Solar UV Doses of Young Americans and Vitamin D ₃ Production

Abstract

Background: Sunlight contains ultraviolet B (UVB) radiation (290–315 nm) that affects human health in both detrimental (skin cancers) and beneficial (vitamin D3) ways. Serum 25-hydroxyvitamin D concentrations from young Americans (≤ 19 years) show that many have deficient (< 50 nmol/L, 20 ng/mL) or insufficient (< 75 nmol/L, 30 ng/mL) vitamin D levels, indicating that they are not getting enough sun exposure. Those findings are in conflict with some calculated, published values that suggest people make “ample” vitamin D3 (~ 1,000 IU/day) from their “casual,” or everyday, outdoor exposures even if they diligently use sunscreens with sun protection factor (SPF) 15.Objective: We estimated how much vitamin D3 young Americans (n = ~ 2,000) produce from their everyday outdoor ultraviolet doses in the North (45°N) and South (35°N) each season of the year with and without vacationing.Methods: For these vitamin D3 calculations, we used geometric conversion factors that change planar to whole-body doses, which previous calculations did not incorporate.Results: Our estimates suggest that American children may not be getting adequate outdoor UVB exposures to satisfy their vitamin D3 needs all year, except some Caucasians during the summer if they do not diligently wear sunscreens except during beach vacations.Conclusion: These estimates suggest that most American children may not be going outside enough to meet their minimal (~ 600 IU/day) or optimal (≥ 1,200 IU/day) vitamin D requirements.

Solar UV Doses of Adult Americans and Vitamin D3Production

“…However, if they wear sunscreen of SPF ≥15, they will make virtually no vitamin D 3 all year including during the summer (see in ref. 44). Thus, as found in the NHANES III study, Caucasian adult Americans with Fitzpatrick skin type II, and especially the darker skin types III, IV and V/VI, are not getting adequate everyday UV exposures for most of the year to make the minimum amounts of vitamin D 3 to prevent deficiency.…”

“…Furthermore, if anyone wears sunscreens with SPF ≥15, they will make virtually no vitamin D 3 (see in ref. 44). …”

“…An evaluation of the vitamin D status of adult Americans (22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50)(51)(52)(53)(54)(55)(56)(57)(58)(59), 60+ yr) show many have deficient or insufficient serum levels of 25-hydroxyvitamin D, indicating they are not getting enough from dietary sources or sunlight. those findings are in conflict with calculated values from the American Academy of Dermatology who insist people make "ample" vitamin D 3 (≥1,000 IU/day) from their "casual," or everyday, outdoor UV exposures even if they use sunscreens with sun protection factor 15. objective: We investigated this situation using the everyday outdoor UV doses of indoor-working adult Americans (~7,000) in the north (45°N) and south (35°N) to calculate how much vitamin D 3 they produce each season with and without vacationing.…”

“…42 However, we found many American children (<20 yr) are not getting enough everyday outdoor UV exposures 43 to meet either their minimum (600 IU/day) or optimum (>1,200 IU/day) vitamin D 3 needs for most of the year, except some Caucasian children during the summer, but only if they do not wear sunscreens except on beach vacations. 44 African American children are not even making the minimum amount of vitamin D all year due to the increased sunscreening effect of the melanin in their skin. 45 Here we investigated the indoor-working adult American's (≥22 yr) situation by calculating the amount of vitamin D 3 they make from their everyday exposure to sunlight.…”

Differences in the prevalence of vitamin D deficiency and hip fractures in nursing home residents and independently living elderly

“…Vitamin D synthesis depends on a number of factors like geographic latitude, climate, clothing, individual sun exposure, air pollution, sunscreen use, gender, obesity (3,4). There are data that skin capacity for cholecalciferol synthesis diminishes with age (5,6). The insufficient skin vitamin D synthesis or food intake lead to vitamin D deficiency, which is common in large parts of the World on both sides of the Equator (7).…”