BONE: VITAMIN D, CALCIUM, MAGNESIUM AND PHOSPHORUS • Bone is living tissue • Osteoclasts still work with Ca2+ intake Cortical is dense compact hard shell. Trabecular is more metabolically active and more likely to be biologically broken with Osteoporosis or Osteopenia. Trabecular usually is affected by the hip girdle, arm, spine and long bones. It has a high turnover rate and is available for resorption. Its density can be measured by DEXA. Ca2+ , when we drink it, is actually for the restoration of the amount in the blood. Our blood, once refilled, will send the rest to bones for storage. Down regulated by PTH, calcitriol • Becomes embedded in matrix and becomes osteocytes Maintains integrity of surrounding bone • Hydroxyapatite- crystal lattice found in bones and teeth made of Ca2+ salts. They are laid on top of matrix Proteins in bone: • Collagen • Osteonectin- binds to both Ca2+ and collagen • Osteopontin- binds hydroxyapatite and bone cells • Down regulated by Calcitonin • Help maintain bone calcium o Bad for bone but good for your body • Up regulated by PTH, CalcitriolYou must only know these from the chart given in notes The rest of the notes will be typed Sources of vitamins and minerals for bone: Dairy products are some of the highest sources such as milk, cheese and yogurt. Vegetable sources include turnip or mustard greens, broccoli, cauliflower, legumes, tofu but not spinach, rhubarb or Swiss chard. Those three are not the best sources because they have compounds called oxalates. These bind to Ca2+ and keep it from getting absorbed. This can cause stones in the kidneys. Seafood such as salmon, sardines with bones, clams, oysters and anchovies are also good sources. Lastly, fortified foods such as orange juice. Vegetable spreads are also good. The average adults absorb 30% of Ca2+ consumed and growing children absorb up to 75%. Fibroblasts form collagen 1. Long rod shaped protein that gives strength 2. Requires iron, vitamin C, and vitamin D Reticulocytes a. Make RBC b. Make leukocytes • Dexa Vitamin D Phosphorus Weight loss Key Players: Calcium Vitamin D Magnesium Phosphorus 20 > 70 yrs.Supplements: Calcium citrate-malate 35% Calcium monophosphate 25% Calcium carbonate 40% Calcium carbonate can be gotten from all natural sources which can be a good thing but these all natural sources may have other minerals in it such as lead and aluminum because they come from oysters or dolomite, so make sure you get it from a reputable source. Bone meal preparations may also contain lead. Supplements, vitamins and minerals do not go through the same pathway as food does but there is a natural supplement foundation that checks for this problem. NSF is one group. Phosphorus: You can get it form organic products such as animals. This includes Meat, poultry, fish, milk and eggs. Think about all the phosphorus that we use for energy reactions, ATP. So inorganic phosphates come from plant sources such as legumes, cereal, and whole grains. These are often in the form of phytic acid or phytates. Other sources include coffee, tea and soft drinks. Magnesium: Coffee, tea, cocoa (darker is better than milk chocolate), whole grains, legumes, green leafy vegetables (chlorophyll), and hard water (tap water). You know you have hard water if you get the white mineral scale buildup around your faucets. It is used to stabilize ATP so every ATP has one Mg to hold the phosphates together. Filtering water can decrease your mineral consumption. Vitamin D: Animal sources such as beef, eggs, fortified milk and dairy (not much quality control) and saltwater fish such as salmon and tuna. Fortified sources include breads and cereals. We also get Vitamin D from plants (almost none) and sunlight (10min=10ugDepends on people because darker skin, older, more up north and fatter people tend to have less vitamin D from cholesterol). Vitamin D forms include Ergocalciferol- D2 and Cholecalciferol-D3. D2 comes from plants, must be put through lab, and are sold commercially. D3 are from animal products and come from cholesterol. You can use both of these forms in your body. The picture depicts the order conversion and remember that Calcitriol is the active form of Vitamin D and is what affects absorption of Ca2+. In the liver we convert Cholecalciferol to Calcidiol. In the kidney we convert Calcidiol to the active hormone Calcitriol by the enzyme 1-hydroxylase. Activity of enzyme is increased by low plasma Ca2+ and PTH (parathyroid hormone). Its activity is decreased by high cholesterol concentrations and dietary phosphorus. Functions of Vitamin D: Regulates calcium and phosphorus. Calcium in the non-osseous (1%) regulates enzyme activation (free calcium induces Phospholipase A which liberates FA from glycerol backbone), blood (Ergocalciferol or pre vitamin D2) (Ergocalciferol or 1,25 (OH)2D2) (Cholecalciferol or 25 OH D3)clotting, muscle contraction (requires Mg), nerve impulses and hormones. Lack of calcium can cause intermittent muscle contractions which are painful. For osseous (99%) we have Ca2+ functioning in bone formation. The functions of phosphorus include skeletal mineralization, energy in the form of ATP and phosphorylase reactions. We can get vitamin D form sun and food. So if we eat it we are in the lumen of the intestine. Let us say we eat fortified milk. That milk has vitamin D, Calcium and fat. Because it has fat we are going to surround it by bile salts and emulsify fat and fat soluble vitamins. Fat soluble vitamins passively diffuse. FA and Vitamin D from the milk passively diffuse into enterocyte. Vitamin D and fat leaves the enterocyte by chylomicron. The chylomicron remnants then deposit FA in other tissues and the V.D goes to the liver to be transformed to D3 after entering the liver by receptor medicated endocytosis. We can also get Vitamin D from the sunlight hitting our skin. The UVB then turns to cholesterol and then Cholecalciferol D3. D3 then exits and enters the liver with the addition of DBP. Once in the liver D3 is converted to Calcidiol by 25 hydroxylase. To get the Calcidiol to the kidney DBP is used again. Calcidiol is then converted to Calcitriol by 1 hydroxylase in the kidney. This then exits the kidney and enters tissues via VDR. How does Vitamin D (Calcitriol) maintain calcium?: With PTH we target three main tissues: intestine, bone and kidney. Our intestine is how it gets into our body. Our bone
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