Chapter 8 Water and Minerals. Copyright 2010, John Wiley & Sons, Inc. Water Water is an essential nutrient that must be consumed for survival. Water is.

Chapter 8Water and Minerals

Copyright 2010, John Wiley & Sons, Inc.

Water

Water is an essential nutrient that must be consumed for survival.

Water is a polar solvent in the body. The polarity of water comes from hydrogen

and oxygen. Blood is 90% water. Blood transports oxygen and nutrients to

cells and removes carbon dioxide and waste products.


Water

Water functions as a lubricant and cleanser. Tears wash away dirt, synovial fluid

lubricates joints, saliva assists in chewing, tasting and swallowing and spinal fluid protects against shock.

Water assists in regulating body temperature by holding onto heat and changing temperature slowly.


Water in the Body About two-thirds of body water is found inside cells. Water

inside cells is called intracellular fluid. Extracellular fluid is found outside the cells. Interstitial fluid consists of lymph, blood plasma and

extracellular fluid. Intracellular fluid has the highest concentration of protein,

extracellular fluid has less, and interstitial fluid has the lowest concentration of protein.

Extracellular fluid has the highest concentration of sodium and chloride and a lower concentration of potassium.

Intracellular fluid has the lowest concentration of sodium and the highest concentration of potassium.

The fluid pressure of blood against the blood vessels is blood pressure.


Water Balance in the Body


Regulating Water Loss


Dehydration


Water Intoxication


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 100mg 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 100mg per day or are present in the body in amounts less than 0.01% of body weight.


Minerals in the Body 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 on the Menu


Compounds that Interfere with

Mineral Absorption


Function of Minerals in the Body


Electrolytes: Sodium, Potassium, and Chloride The correct combination and amounts of

electrolytes are essential for life. Distribution of electrolytes affects the

distribution of water throughout the body. Sodium, potassium and chloride are the

principal electrolytes in body fluids.


Electrolytes in the Body


Electrolytes in the Body


Regulation of Blood Pressure


The Effect of Diet on Blood Pressure






Meeting Electrolyte NeedsStay hydrated Drink before, during, and after you exercise. Guzzle two extra glasses of water when you are out on a hot day. Bring a bottle of water with you in your car.

Boost your potassium intake Double your vegetable serving at dinner. Take two pieces of fruit for lunch. Drink orange juice instead of soda or punch.

Reduce your sodium intake Choose more unprocessed foods. Do not add salt to the water when cooking rice, pasta, and cereals. Flavor foods with lemon juice, onions, garlic, pepper, curry, basil, oregano, or thyme

rather than with salt. Limit salty snacks such as potato chips, salted nuts, salted popcorn, and crackers. Limit condiments such as soy sauce, barbecue sauce, ketchup, and mustard; they

are high in sodium.


Sodium on Food Labels


Summary of Water and Electrolytes


Minerals and Bone Health: Calcium Calcium is the most abundant mineral in the body. Calcium provides structure for 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.


Calcium on the Menu


Bone Mass and Osteoporosis


Bone Mass and Osteoporosis


Risk Factors for Osteoporosis


Phosphorus

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 absorbable 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 About 50% to 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.


Magnesium on the Menu


Calcium, Phosphorus and Magnesium in the DietGet calcium into your body and your bones Have three servings of dairy a day: milk, yogurt, cheese. Bone up on calcium by eating sardines or canned salmon, which are

eaten with the bones. Choose leafy greens—they are a vegetable source of calcium. Walk, jog, or jump up and down—weight-bearing exercises build up

bone.

Don’t fret about phosphorus—it’s in almost everything you eat.

Maximize your magnesium Choose whole grains. Sprinkle nuts and seeds on your salad, cereal, and stir-fry. Go for the green—whenever you eat green, you are eating

magnesium; most greens contain calcium, too.


Sulfur Dietary sulfur is found in protein foods and in

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


Trace Minerals

The trace minerals include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and molybdenum.

They are required in an amount less than 100 mg per day.

Trace minerals have been difficult to study, as they are difficult to remove from the diet.

Rate of bioavailability is a concern for trace minerals.


Iron

Hemoglobin is the iron-containing component of the blood.

Iron from animal products is heme iron. Iron from plant products is nonheme iron. Iron cookware can be a source of nonheme iron in the

diet. Heme iron is more efficiently absorbed than nonheme

iron. Iron from the diet is absorbed into the intestinal

mucosal cells.


Iron in the Body

Ferritin is the major iron storage protein Transferritin is an iron transport protein in the blood. Hemosiderin is an insoluble iron storage compound

produced by the body when iron exceeds the storage capacity of ferritin.

Iron is essential for the delivery of oxygen to cells. Two oxygen-containing proteins, hemoglobin and myoglobin, contain iron.

Most of the iron in the body is part of hemoglobin.


Iron on the Menu


Iron Deficiency When iron is deficient, hemoglobin cannot

be produced. When there is insufficient hemoglobin, red

blood cells are microcyctic and hypochromic and unable to deliver sufficient oxygen to the tissues. This is known as iron deficiency anemia.

It is estimated that as much as 80% of the world’s population may be iron deficient and 30% suffer from iron deficiency anemia.


Iron Toxicity Iron is essential for cellular metabolism, but too

much can be toxic. A UL has been set at 45 mg/day from all sources. Iron poisoning can be life-threatening. It can

damage the intestinal lining and cause abnormalities in body pH, shock and liver failure.

Iron overload can happen over time and accumulates in tissues such as the heart and the liver.

The most common form of iron overload is hemochromatosis.


Copper

Copper may be important in helping to prevent certain types of anemia.

The richest dietary source of copper is organ meat. Seafood, chocolate, nuts, seeds and whole-grain foods are also good sources.

Zinc can decrease the bioavailability of copper. The RDA for copper for adults is 900 micrograms

per day.


Zinc

Zinc is essential in the diet for growth and development. Zinc from animal sources is better absorbed than zinc

from plant sources. Zinc can be bound by phytates, affecting bioavailability. Zinc is the most abundant intracellular trace element. Zinc is involved in the functioning of over 300 different

enzymes, including superoxide dismutase, important for protecting cells from free-radical damage.

Zinc can be toxic if taken in excess.


Zinc on the Menu


Selenium

The selenium content of plant foods, such as grains and seeds, depends on the selenium content of the soil in which they are grown.

Selenium deficiency can lead to Keshan disease, affecting the heart muscle.

Symptoms of selenium deficiency include muscular discomfort and weakness.

There may be a connection, still being researched, between diets low in selenium and higher incidences of cancer.


Selenium as an antioxidant


Iodine

The iodine content of food depends on the soil where plants are grown or where animals graze.

Soil near the ocean or sea is higher in iodine than soil inland.

Most of the iodine in the diet comes from iodized salt. Iodized salt is salt fortified with iodine. “Natural” sea salt may be very low in iodine.

More than half the iodine in the body is found in the thyroid gland.

Iodine is an essential component of thyroid hormones, including thyroxine.


Iodine When the supply of iodine is adequate, the body

can produce the needed thyroid hormones. The RDA for iodine for adult men and women is

150 micrograms per day. The RDA for iodine is higher during pregnancy and lactation.

Consuming diets high in goitrogens, such as cabbage, cassava and millet, limits the bioavailability of iodine.

Iodine deficiency may result in hereditary cretinism.

The UL for adults is 1100 micrograms of iodine per day. Iodine toxicity is possible.


Iodine Deficiency Disorders


Iodine Deficiency Disorders


Iodized Salt


Chromium

Dietary sources of chromium include brewer’s yeast, liver, nuts and whole grains.

Cooking in stainless steel can increase food’s chromium content.

Chromium is involved in carbohydrate and lipid metabolism.


Fluoride

Fluoride is important for dental health. Fluoride is present in small amounts in

almost all soil, water, plants and animals The most common source of fluoride is

fluoridated water, tea, marine fish eaten with their bones (such as canned salmon or sardines) and topical toothpaste.

Calcium-rich foods reduce the bioavailability of fluoride.


Trace Minerals in the DietAdd more iron Eat red meat, poultry, or fish—they are all good sources of heme iron. Add raisins to your oatmeal. Fortify your breakfast by eating iron-fortified cereal. Dust off the iron skillet. Have some beans—they are a good vegetarian source of iron.

Increase iron absorption Have orange juice with your iron-fortified cereal. Don’t take your calcium supplement with your iron sources.

Think zinc Scramble some eggs. Beef up your zinc by having a few ounces of meat. Eat whole grains, but make sure they are yeast leavened.

Trace down your minerals Check to see if your water is fluoridated. See if your salt is iodized. Replace refined grains with whole grains to increase your chromium intake. Have some seafood to add selenium to your diet.


Summary of Trace Minerals


Summary of Trace Minerals


End of Chapter 8

Copyright 2010 John Wiley & Sons, Inc.

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Chapter 8 Water and Minerals. Copyright 2010, John Wiley & Sons, Inc. Water Water is an essential nutrient that must be consumed for survival. Water is.

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