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Low vitamin D status despite abundant sun exposure. Binkley N, Novotny R, Krueger D, Kawahara T, Daida YG, Lensmeyer G, Hollis BW, Drezner MK. J Clin Endocrinol Metab. 2007 Jun;92(6):2130-5. Epub 2007 Apr 10. PMID: 17426097 doi:10.1210/jc.2006-2250 CONCLUSIONS: These data suggest that variable responsiveness to UVB radiation is evident among individuals, causing some to have low vitamin D status despite abundant sun exposure. In addition, because the maximal 25(OH)D concentration produced by natural UV exposure appears to be approximately 60 ng/ml, it seems prudent to use this value as an upper limit when prescribing vitamin D supplementation.

Addressing the health benefits and risks, involving vitamin D or skin cancer, of increased sun exposure.\nMoan J, Porojnicu AC, Dahlback A, Setlow RB.\nProc Natl Acad Sci U S A. 2008 Jan 15;105(2):668-73. Epub 2008 Jan 7.\nPMID: 18180454

According to a study conducted by University of Wisconsin researchers, even people who are regularly exposed to sunlight can have low vitamin D levels. The study focused on subjects who lived in sunny Hawaii and spent an average of 11.1 hours in the sun each week. (None of the participants in the study used any type of sunscreen.) Despite the exposure, 51 percent of participants were found to be deficient in vitamin D.

Childhood sun exposure influences risk of multiple sclerosis in monozygotic twins. Islam T, Gauderman WJ, Cozen W, Mack TM. Neurology. 2007 Jul 24;69(4):381-8. PMID: 17646631 Conclusion: Early sun avoidance seems to precede the diagnosis of multiple sclerosis (MS). This protective effect is independent of genetic susceptibility to MS.

Circulating vitamin D3 and 25-hydroxyvitamin D in humans: An important tool to define adequate nutritional vitamin D status. Hollis BW, Wagner CL, Drezner MK, Binkley NC. J Steroid Biochem Mol Biol. 2007 Mar;103(3-5):631-4. Epub 2007 Jan 10. PMID: 17218096 In the present study, we sought to investigate what circulating 25(OH)D levels would result in populations exhibiting no substrate limitations to the vitamin D-25-hydroxylase. To perform this, we chose two distinct populations. The first were individuals from a year-found sunny environment who spent a good deal of time outdoors. The second were a group of lactating women receiving a substantial daily oral dose of vitamin D3. Surprisingly, a study such as this previously had not been undertaken. There are several reasons for this. First, finding a group of sun-exposed individuals is not an easy task; in fact, we had to go to Hawaii to find them. Secondly, very few studies have been performed where subjects actually received adequate vitamin D3 supplementation to make them replete. Finally, it is very difficult and costly to measure circulating vitamin D3 and relate it to circulating 25(OH)D. The results of our study are far-reaching. This study also demonstrates that individuals can be vitamin D deficient with significant sun exposure if the skin area exposed is limited as was suggested several years ago (19). Finally, whether one receives their vitamin D3 orally or through UV exposure, the vitamin D-25-hydroxylase appears to handle it in an equivalent fashion with respect to maintaining circulating 25(OH)D levels. Thus, we believe that the relationship between circulating vitamin D and 25(OH)D may define adequate nutritional vitamin D status.

SSeason of diagnosis is a prognostic factor in Hodgkin's lymphoma: a possible role of sun-induced vitamin D. Porojnicu AC, Robsahm TE, Ree AH, Moan J. Br J Cancer. 2005 Sep 5;93(5):571-4. PMID: 16136030 doi:10.1038/sj.bjc.6602722 Epidemiological data for this period indicate that season of diagnosis is a strong prognostic factor for Hodgkin's lymphoma, with approximately 20% lower case fatality for patients diagnosed during autumn vs winter diagnosis (RR = 0.783, 95% CI,-0.62 to 0.99; P = 0.041). Notably, the improved autumnal survival rate was higher than 60% (RR = 0.364, 95% CI, -0.15 to 0.87; P = 0.025) for patients younger than 30 years. This finding may be related to higher endogenous levels of vitamin D in autumn, with a favourable influence on the conventional therapy. In conclusion, we have found that the prognosis of Hodgkin's lymphoma is significantly correlated with the season of diagnosis, particularly for patients younger than 30 years. This seasonal effect is presumably due to the vitamin D3 synthesis in skin during sun exposure. The present findings should encourage further investigations of the possible adjuvant role of vitamin D derivatives in cancer therapy

Vitamin D deficiency is a very serious health problem. Most people tend to think of it only in terms of skeletal problems; however, it is much more than that. Vitamin D deficiency has now been linked with a multitude of neoplasms, autoimmune dysfunction, compromised innate immunity and neurodevelopment in utero. Vitamin D is made in huge amounts when we go into intense sun. A fair-skinned individual can produce approximately 20,000 IU in 10 minutes' time with a total body exposure. A person with significant pigmentation will require up to 10 times the exposure to make an equivalent amount. In the winter at the latitude of Chicago, even a fair person cannot photo-produce vitamin D from mid-October through March. Thus, it is VERY important to have a realistic vitamin D recommendation as the current 200 IU/day recommendation is a joke

Investigating the links between muscle strength, sun exposure, dietary vitamin D intake and the vitamin D status of ambulatory older adults in South East Queensland Borradale, David (2008) QUT Thesis]

Cod liver oil, vitamin A toxicity, frequent respiratory infections, and the vitamin D deficiency epidemic. Cannell JJ, Vieth R, Willett W, Zasloff M, Hathcock JN, White JH, Tanumihardjo SA, Larson-Meyer DE, Bischoff-Ferrari HA, Lamberg-Allardt CJ, Lappe JM, Norman AW, Zittermann A, Whiting SJ, Grant WB, Hollis BW, Giovannucci E. Ann Otol Rhinol Laryngol. 2008 Nov;117(11):864-70. Review. PMID: 19102134 Until we have better information on doses of vitamin D that will reliably provide adequate blood levels of 25(OH)D without toxicity, treatment of vitamin D deficiency in otherwise healthy children should be individualized according to the numerous factors that affect 25(OH)D levels, such as body weight, percent body fat, skin melanin, latitude, season of the year, and sun exposure.2 The doses of sunshine or oral vitamin D3 used in healthy children should be designed to maintain 25(OH)D levels above 50 ng/mL. As a rule, in the absence of significant sun exposure, we believe that most healthy children need about 1,000 IU of vitamin D3 daily per 11 kg (25 lb) of body weight to obtain levels greater than 50 ng/mL. Some will need more, and others less. In our opinion, children with chronic illnesses such as autism, diabetes, and/or frequent infections should be supplemented with higher doses of sunshine or vitamin D3, doses adequate to maintain their 25(OH)D levels in the mid-normal of the reference range (65 ng/mL) - and should be so supplemented year round. Otolaryngologists treating children are in a good position to both diagnose and treat vitamin D deficiency.

Barger-Lux MJ, Heaney RP. Effects of above average summer sun exposure on serum 25-hydroxyvitamin D and calcium absorption.J Clin Endocrinol Metab. 2002 Nov;87(11):4952-6.PMID: 12414856 [PubMed - indexed for MEDLINE]

Gonzalez G, Alvarado JN, Rojas A, Navarrete C, Velasquez CG, Arteaga E. High prevalence of vitamin D deficiency in Chilean healthy postmenopausal women with normal sun exposure: additional evidence for a worldwide concern. Menopause. 2007 May-Jun;14(3

Benefits of Vitamin D Supplementation Joel M. Kauffman, Ph.D. Journal of American Physicians and Surgeons Volume 14 Number 2 - Summer 2009 Clinical trials show that vitamin D supplementation at higher levels than previously recommended is beneficial for many conditions. It decreases the frequency of falls and fractures, helps prevent cardiovascular disease, and reduces symptoms of colds or influenza. Benefits are also seen in diabetes mellitus, multiple sclerosis, Crohn disease, pain, depression, and possibly autism. Sunlight does not cause an overdose of vitamin D production, and toxicity from supplementation is rare. Dose recommendations are increasing, but appear to be lagging the favorable trial results. A number of common drugs deplete vitamin D levels, and others may limit its biosynthesis from sunlight. People with adequate levels from sun exposure will not benefit from supplementation. While dietary intake is helpful, supplementation is better able to raise serum 25-hydroxyvitamin D , the major circulating metabolite, to the level now thought adequate, 30-50 ng/mL. Where there is inadequate daily sun exposure, oral doses of 1,000-2,000 IU/d are now considered routine, with much higher doses (up to 50,000 IU) for rapid repletion now considered safe.

Geographic variation in breast cancer mortality in the United States: a hypothesis involving exposure to solar radiation. Garland FC, Garland CF, Gorham ED, Young JF. Prev Med. 1990 Nov;19(6):614-22. PMID: 2263572 doi:10.1016/0091-7435(90)90058-R Vitamin D from sunlight exposure may be associated with low risk for fatal breast cancer, and differences in ultraviolet light reaching the United States population may account for the striking regional differences in breast cancer mortality. The ecological nature of this study is emphasized, and the possibility that an indirect association with dietary and socioeconomic factors could explain these findings is discussed.

Commonly recommended daily intake of vitamin D is not sufficient if sunlight exposure is limited. Glerup H, Mikkelsen K, Poulsen L, Hass E, Overbeck S, Thomsen J, Charles P, Eriksen EF. J Intern Med. 2000 Feb;247(2):260-8. PMID: 10692090 Conclusions. Severe vitamin D deficiency is prevalent amongst sunlight-deprived individuals living in Denmark. In veiled Arab women, vitamin D deficiency is the result of a combination of limitations in sunlight exposure and a low oral intake of vitamin D. The oral intake of vitamin D amongst veiled ethnic Danish Moslems was, however, very high, at 13.53 µg (approximately 600 IU), but they were still vitamin D-deficient. Our results suggest that the daily oral intake of vitamin D in sunlight-deprived individuals should exceed 600 IU; most probably it should be 1000 IU day-1 to secure a normal level of 25-hydroxyvitamin D. This finding is in contrast with the commonly used RDA (recommended daily allowance) for adults in Europe: 200 IU day-1.

Comment: Although lower risk associated with vitamin D exposure was shown most consistently for ER+/PR+ tumors, the result might simply reflect that this tumor subtype was the most common. Nonetheless, these findings support vitamin D's beneficial effects on breast cancer risk, regardless of hormone-receptor status. Sun exposure and dietary intake (Table 1) are key sources of vitamin D.

Seasonality of UV-radiation and vitamin D status at 69 degrees north. Brustad M, Edvardsen K, Wilsgaard T, Engelsen O, Aksnes L, Lund E. Photochem Photobiol Sci. 2007 Aug;6(8):903-8. Epub 2007 Jun 27. PMID: 17668121 The generally high dietary intakes of vitamin D, especially in winter, mask largely the effect of seasonal variation in UV-exposure, causing an atypical seasonal variation in vitamin D status. The UV-hour variable significantly predicted 25(OH)D levels in blood when adjusted for intakes and artificial UV-radiation exposure and sun holidays abroad.

Vitamin D status in apparently healthy adults in Kashmir Valley of Indian subcontinent. Zargar AH, Ahmad S, Masoodi SR, Wani AI, Bashir MI, Laway BA, Shah ZA. Postgrad Med J. 2007 Nov;83(985):713-6. PMID: 17989271 doi:10.1136/pgmj.2007.059113 Conclusions: In spite of abundant sunlight, healthy individuals in Kashmir valley are vitamin D deficient, particularly women. Serum 25 (OH) D concentrations are significantly related to sun exposure

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. Webb AR, Pilbeam C, Hanafin N, Holick MF. Am J Clin Nutr. 1990 Jun;51(6):1075-81. PMID: 2349922

Glerup H, Mikkelsen K, Poulsen L, Hass E, Overbeck S, Thomsen J, Charles P, Eriksen EF. Commonly recommended daily intake of vitamin D is not sufficient if sunlight exposure is limited.J Intern Med. 2000 Feb;247(2):260-8.PMID: 10692090 [PubMed - indexed f

Ultraviolet exposure scenarios: risks of erythema from recommendations on cutaneous vitamin D synthesis. Webb AR, Engelsen O. Adv Exp Med Biol. 2008;624:72-85. PMID: 18348448 DOI: 10.1007/978-0-387-77574-6_6