chapter 11 major minerals and bone health. minerals in the body minerals are elements needed by the...

Chapter 11MAJOR MINERALS AND BONE HEALTH

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.

Copyright 2012, John Wiley & Sons Canada, Ltd.

Minerals


Minerals in the Diet


Calcium, Magnesium and Phosphorus Intake of Canadians


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


Calcium in the Diet


Calcium in the Diet (continued) Intake of soft drinks is affecting the calcium intake of

teenagers. Canadian adolescent males (14–18 years) consume an average of 376 ml/day of regular soft drinks and adolescent girls consume 179 ml/day.

Milk intake declines with age. Teenage boys consume 323 ml/day; girls, 222 ml /day. Young men (19–30 years) consume 201 ml/day; young

women, 178 ml/day. Men over 70 consume 136 ml/day; women, 136 ml/day. Canada’s Food Guide recommends 3 servings of milk or

milk products/day to ensure adequate calcium intake. (Intake as milk would be 750 ml/day).


Calcium in the Diet (continued) Soft drinks are replacing milk, have no

calcium and are higher in sugar. Low calcium intake early in life increases the

risk of osteoporosis and increases the number of overweight and obese individuals.


Calcium in the Diet (continued) You can determine if a packaged food is a good

source of calcium by looking at the label. The Nutrition Facts panel lists the amount of calcium

in mg and as % of Daily Value. The product label may have a nutrient content claim.


Calcium in the Diet (continued) A multivitamin and mineral supplement will not

provide enough calcium to meet your needs. Read labels to find a supplement that contains

calcium alone or calcium with Vitamin D (which aids in absorption of calcium).

The form of calcium is also important. Calcium carbonate should be taken with a meal, whereas calcium citrate can be taken at any time.

Antacids that contain aluminum and magnesium may actually increase calcium loss.


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.


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.


Regulation of Blood Calcium


Calcium and Bone Health


Risk Factors for Osteoporosis


Osteoporosis Osteoporosis is a major public health problem

in Canada. Two million Canadians over age 50 have

osteoporosis. Twice as many women as men have the condition.

Osteoporosis is responsible for 80% of fractures in people over 60 years of age.

Osteoporosis and fractures cost the Canadian health care system $1.9 billion annually to treat.


Osteoporosis Risk


Gender and Bone Mass


Phosphorus in the Diet


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.


Magnesium in the Diet


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.


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.


Summary of Calcium, Phosphorus, Magnesium and Sulfur


Copyright

Copyright © 2012 John Wiley & Sons Canada, Ltd.

All rights reserved. Reproduction or translation of this work beyond that permitted by Access Copyright (The Canadian Copyright Licensing Agency) is unlawful. Requests for further information should be addressed to the Permissions Department, John Wiley & Sons Canada, Ltd. The purchaser may make back-up copies for his or her own use only and not for distribution or resale. The author and the publisher assume no responsibility for errors, omissions, or damages caused by the use of these programs or from the use of the information contained herein.

.


chapter 11 major minerals and bone health. minerals in the body minerals are elements needed by the...

Documents

john wiley sons canada

minerals copyright

low calcium intake

adequate calcium intake

calcium intake of teenagers

major minerals

good source of calcium

trace minerals