Explain Interactions of Macrominerals With Other Nutrients?
Various nutrients interact with minerals thereby affecting their bioavailability. These interactions occur at different sites in the body including gastrointestinal tract, during transport, at the level of storage or in the kidneys. Most of the minerals interact with other nutrients in the intestine which either increase or reduce their absorption. These interactions which occur in the gastrointestinal tract have been covered for Ca, P, and Mg earlier under the section on absorption. The interactions which occur at other sites are briefly enumerated herewith.
1. Calcium excretion through kidneys has been shown to be influenced by the levels of other minerals. Increased potassium (K) reduces urinary loss of Ca. thereby conserving the mineral. On the other hand, sodium load (100 mmoll or 2.3 g/day) increase urinary Ca excretion. In post menopausal women urinary sodium excretion was negatively correlated which changes in hip bone density.
2. Although increased phosphorous level reduces urinary losses of Ct.1, animal studies have indicated that low Ca: P ratios lead to progressive bone loss due to phosphorus induced stimulation of PTH release. Ca and Mg interact at the level of kidneys. Both minerals use overlapping transport systems in the kidney and thus complete with each other for reabsorption.
3. Mg may mimic Ca by binding to calcium binding sites. The ratio of calcium and magnesium has been shown to affect muscle contraction. Magnesium may compete with Ca for non-specific sites on troponin C and myosin.
4. Normally Ca binding initiates acetyl choline release and smooth muscle contraction. However, binding of Mg prevents Ca binding and inhibits its contraction.
5. In blood coagulation, Ca and Mg are antagonistic, with Ca promoting the process and magnesium inhibiting it. A close relationship also exists between Mg and K. Mg appears to be necessary for the function of Na+/K+ -ATPase. Therefore, deficiency of Mg would lead to impaired pumping of sodium out of the cell and the movement of potassium into the cell. Thus, above discussion emphasizes the need of consuming diets containing appropriate amounts of all the nutrients. Prolonged use of a nutrient supplement or fortification with a single nutrient can offset the balance thereby affecting the bio availability and physiological functions of nutrients.