UV light does not activate immunity genes, but Vitamin D supplements do – Feb 2017

Randomized clinical trial in vitamin D-deficient adults comparing replenishment with oral vitamin D3 with narrow-band UV type B light: effects on cholesterol and the transcriptional profiles of skin and blood.

Am J Clin Nutr. 2017 Feb 22. pii: ajcn150367. doi: 10.3945/ajcn.116.150367. [Epub ahead of print]
Ponda MP1, Liang Y2, Kim J3, Hutt R2, Dowd K2, Gilleaudeau P3, Sullivan-Whalen MM3, Rodrick T4, Kim DJ3, Barash I5, Lowes MA3, Breslow JL4.
1Laboratory of Biochemical Genetics and Metabolism, mponda at rockefeller.edu.
2Rockefeller University Hospital Center for Clinical and Translational Science, and.
3Laboratory of Investigative Dermatology, The Rockefeller University, New York, NY; and.
4Laboratory of Biochemical Genetics and Metabolism.
5Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY.

Background: Vitamin D deficiency, defined as a serum 25-hydroxyvitamin D [25(OH)D] concentration <20 ng/mL, is correlated with a more atherogenic lipid profile. However, oral vitamin D supplementation does not lower LDL-cholesterol concentrations or raise HDL-cholesterol concentrations. This uncoupling between association and causation may result from a failure of oral vitamin D to mimic the effect of dermally synthesized vitamin D in response to ultraviolet type B (UVB) light.

Objective: We tested the hypothesis that, in vitamin D-deficient adults, the replenishment of vitamin D with UVB exposure would lower LDL-cholesterol concentrations compared with the effect of oral vitamin D3 supplementation.

Design: We performed a randomized clinical trial in vitamin D-deficient adults and compared vitamin D replenishment between subjects who received oral vitamin D3 (n = 60) and those who received narrow-band UVB exposure (n = 58) ≤6 mo.

Results: There was no difference in the change from baseline LDL-cholesterol concentrations between oral vitamin D3 and UVB groups (difference in median of oral vitamin D3 minus that of UVB: 1.5 mg/dL; 95% CI: -5.0, 7.0 mg/dL). There were also no differences within groups or between groups for changes in total or HDL cholesterol or triglycerides. Transcriptional profiling of skin and blood, however, revealed significant upregulation of immune pathway signaling with oral vitamin D3 but significant downregulation with UVB.

Conclusions: Correcting vitamin D deficiency with either oral vitamin D3 or UVB does not improve the lipid profile. Beyond cholesterol, these 2 modalities of raising 25(OH)D have disparate effects on gene transcription.

This trial was registered at clinicaltrials.gov as NCT01688102.

PMID: 28228421 DOI: 10.3945/ajcn.116.150367

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