MINERALS | NUTRITION & DIETETICS|L-4|

Minerals

The minerals calcium, phosphorus, iron iodine, sodium and others are found in various foods in combination with organic and inorganic compounds. Minerals are necessary for body building, for building bones, teeth and structural parts of soft tissues.

(i) Calcium

Distribution: Calcium makes up between 1.5 to 2 percent of body weight accounting for 1200-1600 g of the adult male body. Ninety percent of calcium is found in min-eralized tissues such as bones and teeth as calcium phosphate and calcium carbonate. The remaining 1% is found in blood, extracellular fluid (ECF), muscle and tissues.

•  Bone formation: 

The important minerals within bone are calcium phosphate and magne-sium. There is 1 kg of calcium in the adult skeleton as a complete crystalline material with phos-phate.

·   Tooth formation: The enamel and dentin of tooth contain considerable amounts of cal-cium which are dense and are present along with keratin.

Growth:  It  is  required  for growth as it forms an important part of the bones and teeth and proper functioning of every cell in the body.

·        Blood clotting: Calcium con-tributes to clotting of blood.

·        Contraction  of  the muscle:

Calcium ions are bound by the electrostatic forces to the pro-teins inside and outside the cells and to cell membranes. Proteins bound by calcium alter their configuration at the neuro muscular junction by the nerve impulses causing free calcium to be released. The free cal-cium bound to troponin leads to an internal trigger and so the contraction of the muscle takes place

·        Metabolic essentiality: Cal-cium acts as a activator for the enzyme renin present in gastric juice which aids the digestion of milk.

Food sources: Calcium is present in both animal and plant foods. The richest source of calcium among animal foods is milk and among the vegetable sources it is green leafy vegetables. 

Among the green leafy vegetables, amaranth, fenu-greek and drumstick leaves are rich sources of calcium. Ragi among cereals is a rich source of calcium. Small dried fish, nuts and oil seeds like gingelly seeds, betel leaf with slaked lime are also a rich source.

Absorption:

•     Factors increasing absorption of calcium: Vitamin D, acidity of digestive mass, lactose, protein and phosphorus are the factors which favor the absorption of calcium.

•     Factors decreasing absorption of calcium: Oxalic acid, phytic acid, high fat diets including steatorrhea, emotional instability, increased gastrointestinal mobility, lack of exercise, ageing, caffeine and drugs decrease the absorption of calcium in the body.

Health Problems/ Deficiency:

·        Osteoporosis: This is a condi-tion associated with a loss in bone density and bone mass which literally means “porous bone”. With the ageing process resorption predominates bone formation resulting in osteopo-rosis.

Risk factors for osteoporosis include

·        Females who are fair complexioned are at eight times more at risk

·        Asian Race

·        Family history

·        Prolonged dietary insuf-ficiency

·        Poor absorption and uti-lization of calcium

·        Restricted movement

·        Decreased levels of estro-gen

·        Hyper parathyroidism

·        Vitamin D sufficiency

·        Osteomalacia: It is a condition where the quality of the bone is diminished and the quantity of the bone is not compromised.

·        Osteopenia: It refers to the bone density that is lower than nor-mal peak density but not low enough to be classified as osteoporosis. The difference between osteopenia and osteoporosis is a matter of severity of the loss of bone density.

·        Tetany: A decrease in serum calcium levels gives rise to a condition called tetany. The symptoms of tetany are severe intermittent spasms of the mus-cles of hands and feet accompa-nied by muscular pain. Twitch-ing of facial muscles occurs.

(ii) Phosphorus

Distribution: It comprises 1 per-cent of total body weight along with calcium. An adult human body contains about 400-700 g of phos-phorus as phosphates. Bones and teeth contain 85 percent of phos-phorus and soft tissues contain15 percent of phosphorus.