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Aging decreases the capacity of human skin to produce vitamin D3. MacLaughlin J, Holick MF. J Clin Invest. 1985 Oct;76(4):1536-8. PMID: 2997282 doi:10.1172/JCI112134 An evaluation of surgically obtained skin (age range, 8-92 yr) revealed that there is an age-dependent decrease in the epidermal concentrations of provitamin D3 (7-dehydrocholesterol). To ascertain that aging indeed decreased the capacity of human skin to produce vitamin D3, some of the skin samples were exposed to ultraviolet radiation and the content of previtamin D3 was determined in the epidermis and dermis. The epidermis in the young and older subjects was the major site for the formation of previtamin D3, accounting for greater than 80% of the total previtamin D3 that was produced in the skin. A comparison of the amount of previtamin D3 produced in the skin from the 8- and 18-yr-old subjects with the amount produced in the skin from the 77- and 82-yr-old subjects revealed that aging can decrease by greater than twofold the capacity of the skin to produce previtamin D3. Recognition of this difference may be extremely important for the elderly, who infrequently expose a small area of skin to sunlight and who depend on this exposure for their vitamin D nutritional needs.

Calcium and vitamin d supplementation decreases incidence of stress fractures in female navy recruits. Lappe J, Cullen D, Haynatzki G, Recker R, Ahlf R, Thompson K. J Bone Miner Res. 2008 May;23(5):741-9. PMID: 18433305 doi: 10.1359/jbmr.080102 Conclusions: Generalizing the findings to the population of 14,416 women who entered basic training at the Great Lakes during the 24 mo of recruitment, calcium and vitamin D supplementation for the entire cohort would have prevented 187 persons from fracturing. Such a decrease in SFx would be associated with a significant decrease in morbidity and financial costs.

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.

Depression is associated with decreased 25-hydroxyvitamin D and increased parathyroid hormone levels in older adults. Hoogendijk WJ, Lips P, Dik MG, Deeg DJ, Beekman AT, Penninx BW. Arch Gen Psychiatry. 2008 May;65(5):508-12. PMID: 18458202 Conclusion The results of this large population-based study show an association of depression status and severity with decreased serum 25(OH)D levels and increased serum PTH levels in older individuals.

Matsuoka, L. Y., Wortsman, J., Hanifan, N. & Holick, M. F. (1988) Chronic sunscreen use decreases circulating concentrations of 25-hydroxyvitamin D: a preliminary study. Arch. Dermatol. 124:1802-1804

Relation of body fat indexes to vitamin D status and deficiency among obese adolescents. Lenders CM, Feldman HA, Von Scheven E, Merewood A, Sweeney C, Wilson DM, Lee PD, Abrams SH, Gitelman SE, Wertz MS, Klish WJ, Taylor GA, Chen TC, Holick MF; Elizabeth Glaser Pediatric Research Network Obesity Study Group. Am J Clin Nutr. 2009 Sep;90(3):459-67. Epub 2009 Jul 29. PMID: 19640956 RESULTS: The mean (+/-SD) age of the adolescents was 14.9 +/- 1.4 y; 38 (66%) were female, and 8 (14%) were black. The mean (+/-SD) body mass index (in kg/m(2)) was 36 +/- 5, FM was 40.0 +/- 5.5%, and VAT was 12.4 +/- 4.3%. Seventeen of the adolescents were vitamin D deficient, but none had elevated PTH concentrations. Bone mineral content and bone mineral density were within 2 SDs of national standards. In a multivariate analysis, 25(OH)D decreased by 0.46 +/- 0.22 ng/mL per 1% increment in FM (beta +/- SE, P = 0.05), whereas PTH decreased by 0.78 +/- 0.29 pg/mL per 1% increment in VAT (P = 0.01). CONCLUSIONS: To the best of our knowledge, our results show for the first time that obese adolescents with 25(OH)D deficiency, but without elevated PTH concentrations, have a bone mass within the range of national standards (+/-2 SD). The findings provide initial evidence that the distribution of fat may be associated with vitamin D status, but this relation may be dependent on metabolic factors

Association of low intake of milk and vitamin D during pregnancy with decreased birth weight. Mannion CA, Gray-Donald K, Koski KG. CMAJ. 2006 Apr 25;174(9):1273-7. PMID: 16636326 doi:10.1503/cmaj.1041388. Interpretation: Milk and vitamin D intakes during pregnancy are each associated with infant birth weight, independently of other risk factors.

March 27, 2009 - A significant decrease in serum 25-hydroxyvitamin D (25[OH]D) levels has led to an increase in vitamin D insufficiency in the US population, especially in racial and ethnic groups, according to results of a population-based study reported in the March 23 issue of the Archives of Internal Medicine. "Vitamin D insufficiency has been associated with increases in cardiovascular disease, cancer, and infection," write Adit A. Ginde, MD, from the Department of Emergency Medicine at the University of Colorado Denver School of Medicine, Aurora, Colorado, and colleagues. "Vitamin D supplementation appears to mitigate the incidence and adverse outcomes of these diseases and may reduce all-cause mortality." [...] "These findings have important implications for health disparities and public health," the study authors conclude. "Our data provide additional evidence that current recommendations for vitamin D supplementation (200-600 IU/d) are inadequate to achieve optimal serum 25(OH)D levels in most of the US population." They add that large, randomized controlled trials of higher doses of vitamin D supplementation are needed to evaluate their effect on general health and mortality.

Vitamin D may not just be good for you, it may help save your life. Recent research from Johns Hopkins University suggests that higher amounts of vitamin D in your diet decreases your likelihood of dying. Studies found that a vitamin D deficiency increases your risk of death by 26 percent, and vitamin D decreases the mortality rate from almost every type of cancer including breast, colon and prostate. Research also suggests that vitamin D helps prevent diabetes, kidney disease and cardiovascular disease.

"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.

Serum vitamin D concentration and prostate cancer risk: a nested case-control study. Ahn J, Peters U, Albanes D, Purdue MP, Abnet CC, Chatterjee N, Horst RL, Hollis BW, Huang WY, Shikany JM, Hayes RB; Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial Project Team. J Natl Cancer Inst. 2008 Jun 4;100(11):796-804. Epub 2008 May 27. PMID: 18505967 doi:10.1093/jnci/djn152 CONCLUSION: The findings of this large prospective study do not support the hypothesis that vitamin D is associated with decreased risk of prostate cancer; indeed, higher circulating 25(OH)D concentrations may be associated with increased risk of aggressive disease. In summary, results from this large prospective study of men who underwent standardized prostate cancer screening in the context of a screening trial do not support the hypothesis that higher serum vitamin D status is associated with decreased risk of prostate cancer. The study showed no association of vitamin D level with nonaggressive disease; however, it raises the possibility that higher vitamin D level may be associated with increased risks for aggressive disease, although a clear monotonic dose-response relationship was lacking. Along with recent reports of adverse associations for higher vitamin D status and risk of pancreatic (32) and esophageal (33,34) cancer, caution should be taken in recommending high doses of vitamin D or sunlight exposure to the general public for prostate cancer prevention. Future analyses are warranted to confirm these results and to further clarify the effects of vitamin D on aggressive prostate cancer.

Aging decreases the capacity of human skin to produce vitamin D3. MacLaughlin J, Holick MF. J Clin Invest. 1985 Oct;76(4):1536-8. PMID: 2997282

Demographic differences and trends of vitamin D insufficiency in the US population, 1988-2004. Ginde AA, Liu MC, Camargo CA Jr. Arch Intern Med. 2009 Mar 23;169(6):626-32. PMID: 19307527 Conclusions National data demonstrate a marked decrease in serum 25(OH)D levels from the 1988-1994 to the 2001-2004 NHANES data collections. Racial/ethnic differences have persisted and may have important implications for known health disparities. Current recommendations for vitamin D supplementation are inadequate to address the growing epidemic of vitamin D insufficiency.

A positive dose-response effect of vitamin D supplementation on site-specific bone mineral augmentation in adolescent girls: a double-blinded randomized placebo-controlled 1-year intervention. Viljakainen HT, Natri AM, Kärkkäinen M, Huttunen MM, Palssa A, Jakobsen J, Cashman KD, Mølgaard C, Lamberg-Allardt C. J Bone Miner Res. 2006 Jun;21(6):836-44. PMID: 16753014 doi: 10.1359/jbmr.060302 We conclude that the current vitamin D recommendation for adolescent girls, at least in the northern latitudes, is too low to ensure sufficient vitamin D status during winter. Intake of vitamin D at rates of 10-15 μg/day aids to maintain stable S-25(OH)D concentrations during winter. Vitamin D induced BMC augmentation by decreasing bone resorption, but not affecting bone formation, which was reflected by the biochemical markers of bone turnover. Optimizing bone mineral gain in adolescence is crucial to the prevention of osteoporosis later in life. Increasing vitamin D intake to 10-15 μg/day aids in attaining this goal.

Effects of Atorvastatin on vitamin D levels in patients with acute ischemic heart disease. Pérez-Castrillón JL, Vega G, Abad L, Sanz A, Chaves J, Hernandez G, Dueñas A. Am J Cardiol. 2007 Apr 1;99(7):903-5. Epub 2007 Feb 8. PMID: 17398180 In conclusion, atorvastatin increases vitamin D levels. This increase could explain some of the beneficial effects of atorvastatin at the cardiovascular level that are unrelated to cholesterol levels. The mechanism by which atorvastatin increases vitamin D levels is related to inhibition of 3-hydroxy-3 methylglutaryl coenzyme A (HMG-CoA) reductase. Cholesterol is synthesized from 7-dehydrocholesterol, which is also a precursor of vitamin D3. For this reason, we initially observed a statistically significant relation between total cholesterol and vitamin D. HMG-CoA enzyme reductase is key to the synthesis of cholesterol, whereas ultraviolet radiation causes the formation of 25-hydroxyvitamin D. Inhibition of the enzyme may increase levels of 7-dehydrocholesterol and increase the synthesis of 25-hydroxycholecalciferol, thereby increasing vitamin D levels,10 although we observed no relation between lower cholesterol and increased vitamin D. In addition, 25-hydroxyvitamin D has been shown to inhibit HMG-CoA enzyme reductase activity in in vitro studies.11 A greater concentration of vitamin D could increase enzymatic inhibition, acting in synergy with the statin in decreasing total cholesterol.

Vitamin D receptor expression in normal, premalignant, and malignant human lung tissue. Menezes RJ, Cheney RT, Husain A, Tretiakova M, Loewen G, Johnson CS, Jayaprakash V, Moysich KB, Salgia R, Reid ME. Cancer Epidemiol Biomarkers Prev. 2008 May;17(5):1104-10. PMID: 18483332 doi: 10.1158/1055-9965.EPI-07-2713 onclusions: VDR expression spanned the lung carcinogenesis spectrum. Nuclear expression was similar across various histologies, whereas cytoplasmic expression decreased with increasing histologic grade. These results indicate that there is potential for the use of calcitriol as a chemopreventive agent against the development of lung cancer. (Cancer Epidemiol Biomarkers Prev 2008;17(5):1104-10)

Serum 25-hydroxyvitamin D and colon cancer: eight-year prospective study. Garland CF, Comstock GW, Garland FC, Helsing KJ, Shaw EK, Gorham ED. Lancet. 1989 Nov 18;2(8673):1176-8. PMID: 2572900 Blood samples taken in 1974 in Washington County, Maryland, from 25 620 volunteers were used to investigate the relation of serum 25-hydroxyvitamin D (25-OHD) with subsequent risk of getting colon cancer. 34 cases of colon cancer diagnosed between August, 1975, and January, 1983, were matched to 67 controls by age, race, sex, and month blood was taken. Risk of colon cancer was reduced by 75% in the third quintile (27-32 ng/ml) and by 80% in the fourth quintile (33-41 ng/ml) of serum 25-OHD. Risk of getting colon cancer decreased three-fold in people with a serum 25-OHD concentration of 20 ng/ml or more. The results are consistent with a protective effect of serum 25-OHD on colon cancer.

Demographic differences and trends of vitamin D insufficiency in the US population, 1988-2004. Ginde AA, Liu MC, Camargo CA Jr. Arch Intern Med. 2009 Mar 23;169(6):626-32. PMID: 19307527 Conclusions National data demonstrate a marked decrease in serum 25(OH)D levels from the 1988-1994 to the 2001-2004 NHANES data collections. Racial/ethnic differences have persisted and may have important implications for known health disparities. Current recommendations for vitamin D supplementation are inadequate to address the growing epidemic of vitamin D insufficiency.

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 supplementation and total mortality: a meta-analysis of randomized controlled trials. Autier P, Gandini S. Arch Intern Med. 2007 Sep 10;167(16):1730-7. Review. PMID: 17846391 Conclusions Intake of ordinary doses of vitamin D supplements seems to be associated with decreases in total mortality rates. The relationship between baseline vitamin D status, dose of vitamin D supplements, and total mortality rates remains to be investigated. Population-based, placebo-controlled randomized trials with total mortality as the main end point should be organized for confirming these findings.