Chapter 11 Major Minerals and Bone Health
Copyright 2010, John Wiley & Sons, Inc. Minerals in the Body Minerals are elements needed by the body in small amounts for health and maintenance. Major minerals are needed in the diet in amounts greater than 100 mg per day or are present in the body in amounts greater than 0.01% of body weight. Trace minerals are required in the diet in amounts less than 100 mg per day or are present in the body in amounts less than 0.01% of body weight.
Minerals Copyright 2010, John Wiley & Sons, Inc.
Minerals in the Diet
Copyright 2010, John Wiley & Sons, Inc. Mineral Talk Minerals are available in unprocessed foods, some processed foods and dietary supplements. To maintain health, minerals must be consumed in the correct proportions. Bioavailability is very important. For example, phytates can limit the body’s ability to absorb calcium, zinc and iron. DRIs for minerals are expressed as RDAs, EARs or AIs. Because certain minerals can be toxic if taken in too high an amount, ULs have been established.
Minerals as Cofactors Copyright 2010, John Wiley & Sons, Inc.
Calcium in the Diet
Copyright 2010, John Wiley & Sons, Inc. Calcium Talk Calcium is the most abundant mineral in the body. Calcium provides the structure to bones and teeth and has important regulatory roles. Calcium is absorbed by active transport and passive diffusion, depending on the availability of the active form of vitamin D. Bioavailability of calcium is decreased in the presence of tannins, fiber, phytates and oxalates. Calcium accounts for 1–2% of adult body weight.
Copyright 2010, John Wiley & Sons, Inc. Calcium’s Role in the Body 99% of calcium in the body is found in solid mineral deposits in the bones and teeth. The remaining 1% is found in intracellular fluid, blood and extracellular fluid. Calcium found in the body’s fluid plays a role in nerve transmission, muscle contractions, blood pressure regulation and the release of hormones.
Copyright 2010, John Wiley & Sons, Inc. Regulation of Blood Calcium
Copyright 2010, John Wiley & Sons, Inc. Calcium and Bone Health
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Risk Factors for Osteoporosis
Copyright 2010, John Wiley & Sons, Inc. Osteoporosis Risk
Gender and Bone Mass Copyright 2010, John Wiley & Sons, Inc.
Phosphorus in the Diet
Copyright 2010, John Wiley & Sons, Inc. Phosphorus Talk Phosphorus makes up about 1% of an adult’s body. 85% of phosphorus in the body is found in the bones and teeth. Phosphorus is more readily absorbed than calcium. Phosphorus is an important component of molecules with structural or regulatory roles. Phosphorus deficiency can lead to bone loss, weakness and loss of appetite. Phosphorus toxicity is rare, but can lead to bone resorption.
Copyright 2010, John Wiley & Sons, Inc. Magnesium in the Diet
Copyright 2010, John Wiley & Sons, Inc. Magnesium Talk About 50-60% of magnesium in the body is found in bone, where it is essential for the maintenance of structure. Most of the remaining magnesium is present inside cells, where it is the second most abundant intracellular ion, after potassium. Magnesium is a cofactor for over 300 enzymes. It is necessary for the generation of energy from carbohydrate, lipid and protein. Magnesium deficiency is rare. When it does occur, especially in individuals with alcoholism, malnutrition, kidney and GI disease or in people taking diuretics, it may cause nausea, muscle weakness and cramping, mental derangement and changes in blood pressure and heartbeat. Magnesium toxicity is rare. The UL for adults has been set at 350 mg from nonfood sources of magnesium.
Copyright 2010, John Wiley & Sons, Inc. Sulfur Talk Dietary sulfur is found in protein foods and sulfur- containing amino acids in vitamins. Dietary sulfur is also found in nonfood additives, such as sulfur dioxide, sodium sulfite and sodium bisulfite. Sulfur-containing amino acids, such as methionine and cysteine, are needed for protein synthesis. The vitamins thiamin and biotin contain sulfur. There is no recommended daily intake for sulfur.
Copyright 2010, John Wiley & Sons, Inc. Summary of Calcium, Phosphorus, Magnesium and Sulfur
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