ABSTRACT
This chapter outlines the biological roles fulfilled by minerals and defines the reasons for their daily requirements. It describes the symptoms of deficiencies and toxicities of these minerals, and identifies the circumstances under which deficiency occurs and the vulnerable population groups. Minerals required in large amounts, such as sodium, potassium and calcium, are often called ‘major minerals’, while those required in very small amounts are called ‘microminerals’, ‘trace elements’ or ‘micro-elements’. Calcium in foods occurs as inorganic calcium salts, complexes with oxalates and phytates, and complexes with proteins. The absorption of calcium is an adaptive physio logical response to diet, because people on low intakes can absorb a larger proportion of calcium than those on high intakes. Magnesium is an element that occurs ubiquitously in nature. Legumes, cereals, nuts and green leafy vegetables are rich sources of magnesium. Sodium (Na) and chloride (Cl) are the principal electrolytes in extracellular body fluids such as blood plasma.
