Limited exposure to ambient ultraviolet radiation and 25-hydroxyvitamin D levels: a systematic review†
S.A. Rice
Dermatopharmacology, Sir Henry Wellcome Laboratories, Faculty of Medicine, University of Southampton, Southampton General Hospital, Tremona Road, Southampton, SO16 6YD U.K
Search for more papers by this authorM. Carpenter
Dermatopharmacology, Sir Henry Wellcome Laboratories, Faculty of Medicine, University of Southampton, Southampton General Hospital, Tremona Road, Southampton, SO16 6YD U.K
Search for more papers by this authorA. Fityan
Southampton Dermatology Centre, Royal South Hants Hospital, University Hospitals Southampton NHS Foundation Trust, Brintons Terrace, Southampton, SO14 0YG U.K
Search for more papers by this authorL.M. Vearncombe
Southampton Dermatology Centre, Royal South Hants Hospital, University Hospitals Southampton NHS Foundation Trust, Brintons Terrace, Southampton, SO14 0YG U.K
Search for more papers by this authorM. Ardern-Jones
Dermatopharmacology, Sir Henry Wellcome Laboratories, Faculty of Medicine, University of Southampton, Southampton General Hospital, Tremona Road, Southampton, SO16 6YD U.K
Southampton Dermatology Centre, Royal South Hants Hospital, University Hospitals Southampton NHS Foundation Trust, Brintons Terrace, Southampton, SO14 0YG U.K
Search for more papers by this authorA.A. Jackson
NIHR Biomedical Research Centre (Nutrition), University of Southampton, Southampton General Hospital, Tremona Road, Southampton, SO16 6YD U.K
Search for more papers by this authorC. Cooper
MRC Lifecourse Epidemiology Unit, Faculty of Medicine, University of Southampton, Southampton General Hospital, Tremona Road, Southampton, SO16 6YD U.K
NIHR Musculoskeletal BRU, University of Oxford, Windmill Road, Headington, Oxford, OX3 7LD U.K
Search for more papers by this authorJ. Baird
MRC Lifecourse Epidemiology Unit, Faculty of Medicine, University of Southampton, Southampton General Hospital, Tremona Road, Southampton, SO16 6YD U.K
Search for more papers by this authorCorresponding Author
E. Healy
Dermatopharmacology, Sir Henry Wellcome Laboratories, Faculty of Medicine, University of Southampton, Southampton General Hospital, Tremona Road, Southampton, SO16 6YD U.K
Southampton Dermatology Centre, Royal South Hants Hospital, University Hospitals Southampton NHS Foundation Trust, Brintons Terrace, Southampton, SO14 0YG U.K
Correspondence
Eugene Healy.
E-mail: [email protected]
Search for more papers by this authorS.A. Rice
Dermatopharmacology, Sir Henry Wellcome Laboratories, Faculty of Medicine, University of Southampton, Southampton General Hospital, Tremona Road, Southampton, SO16 6YD U.K
Search for more papers by this authorM. Carpenter
Dermatopharmacology, Sir Henry Wellcome Laboratories, Faculty of Medicine, University of Southampton, Southampton General Hospital, Tremona Road, Southampton, SO16 6YD U.K
Search for more papers by this authorA. Fityan
Southampton Dermatology Centre, Royal South Hants Hospital, University Hospitals Southampton NHS Foundation Trust, Brintons Terrace, Southampton, SO14 0YG U.K
Search for more papers by this authorL.M. Vearncombe
Southampton Dermatology Centre, Royal South Hants Hospital, University Hospitals Southampton NHS Foundation Trust, Brintons Terrace, Southampton, SO14 0YG U.K
Search for more papers by this authorM. Ardern-Jones
Dermatopharmacology, Sir Henry Wellcome Laboratories, Faculty of Medicine, University of Southampton, Southampton General Hospital, Tremona Road, Southampton, SO16 6YD U.K
Southampton Dermatology Centre, Royal South Hants Hospital, University Hospitals Southampton NHS Foundation Trust, Brintons Terrace, Southampton, SO14 0YG U.K
Search for more papers by this authorA.A. Jackson
NIHR Biomedical Research Centre (Nutrition), University of Southampton, Southampton General Hospital, Tremona Road, Southampton, SO16 6YD U.K
Search for more papers by this authorC. Cooper
MRC Lifecourse Epidemiology Unit, Faculty of Medicine, University of Southampton, Southampton General Hospital, Tremona Road, Southampton, SO16 6YD U.K
NIHR Musculoskeletal BRU, University of Oxford, Windmill Road, Headington, Oxford, OX3 7LD U.K
Search for more papers by this authorJ. Baird
MRC Lifecourse Epidemiology Unit, Faculty of Medicine, University of Southampton, Southampton General Hospital, Tremona Road, Southampton, SO16 6YD U.K
Search for more papers by this authorCorresponding Author
E. Healy
Dermatopharmacology, Sir Henry Wellcome Laboratories, Faculty of Medicine, University of Southampton, Southampton General Hospital, Tremona Road, Southampton, SO16 6YD U.K
Southampton Dermatology Centre, Royal South Hants Hospital, University Hospitals Southampton NHS Foundation Trust, Brintons Terrace, Southampton, SO14 0YG U.K
Correspondence
Eugene Healy.
E-mail: [email protected]
Search for more papers by this authorSummary
Vitamin D can be synthesized following exposure to ultraviolet radiation (UVR), ingested in the diet or provided through oral supplementation. The medical literature frequently states that humans obtain most of their vitamin D from sunshine and that UVR exposure is essential to maintain vitamin D levels. A systematic review was conducted to determine the requirement for UVR in maintaining adequate (> 50 nmol L−1) serum 25-hydroxyvitamin D [25(OH)D] levels. Studies reporting serum 25(OH)D during situations of negligible UVR exposure were sought. Forty-one studies (from a search yielding 42 698 articles) with a total of 4211 healthy adults met the inclusion criteria, providing 56 datasets from different population groups. Over 50% of subjects had > 50 nmol L−1 25(OH)D in 10 of 19 datasets reporting winter levels in areas with limited UVR. In addition, > 50% of subjects had adequate 25(OH)D levels in four of 12 datasets from polar regions during periods of negligible UVR, one of nine datasets documenting clothing-related minimal UVR and two of eight datasets detailing employment-related minimal UVR. The data demonstrate that many adults maintain adequate serum vitamin D levels despite negligible UVR exposure for several months. However, we acknowledge that preceding UVR exposure leading to vitamin D storage and delayed release may account for this maintenance of adequate serum vitamin D levels. There remains a need for further research on whether UVR exposure is required for longer-term maintenance of adequate vitamin D levels.
Supporting Information
| Filename | Description |
|---|---|
| bjd13575-sup-0001-DataS1.docWord document, 168 KB | Data S1. Protocol of the review. |
| bjd13575-sup-0002-TableS1.docWord document, 61 KB | Table S1. Record of databases searched. |
| bjd13575-sup-0003-TableS2.docxWord document, 125.8 KB | Table S2. Summary of vitamin D exposure. |
Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.
References
- 1Bischoff-Ferrari HA, Willett WC, Wong JB et al. Prevention of nonvertebral fractures with oral vitamin D and dose dependency: a meta-analysis of randomized controlled trials. Arch Intern Med 2009; 169: 551–61.
- 2Dobnig H, Pilz S, Scharnagl H et al. Independent association of low serum 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels with all-cause and cardiovascular mortality. Arch Intern Med 2008; 168: 1340–9.
- 3Munger K, Levin LI, Hollis BW et al. Serum 25-hydroxyvitamin D levels and risk of multiple sclerosis. JAMA 2006; 296: 2832–8.
- 4Merlino LA, Curtis J, Mikuls TR et al. Vitamin D intake is inversely associated with rheumatoid arthritis: results from the Iowa Women's Health Study. Arthritis Rheum 2004; 50: 72–7.
- 5Giovannucci E, Liu Y, Rimm EB et al. Prospective study of predictors of vitamin D status and cancer incidence and mortality in men. J Natl Cancer Inst 2006; 98: 451–9.
- 6Melamed ML, Michos ED, Post W, Astor B. 25-Hydroxyvitamin D levels and the risk of mortality in the general population. Arch Intern Med 2008; 168: 1629–37.
- 7Ashwell M, Stone EM, Stolte H et al. U.K. Food Standards Agency Workshop Report: an investigation of the relative contributions of diet and sunlight to vitamin D status. Br J Nutr 2010; 104: 603–11.
- 8Prentice A. Vitamin D deficiency: a global perspective. Nutr Rev 2008; 66 (10 Suppl. 2): S153–64.
- 9Hypponen E, Power C. Hypovitaminosis D in British adults at age 45 y: nationwide cohort study of dietary and lifestyle predictors. Am J Clin Nutr 2007; 85: 860–8.
- 10Holick MF. Evolution and function of vitamin D. Recent Results Cancer Res 2003; 164: 3–28.
- 11Moan J, Porojnicu AC, Dahlback A, Setlow RB. Addressing the health benefits and risks, involving vitamin D or skin cancer, of increased sun exposure. Proc Natl Acad Sci U S A 2008; 105: 668–73.
- 12 Cancer Council Australia. Risks and benefits of sun exposure position statement. Available at: http://www.cancer.org.au/content/pdf/CancerControlPolicy/PositionStatements/PSRisksBenefitsSunExposure03May07.pdf (last accessed 7 November 2014).
- 13 Cancer Research U.K. Joint position statement issued to provide vitamin D clarity. Available at: http://www.cancerresearchuk.org/about-us/cancer-news/news-report/2010-12-16-joint-position-statement-issued-to-provide-vitamin-d-clarity (last accessed 7 November 2014).
- 14Lucas R, McMichael T, Smith W et al. Solar ultraviolet radiation: global burden of disease from solar ultraviolet radiation. In: Environmental Burden of Disease Series No. 13 ( A Prüss-Üstün, H Zeeb, C Mathers et al., eds). Geneva: World Health Organization, 2009; 1–250.
- 15Diffey BL. Modelling the seasonal variation of vitamin D due to sun exposure. Br J Dermatol 2010; 162: 1342–8.
- 16Rhodes LE, Webb AR, Fraser HI et al. Recommended summer sunlight exposure levels can produce sufficient (≥ 20 ng mL−1) but not the proposed optimal (≥ 32 ng mL−1) 25(OH)D levels at U.K. latitudes. J Invest Dermatol 2010; 130: 1411–18.
- 17 International Agency for Research on Cancer. Vitamin D and cancer. Available at: http://www.iarc.fr/en/publications/pdfs-online/wrk/wrk5/Report_VitD.pdf (last accessed 7 November 2014).
- 18Moher D, Liberati A, Tetzlaff JE et al. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. Ann Intern Med 2009; 151: 264–9.
- 19Hall LM, Kimlin MG, Aronov PA et al. Vitamin D intake needed to maintain target serum 25-hydroxyvitamin D concentrations in participants with low sun exposure and dark skin pigmentation is substantially higher than current recommendations. J Nutr 2010; 140: 542–50.
- 20Harris SS, Dawson-Hughes B. Seasonal changes in plasma 25-hydroxyvitamin D concentrations of young American black and white women. Am J Clin Nutr 1998; 67: 1232–6.
- 21Tangpricha V, Pearce EN, Chen TC, Holick MF. Vitamin D insufficiency among free-living healthy young adults. Am J Med 2002; 112: 659–62.
- 22Gozdzik A, Barta JL, Wu H et al. Low wintertime vitamin D levels in a sample of healthy young adults of diverse ancestry living in the Toronto area: associations with vitamin D intake and skin pigmentation. BMC Public Health 2008; 8: 336.
- 23Veith R, Cole DE, Hawker GA et al. Wintertime vitamin D insufficiency is common in young Canadian women, and their vitamin D intake does not prevent it. Eur J Clin Nutr 2001; 55: 1091–7.
- 24Nelson ML, Blum JM, Hollis BW et al. Supplements of 20 μg/d cholecalciferol optimized serum 25-hydroxyvitamin D concentrations in 80% of premenopausal women in winter. J Nutr 2009; 139: 540–6.
- 25Guillemant J, Guillemant S. Acute PTH response to oral calcium load and seasonal variation of vitamin D status in healthy young adult subjects. Eur J Clin Nutr 1996; 50: 469–72.
- 26Beadle PC, Burton JL, Leach JF. Correlation of seasonal variation of 25-hydroxycalciferol with UV radiation dose. Br J Dermatol 1980; 102: 289.
- 27McLaughlin M, Raggatt PR, Fairney A et al. Seasonal variations in serum 25-hydroxycholecalciferol in healthy people. Lancet 1974; 1: 536–8.
- 28Juttmann JR, Visser TJ, Buurman C et al. Seasonal fluctuations in serum concentrations of vitamin D metabolites in normal subjects. Br Med J (Clin Res Ed) 1981; 282: 1349–52.
- 29McKinney K, Breitkopf CR, Berenson AB. Association of race, body fat and season with vitamin D status among young women: a cross-sectional study. Clin Endocrinol (Oxf) 2008; 69: 535–41.
- 30McKenna MJ, Freaney R, Byrne P et al. Safety and efficacy of increasing wintertime vitamin D and calcium intake by milk fortification. QJM 1995; 88: 895–8.
- 31O'Sullivan M, Nic Suibhne T, Cox G et al. High prevalence of vitamin D insufficiency in healthy Irish adults. Ir J Med Sci 2008; 177: 131–4.
- 32Webb AR, Kift R, Durkin MT et al. The role of sunlight exposure in determining the vitamin D status of the U.K. white adult population. Br J Dermatol 2010; 163: 1050–5.
- 33Thieden E, Philipsen PA, Heydenreich J, Wulf HC. Vitamin D level in summer and winter related to measured UVR exposure and behavior. Photochem Photobiol 2009; 85: 1480–4.
- 34Mazess RB, Barden HS, Christiansen C. Bone mineral and vitamin D in Aleutian Islanders. Am J Clin Nutr 1985; 42: 143–6.
- 35Maeda SS, Kunii IS, Hayashi L, Lazaretti-Castro M. The effect of sun exposure on 25-hydroxyvitamin D concentrations in young healthy subjects living in the city of Sao Paulo, Brazil. Braz J Med Biol Res 2007; 40: 1653–9.
- 36Livesey J, Elder P, Ellis MJ et al. Seasonal variation in vitamin D levels in the Canterbury, New Zealand population in relation to available UV radiation. N Z Med J 2007; 120: U2733.
- 37Levis S, Gomez A, Jimenez C et al. Vitamin D deficiency and seasonal variation in an adult South Florida population. J Clin Endocrinol Metab 2005; 90: 1557–62.
- 38Kobayashi T. Nutritional aspects of vitamin D and its metabolites in Japanese children and adults. J Bone Miner Metab 1999; 17: 151–63.
- 39Webb AR, Kline L, Holick MF. Influence of season and latitude on the cutaneous synthesis of vitamin D3: exposure to winter sunlight in Boston and Edmonton will not promote vitamin D3 synthesis in human skin. J Clin Endocrinol Metab 1988; 67: 373–8.
- 40Vik T, Try K, Stromme JH. The vitamin D status of man at 70 degrees north. Scand J Clin Lab Invest 1980; 40: 227–32.
- 41Brustad M, Sandanger T, Aksnes L, Lund E. Vitamin D status in a rural population of northern Norway with high fish liver consumption. Public Health Nutr 2004; 7: 783–9.
- 42Brustad M, Edvardsen K, Wilsgaard T et al. Seasonality of UV-radiation and vitamin D status at 69 degrees north. Photochem Photobiol Sci 2007; 6: 903–8.
- 43Pitson GA, Lugg DJ, Roy CR. Effect of seasonal ultraviolet radiation fluctuations on vitamin D homeostasis during an Antarctic expedition. Eur J Appl Physiol 1996; 72: 231–4.
- 44Yonei T, Hagino H, Katagiri H, Hasimoto H. Bone metabolic changes in Antarctic wintering team members. Bone 1999; 24: 145–50.
- 45Fairney A, Fry J, Lipscomb A. The effect of darkness on vitamin D in adults. Postgrad Med J 1979; 55: 248–50.
- 46Smith SM, Gardner KK, Locke J, Zwart SR. Vitamin D supplementation during Antarctic winter. Am J Clin Nutr 2009; 89: 1092–8.
- 47Oliveri MB, Mautalen C, Bustamante L, Gómez-García V. Serum levels of 25-hydroxyvitamin D in a year of residence on the Antarctic continent. Eur J Clin Nutr 1994; 48: 397–401.
- 48Brustad M, Alsaker E, Engelsen O et al. Vitamin D status of middle-aged women at 65–71°N in relation to dietary intake and exposure to ultraviolet radiation. Public Health Nutr 2004; 7: 327–35.
- 49Guzel R, Kozanoglu E, Guler-Uysal F et al. Vitamin D status and bone mineral density of veiled and unveiled Turkish women. J Womens Health Gend Based Med 2001; 10: 765–70.
- 50Alagol F, Shihadeh Y, Boztepe H et al. Sunlight exposure and vitamin D deficiency in Turkish women. J Endocrinol Invest 2000; 23: 173–7.
- 51Budak N, Cicek B, Sahin H, Tutus A. Bone mineral density and serum 25-hydroxyvitamin D level: is there any difference according to the dressing style of the female university students. Int J Food Sci Nutr 2004; 55: 569–75.
- 52Gharaibeh MA, Stoecker BJ. Assessment of serum 25(OH)D concentration in women of childbearing age and their preschool children in Northern Jordan during summer. Eur J Clin Nutr 2009; 63: 1320–6.
- 53El-Sonbaty MR, Naser A-G. Vitamin D deficiency in veiled Kuwaiti women. Eur J Clin Nutr 1996; 50: 315–18.
- 54Dawodu A, Absood G, Patel M et al. Biosocial factors affecting vitamin D status of women of childbearing age in the United Arab Emirates. J Biosoc Sci 1998; 30: 431–7.
- 55Islam MZ, Shamim AA, Kemi V et al. Vitamin D deficiency and low bone status in adult female garment factory workers in Bangladesh. Br J Nutr 2008; 99: 1322–9.
- 56Sarikaya S, Ozdolap S, Mungan AG et al. Effect of underground working on vitamin D levels and bone mineral densities in coal miners: a controlled study. J Int Med Res 2006; 34: 362–6.
- 57Dlugos DJ, Perrotta PL, Horn WG. Effects of the submarine environment on renal-stone risk factors and vitamin D metabolism. Undersea Hyperb Med 1995; 22: 145–52.
- 58Duplessis CA, Harris EB, Watenpaugh DE, Horn WG. Vitamin D supplementation in underway submariners. Aviat Space Environ Med 2005; 76: 569–75.
- 59Luria T, Matsliah Y, Adir Y et al. Effects of a prolonged submersion on bone strength and metabolism in young healthy submariners. Calcif Tissue Int 2010; 86: 8–13.
- 60Smith SM, Zwart SR, Block G et al. The nutritional status of astronauts is altered after long-term space flight aboard the International Space Station. J Nutr 2005; 135: 437–43.
- 61Goswami R, Gupta N, Ray D et al. Pattern of 25-hydroxy vitamin D response at short (2 month) and long (1 year) interval after 8 weeks of oral supplementation with cholecalciferol in Asian Indians with chronic hypovitaminosis D. Br J Nutr 2008; 100: 526–9.
- 62Kimlin M, Harrison S, Nowak M et al. Does a high UV environment ensure adequate vitamin D status? J Photochem Photobiol, B 2007; 89: 139–47.
- 63Unger MD, Cuppari L, Titan SM et al. Vitamin D status in a sunny country: where has the sun gone? Clin Nutr 2010; 29: 784–8.
- 64Soontrapa S, Soontrapa S, Bunyaratavej N et al. Vitamin D status of Thai premenopausal women. J Med Assoc Thai 2009; 92 (Suppl. 5): S17–20.
- 65 Scientific Advisory Committee on Nutrition. Update on Vitamin D: Position Statement by the Scientific Advisory Committee on Nutrition. London: The Stationery Office, 2007.
- 66Hanley DA, Davison KS. Vitamin D insufficiency in North America. J Nutr 2005; 135: 332–7.
- 67Hollis BW. Circulating 25-hydroxyvitamin D levels indicative of vitamin D sufficiency: implications for establishing a new effective dietary intake recommendation for vitamin D. J Nutr 2005; 135: 317–22.
- 68Bischoff-Ferrari HA, Giovannucci E, Willett WC et al. Estimation of optimal serum concentrations of 25-hydroxyvitamin D for multiple health outcomes. Am J Clin Nutr 2006; 84: 18–28.
- 69Priemel M, von Domarus C, Klatte TO et al. Bone mineralisation defects and vitamin D deficiency: histomorphometric analysis of iliac crest bone biopsies and circulating 25-hydroxyvitamin D in 675 patients. J Bone Miner Res 2010; 25: 305–12.
- 70Friedman CF, DeMichele A, Su HI et al. Vitamin D deficiency in post menopausal breast cancer survivors. J Womens Health 2012; 21: 456–62.
- 71Binkley N, Ramamurthy R, Krueger D. Low vitamin D status: definition, prevalence, consequences and correction. Rheum Dis Clin North Am 2012; 38: 45–59.
- 72Veith R, Bischoff-Ferrari H, Boucher BJ et al. The urgent need to recommend an intake of vitamin D that is effective. Am J Clin Nutr 2007; 85: 649–50.
- 73 Institute of Medicine (US) Committee to Review Dietary Reference Intakes for Vitamin D and Calcium. Dietary Reference Intakes for Calcium and Vitamin D ( AC Ross, CL Taylor, AL Yaktine, eds). Washington, DC: National Academies Press, 2011.
- 74Brot C, Vestergaard P, Kolthoff N et al. Vitamin D status and its adequacy in healthy Danish perimenopausal women: relationships to dietary intake, sun exposure and serum parathyroid hormone. Br J Nutr 2001; 86 (Suppl. 1): S97–103.
- 75Sedrani SH, Elidrissy AW, El Arabi KM. Sunlight and vitamin D status in normal Saudi subjects. Am J Clin Nutr 1983; 38: 129–32.
- 76Webb AR, Pilbeam C, Hanafin N, Holick MF. An evaluation of the relative contributions of exposure to sunlight and of diet to the circulating concentrations of 25-hydroxyvitamin D in an elderly nursing home population in Boston. Am J Clin Nutr 1990; 51: 1075–81.
- 77Kennedy C, Bajdik CD, Willemze R et al. The influence of painful sunburns and lifetime sun exposure on the risk of actinic keratoses, seborrheic warts, melanocytic naevi, atypical naevi, and skin cancer. J Invest Dermatol 2003; 120: 1087–93.
- 78Healy E, Reynolds NJ, Smith MD et al. Dissociation of erythema and p53 protein expression in human skin following UVB irradiation, and induction of p53 protein and mRNA following application of skin irritants. J Invest Dermatol 1994; 103: 493–9.
- 79Seité S, Fourtanier A, Moyal D, Young AR. Photodamage to human skin by suberythemal exposure to solar ultraviolet radiation can be attenuated by sunscreens: a review. Br J Dermatol 2010; 163: 903–14.
- 80 Department of Health and Social Security. Rickets and Osteomalacia: Report on Health and Social Subjects Number 19. London: HMSO, 1980.
- 81 National Institute for Health and Care Excellence. Improving the Nutrition of Pregnant and Breastfeeding Mothers and Children in Low-Income Households. London: NICE, 2008.
- 82Lawson DEM, Douglas J, Lean M, Sedrani S. Estimation of vitamin D3 and 25-hydroxyvitamin D3 in muscle and adipose tissue of rats and man. Clin Chim Acta 1986; 157: 175–81.
- 83Macdonald HM, Mavroeidi A, Reid DM, Fraser WD. Sunlight or diet: what is the answer for providing sufficient vitamin D in the U.K.? Br J Dermatol 2010; 163: 434–5.
- 84Diffey BL. Modelling vitamin D status due to oral intake and sun exposure in an adult British population. Br J Nutr 2013; 110: 569–77.
- 85van der Meer IM, Boeke AJP, Lips P et al. Fatty fish and supplements are the greatest modifiable contributors to the serum 25-hydroxyvitamin D concentration in a multiethnic population. Clin Endocrinol (Oxf) 2008; 68: 466–72.
- 86Wicherts IS, Boeke AJ, van der Meer IM et al. Sunlight exposure or vitamin D supplementation for vitamin D-deficient non-western immigrants: a randomized clinical trial. Osteoporos Int 2010; 22: 873–82.
- 87Cashman KD, FitzGerald AP, Viljakainen HT et al. Estimation of the dietary requirement for vitamin D in healthy adolescent white girls. Am J Clin Nutr 2011; 93: 549–55.
- 88Cashman KD, Hill TR, Lucey AJ et al. Estimation of the dietary requirement for vitamin D in healthy adults. Am J Clin Nutr 2008; 88: 1535–42.
- 89Mavroeidi A, O'Neill F, Lee PA et al. Seasonal 25-hydroxyvitamin D changes in British postmenopausal women at 57°N and 51°N: a longitudinal study. J Steroid Biochem Mol Biol 2010; 121: 459–61.
- 90Macdonald HM, Mavroeidi A, Fraser WD et al. Sunlight and dietary contributions to the seasonal vitamin D status of cohorts of healthy postmenopausal women living at northerly latitudes: a major cause for concern? Osteoporos Int 2011; 22: 2461–72.
- 91Szyszka P, Zmijewski MA, Slominski AT. New vitamin D analogs as potential therapeutics in melanoma. Expert Rev Anticancer Ther 2012; 12: 585–99.
- 92Newton-Bishop JA, Beswick S, Randerson-Moor J et al. Serum 25-hydroxyvitamin D3 levels are associated with Breslow thickness at presentation and survival from melanoma. J Clin Oncol 2009; 27: 5439–44.
- 93Tang JY, Fu T, Leblanc E et al. Calcium plus vitamin D supplementation and the risk of nonmelanoma and melanoma skin cancer: post hoc analyses of the Women's Health Initiative randomized controlled trial. J Clin Oncol 2011; 29: 3078–84.
- 94Field S, Newton-Bishop JA. Melanoma and vitamin D. Mol Oncol 2011; 5: 197–214.
- 95van der Pols JC, Russell A, Bauer U et al. Vitamin D status and skin cancer risk independent of time outdoors: 11-year prospective study in an Australian community. J Invest Dermatol 2013; 133: 637–41.
- 96Liang G, Nan H, Qureshi AA, Han J. Pre-diagnostic plasma 25-hydroxyvitamin D levels and risk of nonmelanoma skin cancer in women. PLoS ONE 2012; 7: e35211.
- 97Tang JY, Parimi N, Wu A et al. Inverse association between serum 25(OH) vitamin D levels and non-melanoma skin cancer in elderly men. Cancer Causes Control 2010; 21: 387–91.
- 98Freedman DM, Looker AC, Chang SC, Graubard BI. Prospective study of serum vitamin D and cancer mortality in the United States. J Natl Cancer Inst 2007; 99: 1594–602.
- 99Lamberg AL, Olesen AB, Jensen AO. Hip fracture history and risk of nonmelanoma skin cancer: a Danish population study. Clin Epidemiol 2011; 3: 285–93.
- 100Eide MJ, Johnson DA, Jacobsen GR et al. Vitamin D and nonmelanoma skin cancer in a health maintenance cohort. Arch Dermatol 2011; 147: 1379–84.
- 101Asgari MM, Tang J, Warton ME et al. Association of prediagnostic serum vitamin D levels with the development of basal cell carcinoma. J Invest Dermatol 2010; 130: 1438–43.
- 102 Centre for Reviews and Dissemination (CRD). Systematic Reviews. CRD's Guidance for Undertaking Reviews in Health Care. York: University of York, 2008.
