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Serum 25-hydroxyvitamin D concentration and subsequent risk of type 2 diabetes. Mattila C, Knekt P, Männistö S, Rissanen H, Laaksonen MA, Montonen J, Reunanen A. Diabetes Care. 2007 Oct;30(10):2569-70. Epub 2007 Jul 12. PMID: 17626891 doi: 10.2337/dc07-0292 We found a significant inverse association between serum 25OHD and risk of type 2 diabetes in the simple model. However, the association was attenuated in the multivariate analysis, adjusting for potential risk factors of type 2 diabetes. To our knowledge, this is the first cohort study investigating the association between serum 25OHD and incidence of type 2 diabetes. Our results are in line with those from the Nurses' Health Study (5), where an inverse association was observed for the intake of vitamin D supplements. We could not differentiate whether the results depended on the effect of vitamin D deficiency on β-cell function or on insulin resistance. In summary, the results are in line with the hypothesis that a high serum 25OHD concentration may reduce the risk of type 2 diabetes. Further research is needed to confirm the association and to distinguish between the independent role of vitamin D and the role of healthy dietary and lifestyle patterns in reducing the risk of type 2 diabetes.

Role of vitamin D in the pathogenesis of type 2 diabetes mellitus. Palomer X, González-Clemente JM, Blanco-Vaca F, Mauricio D. Diabetes Obes Metab. 2008 Mar;10(3):185-97. Review. PMID: 18269634 DOI: 10.1111/j.1463-1326.2007.00710.x Vitamin D deficiency has been shown to alter insulin synthesis and secretion in both humans and animal models. It has been reported that vitamin D deficiency may predispose to glucose intolerance, altered insulin secretion and type 2 diabetes mellitus. Vitamin D replenishment improves glycaemia and insulin secretion in patients with type 2 diabetes with established hypovitaminosis D, thereby suggesting a role for vitamin D in the pathogenesis of type 2 diabetes mellitus.

Intake of vitamin D and risk of type 1 diabetes: a birth-cohort study. Hyppönen E, Läärä E, Reunanen A, Järvelin MR, Virtanen SM. Lancet. 2001 Nov 3;358(9292):1500-3. PMID: 11705562 doi:10.1016/S0140-6736(01)06580-1 INTERPRETATION: Dietary vitamin D supplementation is associated with reduced risk of type 1 diabetes. Ensuring adequate vitamin D supplementation for infants could help to reverse the increasing trend in the incidence of type 1 diabetes.

Serum 25-hydroxyvitamin D3 concentrations and carotid artery intima-media thickness among type 2 diabetic patients. Targher G, Bertolini L, Padovani R, Zenari L, Scala L, Cigolini M, Arcaro G. Clin Endocrinol (Oxf). 2006 Nov;65(5):593-7. PMID: 17054459 DOI: 10.1111/j.1365-2265.2006.02633.x CONCLUSIONS: Hypovitaminosis D is highly prevalent in type 2 diabetic adults and is strongly and independently associated with increased carotid IMT. Further investigation into whether vitamin D may play a role in the prevention of atherosclerosis appears to be warranted. In conclusion, our results show that type 2 diabetic adults have significant reductions in serum 25(OH)D concentrations (vs matched controls) that predict preclinical atherosclerosis, independent of classical risk factors, renal function tests, inflammatory markers, use of medications and presence of the metabolic syndrome. These findings suggest the need for ongoing evaluation of the possible protective role of vitamin D3 supplementation in the development of atherosclerosis.

Vitamin D receptor gene polymorphisms influence susceptibility to type 1 diabetes mellitus in the Taiwanese population. Chang TJ, Lei HH, Yeh JI, Chiu KC, Lee KC, Chen MC, Tai TY, Chuang LM. Clin Endocrinol (Oxf). 2000 May;52(5):575-80. PMID: 10792336 DOI: 10.1046/j.1365-2265.2000.00985.x CONCLUSIONS Vitamin D receptor gene polymorphisms were associated with type 1 diabetes in a Taiwanese population. However, functional studies are needed to establish the role of the vitamin D receptor in the pathogenesis of type 1 diabetes mellitus.

Serum vitamin D and subsequent occurrence of type 2 diabetes. Knekt P, Laaksonen M, Mattila C, Härkänen T, Marniemi J, Heliövaara M, Rissanen H, Montonen J, Reunanen A. Epidemiology. 2008 Sep;19(5):666-71. PMID: 18496468 doi: 10.1097/EDE.0b013e318176b8ad Conclusions: The results support the hypothesis that high vitamin D status provides protection against type 2 diabetes. Residual confounding may contribute to this association.

"Women from India, Pakistan and Sri Lanka with insulin resistance showed marked improvement after taking vitamin D supplements, says a study. Von Hurst, nutrition lecturer at the Institute of Food, Nutrition and Human Health at Albany, conducted the study for her doctoral thesis. Insulin resistance is largely symptom-free and sufferers are unaware of their condition. 'Once it has fully developed into type-2 diabetes, it can be treated, but not cured,' says Von Hurst. Von Hurst says that while diet and exercise play a major part in the onset of type-2 diabetes, her findings reinforce the importance of vitamin D from the sun and supplements to prevent type-2 diabetes. She also found evidence of vitamin D increasing bone strength in older women. "

Vitamin D and type 2 diabetes: are we ready for a prevention trial? Scragg R. Diabetes. 2008 Oct;57(10):2565-6. PMID: 18820212 doi: 10.2337/db08-0879 Despite evidence from the current article (3) and the Finnish study (17), doubts still remain about whether low vitamin status is a cause of type 2 diabetes. Further cohort studies are required, assessing baseline vitamin D status using blood 25(OH)D to be sure that the Ely and Finnish studies are not false-positive results. Glucose clamp studies are also required because we are still not sure of the mechanism influenced by vitamin D-whether it is insulin resistance, secretion, or both. But most importantly, given that nearly three decades have passed since the first studies linking vitamin D with insulin metabolism (6,7), well-designed clinical trials of the effect of vitamin D supplementation on glycemia status and diabetes risk are urgently required to settle this question. And they need to prevent past mistakes. In particular, the vitamin D dose given in such trials needs to be high enough-above 2,000 IU per day (19)-to raise blood 25(OH)D levels above 80 nmol/l because diabetes risk is lowest at this level (9,20). If well-designed trials are carried out and confirm a protective effect from vitamin D, it could be used by the general population as a simple and cheap solution to help prevent the diabetes epidemic.

Use of cod liver oil during the first year of life is associated with lower risk of childhood-onset type 1 diabetes: a large, population-based, case-control study. Stene LC, Joner G; Norwegian Childhood Diabetes Study Group. Am J Clin Nutr. 2003 Dec;78(6):1128-34. PMID: 14668274 Conclusion: Cod liver oil may reduce the risk of type 1 diabetes, perhaps through the antiinflammatory effects of long-chain n-3 fatty acids.

Pittas AG, Lau J, Hu FB, Dawson-Hughes B. The role of vitamin D and calcium in type 2 diabetes. A systematic review and meta-analysis. J Clin Endocrinol Metab. 2007 Jun;92(6):2017-29. Epub 2007 Mar 27. Review. PMID: 17389701 [PubMed - indexed for MEDL

Serum 25-hydroxyvitamin D3 concentrations and carotid artery intima-media thickness among type 2 diabetic patients. Targher G, Bertolini L, Padovani R, Zenari L, Scala L, Cigolini M, Arcaro G. Clin Endocrinol (Oxf). 2006 Nov;65(5):593-7. PMID: 17054459 CONCLUSIONS: Hypovitaminosis D is highly prevalent in type 2 diabetic adults and is strongly and independently associated with increased carotid IMT. Further investigation into whether vitamin D may play a role in the prevention of atherosclerosis appears to be warranted.

Supplementation with cholecalciferol does not improve glycaemic control in diabetic subjects with normal serum 25-hydroxyvitamin D levels. Jorde R, Figenschau Y. Eur J Nutr. 2009 Apr 16. [Epub ahead of print] PMID: 19370371 10.1007/s00394-009-0020-3 Conclusions We were not able to demonstrate that vitamin D supplementation had a significant effect on glucose metabolism in subjects with type 2 diabetes but without vitamin D deficiency. Further studies are needed in larger groups of subjects with type 2 diabetes or impaired glucose tolerance, who also exhibit low serum 25-hydroxyvitamin D levels.

Vitamin D: importance in the prevention of cancers, type 1 diabetes, heart disease, and osteoporosis.\nHolick MF.\nAm J Clin Nutr. 2004 Mar;79(3):362-71. Review. Erratum in: Am J Clin Nutr. 2004 May;79(5):890.\nPMID: 14985208

A New Zealand study has found that South Asian women with insulin resistance improved markedly after taking vitamin D supplements Nutrition researcher Pamela von Hurst of the Institute of Food, Nutrition and Human Health at Albany, said while diet and exercise played a major part in the onset of type-2 diabetes, her findings reinforced the importance of vitamin D from the sun and supplements to prevent type-2 diabetes. Initial screening of 235 Auckland women from India, Pakistan and Sri Lanka aged 20 and older, revealed 47 per cent were insulin deficient and 84 per cent were vitamin D deficient. The 81 recruited for the study were split into two groups for a randomised controlled trial and given a vitamin D supplement or placebo. As well as an improvement in insulin resistance among those who took vitamin D for six months, Ms Von Hurst said post-menopausal women in the study also showed a reduced rate of bone breakdown.

Vitamin D and calcium insufficiency-related chronic diseases: molecular and cellular pathophysiology. Peterlik M, Cross HS. Eur J Clin Nutr. 2009 Dec;63(12):1377-86. Epub 2009 Sep 2. PMID: 19724293 doi:10.1038/ejcn.2009.105 A compromised vitamin D status, characterized by low 25-hydroxyvitamin D (25-(OH)D) serum levels, and a nutritional calcium deficit are widely encountered in European and North American countries, independent of age or gender. Both conditions are linked to the pathogenesis of many degenerative, malignant, inflammatory and metabolic diseases. Studies on tissue-specific expression and activity of vitamin D metabolizing enzymes, 25-(OH)D-1alpha-hydroxylase and 25-(OH)D-24-hydroxylase, and of the extracellular calcium-sensing receptor (CaR) have led to the understanding of how, in non-renal tissues and cellular systems, locally produced 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) and extracellular Ca2+ act jointly as key regulators of cellular proliferation, differentiation and function. Impairment of cooperative signalling from the 1,25-(OH)2D3-activated vitamin D receptor (VDR) and from the CaR in vitamin D and calcium insufficiency causes cellular dysfunction in many organs and biological systems, and, therefore, increases the risk of diseases, particularly of osteoporosis, colorectal and breast cancer, inflammatory bowel disease, insulin-dependent diabetes mellitus type I, metabolic syndrome, diabetes mellitus type II, hypertension and cardiovascular disease. Understanding the underlying molecular and cellular processes provides a rationale for advocating adequate intake of vitamin D and calcium in all populations, thereby preventing many chronic diseases worldwide.

"We are aware of substantial scientific evidence supporting the role of vitamin D in prevention of cancer. It has been reasonably established that adequate serum vitamin D metabolite levels are associated with substantially lower incidence rates of several types of cancer, including those of the breast, colon, and ovary, and other sites. We have concluded that the vitamin D status of most individuals in North America will need to be greatly improved for substantial reduction in incidence of cancer. Epidemiological studies have shown that higher vitamin D levels are also associated with lower risk of Type I diabetes in children and of multiple sclerosis. Several studies have found that markers of higher vitamin D levels are associated with lower incidence and severity of influenza and several other infectious diseases."

The role of vitamin D and calcium in type 2 diabetes. A systematic review and meta-analysis. Pittas AG, Lau J, Hu FB, Dawson-Hughes B. J Clin Endocrinol Metab. 2007 Jun;92(6):2017-29. Epub 2007 Mar 27. Review. PMID: 17389701 .CONCLUSIONS: Vitamin D and calcium insufficiency may negatively influence glycemia, whereas combined supplementation with both nutrients may be beneficial in optimizing glucose metabolism.

Vitamin D in preventive medicine: are we ignoring the evidence? Zittermann A. Br J Nutr. 2003 May;89(5):552-72. Review. PMID: 12720576 Vitamin D is metabolised by a hepatic 25-hydroxylase into 25-hydroxyvitamin D (25(OH)D) and by a renal 1alpha-hydroxylase into the vitamin D hormone calcitriol. Calcitriol receptors are present in more than thirty different tissues. Apart from the kidney, several tissues also possess the enzyme 1alpha-hydroxylase, which is able to use circulating 25(OH)D as a substrate. Serum levels of 25(OH)D are the best indicator to assess vitamin D deficiency, insufficiency, hypovitaminosis, adequacy, and toxicity. European children and young adults often have circulating 25(OH)D levels in the insufficiency range during wintertime. Elderly subjects have mean 25(OH)D levels in the insufficiency range throughout the year. In institutionalized subjects 25(OH)D levels are often in the deficiency range. There is now general agreement that a low vitamin D status is involved in the pathogenesis of osteoporosis. Moreover, vitamin D insufficiency can lead to a disturbed muscle function. Epidemiological data also indicate a low vitamin D status in tuberculosis, rheumatoid arthritis, multiple sclerosis, inflammatory bowel diseases, hypertension, and specific types of cancer. Some intervention trials have demonstrated that supplementation with vitamin D or its metabolites is able: (i) to reduce blood pressure in hypertensive patients; (ii) to improve blood glucose levels in diabetics; (iii) to improve symptoms of rheumatoid arthritis and multiple sclerosis. The oral dose necessary to achieve adequate serum 25(OH)D levels is probably much higher than the current recommendations of 5-15 microg/d.

1,25(OH)2 vitamin d inhibits foam cell formation and suppresses macrophage cholesterol uptake in patients with type 2 diabetes mellitus. Oh J, Weng S, Felton SK, Bhandare S, Riek A, Butler B, Proctor BM, Petty M, Chen Z, Schechtman KB, Bernal-Mizrachi L, Bernal-Mizrachi C. Circulation. 2009 Aug 25;120(8):687-98. Epub 2009 Aug 10. PMID: 19667238 doi: 10.1161/CIRCULATIONAHA.109.856070 Conclusion- These results identify reduced vitamin D receptor signaling as a potential mechanism underlying increased foam cell formation and accelerated cardiovascular disease in diabetic subjects.

Vitamin D supplement in early childhood and risk for Type I (insulin-dependent) diabetes mellitus. The EURODIAB Substudy 2 Study Group. [No authors listed] Diabetologia. 1999 Jan;42(1):51-4. PMID: 10027578 DOI: 10.1007/s001250051112 In conclusion, this large multicentre trial covering many different European settings consistently showed a protective effect of vitamin D supplementation in infancy. The findings indicate that activated vitamin D might contribute to immune modulation and thereby protect or arrest an ongoing immune process initiated in susceptible people by early environmental exposures.