Group items tagged

Dietary eicosapentaenoic acid prevents systemic immunosuppression in mice induced by UVB radiation. Moison RM, Beijersbergen Van Henegouwen GM. Radiat Res. 2001 Jul;156(1):36-44. PMID: 11418071

Vitamin D is a fat-soluble vitamin that is essential for maintaining normal calcium metabolism (1). Vitamin D3 (cholecalciferol) can be synthesized by humans in the skin upon exposure to ultraviolet-B (UVB) radiation from sunlight, or it can be obtained from the diet. Plants synthesize ergosterol, which is converted to vitamin D2 (ergocalciferol) by ultraviolet light. Vitamin D2 is less active in birds than vitamin D3 and may also be less active in humans (2). When exposure to UVB radiation is insufficient for the synthesis of adequate amounts of vitamin D3 in the skin, adequate intake of vitamin D from the diet is essential for health.

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.

Holick, M. F., MacLaughlin, J. A. & Doppelt, S. H. (1981) Factors that influence the cutaneous photosynthesis of previtamin D3. Science 211:590-593 When human skin was exposed to simulated solar ultraviolet radiation, epidermal 7-dehydrocholesterol was converted to previtamin D3. During prolonged exposure to simulated solar ultraviolet radiation, the synthesis of previtamin D3 reached a plateau at about 10 to 15 percent of the original 7-dehydrocholesterol content, and previtamin D3 was photoisomerized to two biologically inert isomers, lumisterol3 and tachysterol3. Increases either in skin melanin concentration or in latitude necessitated increases in the exposure time to simulated solar ultraviolet radiation required to maximize the formation, but not the total content, of previtamin D3. In order of importance, the significant determinants limiting the cutaneous production of previtamin D3 are (i) photochemical regulation, (ii) pigmentation, and (iii) latitude.

Are sunlight deprivation and influenza epidemics associated with the onset of acute leukemia? Timonen T, Näyhä S, Koskela T, Pukkala E. Haematologica. 2007 Nov;92(11):1553-6. PMID: 18024404 doi:10.3324/haematol.10799 Month of diagnosis of 7,423 cases of acute leukemia (AL) in Finland during 1964-2003 were linked with data on influenza and solar radiation. Acute myeloblastic leukemia (AML) showed the highest risk in the dark season. During the light season, the incidence decreased by 58% (95% confidence interval, 16-79%) per 1,000 kJ/m2/d increase of solar radiation. Independent of solar radiation, AML increased by 9% (95% confidence interval, 0-19%) during influenza epidemics. Reoccurring at the same time annually, darkness-related vitamin D deficiency and influenza could cause successive and co-operative mutations leading to AL with a short latency.

Vitamin D deficiency is the cause of common obesity. Foss YJ. Med Hypotheses. 2009 Mar;72(3):314-21. Epub 2008 Dec 2. PMID: 19054627 doi:10.1016/j.mehy.2008.10.005 Common obesity and the metabolic syndrome may therefore result from an anomalous adaptive winter response. The stimulus for the winter response is proposed to be a fall in vitamin D. The synthesis of vitamin D is dependent upon the absorption of radiation in the ultraviolet-B range of sunlight. At ground level at mid-latitudes, UV-B radiation falls in the autumn and becomes negligible in winter. It has previously been proposed that vitamin D evolved in primitive organisms as a UV-B sensitive photoreceptor with the function of signaling changes in sunlight intensity. It is here proposed that a fall in vitamin D in the form of circulating calcidiol is the stimulus for the winter response, which consists of an accumulation of fat mass (obesity) and the induction of a winter metabolism (the metabolic syndrome). Vitamin D deficiency can account for the secular trends in the prevalence of obesity and for individual differences in its onset and severity. It may be possible to reverse the increasing prevalence of obesity by improving vitamin D status.

Use of vitamin D in clinical practice. Cannell JJ, Hollis BW. Altern Med Rev. 2008 Mar;13(1):6-20. PMID: 18377099 The recent discovery--from a meta-analysis of 18 randomized controlled trials--that supplemental cholecalciferol (vitamin D) significantly reduces all-cause mortality emphasizes the medical, ethical, and legal implications of promptly diagnosing and adequately treating vitamin D deficiency. Not only are such deficiencies common, and probably the rule, vitamin D deficiency is implicated in most of the diseases of civilization. Vitamin D's final metabolic product is a potent, pleiotropic, repair and maintenance, seco-steroid hormone that targets more than 200 human genes in a wide variety of tissues, meaning it has as many mechanisms of action as genes it targets. One of the most important genes vitamin D up-regulates is for cathelicidin, a naturally occurring broad-spectrum antibiotic. Natural vitamin D levels, those found in humans living in a sun-rich environment, are between 40-70 ng per ml, levels obtained by few modern humans. Assessing serum 25-hydroxy-vitamin D (25(OH)D) is the only way to make the diagnosis and to assure treatment is adequate and safe. Three treatment modalities exist for vitamin D deficiency: sunlight, artificial ultraviolet B (UVB) radiation, and vitamin D3 supplementation. Treatment of vitamin D deficiency in otherwise healthy patients with 2,000-7,000 IU vitamin D per day should be sufficient to maintain year-round 25(OH)D levels between 40-70 ng per mL. In those with serious illnesses associated with vitamin D deficiency, such as cancer, heart disease, multiple sclerosis, diabetes, autism, and a host of other illnesses, doses should be sufficient to maintain year-round 25(OH)D levels between 55 -70 ng per mL. Vitamin D-deficient patients with serious illness should not only be supplemented more aggressively than the well, they should have more frequent monitoring of serum 25(OH)D and serum calcium. Vitamin D should always be

Vitamin D and living in northern latitudes--an endemic risk area for vitamin D deficiency. Huotari A, Herzig KH. Int J Circumpolar Health. 2008 Jun;67(2-3):164-78. Review. PMID: 18767337 CONCLUSIONS: Vitamin D plays a fundamental role in calcium and phosphate homeostasis. A deficiency of vitamin D has been attributed to several diseases. Since its production in the skin depends on exposure to UVB-radiation via the sunlight, the level of vitamin D is of crucial importance for the health of inhabitants who live in the Nordic latitudes where there is diminished exposure to sunlight during the winter season. Therefore, fortification or supplementation of vitamin D is necessary for most of the people living in the northern latitudes during the winter season to maintain adequate levels of circulating 25(OH)D3 to maintain optimal body function and prevent diseases.

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.

Explaining multiple sclerosis prevalence by ultraviolet exposure: a geospatial analysis. Beretich B, Beretich T. Mult Scler. 2009 Aug;15(8):891-8. PMID: 19667017 DOI: 10.1177/1352458509105579 Conclusion This analysis suggests a strong association between UV radiation and MS distribution, and an increase in risk for MS in those areas with a low UVI.

This critical nutrient builds bones, helps fight infection and may protect against some cancers. Do we get enough?

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.

Ecological Studies Of Ultraviolet B, Vitamin D And Cancer Since 2000. Grant WB, Mohr SB. Ann Epidemiol. 2009 Mar 6. [Epub ahead of print] PMID: 19269856

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.

"We are fond of grumbling about Britain's grey skies, but there may be a good medical reason for doing so. It seems the dreary weather is bad for our hearts - worse, even, than raised cholesterol and an unhealthy diet. That's the controversial claim being made by Dr David Grimes, a gastroenterologist from Blackburn. He's been gazing at the sky for 20 years for clues about why his patients get more sick than those in the south of the country. And what he's found turns key assumptions about heart disease on their head. 'It's not diet or cholesterol levels that raise your risk of heart disease,' he claims. 'It's where you live. People in the north are more likely to be ill because they get less sunshine Basically they are suffering from 'latitude' sickness. The link is vitamin D. While we get some from our diet, the main source is the sun - sunlight converts a compound in the skin into vitamin D, so the amount you make is directly related to the amount of sunshine you get. In a new book Dr Grimes argues the higher the level of vitamin D in your blood, the lower your risk of heart disease and a range of other illnesses. If he's right, what we need is not diet and lifestyle advice, but food fortified with vitamin D. For years the vitamin was thought to be useful only for preventing rickets. So how does he treat them? 'You can do it with diet,' he says 'One Bangladeshi woman eats oily fish every day and now has a vitamin D blood level of 40. 'We give supplements of 1,000 international units (IU) a day or we can give an injection of 300,000 IU that lasts for a year. 'The patients respond well,' says Grimes 'but what's needed is a proper controlled, long-term trial and who is going to fund that? Not a drug company.'"