CALCIUM & FACTORS AFFECTING

ABSORTION OF ITROSHNI MAURYA

Calcium is the “earth alkali” mineral found in earth’s crust, usually as fairly soluble salts.The word calcium comes from Latin calc, meaning ‘lime’ as in limestone,a

calcium carbonate substance.

INTRODUCTION

ATOMIC NUMBER: 20

ATOMIC SYMBOL: Ca

ATOMIC WEIGTH: 40.08

ELECTRONIC CONFIGURATION:[Ar]4s2

ATOMIC RADIUS: 197.3pm

MELTING POINT: 842 0C

BOILING POINT : 1484 0C

OXIDATION STATE: 2

Ca STATUS

• Fifth most abundant element in biosphere– (After iron, aluminum, silicon, and oxygen)

• Made from calcium:– Limestone and marble– Coral and pearls– Sea shells and egg shells– Antlers and bones

• Found in rocks, seawater, fresh water, soils• Land living mammals: 2-4% of gross body

weight

Ca:DISTRIBUTION & OCCURRENCE IN NATURE

99 % of the body’s calcium is stored in bone as hydroxyapatite Second reservoir is intracellular calcium

o Low concentration in cytosol when cell is inactive

o Stored bound to proteins in mitochondria

o Endoplasmic reticulum

Smallest reservoir in extra-cellular fluido Most important to regulate circulatory concentrations

Figure 17-1. Generalities about calcium

Calcium deposits in damaged tissueOccurs with advancing age

Found in atherosclerotic plaques in arteriesScar tissue from disease or injury

Not caused by dietary calciumCaused by tendency of calcium to bind with proteins

Calcification of tissue (other than bones and teeth) is sign of tissue damage and death

As in end-stage kidney disease

Calcium is the most abundant mineral in human body and is essential to:

Bone health Cardiovascular health Muscle maintenance Circulatory health Blood clotting Acts as an enzyme activator

BIOCHEMICAL FUNCTIONS

Recommended Daily Intake •Infants- 600-900mg•

Adults- 400-500mg• Pregnancy and lactation-1000-1200mg

Extra calcium is needed in Menopausal Woman Amenorrheic Women and the Female

Athlete Triad Lactose Intolerant Individuals Vegetarians

PLASMA CALCIUM Plasma calcium : Normal level -9-11mg/dl . 50% - present as ionized form.(biologically active) 40% - bound to proteins i.e. albumin.(non-diffusible Ca) 10% - complexed calcium –calcium citrate, bicarbonate and phosphate.(diffusible)

•Ca X P in serum children – 50 and adults 30-40.

•Calcium: Phosphate ratio in diet: During growth – 1:1 After cessation of growth- 1: 2.

RICH SOURCES OF CALCIUM Dairy Products, such as Milk, Cheese, and Yogurt• Canned Salmon and Sardines with Bones Leafy Green Vegetables, such as Broccoli, Spinach Calcium-Fortified foods - from Orange juice to Cereals and

Crackers Ice Cream, Oysters, Ricotta. CALCIUM BALANCE: It is the net gain or loss of calcium by body over a specific period

of time. Amount absorbed = Amount ingested - Amount egested in faeces

Amount retained = Amount absorbed –Urinary calcium(excreted)

SOURCES

Food Portion Calcium (mgs.)

Swiss cheese 2 oz. 530Jack cheese 2 oz. 420Cheddar cheese 2 oz 400Other cheeses 2 oz. 300–400Yogurt 6 oz. 300Broccoli, cooked 2 stalks 250Sardines (w/bones) 2 oz. 240Goat milk 6 oz. 240Cow’s milk 6 oz. 225Collard greens, cooked 6 oz. 225Turnip greens, cooked 6 oz. 220Almonds 3 oz. 210Brazil nuts 3 oz. 160

Calcium Sources

Soybeans, cooked 6 oz. 150Molasses,blackstrap 1 Tbl. 130Corn tortillas (4, w/lime) 2 oz. 125Carob flour 2 oz. 110Tofu 3 oz. 110Dried figs 3 oz. 100Dried apricots 3 oz. 80 Parsley 1½ oz. 80Kelp ¼ oz. 80Sunflower seeds 2 oz. 80Sesame seeds 2 oz. 75

It is regulated by : PTH and 1,25-(OH)2D3 on gut, kidney and

bone

Calcium receptors: are present in the parathyroid gland, kidney

, brain and other organs.

REGULATING FACTORS

The active form of vitamin D is 1,25-dihydroxycholecalcififerol(Calcitriol). Its production in the kidney is catalyzed by 1 a-hydroxylase .

1 a-hydroxylase activity is by : Decreased serum Ca2+ Increased PTH level Decreased serum phosphate

VITAMIN D METABOLISM

Vitamin D allows calcium to capture good bone. (A bone below left), increasing calcium absorption from the intestine. (A coil intestine below the middle), and help prevent loss of calcium to the kidney. (A similar red beans Luang below right).

Path life of vitamin D is absorbed from the intestine (Gastrointestinal), live sunlight helps the skin processing, after processing requiring additional time is 2 to liver and kidney. 

Increases intestinal Ca2+ absorption Incases intestinal phosphate absorption Increase renal reabsorption of Ca2+ and

phosphate Increases resorption of bone

Action of 1,25-dihydroxycholecalcififerol(Calcitriol)

Eat more swordfish, bluefish, salmon, mackerel, or

sardines. But swordfish and some species of mackerel are on the list of fish with high mercury levels, so don’t go overboard.

Take a calcium supplement that includes vitamin D. Many brands combine calcium with 200–400 IU of vitamin D.

Take a multivitamin. Multivitamins are a safety net for many nutrients that might otherwise fall through the cracks. Most brands contain 400 IU of vitamin D.

Spend more time outdoors. This is a balancing act, because you don’t want to risk skin cancer in pursuit of more vitamin D production.

TIPS FOR INCREASING VIT.D INTAKE

it is an 84-amino-acid hormone.

Secretion: from the chief cells of the parathyroid glands. Function: increase renal phosphate excretion , and increases plasma

calcium by: Increasing osteoclastic resorption of bone (occurring rapidly). Increasing intestinal absorption of calcium (a slower response). Increasing synthesis of 1,25-(OH)2D3 (stimulating GIT

absorption). Increasing renal tubular reabsorption of calcium

Parathyroid hormone (PTH):

Low serum [Ca+2] Increased PTH secretion

High serum [Ca+2] Decreased PTH secretion

Regulation of PTH

Produced by : thyroid C cell.

Function: Inhibition of osteoclastic bone resorption . Increasing the renal excretion of calcium

and phosphate.

CALCITONIN

CALCIUM ABSORPTION◦ Transcellular: active transport involving a calcium

binding protein, calbindin Stimulates calbindin

◦ Paracellular: by diffusion A function of calcium content of chyme

◦ Most absorption in ileum◦ 1,25(OH)2D stimulates synthesis of calbindin in

gut cells◦ Calbindin can bind 2 Ca2+ per molecule

Calcium dependent ATP pump moves calcium into extracellular fluid against the electochemical gradient

Ca is not absorbed well in an alkaline medium as it is less soluble

Best taken between meals or in absence of food when stomach is more acidic

Taking Ca with vit.D & xtra HCl absorption

Supplements of ca or of Ca &Mg are often taken at night be4 bed to help absorption and to prevent the xtra loss of body ca that can during night,ca &Mg is a good evening tranquilizer.

Recently,trace min.boron has been shown to help in ca utilization and bone health.

Form in which ca is supplied is also important.Most highly recommended is aspartate or citrate salts of ca,chelated ca with aa, ca gluconate,followed by CaCO3 & lactate-all are absorbable sources.

Increased by: Body needs—growth,

pregnancy, lactation Vitamin D Milk lactose Acid environment—

hydrochloric acid, citric acid, ascorbic acid (vitamin C)

Protein intake and amino acids such as lysine and glycine

Fat intake Exercise Phosphorus balance

Decreased by: Vitamin D deficiency Gastrointestinal problems Hypochlorhydria (low stomach

acid) Stress Lack of exercise High fat intake High protein intake Oxalic acid foods (beet

greens, chard, spinach, rhubarb, cocoa)

Phytic acid foods (whole grains)

High phosphorus intake

FACTORS AFFECTING Ca ABSORPTION

Calcium supplements usually come in 500- to 600-mg tablets. You don’t absorb large doses of calcium as efficiently as you do small ones. Thus, much of a 1,000-mg tablet is going to waste, although unabsorbed calcium in the gut may have benefits. Taking a regular-size pill with calcium-fortified orange juice might also be a waste.

The calcium in most supplements is either in the form of calcium carbonate or calcium citrate. Research shows that they are absorbed equally well with meals, but calcium carbonate is harder to digest than calcium citrate. People are usually advised to take calcium carbonate with or soon after a meal. Calcium citrate can be taken at any time.

Most multivitamin pills contain a relatively small amount of calcium — about 100–200 mg.

AlgaeCal is the world’s only plant source of Ca, so it is bio available pre-digested minerals . It also includes Mg trace minerals, vit.D3 & k2 at full dosages.

Supplements and vitamin pills

Acid rebound. Calcium carbonate may cause acid rebound: the stomach overcompensates for the high dose of calcium carbonate, which is alkaline, by churning out more acid. For that

reason, people with a history of stomach ulcers are advised that they may not tolerate it and may have to switch to calcium citrate.

Constipation. Calcium supplements can have a mild binding effect but by themselves don’t usually cause serious constipation. But if you’re taking another supplement or medication that binds the stool, the addition of calcium supplements could cause a problem.

Too much calcium. Although it doesn’t happen often, some people have taken so much calcium that it causes hypercalcemia, an above-normal level of calcium in the blood. Hypercalcemia may cause nausea, vomiting, confusion, and other neurological symptoms.

Drug interactions. Large doses of calcium interfere with the absorption of a variety of drugs. You

should avoid consuming large amounts of calcium — either in food or as a supplement — within 2–4 hours of taking a tetracycline or quinolone antibiotic. After taking alendronate (Fosamax), risedronate (Actonel), or another one of the bisphosphonate drugs for osteoporosis, you should wait at least 30 minutes before consuming a large amount of calcium. People taking calcium-channel blockers or beta blockers should discuss taking calcium with their doctors because it can reduce the effectiveness of these drugs.

Problems with supplements

It refers to the amount of Ca eliminated from the body in urine;feces and sweat.

Renal threshold for serum Ca is 10 mg/dl . FACTORS:

Typically,dietary Na & protein s ca excretion as the amt. of their

intake is sd . However, if a high protein, high sodium food also contains Ca, this may help counteract the loss of Ca .

ing dietary potassium intake in the presence of a high Na diet may help Ca excretion, particularly in postmenopausal women . intake of Na .

Caffeine can temporarily Ca excretion and may modestly Ca absorption, an effect easily offset ing Ca consumption in the diet .

Alcohol can affect Ca status by reducing intestinal absorption . It can also inhibit enzymes in the liver that help convert vitamin D to its active form which in turn reduces Ca absorption .

FACTORS AFFECTING Ca EXCRETION

Deficiency of calcium levels in the body may induce several diseases:

Rickets disease Adult osteomalacia Osteoporosis

Deficiency:

Rickets : is a softening of bones in children potentially leading

to fractures and deformity. The predominant cause is a vitamin D deficiency, lack calcium in the diet may also leads to rickets

Osteomalacia : is the softening of the bones due to defective bone mineralization It may show signs as diffuse body pains, fragility of the bones. A common cause of the disease is

deficiency in vitamin D, which is normally obtained from the diet and/or sunlight exposure

Some calcium disorders

Calcium metabolism disorder include:

Hypercalcemia

Hypocalcemia

hyperparathyrodism

Calcium metabolism disorders

Is condition in which the calcium level in the body is above the normal. The need of the calcium for the bone formation and muscle contraction, releasing

hormone . The main cause is over activity of the parathyroid gland. Cancer and some medication may cause over activity of the calcium level.

Etiology :- Increased GI Absorption: Vitamin D excess Elevated PTH Decreased Urinary Excretion: Thiazide diuretics Increased Loss From Bone:

Elevated PTHHyperparathyroidismMalignancyOsteolytic metastases

Hypercalcemia

Metastatic calcification Renal stones

Complication:

Is a condition in which the calcium level below the normal level Is caused by low level of PTH , low level of magnesium, deficiency

of vitamin D The kidney dysfunction play role in hypocalcaemia .

Etiology :- Decreased GI Absorption Poor dietary intake of calcium,impair absorption Increased Urinary Excretion Decreased Bone Resorption/Increased Mineralization Low PTH PTH resistance Vitamin D deficiency

Hypocalcaemia

Tetany: condition of mineral imbalance in the body that results in severe muscle spasms. usually occurs when the concentration of calcium ions (Ca++) in extracellular fluids below normal

Complication

Hyperparathyroidism occur in two major forms:

Primary: most common cause of hypercalceimia.it represents autonomous production of PTH.

Secondary:is caused by any chroinc condition assocaited with chroinc depression in the calcuim level.

Tertiary hyperparathyroidism: rarely occur

Hyperparathyroidism.

Overall, we need good sources of calcium in our diets, good nutritional habits, and a diet that promotes healthy gastrointestinal function. Taking calcium and magnesium at bedtime or between meals, when the stomach may be more acidic, is often helpful for better absorption. Regular exercise, good nutrition, and lots of vegetables are important basics for providing the essential calcium we need and good health in general