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Calcium & Vitamin D: Osteoporosis, Rickets

Calcium & Vitamin D: Osteoporosis, Rickets . By Grace Benson Russell Sage College . Calcium . Most abundant cation in body 40% of body’s mineral mass 1.5%- 2% body weight 99% in bones and teeth 1% intra- and extracellular fluids. Vitamin D. Calciferol Fat- soluble

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Calcium & Vitamin D: Osteoporosis, Rickets

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  1. Calcium & Vitamin D:Osteoporosis, Rickets By Grace Benson Russell Sage College

  2. Calcium • Most abundant cation in body • 40% of body’s mineral mass • 1.5%- 2% body weight • 99% in bones and teeth • 1% intra- and extracellular fluids Vitamin D • Calciferol • Fat- soluble • Derived from steroid; seco- steroid • Two main forms: D2, D3

  3. Calcium Absorption • Ingested as relatively insoluble salts • Absorbed via carrier- mediated active transport, diffusion • Transport regulated by calcitriol – Important! • Three specific mechanisms required for active transport • The amount absorbed varies Calcium Transport/ Function • From blood, deposited in bone for storage to replenish blood calcium if necessary • Bone formation just one of calcium’s important functions in the body: Mineralization • Bone made of organic and inorganic materials; Calcium facilitates interaction = strength

  4. Vitamin D Absorption • No digestion: absorbed from micelle with fat and bile salts • Passive diffusion • Approximately 50% absorbed • Chylomicrons- to lymphatic system- to blood • D3 diffuses from skin into the blood Vitamin D Transport/ Function • DBP – Vitamin D Binding Protein • Goes to tissues and then to liver; obese and overweight store more in adipose = higher doses • Two forms transported slightly differently • Cytochrome P-450 hydroxylases hydroxylate to active form • 25- hydroxylase; found mostly in liver but other tissue as well- first step to 25- OH Vitamin D, calcidiol • Transported back to blood by DBP; storage • 15 day to > 3 week half- life • Vitamin D status

  5. Vitamin D Cont’d • Hydroxylated again by 1- hydroxylase to 1,25- (OH)2 D, Calcitriol= active form • Regulated by enzymes PTH and FGF 23- counteract • DBP- pick up and release • Calcitriol half- life of 2-6 hours • Many body tissues have receptors • Broken down to calcitroic acid via hydroxylation

  6. Osteoporosis • Skeletal disease characterized by deterioration of bone and low bone mineral density • 1 in 2 women; 1 in 4 men will suffer fx • Can be devastating • 80% of sufferers are women • Calcium/ Vitamin D deficiency • Recommendations: • 1,000- 1,200 mg/day Ca • 600 IU, 800 IU Vit. D • Sun exposure Lactose aids Calcium absorption!!

  7. Rickets • Vitamin D deficiency disease • Seizures, growth retardation, failure of bone to mineralize • Epiphyseal plates in infants • Wrists, ankles, knees enlarge • Spine becomes curved • Other deformities • Infants at risk- Vitamin D supplement for breastfed infants • Supplements, mega dose for those deficient

  8. CURRENT NEWS: Return of Rickets in the U.K • Common during the Victorian Era among children who worked in factories • Dr. Sally Davies, Chief Medical Officer, recommends free vitamins to children under 5 • Largely eliminated during the 1950’s (cod liver oil) • Numbers have increased fourfold in the last 15 years • No official surveillance system • Environmental? Cultural? • Preventable!

  9. References Cheng, M. (2013). Rickets making a comeback in the UK, doctors say. Retrieved from http://onlineathens.com/health/2013-11-08/rickets-making-comeback-uk-doctors-say Gropper, S.S., Smith, J.L. (2013). Advanced Nutrition and Human Metabolism. 6th ed. Belmont, CA: Wadsworth. Hansen, C.M., Binderup, L., Hamberg, K.J., Carlberg, C., (2001). VITAMIN D AND CANCER: EFFECTS OF 1,25(OH)2D3 AND ITS ANALOGS ON GROWTH CONTROL AND TUMORIGENESIS. Retrieved from http://www.bioscience.org/2001/v6/d/hansen/figures.htm Inn, D., (2013). Calcium is Important. Retrieved from healthandfashion.US/calcium-is-important New Health Guide. (2013). How Much Calcium do We Need? Retrieved from http://www.newhealthguide.org/how-much-calcium-Do-we-need.html 2011). Retrieved from http://tuesday-johnson.tumblr.com/post/13994711622/ca-1870-1910-portrait-of-a-young-girl-with BBC News. (2012). Cheap vitamin D 'would boost health. Retrieved from http://www.bbc.co.uk/news/health-20710028 WebMD. (2011). Slideshow: A Visual Guide to Osteoporosis. Retrieved from http://www.webmd.com/osteoporosis/ss/slideshow-osteoporosis-overview

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