The Encyclopedia Of Nutrition And Good Health - W pptx

A human embryo represents about 98 percent water; an infant’s weight is about 75 percent water; and water accounts for 50 percent to 65 percent of an adult’s weight.. EXTRACELLULAR FLUID

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walnut (Juglans spp.) A popular commercial nut

with a hard, deeply furrowed shell surrounding the

meat The English walnut (J regia) is the most

important commercial walnut It is native to

south-eastern Europe and western Asia and probably

originated in Persia The black walnut (J nigra) is

native to the Mississippi Valley and Appalachians of

the United States; there is limited commercial

pro-duction of black walnuts, however The United

States produces over half the world crop; most of it

comes from California About 40 percent of the

walnut crop is marketed in shells, the remainder is

processed Machine-shelled nuts may be blanched

to remove the inner skins, which give walnuts

their somewhat bitter aftertaste They may be

blanched to even out the color

Walnuts contain a large percentage of oil, with

66 percent of it as polyunsaturated fatty acids It is

a good source of alpha linolenic acid, an omega-3

fatty acid essential to the diet Cholesterol-lowering

diets in which meat and dairy products are

substi-tuted by walnuts may lower blood cholesterol

lev-els because of their polyunsaturated fat Shelled

nuts are subject to rancidity; they should be

vacuum-packed or stored in sealed plastic bags in

the freezer On the other hand, whole walnuts can

be stored for months in a cool environment If

antioxidants are added to extend shelf life, they are

listed on the food label Walnuts are used in baking

and confections The nutrient content of 1 cup (120

g) of chopped English walnuts is: 770 calories;

pro-tein, 17.2 g; carbohydrate, 22 g; fiber, 8.4 g; fat,

74.2 g; iron, 2.8 mg; potassium, 602 mg; thiamine,

0.46 mg; riboflavin, 0.18 mg; niacin, 1.256 mg

water A clear, colorless, odorless liquid that is

essential for all life forms Water is the most

abun-dant nutrient in the body More water is needed

daily than any other nutrient because cells contain mainly water A human embryo represents about

98 percent water; an infant’s weight is about 75 percent water; and water accounts for 50 percent

to 65 percent of an adult’s weight EXTRACELLULAR FLUID including blood and lymph accounts for 20 percent of body weight; INTRACELLULAR FLUID, the water within cells, accounts for 45 percent Water represents 75 percent of muscle tissue and 92 per-cent of the cell-free fluid of blood (plasma) Exces-sive water can accumulate in tissues, a condition called EDEMA Edema is caused by heart failure, low blood pressure due to low blood protein resulting from STARVATION, or to increased capillary leakiness due to INFLAMMATION

Water serves many roles for the body Water functions as a lubricant and is a major constituent

of joint fluid It helps internal organs slide by each other, for example, during PERISTALSIS, the muscu-lar contraction that moves food down the digestive tract Water comprises the major constituent of flu-ids important in digestion: SALIVA, MUCUS, gastric juice, BILE, pancreatic juices, and intestinal secre-tions Because water is so prevalent in cells, most cellular macromolecules of the body like DNA, RNA, proteins, and polysaccharides function in a water environment Water participates in many chemical reactions of the body Thus DIGESTIONrefers to the hydrolysis of nutrients, that is, the breaking of chemical bonds by means of water molecules Because water is an excellent solvent, it readily transports nutrients and waste products in the bloodstream Water also absorbs and releases heat slowly so that it can slow changes in body temper-ature as environmental tempertemper-atures fluctuate Water possesses a high heat of vaporization; that is,

a lot of heat is used up in evaporation Thus when water evaporates as sweat, it provides an effective

means of cooling the body Gases dissolve readily in

water, and moist tissue surfaces promote the

absorption of gases like OXYGENand the release of

CARBON DIOXIDEin the lungs

Water Balance

Water balance refers to the ability of the body to

adjust water output to water intake When a large

volume of water is consumed, urine excretion

increases; with limited water intake, urine

produc-tion declines Water is lost daily from the skin (450

ml), urine (1,400 ml), expired air from the lungs

(350 ml) and in stools (200 ml) To make up for

these losses, a typical adult uses 2 to 2.9 quarts (2

to 2.7 liters) of water daily Beverages provide

about 1.5 l; foods contribute about 0.70 l, and

water from metabolism yields 0.20 l RESPIRATION,

the oxidation of nutrients to carbon dioxide,

pro-duces on the average 13 g of water per 100 calories

with a typical diet Thus oxidation of 100 g of

car-bohydrate yields 60 g of water; the oxidation of 100

g of protein, 42 g of water; and 100 g of fat, 110 g

of water

Water is also recycled Each day the intestine

receives 8 to 10 liters of secretions, including saliva,

gastric juices and glandular products Most water is

reabsorbed; only 100 to 200 ml of water is lost

through feces Exceptions are DIARRHEAand

vomit-ing The kidneys play a major role in water

conser-vation while removing waste materials in urine

Each day the kidneys filter nearly 2,000 liters of

blood Only 0.1 percent of this volume is released

as urine

Water balance is regulated by an elegant

feed-back system involving the brain and hormones

Nerve centers in the region of the brain called the

HYPOTHALAMUS regulate hunger, thirst, and urine

output A loss of about 1 percent of body water

cre-ates the sensation of THIRST Decreased water and

elevated sodium in the blood are detected by

osmoreceptor cells, regulatory cells located in the

hypothalamus As the effective ion concentration

of blood increases, water leaves these cells and they

shrink, generating nerve impulses that trigger thirst

and stimulate the release of ANTIDIURETIC HORMONE

(ADH) from the PITUITARY GLAND ADH in turn

increases the ability of NEPHRONS(the kidneys’

fil-tration device) to absorb water that would

other-wise be lost as urine As a result, the sodium con-centration of the blood decreases, cells of the hypo-thalamus regain water, and the thirst sensation diminishes

Dehydration

DEHYDRATION can be caused by evaporation, diar-rhea, blood losses, burns or excessive urine pro-duction, as in uncontrolled diabetes Physical activity increases water loss through perspiration and breathing Water depletion can become a serious problem with prolonged EXERCISE With ele-vated temperatures, strenuous exercise can in-crease water losses three- to tenfold above normal

DIURETICS (water pills) increase urine output by increasing water and sodium excretion, as do CAF

-FEINE and related compounds like theophylline

ALCOHOLincreases urination because it inhibits the release of ADH Dehydration can cause discomfort, flushed skin, tingling in hands and feet, then increased heart rate, increased body temperature, weakness, confusion, spastic muscles, and de-creased blood volume

Overhydration

With excessive water intake, brain cells become swollen This can cause drowsiness, lowered blood pressure, weakened heart, weakness, and even convulsions and coma Patients administered ex-cessive IV solutions too rapidly or who have im-paired ADH production may develop symptoms of water intoxication

Minerals in Drinking Water

All water except distilled water contains minerals, and domestic water supplies vary in their mineral content

Hard water contains calcium and magnesium salts of bicarbonate and sulfate The mineral con-tent can be sufficiently high to contribute to daily requirements of these minerals Boiling hard water converts bicarbonate to carbonate, and insoluble magnesium and calcium carbonate deposits form in tea kettles, hot water, and steam pipes Calcium and magnesium in hard water also form solids with typical soaps

Soft water contains sodium sulfate and sodium bicarbonate, which are soluble and do not form solids as water is boiled, nor do they react with

water 663

soap Soft water is associated with an increased risk

of CARDIOVASCULAR DISEASE, possibly because low

dietary calcium and magnesium increase the risk of

heart disease When drinking water contains more

than 20 mg of sodium per liter, it represents a

sig-nificant source of sodium for people on

sodium-restricted diets Soft water is more corrosive to

plumbing and can dissolve CADMIUMand LEADfrom

galvanized pipes and soldered joints

Water hardness is expressed in parts per million

(ppm) equivalent to calcium carbonate, though

magnesium or other minerals may be present

Water with a hardness less than 100 ppm of calcium

carbonate is considered soft, while water with a

hardness greater than 300 ppm is considered hard

Over half of the municipal water supplies in the

United States add FLUORIDEto reduce tooth decay

This has become a controversial issue because too

much fluoride can cause health problems

Demineralized water that is free of mineral ions,

like calcium, magnesium, and carbonate, is

pre-pared by ion exchange columns that replace

cal-cium and magnesium with sodium and hydrogen

ions, and replace carbonate with sulfate Non-ionic

materials such as pesticides are not removed

Distillation, in which water is converted to

steam and then condensed and collected, removes

most organic residues as well as minerals Volatile

materials (those that readily vaporize) such as

sol-vents may not be removed by distillation

Disinfecting Drinking Water

Chlorination has long been used as a chemical

treatment to disinfect water In most industrialized

countries, water treatment by chlorination has

removed the threat of water-borne diseases like

cholera, typhoid, dysentery, and gastroenteritis

However, inadequate treatment of sewage leads to

periodic outbreaks of hepatitis A and other diseases

There are hints that chlorination by-products

slightly increase the risk of cancer Most public

health officials agree that the health risks of not

dis-infecting water are very much greater than those

posed by chlorination

An alternative treatment to kill disease-causing

microbes, chloramination, incorporates chlorine

and ammonia to treat water supplies It is as

effec-tive as chlorine, and this method is used by about

20 percent of the largest municipal water supplies Ozonation disinfects water with ozone, with a follow-up chlorination or chloramination treat-ment to destroy microbes that may multiply after ozone wears off Less than 1 percent of water sys-tems use this method

Parasites can contaminate water supplies in the United States In 1993, an estimated 370,000 peo-ple in Milwaukee experienced diarrhea and flu-like symptoms due to water contamination by a

para-site called Cryptosporidium Elevated levels of

partic-ulate matter in drinking water in Washington, D.C., the same year caused the EPA to issue an alert

to boil drinking water as a defense against

Cryp-tosporidium, which resists chlorination Although

most people experience only mild discomfort with

infection, Cryptosporidium can cause

life-threaten-ing illness in newborn infants and in people with impaired immune systems

There are no standards for acceptable levels of

this parasite in drinking water Giardia, another

intestinal parasite that can also cause intestinal

dis-tress, is larger than Cryptosporidium and is more

eas-ily removed by filtration in municipal water treatments The presence of this parasite in water is essentially unacceptable to the EPA

Suggestions for Water Purification When Camping

Boiling water up to 20 minutes is a tried and true method of disinfecting drinking water, and it is probably the safest Using iodine to disinfect water may pose a hazard because excessive amounts of iodine can be toxic Another form of iodine, hypoperiodide, is safer Adding a couple of tablets

of activated charcoal per quart can remove the unpleasant taste from sterilized water Travelers should avoid drinking tap water and iced drinks when in countries where water quality is question-able If water used to make ice cubes is contami-nated, the iced beverage will be too

Chemical Water Pollutants

Industrialization has introduced thousands of new chemicals into the environment, and about 700 chemical contaminants have been detected in drinking water in the United States including PESTI

-CIDES; industrial solvents; toxic heavy metals like lead and MERCURY; NITRATESfrom fertilizer use; and

664 water

radioactive contaminants like radon Under the

Safe Drinking Water Act of 1974, the

Environmen-tal Protection Agency is charged with setting

stan-dards of water quality for all local water systems

and to make certain that states enforce the

stan-dards According to the EPA more than 90 percent

of the tap water supplied by public systems meets

federal standards for safety

Over 80 compounds and toxic substances are

regulated in terms of maximum upper limits for

concentrations in drinking water The legal limits,

called maximum contaminant levels (MCLs), are

administered by individual states Included are

minerals like ARSENIC; nitrates; heavy metals like

cadmium; lead; mercury; solvents like benzene and

phenol; pesticides like Endrin, Diquat, Dalapon,

and Simazine; products of incomplete combustion

like BENZOPYRENE and DIOXIN Antimony, NICKEL,

pesticides like dinoseb (used on soybeans and other

crops), atrazine (a herbicide used on corn), and

halogenated hydrocarbons are among the most

commonly found compounds in water supplies

Halogenated hydrocarbons are quite stable in the

environment and can contaminate the

environ-ment for decades One class is called CHLORINATED

HYDROCARBONS As an example, trichloroethylene

(TCE) and its degradation products are important

contaminants of ground water TCE was used as a

degreasing agent Since TCE is volatile, drinking

water can be treated by air evaporation process (air

stripping) Other regulated volatile chlorinated

hydrocarbons include dichloromethane and

tri-halomethane, by-products of the reaction of

chlo-rine with organic materials in drinking water

Because they evaporate easily, they may pose a

haz-ard when taking a shower

Home Water Treatment

No single device removes all contaminants Water

purifiers remove bacteria while water filters

remove nonbacterial contaminants but not

bacte-ria The best systems can remove up to 99 percent

of the chlorine and over 70 percent of other

conta-minants Units should be certified by the nonprofit

National Sanitation Foundation in Ann Arbor,

Michigan Water softeners or water treatment units

to improve the taste or smell of drinking water may

be certified by the Water Quality Association

Activated carbon filtration units with high-quality carbon can absorb chlorine and organic com-pounds but are not very effective in removing min-erals like IRON, lead, or fluoride Carbon filters must

be replaced about once a month Some filters can become breeding grounds for harmful bacteria unless properly maintained The best filters are solid blocks of activated charcoal with a diversion valve,

so that unfiltered water can be used for dishes Fil-ters need to be changed regularly

Reverse osmosis filtration forces water through a porous membrane at high pressures Reverse osmo-sis effectively removes inorganic ions like fluoride and a few organic contaminants, but reverse osmo-sis also wastes about 75 percent of the water and the membranes need to be replaced periodically Water softener units incorporate ion exchang-ers, which will remove iron, calcium, and other minerals of hard water and replace them with sodium Cooking with or drinking softened water is not advised due to the high sodium content Home distillation removes minerals and non-volatile organic compounds (those that do not evaporate), but the process is slow and costly because of heating costs

BOTTLED WATER is another alternative to tap water Bottled water is classified as a food product

by the U.S FDA, but this is no guarantee that it will

be safe or wholesome Producers are not required

to list the source of the water Most bottled water comes from wells or springs, but it may be munici-pal water Bottled water is less regulated than tap water, and spot checks have turned up traces of organic solvents, nitrates, and toxic heavy metals— and the sodium content can be high Tests of domestic bottled water have seldom turned up harmful levels of chemical contaminants, though sampled bottled water may only meet, not exceed, health department standards Bottled water is dis-infected by ozone, not chlorine treatment, and it is not fluoridated

Recommendations

To minimize chemical contaminants, use cold tap water for drinking because hot water tends to dis-solve metals from pipes Let the cold tap run until the water gets cold This water contains the least amount of contaminants leached from metal pipes

water 665

Water suppliers must provide the results of

annual water tests for regulated contaminants to

their customers

Though bottled water generally appears to be

good quality it may be prudent to request the latest

chemical analysis from the bottler, or have a

sam-ple tested independently To minimize the RISK of

exposure to contaminants, vary your water supply

from time to time

“Over 50 Million Drink Water Failing Health Standards,”

Nutrition Week 25, no 22 (June 9, 1995): 6.

watermelon (Citrullus vulgaris) The fruit of an

annual vine belonging to the squash and melon

family This round or cylindrical fruit can weigh

from 5 lb to 85 lb (2.3 to 38.3 kg) There are more

than 50 varieties, including seedless watermelons

The juicy flesh may be red, pink, orange, yellow, or

white Watermelons originated in Africa and have

been cultivated since ancient times in the

Mediter-ranean region, Egypt, and India Watermelons are

now cultivated throughout the world from tropical

to temperate regions Florida, Texas, and California

lead domestic production The fruit is eaten fresh

Watermelon is a good source of vitamin C; it

con-tains about 90 percent water and 8 percent sugar

The nutrient content of a slice of raw watermelon

that is 1 in thick and 10 in in diameter, without

refuse (480 g), is: 152 calories; protein, 3 g;

carbo-hydrate, 34.6 g; fiber, 2.4 g; fat, 2.1 g; iron, 0.82 g;

potassium, 560 mg; vitamin A, 176 retinol

equiva-lents; vitamin C, 47 mg; thiamin, 0.3 mg;

riboflavin, 0.1 mg; niacin, 0.96 mg

water pills See DIURETICS

water-soluble vitamins See VITAMIN

wax A family of water resistant compounds that

are solids or thick (viscous) liquids Waxes consist

of long chains of carbon atoms, and are obtained

from petroleum products (paraffin), fat, beeswax,

synthetic resins, and palm oil derivatives Only

insect-based waxes and vegetable waxes are

applied on domestic produce, although imported

produce may contain animal-based waxes

Com-mercially, waxes are generally sprayed as a thin film on produce to prevent loss of moisture and to enhance consumer appeal after polishing Natu-rally occurring protective waxes on fruits and veg-etables are generally washed off when the produce

is harvested Producers commonly wax APPLES,

AVOCADOS, BEETS, green PEPPERS, CUCUMBERS, EGG

-PLANT, MELONS, certain nuts, PAPAYAS, PEACHES,

PINEAPPLES, POTATOES, SQUASH, TANGERINES, TOMA

-TOES, SWEET POTATOES, and WATERMELONS Waxes are classified as PRESERVATIVES, and the U.S FDA regulations specify that waxes must be identified where the consumer purchases the pro-duce The type of wax applied is not specified, a concern for those following dietary laws or making dietary choices such as KOSHER, Muslim, Seventh-day Adventist, or vegetarian diets

FUNGICIDESare generally applied before waxing

or are mixed with waxes before application, and waxed produce cannot be washed free of fungi-cides Benomyl, thiabendazole, phenol, captan, folpet, dicloran, and others are permitted to be used with waxes The U.S National Academy of Sciences estimates that 90 percent of fungicides are potential cancer-causing agents (carcinogens) Specifically, benomyl, captan, and folpet increase the risk of cancer (See also DELANEY CLAUSE; FOOD ADDITIVES; ORGANIC FOODS; PESTICIDES; PRODUCE WASH.)

weight management Generally, programs de-signed to assist individuals to lose weight or to maintain a desired body weight Americans who diet to lose weight frequently participate in weight management programs for many reasons Statistics show that meeting external expectations motivates most dieters Current American images of attrac-tiveness and success place a premium on being slender, especially for women

A second motivation to manage weight is an awareness of the ramifications of being excessively overweight OBESITY, defined as having a BODY MASS INDEXof 25 or higher, carries increased risks for dia-betes, HYPERTENSION, and CARDIOVASCULAR DISEASE Certain people tend to gain excess fat on their upper body, and upper body fat increases the waist

to hip ratio, which correlates with a greater risk of heart disease

666 watermelon

Strategies for Weight Loss

Short-term weight loss readily can be attained by

extreme measures: a drastic reduction in caloric

intake (semi-starvation); CRASH DIETING;

unbal-anced diets emphasizing high fat and high protein

with little or no CARBOHYDRATE However, most of

this lost weight represents WATERand muscle

pro-tein loss rather than fat loss Without a

commit-ment to changing long-term behavior, pounds lost

will be rapidly regained; frequently lost muscle is

replaced by fat at the termination of the weight loss

program Several popular, doctor-supervised, very

low-calorie programs are available There is little

published data on the success rates of most weight

management programs The limited information

available suggests that only 2 percent to 10 percent

of people who have enrolled in such programs

suc-cessfully keep off lost pounds for a year or more

These strategies can lead to weight losses of several

pounds per week and often employ liquid protein

meal replacements Current liquid formula diets

are much improved over 1970s versions Regular

food allotments plus three meal replacements can

bring the total calories up to 1,200 per day, and

with supervision they are often safe for several

weeks A major disadvantage: They often reinforce

the unhealthy pattern of eating lightly at breakfast

and lunch, and eating heavily at dinner or later

Under starvation or semi-starvation conditions,

usually less than 1,200 calories per day, the body’s

metabolism compensates for decreased caloric

intake by gearing down the rate at which calories

are burned In other words the BASAL METABOLIC

RATE declines as a protective adaptation

Further-more, the body preferentially breaks down protein

in the early stages of semi-starvation to meet

energy requirements; paradoxically, the body can

therefore become proportionately fatter during this

period Programs that incorporate medications to

curb CRAVING as well as increased exercise and

restricted caloric intake have been recommended

for obese people

Recommendations for Weight Management

People who have lost weight permanently and have

maintained a desired weight for a number of years

share certain characteristics that permit several

gen-eralizations for managing weight successfully

Committing to Exercising for Life Daily exer-cises can temporarily increase the basal metabolic rate and thus increase the efficiency of burning calories, even when calories are restricted Even a daily half-hour of vigorous walking will help main-tain weight Regular exercise is often sufficient to lose a small amount of weight and to become leaner Moderate exercise is more effective for weight management because it preferentially burns fat, and intense exercise burns carbohydrate (glycogen), which is easily replenished

Committing to Changing Eating Habits High-calorie, high-fat foods make up a large percentage

of the American diet Fat provides more than twice

as many calories per gram as carbohydrate or pro-tein, and fat calories are more readily converted to body fat Eating less fat will help bring about weight loss High dietary fat correlates with increased risk of disease; generally, dietary guide-lines call for consuming less saturated fat while increasing fresh fruits and vegetables, whole grains, and legumes Foods containing high levels of refined carbohydrate, like sugar, white flour, and fat, provide few other nutrients People relying on such foods need to select extra nutrient-rich foods

to make up for this deficiency, not a usual pattern

in the United States A combination of exercise and improved food selection is often adequate to lose

10 to 20 pounds a year without dieting

Dieting and Exercising Combined To lose up to

50 pounds, dieting combined with exercise is rec-ommended Patients should:

• Lose weight gradually, no more than a pound per week Conditions that promote rapid weight loss cause the body’s METABOLISM to switch to favor loss of muscle protein and water and, less rapidly, fat Severe caloric restriction reduces thyroid gland activity, slowing the metabolism and slowing fat loss

• Consume at least 1,200 calories daily with ade-quate intake of high-quality protein, vitamins, and minerals to meet daily needs in order to accomplish gradual weight loss Generally 45 to

60 g of FISH, POULTRY, lean MEAT, soy protein, or other complete protein will meet daily require-ments of all essential amino acids This step will assure an adequate supply of all essential amino

weight management 667

acids and will help prevent loss of muscle Diets

supplying less than 1,500 calories per day

require supplementation—for example, with

calcium—to achieve adequate intake VITAMIN C,

the B COMPLEX, and TRACE MINERALS are known

to help metabolize fat, and adequate intakes are

important

• Eat adequate FIBER: Both soluble fiber, as found

in fresh FRUITS, VEGETABLES, LEGUMES, and

cer-tain grains, and insoluble fiber, as found in

whole grains and bran Fiber contributes to

nor-mal digestion, maintenance of the digestive

tract, and a feeling of satiety

• Drink plenty of water The kidneys require

water to excrete metabolic wastes and fat

break-down products

Seeking Out Emotional Support Overeating

usually is symptomatic of deeper emotional issues

Until these are dealt with, long-term changes in

eat-ing behavior are difficult to achieve When people

substitute eating for self-acceptance or for avoiding

emotional pain, weight management becomes

increasingly difficult Overeaters Anonymous and

other support groups can help nurture self-esteem

and self-forgiveness (See also ANOREXIA NERVOSA;

BULIMIA NERVOSA; DIETARY GUIDELINES FOR AMERI

-CANS; DIETING; EATING DISORDERS.)

Gibbs, W W “Gaining on Fat,” Scientific American 275, no.

2 (1996): 88–94.

weights and measures See MEASURES

Wernicke’s disease (Wernicke-Korsakoff

syn-drome) A disorder of the NERVOUS SYSTEMusually

associated with a deficiency of the B vitamin, THI

-AMIN Typical symptoms include: poor balance and

uncoordinated walk, double vision, confusion,

delusion, and psychosis It can occur in chronic

ALCOHOLISM, BERIBERI, and STARVATION Some

alco-holics apparently possess enzymes that require

higher than normal levels of thiamin for energy

production from carbohydrate When the diet is

depleted in B vitamins and the need for B vitamins

increases, these individuals are more prone to

thi-amin deficiency symptoms Wernicke’s disease

rep-resents a medical emergency Massive doses of

thiamin are used therapeutically (See also MALNU

-TRITION; NEUROPATHY; PERIPHERAL.)

wheat A cereal GRAINthat serves as a staple for one-third of the world’s population Wheat accounts for 40 percent to 60 percent of the calorie and protein intake in many developing countries Wheat is related to other true grains including RICE,

CORN, BARLEY, and RYE Wheat apparently devel-oped from a wild grass in southwestern Asia, and it was cultivated as early as 6000 B.C in the regions

of China, Egypt, and Iraq The United States, south-eastern European nations, India, Canada, and Aus-tralia rank among the leading wheat-producing countries In the United States, wheat ranks second

to corn in terms of total grain production and is still the most important cereal grain for human con-sumption The general trend in grain consumption since the early 1900s has been a gradual decline as processed sugar and fat have become more promi-nent carbohydrates

During the 1960s, new high-yield strains of wheat and rice were developed and cultivated in the Philip-pines, Mexico, India, and Pakistan These advances, together with increased use of pesticides and irriga-tion, ushered in the GREEN REVOLUTION, which dra-matically increased grain production Despite the Green Revolution, domestic food production remains critical in many regions of the world Efforts continue to develop new strains of wheat In the past, development of new wheat strains required up to 10 years Now biotechnology offers new techniques for screening different strains and for breeding wheat A new wheat strain

is likely to be profitable for only an estimated 10 years before it is improved upon or becomes sus-ceptible to pests and disease Efforts are being directed toward breeding pesticide-resistant strains Nonetheless, food production alone cannot eradi-cate hunger in countries disrupted by civil strife, breakdown of government services, drought, poverty, illiteracy, and high birth rates

Types of Wheat

Thousands of varieties of wheat exist today; about

100 varieties are cultivated in the United States Wheat varieties fall into two broad categories: win-ter wheat and spring wheat Winwin-ter wheat is planted

668 weights and measures

in the fall and harvested the following summer in

the midwestern United States Spring wheat is

planted in the spring in regions where winters are

severe and harvested later in the summer Most

bread is made from hard, red winter wheat grown in

the United States As an example, durum wheat is

grown mainly for PASTA, like spaghetti and noodles

Hard wheats contain a higher protein content than

spring wheat Soft, white winter wheat is best suited

for pastries and Asian noodles

Wheat Products

Wheat berries are kernels after the chaff (husk) has

been removed by threshing The wheat kernel has

a tough outer layer with FIBER(BRAN); a soft, oily,

nutrient-rich section (germ); and a starchy

endosperm or inner core that represents about 80

percent of the kernel The endosperm is the source

of wheat flour

Wheat germ represents 2.5 percent of the

ker-nel It contains many nutrients, including essential

fatty acids and high-quality protein Wheat germ

can be used to supplement cereals, breads, cookies,

and hot dishes Because wheat germ can become

rancid, it should be refrigerated after opening the

container or frozen for long-term storage

The kernel is surrounded with a tough outer

coating called bran Milling or grinding wheat

ker-nels separates the starchy endosperm from the germ

and bran to produce flour Stone ground flour is

thought to be more nutritious because the flour is

not heated as much as it is in conventional milling

Different types of wheat yield flour with different

properties For example, bakery flour with a higher

protein concentration creates doughs strong enough

to permit extensive mechanical kneading

Wheat flour contains a protein fraction called

GLUTEN, consisting of GLIADEN and glutenin When

mixed with water they form an elastic dough that

traps the carbon dioxide released by LEAVENING

AGENTS This accounts for the unique leavening

properties of wheat doughs The use of leavening

agents is credited to the Egyptians who introduced

yeast Beating or kneading dough traps air bubbles

in the mixture to give baked goods a lighter

tex-ture Starch yields glucose, which is broken down

by the yeast enzymes to carbon dioxide Bubbles of

carbon dioxide are trapped in elastic doughs

Alter-natively, BAKING POWDERcan be used as a leavening agent; it contains chemicals that yield carbon diox-ide upon mixing and heating the dough

White bleached flour accounts for more than 95 percent of the wheat flour used in the United States In terms of nutrients, the annual consump-tion of 120 lb of refined wheat products per year is comparable to consuming 30 lb of whole wheat plus 90 lb of pure starch White flour is aged to increase its elasticity as a dough, using several oxi-dizing agents to modify gluten It may contain phosphate and other additives to shorten kneading time All-purpose flour was developed in the 1960s for greater convenience in home cooking The flour does not form clumps readily, it is dust free, and it disperses in cold water Special flours have also been developed for cakes, pastries, Italian and French breads, and rolls The food label will indi-cate whether the flour has been bleached

REPRESENTATIVE NUTRIENT CONTENTS OF WHEAT Nutrient Whole Wheat White Flour*

Energy, calories 300 355

Linoleic acid 1.5 g 0.75 g

Vitamin B6 0.30 mg 0.05 mg

Folic acid 0.04 mg 0.01 mg Vitamin K 0.017 mg 0.004 mg

Molybdenum 0.05 mg 0.025 mg

Pantothenic acid 1.0 mg 0.5 mg

Riboflavin 0.12 mg 0.04 (0.4) mg

* Based on 60 percent to 72 percent extraction white flour, per 100 g (13 percent moisture basis) Values in parentheses are after U.S enrichment and are valid only for iron, niacin, riboflavin, and thi-amin Amounts are representative of U.S samples, which may vary widely in composition especially for minerals.

wheat 669

Whole wheat flour represents 95 percent of the

whole kernel contents It provides all common

nu-trients except VITAMIN A, VITAMIN B12, VITAMIN C,

and IODINE Whole wheat also contains trace

min-erals like tin and nickel for which there is no

estab-lished role in the body The amounts of nutrients

vary according to the variety of wheat and the soil

conditions where it was grown Whole wheat flour

is less stable than bleached white flour because it

contains wheat germ oils and can become rancid

when stored Whole wheat flour should be used

soon after purchase and refrigerated to preserve

freshness

White flour represents a refined or purified

car-bohydrate with lesser amounts of key nutrients

than whole wheat flour The production of white

flour requires about two dozen different steps that

remove or destroy substantial amounts of nutrients

found in whole wheat White flour retains starch

and about 70 percent of the protein, but losses of

other nutrients average 70 percent to 80 percent

In order to partially remedy this deficiency, an

enrichment program increases the levels of IRON,

THIAMIN, and NIACINto those approximating whole

wheat RIBOFLAVINis increased threefold; CALCIUMis

often added Canada and Britain have similar

en-richment programs Other nutrients—including

FOLIC ACID, VITAMIN B6, VITAMIN E, BIOTIN, CHROM

-IUM, COPPER, MAGNESIUM, MANGANESE, ZINC, and

fiber—are not added back All white flour

pro-duced in the United States is enriched, as are about

90 percent of commercial baked goods prepared

from white flour The accompanying table

com-pares the nutrient contents of whole wheat,

nonenriched white flour and enriched flour (See

also BREAKFAST CEREAL.)

whey protein High quality, nutritious dairy

pro-tein found in milk that is a complete propro-tein

con-taining all the essential amino acids required by the

body Proponents of whey protein take it as a

sup-plement to boost the immune system; build strong,

lean muscles; and lower elevated cholesterol and

high blood pressure It is also being researched as a

possible preventive treatment for cancer in

labora-tory animals

When cheese is produced, liquid whey separates

from the curd (casein); whey proteins are then

sep-arated from the liquid whey and purified to various concentrations Whey protein is not a single pro-tein but includes a number of individual propro-tein components, many of which are commercially available in isolated form Individual components

in whey protein include beta-lactoglobulin, glyco-macropeptide, alpha-lactalbumin, lactoferrin, immunoglobulins, lactoperoxidase, bovine serum albumin, and lysozyme The composition of specific whey protein products varies based on several fac-tors including source of the milk, method of pro-duction, type of cheese being produced, and individual manufacturer specifications

Groziak S M., and Miller G D “Natural Bioactive Sub-stances in Milk and Colostrum: Effects on the Arterial

Blood Pressure System,” British Journal of Nutrition

Suppl 84, no 1 (2000): S119–S125.

Lemon, W R “Effects of Exercise on Dietary Protein

Requirements,” International Journal of Sport Nutrition and Exercise Metabolism 8, no 4: 426–447.

white blood cells See LEUKOCYTES

WIC (Supplemental Food Program for Women, Infants, Children) A federal program initiated in

1972 to improve pregnant women’s health and the health of their children by providing them with a good diet Since 1972 WIC has assisted state agen-cies in giving food to impoverished women and children Due to sharp increases in food prices and

a scarcity of funding, thousands of recipients in many states were dropped from assistance pro-grams in 1990, when a House Select Committee on Hunger found at least 50,000 people were dropped

in 27 states In 2002 the program had more than 7 million participants and cost $4.39 billion

The original philosophy was preventative, rather than therapeutic Full disclosure of a com-prehensive study of its efficacy revealed that between 1972 and 1980 WIC reduced infant mor-tality There is a possibility that WIC food supple-ments might have increased skull growth and mental development in poor children Other stud-ies since 1980 have shown that adequate prenatal nutrition helps prevent low birth weight babies and reduces long-term medical expenses that would otherwise be publicly financed The U.S General Accounting Office reported that the WIC funding

670 whey protein

of $2.6 billion for 1992 paid for itself in a year due

to reduced health costs

Each state WIC program authorizes food that

will be redeemable with WIC checks WIC clients

are provided with coupons to obtain fresh fruit and

vegetables, in addition to milk, eggs, cheese, cereal,

juice, and infant formula WIC actively promotes

breast-feeding, but the program supplies formula

for infants up to one year of age For any new food

to be authorized, in general the food manufacturer

must submit a request for authorization, the

prod-uct must meet state requirements in packaging, the

food must be available statewide, and the product

must be consistent with the WIC program

promo-tion of healthy, economic food purchasing

prac-tices (See also PREGNANCY AND NUTRITIONAL

REQUIREMENTS; SCHOOL LUNCH PROGRAM.)

Auruch, S., and A P Cackley “Savings Achieved by

Giv-ing WIC Benefits to Women Prenatally,” Public Health

Report 110, no 7 (January–February 1995): 27–34.

wild rice (Zizania aquatica; Indian rice) The only

native cereal GRAINdomesticated in North America

Wild RICEgrows in Minnesota and Wisconsin in the

United States, and in Manitoba, Canada

Harvest-ing has traditionally been performed by hand

because kernels of wild rice fall off the stalks as

they ripen Improved varieties can be harvested

mechanically like wheat and barley, and 90 percent

of the annual wild rice crop in Minnesota is grown

in paddies and harvested by combines

Wild rice is cooked like regular rice: The larger

the kernel and the darker its color, the longer the

required cooking time Its protein content is higher

than typical grains The nutrient content of a

half-cup (100 g) of cooked wild rice is: 92 calories;

pro-tein, 3.6 g; carbohydrate, 11 g; fiber, 2.6 g; fat, 0.2

g; iron, 1.1 mg; thiamin, 0.11 mg; riboflavin, 0.16

mg; niacin, 1.6 mg

wine The fermented juice of grapes When other

fruit juices are fermented, the name of the fruit is

given, as in blackberry wine or plum wine

Archae-ological evidence indicates that wine was prepared

between 6000 and 5000 B.C in the Middle East

Wine making was described in Egypt by 2500 B.C

American grapes, Vitus labrusca, are pest-resistant,

and European varieties, V vinifera, are grafted onto

American root stocks The Concord grape, devel-oped in 1852 in Massachusetts, yields a full-bodied wine Grapes grown in cooler regions of California, Oregon, and Washington yield grapes with the higher acid content and the low to medium alcohol content of typical table wines Dessert wines require grapes with a high sugar content

To prepare wine, grapes are crushed and treated with sulfur dioxide to kill wild yeasts on the grapes Additional dextrose (glucose) may be added if the sugar content is inadequate and the mixture is inoculated with a culture of a pure yeast strain Fermentation is then carried out in temperature-controlled vats Red wines are produced by fer-menting grape pulp with skins; white wines are fermented with only minimal contact with skin After fermentation, the wine is clarified by adding gelatin or egg white protein to coagulate suspended materials After settling, the mixture is filtered Most wine is mellowed by aging from several months to several years to remove bitter or harsh flavors Among the many chemical changes that occur, acidic substances slowly form fragrant com-pounds called esters Wooden barrels have tradi-tionally been used for aging because they absorb astringent substances and contribute their own subtle flavors Wine is filtered and usually treated with sulfur dioxide to prevent spoilage Aging con-tinues after the wine is bottled

Drinking red wine may lower LOW-DENSITY LIPOPROTEINS(LDL), the less desirable form of blood cholesterol During fermentation of grape skins, a compound called resveratrol leaches out of the skin Resveratrol is responsible in part for the cho-lesterol-lowering effect of red wine in experimen-tal animals It occurs naturally in grapes and offers natural protection against fungus Heat treatment

of Concord grapes, used to prepare red grape juice, releases resveratrol also The cholesterol lowering effect of alcoholic beverages declines rapidly after more than one or two drinks are consumed daily Alcohol is inappropriate for people with a history

of ALCOHOLISM, HYPERTENSION, liver disease, smok-ing, DIABETES, OBESITY, or PEPTIC ULCERS

Red wine contains substantial amounts of IRON However, the amounts of most nutrients found in grapes are quite low Red wine also contains a

mix-wine 671