W 662 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 DIGESTION refers 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 temperatures 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 OXYGEN and the release of CARBON DIOXIDE in 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 DIARRHEA and 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. ALCOHOL increases 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 CADMIUM and LEAD from 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 FLUORIDE to 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; NITRATES from 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. FUNGICIDES are 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 INDEX of 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 WATER and 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 SYSTEM usually 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 GRAIN that 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. Winter 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 POWDER can 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 Crude fiber 2.3 g 0.3 g Linoleic acid 1.5 g 0.75 g Protein 13 g 11 g Biotin 0.010 mg 0.002 mg Vitamin B 6 0.30 mg 0.05 mg Calcium 35 mg 17 mg Choline 170 mg 80 mg Chromium 0.06 mg 0.02 mg Copper 0.5 mg 0.1 mg Vitamin E 1.5 IU 0.03 IU Fluoride 0.1 mg 0.06 mg Folic acid 0.04 mg 0.01 mg Vitamin K 0.017 mg 0.004 mg Iron 3.0 mg 0.6 (3.0) mg Magnesium 140 mg 25 mg Manganese 3 mg 0.3 mg Molybdenum 0.05 mg 0.025 mg Niacin 5 mg 1.0 (5.3) mg Pantothenic acid 1.0 mg 0.5 mg Phosphorus 350 mg 90 mg Potassium 400 mg 90 mg Riboflavin 0.12 mg 0.04 (0.4) mg Selenium 0.04 mg 0.03 mg Thiamin 0.5 mg 0.09 (0.64) mg Zinc 3 mg 0.6 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 B 12 , 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 NIACIN to those approximating whole wheat. RIBOFLAVIN is increased threefold; CALCIUM is often added. Canada and Britain have similar en- richment programs. Other nutrients—including FOLIC ACID , VITAMIN B 6 , 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 protein 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 protein 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 GRAIN domesticated in North America. Wild RICE grows 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 [...]...672 World Health Organization ture of FLAVONOIDS, complex plant substances that can function as ANTIOXIDANTS Test-tube experiments demonstrated that red wine flavonoids can protect LDL-cholesterol, the most prevalent form of cholesterol in blood, from oxidation Whether this occurs in the body remains unclear The so-called “French Paradox” describes the phenomenon of those who consume wine, together with... animal fat and meat, yet have lower rates of heart disease than those who do not consume wine Moderate consumption of alcoholic beverages, regardless of the source, raise HDL cholesterol, the beneficial form In addition, the MEDITERRANEAN DIET entails a higher consumption of fruits, legumes, and vegetables than in the typical U.S diet These factors also decrease the risk of heart disease Wine like all... disease Wine like all alcoholic beverages has a low nutrient density and displaces more nutrient-rich sources of calories when consumed in excess An estimated 4 percent of domestic and imported wines contain 0.3 parts per million of LEAD The lead cap can leach a lead residue that dissolves as the wine is poured The nutrient contents of 3.5 fl oz of wine is: 74 calories; protein, 0.2 g; carbohydrate,... finance WHO with annual contributions on the basis of their relative ability to pay WHO works in conjunction with the FOOD AND AGRICULTURAL ORGANIZATION to focus on three areas: 1 International sanitary regulations WHO provides current information regarding such matters as control of drug addicts, vaccination practices, advances in nutrition, cancer research, and hazards of nuclear radiation It standardizes... mg; and about 10 ml of pure ethanol (See also BEER; CARDIOVASCULAR DISEASE.) Vinson, Joe L., and Barbara A Hontz “Phenol Antioxidant Index: Comparative Antioxidant Effectiveness of Red and White Wines,” Journal of Agriculture and Food Chemistry 43 (1995): 401–403 World Health Organization (WHO) A specialized agency of the United Nations founded in 1948 to promote international cooperation to improve health. .. 2 Support of member health programs Upon request, WHO provides technical advice, assists in setting up health centers, and aids in training of medical personnel 3 Control of epidemics WHO promotes nationwide vaccination programs, clinics for disease prevention, clean water supplies, and modern sanitation systems, health education, antibiotic use and insecticide application It has helped wage campaigns... prevention, clean water supplies, and modern sanitation systems, health education, antibiotic use and insecticide application It has helped wage campaigns against tuberculosis, smallpox, malaria, and, more recently, the AIDS epidemic (See also GREEN REVOLUTION.) . States. Wheat varieties fall into two broad categories: win- ter wheat and spring wheat. Winter wheat is planted 668 weights and measures in the fall and harvested the following summer in the midwestern. 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. 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