Calcium overview - Calcium nutrition

Apr 2014   › › › Calcium in human nutrition
Calcium nutrition
Calcium, a highly essential mineral, is required in human nutrition for several critical biochemical processes.
Advertisements
Calcium brings about several metabolic functions like intracellular signaling, hormonal secretion, enzyme secretion, muscle contraction and nerve transmission. Skeletal system and teeth account for 99% of the calcium present in the body. Rest of the mineral is dispersed among soft tissues and blood serum. Dairy products are the best dietary sources of the mineral.

For the smooth functioning of the bone remodeling process, adequate dietary nutrition of the mineral is necessary. Postmenopausal women, due to decrease in estrogen production and intestinal absorption of the mineral, suffer loss of bone mass and develop osteoporosis. The presence of oxalic acid and phytic acid in the diet reduces the bioavailability of calcium present in the diet. Too much calcium supplementation can cause hypercalcemia, kidney stones and renal failure.

Adequate calcium intake is vital for bone and dental health. Many of the biological processes require adequate calcium in the system for their efficient function.
  • Adequate dietary calcium nutrition is required for optimising bone mass, bone mineral accretion and bone homeostasis.
  • The growth, mineralisation and maintenance of the mineral composition of teeth depend on the mineral status.
  • Intracellular calcium is vital for triggering cellular events like intracellular signals, vesicular secretion, cell aggregation, cell transformation and cell division.
  • Several extracellular digestive enzymes require the intervention of the mineral for optimum activity.
  • The presence of adequate calcium in nutrition brings about the skeletal, heart and smooth muscle contraction and neurotransmitter release.
  • Adequate intake of the mineral lowers the high blood pressure and reduces the risk of hypertension.

    • Plasma ionic calcium is tightly regulated between 1.1 and 1.3 mmol/L irrespective of its nutrition and the bones function as storage buffers. If the concentrations decrease considerably, tetany may occur. If the levels increase considerably, hypercalcemia, kidney stones and kidney failure may occur. Parathyroid hormone, either directly, indirectly or along with calcitonin and calcitriol, controls the homeostasis of calcium in the kidneys, bone and gastrointestinal tract.

  • .
  • .
    • In an healthy individual only about 20% to 30% of the dietary calcium is absorbed in the gastrointestinal tract; the rest being excreted in faeces. During growing phase, pregnancy and lactation the percentage of absorption may increase marginally. Further the form of the mineral salt, its solubility, relative presence of minerals like zinc, iron and magnesium in the diet, age of the individual and vitamin D status of the individual promotes or inhibits the absorption. The presence of oxalate in the diet reduces the nutritional bioavailability of the mineral.

    The richest food sources of the mineral are milk and dairy products with the exception of butter. Broccoli, cabbage, beans and kale are good plant sources. Fortified cereals and soy products also contain fairly good amounts of the mineral. Eggs, fish and animal products also have calcium. Canned small fish becomes a very good source if eaten with bones. The drinking water may also contain useful levels of dissolved salts of the mineral, especially if it is hard water.

    The basic cause of the deficiency is the inadequacy of the mineral in the nutrition. Certain disorders, physiological conditions and hormonal imbalances can also cause the deficiency of the mineral. The insufficiency of vitamin D and lack of exposure to sunlight can also cause insufficient absorption from the intestinal tract. Persons with lactose intolerance cannot take milk and may develop the deficiency. Short term deficiency may not have any apparent symptoms. Calcium deficiency can cause loss of bone mass, osteoporosis or hypocalcemia.

    The supplementation of the mineral below the tolerable upper intake levels is normally tolerated and rarely has any side effects. In some individuals, irritation of the gastrointestinal tract, flatulence, belching and constipation may be noticed. Individuals with decreased renal function may develop hypercalcemia, renal stones, metastatic calcification and related symptoms. Supplements of the mineral are known to react/interfere with absorption of certain dietary minerals, certain types of medicines and antibiotics.

    • The condition of overdose may occur in case of too much intake of the mineral in the form of supplements, antacids, intravenous administrations and fortified food. In normal conditions there is limited and controlled absorption of the mineral from the intestines. Intake of excess of vitamin D can also cause excessive absorption of the mineral from the gastrointestinal tract.

    Accidental or intentional ingestion of the mineral exceeding the upper tolerance levels of 2,500 milligrams can result in hypercalcemia with symptoms like nausea, constipation, arrhythmia, confusion, polyuria, kidney stones and kidney failure. Taking high doses of alkaline supplement of the mineral or taking absorbable alkali along with calcium supplement can lead to milk-alkali syndrome with symptoms of hypercalcemia, alkalosis and renal failure.
    Advertisements

    Related topics in nutrition, deficiency
    and diseases:
    .
    .
    .
    .
    .
    .
    .
    .
    .
    .
    Interesting topics in nutrition, deficiency
    and diseases:
    .
    .
    .
    .
    .
    .
    .
    .
    .
    .

    References:
    Dietary Supplement Fact Sheet. National Institutes of Health.
    http://ods.od.nih.gov/factsheets/Calcium-HealthProfessional/

    Current topic on nutrition deficiency diseases: Calcium nutrition.
    by
    Labels: ,

    No comments:

    Post a Comment

    Subscribe to: Post Comments (Atom)