Skin pigmentation is negatively associated with circulating vitamin D concentration and cutaneous microvascular...

Area of Science:

• Physiology
• Nutritional Science
• Dermatology

Background:

• Darkly pigmented individuals face higher risks of vitamin D deficiency (hypovitaminosis D).
• Hypovitaminosis D can lead to microvascular endothelial dysfunction through reduced nitric oxide (NO) bioavailability and increased oxidative stress/inflammation.
• Understanding the link between skin pigmentation, vitamin D, and endothelial function is crucial for cardiovascular health.

Purpose of the Study:

• To investigate the associations between skin pigmentation, serum vitamin D concentration, inflammatory cytokines, and nitric oxide-mediated vasodilation.
• To determine if vitamin D status mediates the relationship between skin pigmentation and microvascular endothelial function in young adults.

Main Methods:

• Assessed skin pigmentation (M-index) and serum 25(OH)D concentrations in 33 healthy young adults.
• Measured nitric oxide-mediated cutaneous vasodilation (%NO-mediated vasodilation) using microdialysis and laser-Doppler flowmetry.
• Quantified circulating inflammatory cytokines (TNF-α, IL-6, IL-10) via ELISA and multiplex assays.

Main Results:

• Higher M-index (darker pigmentation) was associated with lower serum [25(OH)D] and reduced %NO-mediated vasodilation.
• Serum [25(OH)D] was positively related to %NO-mediated vasodilation.
• Lower [25(OH)D] showed a negative curvilinear relationship with IL-6, but controlling for [25(OH)D] attenuated the link between M-index and vasodilation.

Conclusions:

• Vitamin D insufficiency/deficiency may contribute to impaired microvascular endothelial function in darkly pigmented young adults.
• Reduced vitamin D availability associated with darker skin pigmentation may increase the risk of endothelial dysfunction.
• Findings highlight a potential mechanism linking skin pigmentation, vitamin D status, and cardiovascular risk independent of race.