Calcium and magnesium - Relationship - Supplements - Benefits

Mar 2014   Calcium magnesium relationship, supplements and benefits
Calcium (Ca) and magnesium (Mg) have a complex relationship, being antagonistic as well as complementing each other. Magnesium and calcium are two sides of the physiological processes, required at appropriate ratios for getting optimal benefits from diet and supplements.
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Above 90% of the body's calcium is present in bones and teeth whereas 60% of Magnesium is present in bones.

is the root cause of most of the ailments and diseases. The health of the bones and kidneys as well as the functions of neuromusculoskeletal and cardiovascular systems depend on the Ca and Mg status of an individual. Many biochemical reactions in the body as well as enzymes are magnesium-dependent or calcium-dependent.

Relationship between calcium and magnesium

The relationship between Ca and Mg is not yet fully understood. Bones function as reservoirs of Ca and Mg. Severe Mg deficiency has been found to induce low calcium levels in the blood. Severe hypomagnesemia is also found to cause hypoparathyroidism, which in turn induces hypocalcemia. The decrease in blood levels of either Mg or Ca increases the parathyroid hormone (PTH) secretion.

Both the minerals have active role in the regulation of muscle contraction and relaxation including cardiac muscle.
  • Ca helps in the contraction of muscles, while Mg relaxes them. Deficiency of either Ca or Mg is found to cause insomnia and interrupted sleep. The normal ratio of Ca to Mg in the blood is approximately 2:1. The suggested proportion for calcium magnesium supplement for optimal benefits is 2 parts Ca with 1 part Mg. A higher Ca to Mg ratio can cause Mg inefficiency or deficiency.

    Being divalent cations, calcium and magnesium supplements compete for the same active transport system for absorption into the body. Mg deficiency can lead to increase in intracellular Ca concentrations and calcification of otherwise normal soft tissues. It is also observed that phosphate depletion in the body increases the excretion of Ca and Mg in the urine.

    Calcium and magnesium absorption

    The absorption of calcium in the gastrointestinal system is by two mechanisms.
  • Active transcellular process occurs in the duodenum and upper jejunum. As the chyme passage through the duodenum is only for a minute or so, active transport contributes only for a fraction of the absorbed mineral. However when the intestinal Calcium concentration is low, the active transport becomes the predominant process.

    The transcellular process is mediated by cytosolic calcium-binding protein (Calbindin-D9k) which in turn is mediated by caATPase.
  • The functioning of caATPase and the synthesis of Calbindin-D9k is vitamin D-dependent. The second process is a passive paracellular process. It takes place throughout the intestine, driven by chemical, osmotic and electrical gradients and solvent drag. When the intestinal Ca concentration is high, greater proportions of calcium in diet and supplement are absorbed by the passive process.

    Magnesium in diet or supplement is mostly absorbed by the small intestine. Most of the Mg is absorbed by a passive paracellular process, driven by chemical, osmotic and electrical gradients and solvent drag. There is also a active transcellular transport mechanism taking place in the distal end of intestine and colon. When intestinal Mg concentration is low, active transport is dominant. Mg supplement absorption is dependent mainly on Mg status and not on the amount of the mineral intake.

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

    Current topic on nutrition, deficiency diseases:
    Calcium magnesium relationship - Calcium magnesium supplements and benefits.