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.
An ecologic study of dietary and solar ultraviolet-B links to breast carcinoma mortality rates.
Grant WB.
Cancer. 2002 Jan 1;94(1):272-81.
PMID: 11815987
CONCLUSIONS
It is hypothesized that animal products are associated with risk for breast carcinoma because they are associated with greater amounts of insulin-like growth factor-1and lifetime doses of estrogen. Vegetable products contain several risk reduction components including antioxidants and phytoestrogens. The association with latitude is very likely because of solar UV-B radiation and vitamin D. Alcohol modulates estrogen's effects on breasts. Fish intake is associated with risk reduction through vitamin D and n-3 oils. These results are consistent with those of many case-control and cohort studies but should be assessed in well designed cohort studies.
Decreased bioavailability of vitamin D in obesity.
Wortsman J, Matsuoka LY, Chen TC, Lu Z, Holick MF.
Am J Clin Nutr. 2000 Sep;72(3):690-3. Erratum in: Am J Clin Nutr. 2003 May;77(5):1342.
PMID: 10966885
Conclusions: Obesity-associated vitamin D insufficiency is likely due to the decreased bioavailability of vitamin D3 from cutaneous and dietary sources because of its deposition in body fat compartments.