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Article

Vitamin D Synthesis Following a Single Bout of Sun Exposure in Older and Younger Men and Women

1
Department of Family and Consumer Sciences, University of Wyoming, Laramie, WY 82071, USA
2
Billings Clinic, Cody, WY 82414, USA
3
Alpenglow Instruments, Laramie, WY 82072, USA
4
Dr Bruce Hollis’ Laboratory, Medical University of South Carolina, Charleston, SC 29425, USA
5
Department of Mathematics & Statistics, University of Wyoming, Laramie WY 82071, USA
6
Department of Animal Sciences, University of Wyoming, Laramie, WY 82071, USA
7
Department of Human Nutrition, Foods & Exercise, Virginia Tech, Blacksburg, VA 24061, USA
*
Author to whom correspondence should be addressed.
Designated shared first authorship.
Nutrients 2020, 12(8), 2237; https://doi.org/10.3390/nu12082237
Received: 30 May 2020 / Revised: 16 July 2020 / Accepted: 16 July 2020 / Published: 27 July 2020
(This article belongs to the Special Issue Vitamin D in 2020: Stop or Not Yet?)
Older adults are frequently cited as an at-risk population for vitamin D deficiency that may in part be due to decreased cutaneous synthesis, a potentially important source of cholecalciferol (vitamin D3). Previous studies found that cutaneous D3 production declines with age; however, most studies have been conducted ex vivo or in the photobiology lab. The purpose of this study was to characterize the response of vitamin D metabolites following a 30-min bout of sun exposure (15-min each to the dorsal and ventral sides) at close to solar noon in younger and older adults. Methods: 30 healthy individuals with skin type II/III were recruited; a younger cohort, aged 20–37 (n = 18) and an older cohort (n = 12), age 51–69 years. Exposure was at outer limits of sensible sun exposure designed to enhance vitamin D synthesis without increasing risk of photo ageing and non-melanoma skin cancer. Serum D3 concentration was measured at baseline, 24, 48 and 72 h post-exposure. Serum 25(OH)D was measured at baseline and 72 h post-exposure plus 168 h post-exposure in the older cohort. Results: D3 increased in response to sun exposure (time effect; p = 0.002) with a trend for a difference in D3 between cohorts (time*group; p = 0.09). By regression modeling of continuous data, age accounted for 20% of the variation in D3 production. D3 production decreased by 13% per decade. Despite changes in D3, however, serum 25(OH)D did not change from baseline to 72 or 168 h post exposure (p > 0.10). Conclusions: Serum D3 concentration increased significantly in response to outdoor sun exposure in younger and older adults. While ageing may dampen cutaneous synthesis, sunlight exposure is still a significant source of vitamin D3. View Full-Text
Keywords: ageing; older persons; sensible sun exposure; cutaneous synthesis; vitamin D3; natural sunlight; serum 25(OH)D ageing; older persons; sensible sun exposure; cutaneous synthesis; vitamin D3; natural sunlight; serum 25(OH)D
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MDPI and ACS Style

Chalcraft, J.R.; Cardinal, L.M.; Wechsler, P.J.; Hollis, B.W.; Gerow, K.G.; Alexander, B.M.; Keith, J.F.; Larson-Meyer, D.E. Vitamin D Synthesis Following a Single Bout of Sun Exposure in Older and Younger Men and Women. Nutrients 2020, 12, 2237. https://doi.org/10.3390/nu12082237

AMA Style

Chalcraft JR, Cardinal LM, Wechsler PJ, Hollis BW, Gerow KG, Alexander BM, Keith JF, Larson-Meyer DE. Vitamin D Synthesis Following a Single Bout of Sun Exposure in Older and Younger Men and Women. Nutrients. 2020; 12(8):2237. https://doi.org/10.3390/nu12082237

Chicago/Turabian Style

Chalcraft, Jenna R., Linda M. Cardinal, Perry J. Wechsler, Bruce W. Hollis, Kenneth G. Gerow, Brenda M. Alexander, Jill F. Keith, and D. E. Larson-Meyer 2020. "Vitamin D Synthesis Following a Single Bout of Sun Exposure in Older and Younger Men and Women" Nutrients 12, no. 8: 2237. https://doi.org/10.3390/nu12082237

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