Sun holidays are an important, but expensive, source of vitamin D in Sweden - Sept 2013

Evaluation of sun holiday, diet habits, origin and other factors as determinants of vitamin D status in Swedish primary health care patients: a cross-sectional study with regression analysis of ethnic Swedish and immigrant women.

BMC Fam Pract. 2013 Sep 3;14:129. doi: 10.1186/1471-2296-14-129.
Björk A1, Andersson Å, Johansson G, Björkegren K, Bardel A, Kristiansson P.
1Department of Public Health and Caring Sciences, Family Medicine and Preventive Medicine unit, Uppsala University, Box 564, Uppsala SE-751 22, Sweden. anne.bjork@pubcare.uu.se.

BACKGROUND:
Determinants of vitamin D status measured as 25-OH-vitamin D in blood are exposure to sunlight and intake of vitamin D through food and supplements. It is unclear how large the contributions are from these determinants in Swedish primary care patients, considering the low radiation of UVB in Sweden and the fortification of some foods. Asian and African immigrants in Norway and Denmark have been found to have very low levels, but it is not clear whether the same applies to Swedish patients. The purpose of our study was to identify contributors to vitamin D status in Swedish women attending a primary health care centre at latitude 60°N in Sweden.

METHODS:
In this cross-sectional, observational study, 61 female patients were consecutively recruited between January and March 2009, irrespective of reason for attending the clinic. The women were interviewed about their sun habits, smoking, education and food intake at a personal appointment and blood samples were drawn for measurements of vitamin D and calcium concentrations.

RESULTS:
Plasma concentration of 25-OH-vitamin D below 25 nmol/L was found in 61% (19/31) of immigrant and 7% (2/30) of native women. Multivariate analysis showed that reported sun holiday of one week during the last year at latitude below 40°N with the purpose of sun-bathing and native origin, were significantly, independently and positively associated with 25-OH-vitamin D concentrations in plasma with the strongest association for sun holiday during the past year.

CONCLUSIONS:
Vitamin D deficiency was common among the women in the present study, with sun holiday and origin as main determinants of 25-OH-vitamin D concentrations in plasma. Given a negative effect on health this would imply needs for vitamin D treatment particularly in women with immigrant background who have moved from lower to higher latitudes.

PMID: 24004547


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Sun and Ski Holidays Improve Vitamin D Status, but Are Associated with High Levels of DNA Damage
Journal of Investigative Dermatology (20 May 2014) | doi:10.1038/jid.2014.223
Bibi Petersen, Hans C Wulf, Margarita Triguero-Mas, Peter A Philipsen, Elisabeth Thieden, Peter Olsen, Jakob Heydenreich, Payam Dadvand, Xavier Basagaña, Tove S Liljendahl, Graham I Harrison, Dan Segerbäck, Alois W Schmalwieser, Antony R Young and Mark J Nieuwenhuijsen

Skin cancer is caused by solar UVR, which is also essential for vitamin D production. DNA damage (thymine dimers: T-T dimers) and vitamin D (25(OH)D) synthesis are both initiated by solar UVB. We aimed to investigate the simultaneous adverse and beneficial effects of solar UVB exposure in holidaymakers. Sun-seekers and skiers (n=71) were observed over 6 days through on-site monitoring, personal diary entries, and recording of personal UVB exposure doses with electronic dosimeters. Urine and blood samples were analyzed for T-T dimers and 25(OH)D, respectively. The volunteers had a statistically significant increase in vitamin D. There were strong associations between UVB exposure and post-holiday levels of T-T dimers and vitamin D, as well as between post-holiday T-T dimers and vitamin D. We conclude that UVB-induced vitamin D synthesis is associated with considerable DNA damage in the skin. These data, on two major health predictors, provide a basis for further field studies that may result in better understanding of the risks and benefits of “real life” solar exposure. However, vitamin D status can be improved more safely through the use of vitamin D dietary supplements.

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