MINERALS IN HUMAN HEALTH

Learning Outcomes Distribution in the body Dietary sources Daily Requirements Absorption / Excretion Factors affecting Calcium Absorption

At.No.20 Calcium At .Wt 40

BONES AND SKELETON Higher animals have an internal frame work – endoskeleton Skeleton is made almost entirely of a hard, rigid tissue – bone Bone consists like other living tissues of living cells suspended in an inert ground substance

GROUND SUBSTANCE OF BONES is The determining factor of bone characteristic properties Network of protein fibers with insoluble mineral salts Mostly phosphate of calcium. Responsible for hardness of bone

BONE GROWTH Bone grows by the activity of osteoblasts. These have enzyme which separates Insoluble calcium phosphate from soluble phosphate in blood by precipitation Osteoblast will do their work only if the essential elements of bones are present in diet in reasonable quantity. Of course the dietary minerals will have to be absorbed properly which depends on many factors.

Distribution More than 99% of calcium is in bones and teeth Ca++ in bone constantly exchanged with that of interstitial fluid. 0.03% of Total Body calcium in blood Normal Serum / plasma contains 9 – 11 mg/dl RBCs contain very little Ca++ Regulated by PTH, Vit - D3 and calcitonin

In plasma Ca++ occurs in two forms Non diffusible 3.4 – 4.4 mg/dl Combined with plasma proteins (Albumin) Not dialyzable Low in hypoproteinemia

In plasma Ca++ occurs in two forms Diffusible Ionized 5.45 – 6.23 mg/dl Physiologically active  Hyperparathyroidism  Hypoparathyroidism If level drops to 4.3 mg/dl Tetany occurs

Dietary sources Milk and Dairy products Hard cheese concentrated source Cottage cheese and ice cream Egg yolk , leafy vegetable Water

Dietary sources Shrimps, oysters and salmon Mustard green, turnip and spinach Whole wheat bread Inorganic salts CaCl2, CaCo3

Dietary sources When diet is deficient : salts of Calcium with carbonate, gluconate, lactate, Sulphate may be taken as supplement Milk and milk products: 2 – 3 cups /day -Adults 3 – 4 cups/day - Children

Recommended Dietary Allowance Infants 0 – 0.5 years 360 mg. 0.5 – 1.0 540 Children 1 – 3 800 4 – 6 800 7 – 10 800

Recommended Dietary Allowance Male / Females 11 – 14 1200 15 – 18 1200 19 – 22 800 23 – 50 800 51+ 800 Pregnancy +400 Lactation +400

Absorption Both organic and inorganic forms of Ca++ are utilized and absorbed Mostly in proximal part of small intestine

Absorption Calcium is absorbed against a concentration gradient and requires energy. Requires a carrier protein Helped by calcium dependent ATP ase.

Absorption Absorbed by active transport mechanism in two steps Uptake of calcium through Ca++ specific channels Efflux – Ca++, Mg++ and ATPase Some absorption through passive transport / facilitated diffusion

Kidneys filters out calcium Calcium is absorbed by GIT Soft tissue Calcium Extra Cellular Fluid Calcium in Bone Kidneys filters out calcium

Factors affecting calcium absorption Vitamin – D Increases the absorption of calcium Increase the specific transport protein responsible for active transport of calcium in proximal small intestine wall

Factors affecting calcium absorption 2. PTH  calcium absorption but effect is less marked than vitamin D 3. Calcium : P when 1 : 2 or 2 : 1 in food optimum absorption 4. Excess of Po4 in GIT  calcium absorptio 240 mg Ca++ absorbed/day

Presence of FFA Excessive fat intake lowers Ca absorption . Due to impairment in absorption , free fatty acid react with free calcium and forms insoluble complex ( Ca-soaps) Bile salts increase absorption of Ca++ by properly absorbing FFA & prevents formation of Ca-complexes

Presence of Anions Oxalates, carbonates and sulfates inhibit Ca++ absorption as Ca complexes with these are insoluble Ca++ salts with chloride , glucose and lactate are soluble & absorbed to greater extent. Ca++ salts with AA from proteins taken in diet, are more soluble in aq. Solutions of AA & thus facilitate Ca++ absorption.

Intestinal pH. Ca++ is well absorbed in acidic medium .If pH is low, calcium salts are more soluble.

Calcium Deficiency If the body is deficient in Calcium, then increased absorption and this is mediated through an increased parathyroid activity

Less calcium is absorbed in old age

Intestinal Disease like Malabsorption , Ceolic Diseases , and Steathorea decrease Ca++ absorption Idiopathic hyper calcaemia ,Ca++ absorption from intestine is greatly increased due to unknown reasons.