Answer to Question 1
Calcium, phosphorus, magnesium, sodium, chloride, and potassium are major minerals. Major minerals have both structural and functional roles. Examples of structural roles: calcium and phosphorus provide strength and structure to skeleton. Functional roles: sodium, chloride, and potassium are essential for maintaining fluid balance in and outside of the cell. Minerals also function in chemical reactions (calcium as a cofactor), energy metabolism (calcium, phosphorus, magnesium, potassium), nerve function and muscle contraction (calcium, phosphorus, magnesium, sodium, chloride, and potassium), and immune function (sodium and chloride).
Answer to Question 2
Essential minerals are classified by how much you need as major or trace minerals. Major minerals are needed in amounts >100 mg per day and are found in seafood, meat, and dairy products (some are also obtained from fruit, vegetables, and legumes). Absorption of some minerals is not regulated and decreases with age. Bioavailability of others is influenced by genetics, nutritional status, and interactions with other components in food. The primary site of absorption is the small intestine. Major minerals circulate directly from the GI tract to the liver and are transported via the blood. Blood levels are regulated by the small intestine at the time of absorption and by the kidneys at the time of excretion.
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