Nutrition expert-Trupti, at Sushruta clinic, Baroda
Calcium, the most abundant mineral in the body, is found in some foods, added to others, available as a dietary supplement, and present in some medicines (such as antacids). Calcium is required for vascular contraction and vasodilation, muscle function, nerve transmission, intracellular signaling and hormonal secretion, though less than 1% of total body calcium is needed to support these critical metabolic functions. Serum calcium is very tightly regulated and does not fluctuate with changes in dietary intakes; the body uses bone tissue as a reservoir for, and source of calcium, to maintain constant concentrations of calcium in blood, muscle, and intercellular fluid
At particular risk are female adolescents when bone formation and growth is most crucial. Later in the life cycle, women continue to be at highest risk and this risk is elevated if early baseline bone is not strong during adolescence. Women who have diagnosed eating disorders or exhibit physical hyperactivity with female athlete triad syndrome have been shown to be at high risk for calcium deficiency. Postmenopausal women, due to hormonal changes that may affect bone mineralization processes, have also been widely studied for calcium deficiency risk. Calcium is essential to maintaining total body health. Your body needs it every day not just to keep your bones and teeth strong over your life time but to ensure proper functioning of muscles and nerves. It even helps your blood clot. Ca deficiency is
usually due to an inadequate intake of Ca when blood Ca levels drop too low, the vital mineral is borrowed from the bones. It is returned to the bones from Ca supplied through the diet. If an individual’s diet is low in Ca, there may not be sufficient amount of Ca available in the blood to be returned to the bones to maintain strong bones and total body health. Taking Ca regularly everyday is key to preventing and treating Ca deficiency.
Maximum-calcium-retention studies, which examine the maximum amount of calcium that can be forced into bones, suggest a fairly high requirement. To ensure that 95% of the population gets this much calcium, the National Academy of Sciences established the following recommended intake levels:
- 1,000 milligrams/day for those ages 19 to 50
- 1,200 milligrams/day for those ages 50 or over
- 1,000 milligrams/day for pregnant or lactating adult women.
Phosphorus is an essential structural component of cell membranes and nucleic acids but is also involved in several biological processes, including bone mineralization, energy production, cell signaling through phosphorylation reactions, and regulation of acid-base homeostasis.
Some investigators are concerned about the increasing amounts of phosphates in the diet, which they largely attribute to phosphoric acid in some soft drinks and the increasing use of phosphate additives in processed foods. High serum phosphorus has been shown to impair synthesis of the active form of vitamin D (1,25-dihydroxyvitamin D) in the kidneys, reduce blood calcium, and lead to increased PTH release by the parathyroid glands . PTH stimulation then results in decreased urinary calcium excretion and increased bone resorption; both contribute to serum calcium concentrations returning to normal. If sustained, elevated PTH levels could have an adverse effect on bone mineral content, but this effect appears to be observed with diets that are high in phosphorus and low in calcium, underscoring the importance of a balanced dietary calcium-to-phosphorus ratio. In a small cross-sectional study, which enrolled 147 premenopausal women with adequate calcium intakes, participants with lower calcium-to-phosphorus (Ca:P) intakes (ratios ≤0.5) had significantly higher serum PTH levels and urinary calcium excretion than those with higher Ca:P ratios (ratios >0.5). A controlled trial in 10 young women found no adverse effects of a phosphorus-rich diet (3,000 mg/day) on bone-related hormones and biochemical markers of bone resorption when dietary calcium intakes were maintained at almost 2,000 mg/day (Ca:P = 0.66), again demonstrating the importance of the balance between dietary calcium and phosphorus.