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.
Sunlight, vitamin D and the prevention of cancer: a systematic review of epidemiological studies.
Rhee HV, Coebergh JW, Vries ED.
Eur J Cancer Prev. 2009 Aug 26. [Epub ahead of print]
PMID: 19730382
We, therefore, conclude that there is accumulating evidence for sunlight as a protective factor for several types of cancer. The same conclusion can be made concerning high vitamin D levels and the risk of colorectal cancer. This evidence, however, is not conclusive, because the number of (good quality) studies is still limited and publication biases cannot be excluded. The discrepancies between the epidemiological evidence for a possible preventive effect of sunlight and vitamin D and the question of how to apply the findings on the beneficial effects of sunlight to (public) health recommendations are discussed.
Vitamin D and breast cancer.
Bertone-Johnson ER.
Ann Epidemiol. 2009 Jul;19(7):462-7. Epub 2009 Feb 20. Review.
PMID: 19230714
Though the relationship between vitamin D and breast cancer remains unclear, a growing body of evidence suggests that vitamin D may modestly reduce risk. A large number of in vitro studies indicate that vitamin D can inhibit cell proliferation and promote apoptosis and cell differentiation in breast tumor tissue. Results from analytic studies of sunlight exposure and dietary intake have been inconsistent but together generally support a modestly protective role of vitamin D, at least in some population subgroups. Studies using blood vitamin D metabolites to assess vitamin D status may be less prone to misclassification than those of diet and sunlight exposure. Overall, the two prospective and four case-control studies of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D tend to support a protective effect in older women. The relationship between common vitamin D receptor polymorphisms and risk remains unclear. Many questions about this relationship clearly remain, including the utility of assessing vitamin D through diet and sunlight exposure, the relationship between plasma metabolites, and the potential modifying effects of age, menopausal status and tumor characteristics. Given that vitamin D status is modifiable, additional prospective studies are necessary to determine if vitamin D may have important potential for breast cancer prevention.
Vitamin d and its role in cancer and immunity: a prescription for sunlight.
Mullin GE, Dobs A.
Nutr Clin Pract. 2007 Jun;22(3):305-22. Review.
PMID: 17507731
(free full text PDF available)
Holick MF.
Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease.
Am J Clin Nutr. 2004 Dec;80(6 Suppl):1678S-88S. Review.
PMID: 15585788 [PubMed - indexed for MEDLINE]
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
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
Sunlight and vitamin D: both good for cardiovascular health.
Holick MF.
J Gen Intern Med. 2002 Sep;17(9):733-5.
PMID: 12220371
doi: 10.1046/j.1525-1497.2002.20731.x.
Vitamin d and its role in cancer and immunity: a prescription for sunlight.
Mullin GE, Dobs A.
Nutr Clin Pract. 2007 Jun;22(3):305-22. Review.
PMID: 17507731
DOI: 10.1177/0115426507022003305
Vitamin D from dietary intake and sunlight exposure and the risk of hormone-receptor-defined breast cancer.
Blackmore KM, Lesosky M, Barnett H, Raboud JM, Vieth R, Knight JA.
Am J Epidemiol. 2008 Oct 15;168(8):915-24. Epub 2008 Aug 27.
PMID: 18756015
doi:10.1093/aje/kwn198
This study suggests that vitamin D is associated with a reduced risk of breast cancer regardless of ER/PR status of the tumor. Future studies with a larger number of receptor-negative and mixed tumors are required.
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 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.
Mullin GE, Dobs A.
Vitamin d and its role in cancer and immunity: a prescription for sunlight.
Nutr Clin Pract. 2007 Jun;22(3):305-22. Review.
PMID: 17507731 [PubMed - indexed for MEDLINE]
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.
"The major factor which stimulates weight gain in winter months is vitamin D. Human bodies get vitamin D from sunlight; as the hours of sunlight become less with the onset of fall, so our levels of vitamin D decrease.
Low levels of vitamin D affect the brain's production of the hormone leptin. Leptin plays a vital role in controlling appetite and metabolism; so as the amount of vitamin D in our bodies decreases so does the leptin, and this causes an increase in our appetite and a change in our metabolism.
Researchers at Aberdeen University found that obese people had 10% less vitamin D than people of average weight. The study also found that excess body fat absorbed vitamin D so the body couldn't use it. Scientists now believe that there is a direct correlation between obesity and low levels of vitamin D.
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.
"Hypovitaminosis D is a deficiency of Vitamin D. It can result from: inadequate intake coupled with inadequate sunlight exposure (in particular sunlight with adequate ultra violet B rays), disorders that limit its absorption, conditions that impair conversion of vitamin D into active metabolites, such as liver or kidney disorders, or, rarely, by a number of hereditary disorders.[1] Deficiency results in impaired bone mineralization, and leads to bone softening diseases, rickets in children and osteomalacia in adults, and contributes to osteoporosis.[1] Osteomalacia may also occur rarely as a side-effect of phenytoin use
Hypovitaminosis D is typically diagnosed by measuring the concentration in blood of the compound 25-hydroxyvitamin D (calcidiol), which is a precursor to the active form 1,25-dihydroxyvitamin D (calcitriol).[6] One recent review has proposed the following four categories for hypovitaminosis D:[7]
* Insufficient 50-100 nmol/L (20-40 ng/mL)
* Mild 25-50 nmol/L (10-20 ng/mL)
* Moderate 12.5-25.0 nmol/L (5-10 ng/mL)
* Severe < 12.5 nmol/L (< 5 ng/mL)
Note that 1.0 nmol/L = 0.4 ng/mL for this compound.[8] Other authors have suggested that a 25-hydroxyvitamin D level of 75-80 nmol/L (30-32 ng/mL) may be sufficient
According to a study conducted by University of Wisconsin researchers, even people who are regularly exposed to sunlight can have low vitamin D levels.\n\nThe 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.
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.
Vitamin D deficiency: a worldwide problem with health consequences.
Holick MF, Chen TC.
Am J Clin Nutr. 2008 Apr;87(4):1080S-6S. Review.
PMID: 18400738
A reevaluation needs to take place of what the adequate intakes of vitamin D should be for children and adults. The literature over the past decade suggests that the Institute of Medicine recommendations in 1997 (83) are inadequate, and some experts including us suggest that both children and adults should take ≥800-1000 IU vitamin D/d from dietary and supplemental sources (4, 9, 77) when sunlight is unable to provide it. This recommendation, however, has not yet been embraced either by official government or pediatric organizations in the United States, Canada, or Europe for either children or adults.