1 / 23

Vitamin D

Vitamin D. Swedish Weight Loss Services Dharti Shah (Volunteer Research Assistant) October 2010. Discoverers…. Elmer McCollum. Marguerite Davis. Edward Mellanby. A vitamin? A hormone?. Sources: Skin synthesis through UVB 270-300 nm Diet Supplementation Hormone. Forms.

marvin-sampson
Télécharger la présentation

Vitamin D

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Vitamin D Swedish Weight Loss Services Dharti Shah (Volunteer Research Assistant) October 2010

  2. Discoverers… Elmer McCollum Marguerite Davis Edward Mellanby

  3. A vitamin? A hormone? • Sources: • Skin synthesis through UVB • 270-300 nm • Diet • Supplementation • Hormone

  4. Forms • Ergocalciferol (vitamin D2, plants, algae) • Cholecalciferol (vitamin D3, mammals) • 25- hydroxycholecalciferol (25(OH)D3 circulating form) • 1, 25 dihyroxycholecalciferol (1,25 (OH)2D3 – active form)

  5. 7- dehydrocholesterol (skin) Ultraviolet B Vitamin D3 (cholecalciferol) Liver enzyme 25-hydroxylase 25-hydroxycholecalciferol {25 (OH)D3, calcidiol, circulating form} Kidney enzyme 25(OH)-D-1α-hydroxylase 1,25-dihydroxycholecalciferol {1,25 (OH)2D3,calcitriol, active form} Production?

  6. “D” action… Vitamin D VDBP Vitamin D receptor (VDR) D D Retinoid X receptor (RXR) D Vitamin D Response Elements(VDRE’s) Gene transcription

  7. Multifunctional

  8. Deficiency • Cut-off values (Dynacare/Know your D) • Optimal levels ≥ 32-100 ng/dl • Insufficiency – 20-32 ng/ml • Deficiency • < 20 ng/ml – very low • <8 ng/ml – extremely low

  9. Deficiency in the Pacific Northwest

  10. Implications • Obesity • Diabetes • Cardiovascular diseases • Cancer • Compromised bone health • Multiple Sclerosis • Depression

  11. Obesity Adiposity, Cardiometabolic Risk, and Vitamin D Status: The Framingham Heart Study • Causal relationship • Type of obesity • Visceral • Subcutaneous • BMI • Parathyroid hormone Cheng S et.al. Diabetes Platinum Periodicals Jan 2010 59,1, pg.432

  12. BMI and vitamin D status BMI is inversely correlated to vitamin D status Wortsman. J. et. al. Am J Clin Nutr 2000;72:690-3

  13. Parathyroid hormone(PTH) PTH Phospholipase C-β Free intracellular Ca2+ insulin catecholamines Fatty acid synthase Dephosphorylation of GLUT4 Lipolysis Lipogenesis Glucose uptake in adipocytes Fatty acid storage Insulin resistance Metabolic syndrome Mccarty MF, ThomasCA. Medical Hypotheses 2003; 61(5-6) 535-542

  14. Vitamin D/calcium on Insulin Secretion Sensitivity • Pancreatic β cells • Vitamin D receptors • 1-α-hydroxylase enzyme • Vitamin D response element in insulin gene promoter • Intracellular (nM)/extracellular (mM) calcium pools - Calbindin • Transcription of insulin gene • VDR in skeletal muscle • Expression of insulin receptors, responsiveness • Activates PPAR-δ – regulates fatty acid metabolism • Optimal insulin action dependent on a very specific and narrow range of calcium • Insulin receptor phosphorylation is also calcium dependent

  15. Diabetes • β-cell function defect - autoimmune • Insulin resistance • Disturbances in Ca2+ pools • Inflammation • Cytokines – β-cell apoptosis • Interleukin-2, TNF-α, interferon-gamma

  16. Diabetes • NHANES (1988-1994) • Serum samples – 6228 subjects • 2766 – non-Hispanic whites • 1736 – non-Hispanic blacks • 1726 – Mexican Americans • Age > 20y • Results were ethnic-specific Scragg R. Sowers M. Bell C. Diabetes Care 2004 27:2813-2818

  17. Results Non- Hispanic Non-Hispanic black Mexican American white 25(OH)D nmol/L Fasting glucose N OR Y Y N OR Y N OR

  18. Effect of Bariatric surgery • Vitamin D levels corrected after surgery and supplementation • BPD • Morbidly obese women followed 5 and 10 years after BPD • Supplemented with 400,000 IU D2 every 2 weeks • Results • Hypovitaminosis • 76% - obese state • 91% after 5 years • 89% after 10 years • Increase in whole-body glucose uptake • Conclusion • Fat mass and BMI are predictors of 25(OH)D • Hypovitaminosis does not imply insulin resistance Manco M. Calvani M. et.al. Obesity Research 2005 Vol.13 No.10 pg:1692-1700

  19. Supplementation • D2 and D3 potency evaluated • Single dose of 50,000 IU of each calciferol administered • Followed time course for rise in 25(OH)D levels over 28 days Armas L.A.G. Hollis B. Heany. R J Clin Endocrinol Metab Nov 2004 89(11):5387-5391

  20. Vitamin D levels – Bariatric patients

  21. Medical patients

  22. Other effects.. • Multiple Sclerosis • Increases anti-inflammatory cytokines • Cancer • Cell differentiation • CVD • NHANES III – 13,131 individuals • Followed for mortality through yr. 2000 • Follow-up period – 3,266 deaths • Premature deaths – 1,066 • Deaths from CVD accounted for 34% of PD • Heart failure deaths – 101 • Rate of vitamin D def. among heart failure deaths – 37% • Low vit. D levels – 3.4 times more likely to die from heart failure

  23. Summary • BMI and fat mass are inversely correlated with vit. D status • PTH is implicated in MS, adipogenesis • Adequate vit. D levels may prevent or delay the progress of diseases

More Related