey (CHMS). Skin melanin levels among first-generation immigrants based on their ethnicity and origin/country of birth were compared with white and native-born populations. We assessed the association between S-25(OH)D and melanin after adjusting for independent variables related to S-25(OH)D, melanin level, and immigration status.

Results: Of 11,579 participants, 21.9% were immigrants aged 3-79 years (mean age 39.23 years). Compared with non-immigrants, immigrants had lower S-25(OH)D levels (mean: 51.23 vs. 62.72; 95% CI: 8.37, 14.62; P < 0.001) but higher melanin levels (mean [SE]: 17.08 [0.25] vs. 16.29 [0.29]; 95% CI: -1.29, -0.281; P = 0.004). Melanin did not differ by length of stay in Canada but was weakly positively correlated (r = 0.088, P < 0.001) with S-25(OH)D. Sex (male), age (≥18 years), summer/fall seasons, sunlight exposure, sunscreen non-use, smoking, and alcohol consumption were associated with higher melanin levels, whereas indoor tanning use was not.

Conclusion: Skin melanin levels were associated with sociodemographic and behavioral characteristics. Immigrants had higher melanin levels, but melanin did not differ by length of stay in Canada. The weak positive correlation between melanin and S-25(OH)D suggested confounding factors may impact the relationship between melanin levels, S-25(OH)D, and immigration status.

Keywords: 25(OH)D; immigrants; indoor tanning; melanin; serum vitamin D.

Grants and funding

CHMS data were obtained and supported by funding to the Canadian Research Data Network from the Social Sciences and Humanities Research Council, the Canadian Institute for Health Research, the Canadian Foundation for Innovation, and Statistics Canada. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.