The Encyclopedia Of Nutrition And Good Health - D ppsx

D 183 Daily Reference Values (DRVs) A set of dietary reference values established for nutrients for which no standards have previously existed. This includes FAT , SATURATED FAT , CHOLESTEROL, total CARBOHY- DRATE, PROTEIN, FIBER, and POTASSIUM. The DRVs for nutrients that produce energy, including fat, pro- tein, carbohydrate, and fiber, are based on a 2,000 CALORIE-a-day diet, unless listed otherwise for a 2,500 calorie diet. DRVs are calculated according to the following guidelines: • fat: 65 g, based on 30 percent of calories and sat- urated fat 20 g, based on 10 percent of calories • total carbohydrate: 300 g, based on 60 percent of calories • fiber: 25 g • protein: 50 g, based on 10 percent of calories. (This DRV for protein is for adults, except for pregnant women and nursing mothers, and chil- dren over the age of 4 years: The DRV for infants under 1 year is 14 g; for children between 1 and 4 years, 16 g; pregnant women, 60 g; and nurs- ing mothers, 65 g.) The DRVs for cholesterol, sodium, and potas- sium do not change with the calorie level because they do not yield energy: cholesterol: 300 mg sodium: 2,400 mg potassium: 3,500 mg Daily Values (DVs) A set of reference values designed to help consumers use food labels and assist them in planning a healthful diet. They appear on food labels and are comprised of two sets of nutrient reference values, the Daily Reference Values (DRVs) and the REFERENCE DAILY INTAKES (RDIs), as the basis for declaring the nutrient con- tent on a food label. Food labels now provide the amount of key nutrients as percentages of the DVs for each nutrient provided by one serving. DVs also provide a basis for thresholds in such descriptions as “high FIBER” or “low FAT.” Thus the term “high fiber” designates the fiber content in a serving of food providing 20 percent or more of the daily value for fiber, that is, 5 g or more. (See also DIETARY REFERENCE INTAKES.) dairy-free frozen desserts Ice cream substitutes that contain no MILK, cream, lactose (milk sugar), or cholesterol. TOFU and soy-milk frozen DESSERTS, frozen natural fruit confections, and even frozen rice desserts are now marketed. Usually these desserts lack CALCIUM, ARTIFICIAL FLAVORS, and arti- ficial colors, artificial stabilizers, preservatives, or the SATURATED FAT found in ice cream. On the other hand, frozen desserts generally contain large amounts of SUGAR or other sweeteners (FRUCTOSE CORN SYRUP , FRUCTOSE , or HONEY). Rice-based frozen desserts may contain maple syrup and fermented rice sweetener in addition to rice. Some brands of frozen desserts also contain VEG- ETABLE OIL. Tofu-based frozen desserts are usually high-calorie, high-fat foods. The calories in dairy- free desserts range from 128 to 247 per half-cup serving, and the fat or oil content of soy-derived desserts ranges from 6 to 14 g per serving, which is equivalent to ice cream. The amount of tofu varies from brand to brand and can be less than 10 per- cent of the ingredients. Fruit-based frozen desserts are prepared from whipped fruit juices and fruit purees. Some brands 184 dairy product contain only 9 percent fruit and fruit juices and may contain GUMS and PECTIN. Sugar or fat are not usually added, so fruit-based desserts are lower in fat and total calories than the tofu frozen desserts or ice cream. They generally provide 63 to 80 calo- ries per 4 oz. serving. Sorbet and fruit ices are al- most fat free, but they contain more sugar, including corn syrup. Sometimes people who are sensitive to cow’s milk react to foods labeled as “nondairy” or “pa- reve” (containing neither milk nor milk products). Traces of milk protein have been found in samples of frozen soy and rice desserts. This is an important consideration because an estimated 0.1 percent to 7.5 percent of children have adverse reactions to cow’s milk. (See also BALANCED DIET; PROCESSED FOOD ; SOYBEAN.) dairy product MILK or a food that is derived from it, including CHEESE, BUTTER, ICE CREAM, and YOGURT. Consuming dairy products, which are typ- ically high in CHOLESTEROL and SATURATED FAT, can increase the risk of CARDIOVASCULAR DISEASE and OBESITY. Dairy products make up about 15 percent to 20 percent of the American diet. Dairy products are generally good sources of calcium. dandelion (Taraxacum officinale) A green leafy plant that is a member of the sunflower family. Though gardeners have long confronted the dan- delion, dandelion greens are a nutritious food. Like other vegetable greens they are a rich source of IRON and CALCIUM. The BETA-CAROTENE content of dandelion greens exceeds that of CARROTS. Dande- lion greens also provide INULIN and PECTIN (soluble FIBER). Herbalists throughout the world use dande- lion to improve liver function and bile flow and for liver conditions such as hepatitis and jaundice. Dandelion also seems to act as a diuretic (increases water loss). Cultivated dandelion greens are more tender than wild greens. Wild dandelions may have been sprayed with a weed killer or fungicide, and plants growing next to roads with a high volume of traf- fic may have been contaminated by exhaust pollu- tion. A cup of chopped, cooked dandelion greens contains 35 calories; protein, 2.1 g; carbohydrate, 6.7 g; fiber, 1.4 g; calcium, 147 mg; iron, 1.89 mg; vitamin A, 1,229 retinol equivalents; and vitamin C, 19 mg. DASH diet (Dietary Approaches to Stop Hyperten- sion) A clinical study sponsored by the National Heart, Lung, and Blood Institute that tested the effects of diet on patients with elevated blood pres- sure ( HYPERTENSION). Participants ate a diet rich in FRUITS, VEGETABLES, and low-fat DAIRY PRODUCTS . They avoided red MEAT, sweets, and SUGAR-rich drinks. The DASH diet provides high amounts of FIBER, POTASSIUM (4,700 mg), CALCIUM (1,240 mg), and MAGNESIUM. Study participants exhibited low- ered blood pressure and LOW-DENSITY LIPOPROTEIN (LDL) cholesterol (the less desirable form of cho- lesterol). High blood pressure and cholesterol levels are major risk factors for CARDIOVASCULAR DISEASE. In a second clinical study, participants reduced their consumption of dietary SODIUM. Some partic- ipants followed the DASH diet while the remainder ate a typical American diet. Results showed that lowered sodium intake reduced blood pressure lev- els in both groups, but the group that followed the DASH diet had the most significant results. Svetkey, Laura P. et al. “Effects of Dietary Patterns on Blood Pressure: Subgroup Analysis of the Dietary Approaches to Stop Hypertension (DASH) Random- ized Clinical Trial,” Archives of Internal Medicine 159, no. 3 (February 8, 1999): 285–293. date (Phoenix dactylifera) The fruit of the date palm tree. Dates are actually a single-seeded berry. They have been cultivated in North Africa and regions of the Middle East since 2,000 B.C. or ear- lier. The Middle East still supplies most of the world’s date crop, although Arizona and California supply U.S. domestic needs. Unripened dates are green. When ripened, they are yellow or red with a thick, syrupy flesh. Dates are harvested, ripened, and dried before shipping. Dates are good sources of dietary FIBER and IRON; although, unlike most fruits, dates do not contain significant amounts of VITAMIN C. The most common variety of date pro- duced in the United States is the Deglet Noor, which is semisoft. Semisoft dates can be stored up to eight months if refrigerated. Dry dates contain little moisture and are often pasteurized to inhibit MOLD growth. Dates are a very sweet fruit, they can contain up to 70 percent SUGAR. Ten pitted dates provide 228 calories; protein, 1.6 g; carbohydrate, 61 g; fiber, 7.23 g; potassium, 540 mg; iron, 1 mg; niacin, 1.83 mg; thiamin, 0.07 mg; riboflavin, 0.08 mg. Most of the CARBOHYDRATE is in the form of sugar. DDT (dichloro-diphenyl-trichloroethane, chloro- phenothane) One of the first powerful, synthetic PESTICIDES to be used worldwide. DDT has been used against a wide range of insects, especially Japanese beetle and European cornborer, as well as louse, mosquito, bedbug, fly, flea, and cockroach. DDT is classified as a CHLORINATED HYDROCARBON,a type of compound that is neither easily degraded in the environment, nor readily broken down in the body. The first pesticides were designed to persist in the environment in order to control pests longer. This has had profound ramifications. First, the widespread use of DDT rapidly led to DDT-resistant insects. Second, DDT and other chlorinated hydrocarbons accumulate in the FOOD CHAIN because they are not readily biodegradable. Birds, including the American eagle, and fish suffer well- documented toxic effects from DDT, and in 1972 the United States banned DDT except for public health use (to control insects that can spread dis- ease) and for crop protection where no alternative pesticide was available. In spite of the ban on DDT, high levels were reported in fish caught off Califor- nia coastal waters nine years after its manufactur- ing was terminated. Individuals eating polluted fish have more DDT in their blood. DDT causes CANCER in mice, but the effects that chronic exposure to small doses have had on human health are unknown. Breast cancer rates in the United States have risen steadily, and an increased environmental exposure to pollutants has been implicated. A Kaiser Foundation Research Study of 57,000 women did not find a link between DDT exposure and increased risk of breast cancer. In the United States a woman’s breast milk can contain DDT at a level that is one-and-a-half times more concentrated than in the woman’s blood. For an average infant, this represents a daily intake of about 50 mcg of DDT—on a weight basis, equiv- alent to about 10 times the average adult intake. The long-term effects on childhood development of this exposure are unknown. (See also GREEN REVOLUTION .) Snedecker, Suzanne M. “Pesticides and Breast Cancer Risk: A Review of DDT, DDE, and Dieldrin,” Environ- mental Health Perspectives 109, suppl. 1 (March 2001): 35–47. decaffeinated beverages Drinks, especially COF- FEE , TEA, and SOFT DRINKS, from which most of the caffeine has been extracted. The process of decaf- feination causes a small loss in flavor and aroma. Decaffeinated coffee is not caffeine free; it contains low levels of caffeine, 1 to 5 mg per cup, compared to 100 to 150 mg for a cup of regular. This level may be enough to trigger cravings in those attempting to overcome caffeine addiction. Some producers extract caffeine from roasted ground cof- fee with organic solvents, either methylene chlo- ride or ethyl acetate. Following solvent extraction, the decaffeinated beans are steamed to remove residual solvent. The excess moisture is removed and the decaffeinated beans are roasted. Ethyl acetate seems to be a safe solvent for caffeine extraction, though concern was raised about the use of methylene chloride because it is a weak car- cinogen. The U.S. FDA has ruled that the trace amounts of these solvents present in some decaf- feinated coffee pose no health threat. To avoid organic solvents altogether, caffeine can be extracted with water, followed by charcoal filtration. In this process, beans are first steamed, then soaked in water for long periods to remove 97 percent of the caffeine. They are then dried and roasted to develop aroma and flavor. Tea can also be decaffeinated. Typically, solvent extraction either with ethylacetate or with carbon dioxide at high temperature and pressure can remove most of the caffeine from tea. Decaffeination affects the fla- vor of tea more than coffee. decalcification The removal of CALCIUM from BONES. A deficiency of calcium or inadequate VITA- MIN D required for calcium uptake, and an imbal- ance of certain HORMONES (parathyroid hormone decalcification 185 and calcitonin), can cause mineral loss from bone (dissolution). Calcium usage in the body and bone loss depend upon complex interactions. If calcium levels in the blood begin to decrease, the parathy- roid glands secrete parathyroid hormone, parathor- mone, which increases calcium levels by activating osteoclasts (cells that break down bone) while decreasing calcium excretion by the kidney and increasing calcium uptake by the intestine. Parathormone stimulates the kidneys to convert vitamin D to the hormone, CHOLECALCIFEROL. It is believed that a deficiency of the female sex hormone ESTROGEN after menopause causes osteo- clasts to be more sensitive to parathormone, result- ing in increased bone breakdown and elevated blood calcium levels. Elevated blood calcium in turn would decrease parathormone output, de- crease vitamin D activation and thus further in- crease excretion of calcium. Estrogen replacement therapy is ultimately aimed at maintaining bone mass in postmenopausal women. Calcium losses are influenced by the diet. High protein intake, high phosphate intake (from SOFT DRINKS ), and excessive sugar consumption increase calcium loss in the urine. Calcium is also lost when excessive dietary FIBER is ingested. MAGNESIUM, VIT - AMIN B 6 , FOLIC ACID, VITAMIN B 12 , BORON, and STRONTIUM have been shown to stabilize bone cal- cium and bone density. Boron seems to increase estrogen levels in postmenopausal women; it may also help activate vitamin D. (See also HORMONE; OSTEOMALACIA; OSTEOPOROSIS.) decoction The extraction of water-soluble mate- rials and flavors from meat and vegetables by boil- ing in water for varying times. BOUILLONS are prepared in this way. In botanical medicine, essences may be extracted from plant material by boiling in water. Decoction differs from an infu- sion, in which boiling water is poured on a plant material; extraction continues without further boil- ing. A common example of infusion is TEA steeped in hot water. Because the act of boiling is more vig- orous and occurs at a higher temperature, decoc- tion extracts more material than infusion. deficiency, subclinical The state of being mar- ginally nourished. In contrast with overt malnutri- tion, which causes identifiable diseases, mild or moderate nutrient deficiencies need not reveal obvious signs of illness. Nonetheless, subclinical deficiencies lead to lowered immunity and decreased resistance to viral, bacterial, and fungal infections; difficult pregnancies, low birth-weight infants, and delayed growth and development; learning problems; short-term memory loss; and a host of vague symptoms ranging from fatigue to depression. A marginal nutrient deficiency can lead to inad- equate reserve to meet emergencies. For example, a woman who diets, especially a teenage woman whose body is growing, may not have enough IRON reserves to support a pregnancy adequately. Sub- clinical malnutrition can have long-term conse- quences. Subclinical deficiencies can set the stage for DEGENERATIVE DISEASES that include CANCER, HEART DISEASE, high blood pressure, diabetes, OSTEOPOROSIS, ARTHRITIS, PERIODONTAL DISEASE, AUTOIMMUNE DISEASES, and SENILITY. For optimal health, the body needs more than minimum amounts of vitamins and minerals to prevent full-blown disease. However, the nutrient requirements for optimal health are unknown for most nutrients. The RECOMMENDED DIETARY AL- LOWANCES (RDAs) are standards designed to main- tain health for a healthy population and do not define the optimal amount for each of the nutrients for individuals. As a general guideline, an intake of a given nutrient that is consistently two-thirds of the RDA or less increases the risk of malnutrition. When several nutrients fall substantially below the RDA, there is a much greater risk of malnutrition and its consequences. Problem Nutrients Surveys in the United States and Canada indicate the most common nutrient deficiencies are: CAL- CIUM, IRON, MAGNESIUM, ZINC, VITAMIN A, VITAMIN C, VITAMIN B 6 , and FOLIC ACID, among certain groups. In developing countries, protein-calorie malnutri- tion is the major nutritional disorder, followed by vitamin A deficiency. In developed countries, the most obvious cause of subclinical nutrient defi- ciency is an inadequate diet. Reliance on highly processed foods can lead to inadequate intake of key nutrients beyond those used as food enrich- ment or fortification. 186 decoction Causes of Subclinical Deficiencies Historically, poverty, illiteracy, and malnutrition are intertwined. Infants and children in low- income families, pregnant teenagers, elderly per- sons, and institutionalized clients are most likely to be inadequately nourished in the United States. Nutritional deficiencies can occur even with an adequate diet. Inadequate stomach acid and DIGES- TIVE ENZYMES limit nutrient assimilation. A diseased or inflamed intestine will not be able to complete DIGESTION, nor will it absorb individual nutrients effectively, especially if transit through the gas- trointestinal tract is too rapid for efficient absorp- tion, as during diarrhea. Strategies to Correct Marginal Nutrition Even if the amount of each nutrient needed for optimal health were known for the average per- son, the amounts needed by individuals would still differ, due to the unique biochemical makeup of each individual. Variations in nutrient needs reflect different genetic compositions, overall health, diet histories, lifestyles, ages, and exercise patterns. Therefore, individualized nutrition counseling is a most effective strategy to over- come nutritional deficiencies. Nutrition counsel- ing relies on evaluating how well the body is stocked with nutrients and on dietary planning to correct nutritional imbalances. Optimally, the physician and nutritionist work as a team in evaluating results of diagnostic tests, compre- hensive physical examinations and medical his- tory, as well as assessment of nutrient intake, to work out an individualized program that meets the client’s needs, including patient education. (See also BIOCHEMICAL INDIVIDUALITY; DIETING; MALABSORPTION .) deficiency disease A disease state caused by inadequate nutrient uptake and assimilation. Mod- ern nutrition has its origins in the repeated demon- stration that severe diseases can be the result of severe, chronic nutrient shortages and are treatable with the appropriate VITAMINS and minerals. In this respect, the importance of vitamins to human nutrition was well established before 1940. Most outright nutrient deficiency diseases have vanished in the United States, though worldwide they are all too prevalent. It is worth noting that nutritional deficiencies can occur with maldigestion and MAL- ABSORPTION even if the diet supplies adequate amounts of vitamins and minerals. Foods must be digested and nutrients must be absorbed to be effective. Conditions related to severe vitamin deficiencies are listed below. • NIACIN deficiency causes PELLAGRA. • THIAMIN deficiency causes BERIBERI. • VITAMIN B 12 deficiency leads to PERNICIOUS ANE- MIA. • VITAMIN A deficiency promotes NIGHT BLINDNESS . • VITAMIN D deficiency causes RICKETS and bone disease. • VITAMIN B 6 , VITAMIN E, vitamin A, and FOLIC ACID deficiencies can cause ANEMIAS. • VITAMIN C deficiency causes SCURVY. The following conditions are related to mineral deficiencies: • CALCIUM deficiency leads to bone disease and bone malformation ( OSTEOPOROSIS, OSTEOMALA- CIA , RICKETS). • Zinc deficiency causes BIRTH DEFECTS. • IRON and COPPER deficiencies cause deficiency anemia. • IODINE deficiency causes GOITER. • ESSENTIAL FATTY ACID deficiencies cause skin con- ditions and can contribute to heart disease. Conditions Related to Protein-Energy Malnutrition An inadequate intake of protein and energy is the most important nutritional problem in developing nations. Protein and energy deficiencies cause STAR- VATION syndromes, KWASHIORKOR, and MARASMUS, as extremes. Children bear the brunt. The World Health Organization has suggested that close to 500 million people suffer from nutritional deficiencies. The effects of starvation and semi-starvation on children are profound: anemia, infections due to depressed immunity, chronic DIARRHEA, stunted growth, and failure to thrive. Growth retardation may be irreversible. (See also BALANCED DIET; DIETARY GUIDELINES FOR AMERICANS.) deficiency disease 187 degenerative diseases Diseases commonly asso- ciated with aging in Western, developed countries. They include CARDIOVASCULAR DISEASE (ATHERO- SCLEROSIS or clogged arteries; ARTERIOSCLEROSIS or hardening of the arteries, coronary heart disease, STROKE , HEART ATTACK ); OSTEOPOROSIS (brittle bones); SENILITY (dementia, ALZHEIMER’S DISEASE); adult diabetes; PERIODONTAL DISEASE; AUTOIMMUNE DISEASES (rheumatoid ARTHRITIS, SPRUE, insulin- dependent diabetes); and CANCER. Several of these diseases are now epidemics of industrialized na- tions. Cardiovascular disease, cancer, diabetes, and others are linked to OBESITY, itself a potential harm- ful condition characteristic of affluent societies. Although a history of inherited tendencies plays a role, degenerative diseases are not necessarily inevitable because lifestyle choices profoundly affect susceptibility to chronic diseases. Often many can be prevented, or at least reduced in their inten- sity, with a lifelong commitment to EXERCISE, wise food choices, emotional well-being, and avoiding exposure to harmful substances. Many degenerative diseases respond to nutri- tionally sound practices. Moderate CALORIE intake and WEIGHT MANAGEMENT help prevent obesity, diabetes, and hypertension, while adequate CAL - CIUM, trace minerals, VITAMIN D, and exercise help prevent later bone loss. Moderate SODIUM con- sumption lowers the risk of hypertension and related heart and kidney diseases, and adequate FIBER intake helps maintain the health of the digestive tract and lowers the risk of colon cancer. ANTIOXIDANTS found in fruits and vegetables, like VITAMIN C, VITAMIN E, BETA-CAROTENE, and CARO- TENOIDS may decrease the risk of some forms of cancer, cataracts, mental aging, and heart disease. Moderation is a key. Moderate sugar consumption lowers the risk of dental caries; moderate alcohol consumption helps prevent liver disease; and moderate fat consumption lowers the risk of obe- sity, heart disease, and some forms of cancer. (See also AGING.) deglutition The process of swallowing, especially foods. Deglutible refers to a substance that can be swallowed. In the first stage of swallowing, chew- ing pulverizes food and mixes it thoroughly with SALIVA. The tongue forces the BOLUS (wad) of food back into the mouth and into the upper part of the throat. In the involuntary or automatic stage of swallowing, the bolus moves into the ESOPHAGUS, the tube leading to the stomach. The bolus triggers nerve signals to the deglutition center in the brain stem. In turn, the brain signals the palate to close the nasal passage. Breathing is interrupted for about two seconds and the palate again reopens. PERISTALSIS , rhythmic contractions, conducts the bolus through the esophagus to the stomach. Gulping food can lead to swallowing an exces- sive amount of air, which in turn can cause an excessive air buildup in the stomach, which is one cause of heartburn. Chewing food thoroughly not only eases swallowing but also aids digestion because pulverized food is more easily broken down. Furthermore, up to 20 minutes may elapse before the stomach senses that food has entered the stomach itself and relays that signal to the brain. The brain responds by triggering the release of hormones that stimulate the release of stomach acid and digestive enzymes. (See also DIGESTIVE TRACT .) dehydrated food Refers to a wide range of dried foods. The removal of most of the water content of foods is an ancient form of preservation. Modern dehydration methods employ freeze-drying tech- nology to remove the water rapidly and to preserve nutrients and food quality. Microbial breakdown and many chemical reactions are minimized in dehydrated foods. However, light-induced reac- tions and lipid oxidation can still occur. Therefore, dehydrated foods are generally sealed both from air and from light, as well as from moisture. Freeze-drying works best with foods that can be frozen quickly and can be spread in thin layers. For example, soups, vegetables, and stews are quick-frozen at very low temperature, then sub- jected to a vacuum (reduced pressure). Under reduced pressure, ice evaporates (sublimes), leav- ing behind the powdery residue minus the weight of water. On the other hand, sliced fresh fruit, like pears, plums, apples, apricots, and other watery fruit, can be dried in an evaporator that blows warmed air over the food. Dates, figs, currants, and raisins are traditionally sun-dried. Modern production of 188 degenerative diseases dried vine fruit employs blown hot air over the fruit on racks. Dehydrated milk, powdered eggs, and cheeses are commercially dehydrated. They are first blown through a nozzle to create a mist of fine droplets, which is sprayed into a heated chamber for drying. Studies indicate such processes create oxidized forms of CHOLESTEROL, which promotes PLAQUE buildup in arteries in experimental animals. (See also ATHEROSCLEROSIS.) dehydration A condition resulting from exces- sive WATER loss. The importance of adequate water for health cannot be overemphasized. The body is a watery environment containing 60 percent water, and blood is 90 percent water. The internal environment of the cell, the cytoplasm, is primarily water. Water also functions in digestion and absorption. Water helps maintain the ELECTROLYTE balance, the balance of dissolved ions in body flu- ids. Water is the medium for acid-base balance, so that the appropriate pH can be maintained. Water helps the body dispose of wastes. The kidney requires water to filter wastes out of the blood, and the liver requires water to remove toxic materials and waste products. Water evaporation helps regu- late body temperature. During dehydration, the kidneys do not filter out wastes efficiently, and toxic products such as AMMONIA can accumulate in the blood. Extreme dehydration can lead to coma, and even death. COFFEE, TEA, BEER, and COLA SOFT DRINKS can increase water loss through increased urination. People with busy lifestyles often do not drink enough water. THIRST may not be a good indicator of how much water is needed because the sensa- tion of thirst lags behind real need. Consumption of eight to 10 glasses daily of water and other bever- ages will replace water lost through urine, sweat, and wastes. Food supplies the equivalent of about four glasses of water daily. Many situations can lead to dehydration. Dehy- dration can affect athletes (especially during pro- longed exertion in hot weather); individuals working in a hot environment; elderly people who gradually lose their sense of thirst; and institution- alized patients. Other situations causing dehydra- tion are prolonged vomiting or DIARRHEA; use of DIURETICS (water pills) that cause excessive urina- tion; and excessive sweating. (See also ANTIDIURETIC HORMONE ; EXERCISE.) dehydrocholesterol (7-dehydrocholecalciferol) A substance formed by the skin that can be con- verted to VITAMIN D. As the name implies, dehy- drocholesterol is closely related to its parent compound, CHOLESTEROL. The skin and other tis- sues convert cholesterol to dehydrocholesterol. Exposure to ultraviolet light in sunlight converts this cholesterol derivative into vitamin D. In north- ern latitudes (Scandinavia, Canada, northern United States) winter skin exposure to sunlight may be inadequate for vitamin D formation. Insti- tutionalized patients who are not exposed to sun- light and who do not drink vitamin D-fortified milk are also prone to the effects of vitamin D defi- ciency because of inadequate formation of vitamin D from dehydrocholesterol. (See also CALCIUM; MALNUTRITION.) Delaney Clause An amendment to the Federal Food, Drug and Cosmetic Act banning the addition of CANCER-causing additives to processed food, cos- metics, and drugs. This legislation reflected the belief that there is no safe limit of exposure to a cancer-causing material ( CARCINOGEN). Contro- versy has surrounded the Delaney Clause since it was enacted in 1958. In the 1980s reinterpretation of the existing law directed the U.S. FDA to permit the low-level use of known carcinogens. The Food Quality Protection Act of 1996 supersedes the Delaney Clause and it amends the Federal Insecticide, Fungicide, and Rotenticide Act by establishing a single health- based standard for PESTICIDE residues in all foods. The new safety standard is defined as “a reasonable certainty that no harm will result from aggregate exposure to the pesticide chemical residues.” This act will allow the use of additives that present a negligible risk. The EPA will have authority to require chemical manufacturers to disclose infor- mation about their pesticides. All existing toler- ances for pesticides will be reviewed within 10 years. Provisions to ensure the safety of children are included. When the evidence for safety is ques- tionable, then the allowable levels will be lowered Delaney Clause 189 to permit up to 10-fold more protection for chil- dren. The act also requires distribution of health information about pesticides in foods by food stores nationwide. Only a fraction of chemicals cause cancer. Iden- tifying the risks of cancer due to new additives and chemicals, as well as to food additives introduced before the legislation in the 1960s, are major goals of medical research. A fundamental issue lies in the estimated number of cancer-related deaths that are tolerable when balanced against the benefits of using a given additive. An additional complication is a result of modern technology. Chemical analyt- ical techniques are now ultrasensitive so that car- cinogens at extremely small concentrations, a few molecules in a billion or less, are routinely mea- sured. The consequences of exposure to such minute amounts of carcinogens, pollutants, and possible additive effects, are areas of active research. (See also EPIDEMIOLOGY; CHEMICALS.) Degnan, Frederick H., and Gary W. Flamm. “Living With and Reforming the Delaney Clause,” Food and Drug Law Journal 50 (1995): 235–256. dementia A permanent mental deterioration characterized by impaired judgment, memory loss, orientation problems, poor intellectual functioning, and changeable emotional response. General men- tal deterioration often occurs after the age of 70 with a gradual onset. Dementia occurs more often in women than in men. Typically, dementia brings short-term memory lapses, loss of interest in life, fitful sleep, mood swings, and confusion. It can progress to tantrums, paranoia, severe depression, and refusal to eat. The patient may become incon- tinent and unable to feed herself. Dementia may be caused by decreased blood supply to the brain, hardening of the arteries (cere- bral ARTERIOSCLEROSIS), high blood pressure, and nutrient deficiencies, including severe deficiencies of VITAMIN B 12 and NIACIN. Certain illnesses can create apparent dementia: heavy metal poisoning (such as lead poisoning); alcoholism; high fever due to infections; disorders of the liver and kidney; hormonal imbalances. Many common medications can produce apa- thy, weakness, depression, and mental confu- sion; this is an increasing problem among the elderly, who often take multiple medications. (See also AGING; AIDS; ALZHEIMER’S DISEASE; PELLAGRA; SENILITY.) denatured protein A PROTEIN that has lost its bio- logical function or activity. Typically, ENZYMES become inactive and no longer serve as catalysts. Proteins are fragile molecules; their biological func- tion depends upon the maintenance of a single shape or conformation, which can be altered by a wide variety of agents, including heat; extreme acid or alkaline conditions; foaming; oxidation; and removal of ions from solution. Organic solvents and detergents are also denaturing agents. BLANCH- ING vegetables denatures enzymes that cause changes in texture, color, and flavor of food. Cook- ing protein-rich foods like MEAT, EGGS, and legumes denatures the protein, making it more accessible to DIGESTIVE ENZYMES and speeding DIGESTION. Stom- ach acid (hydrochloric acid) also serves as a protein denaturant, significantly increasing digestion. (See also COAGULATED PROTEIN.) dental caries See TEETH. dental fluoridosis A light brown mottling of tooth enamel due to excessive FLUORIDE consump- tion during tooth maturation and before the tooth has erupted from the gum. The mottling of teeth is not considered a health risk. Continued exposure to high levels of fluoride may be related to a risk of bone fractures later in life. (See also FLUORIDATED WATER .) dental plaque Transparent deposits of BACTERIA and debris adhering to tooth surfaces. Dental plaque precedes tooth decay and PERIODONTAL DISEASE . Diet has an important role in the formation of plaque, and sugar remains the leading dietary cause of tooth decay because it is a particularly effective food for the bacteria. Bacteria responsible for dental plaque, such as Streptococcus mutans, fer- ment sugars in food to organic acids, which dis- solve the minerals in teeth. Tooth enamel cannot repair itself. Bacteria can then infect pockets in enamel, leading to cavities. In addition, several 190 dementia strains of bacteria can infect gums. Plaque buildup and periodontal disease may be prevented by proper flossing, brushing, and periodic cleaning by a dental hygienist and by limiting consumption of sugar-rich foods like candy and sweets. Brushing immediately after eating such foods limits plaque formation. (See also CANDY; CARBOHYDRATE.) deoxycholic acid See BILE ACIDS. deoxyribonucleic acid See DNA. deoxyribose A simple SUGAR building block of DNA, the genetic material of cells. The DNA mole- cule consists of very long chains with a “backbone” of deoxyribose. Deoxyribose is not an essential nutrient because the body makes ample amounts from ribose, a common sugar containing five car- bon atoms. (See also CARBOHYDRATE METABOLISM; GLUCOSE.) depression A prolonged feeling of overwhelming sadness, with an inability to feel pleasure, loss of appetite, weight loss or weight gain, excessive guilt, diminished ability to concentrate, sense of hope- lessness, lethargy, insomnia, suicidal thoughts, and persistent headaches. Chronic and severe depres- sion can lead to psychosis and suicide. Depression is a serious health problem; an estimated 25 per- cent of Americans suffer from clinical depression at some time in their lives. Depression may indirectly increase the risk of clogged arteries by increasing the risk of cigarette smoking, which raises levels of a clotting protein (fibrinogen). Causes Depression has no one specific cause but is the result of a complex interaction among genetics, biochemistry, and psychological factors that leads to abnormally low levels of several important brain chemicals related to emotions. Food allergy and environmental sensitivities as causes of psychological symptoms remains contro- versial. However, in some cases, food allergies or chronic exposure to toxic chemicals, solvents, and toxic metals may cause mental disturbances. Nutritional deficiencies, hormonal imbalances, and reactions to medications can contribute to depression. Many nutrient deficiencies can influence the onset of depression. A deficiency of the essential amino acid TRYPTOPHAN, and several mineral defi- ciencies, including calcium, iron, magnesium, and potassium, lead to depression. Certain vitamins are specifically associated with behavioral changes: These include VITAMIN C, BIOTIN, VITAMIN B 12 , FOLIC ACID , NIACIN, RIBOFLAVIN, PANTOTHENIC ACID, VITA- MIN B 6 , and THIAMIN. Folic acid and vitamin B 12 status are low in some patients suffering from depression; 31 percent to 35 percent of patients suffering from depression in the United States may be deficient in folic acid. In the brain, folic acid and vitamin B 12 , together with the essential amino acid methionine, seem to raise levels of the neuro- transmitter SEROTONIN, which acts as an antide- pressant. Circumstantial evidence links thiamin defi- ciency and depression. Thiamin deficiency alters brain chemistry, and thus, on admission, psychi- atric patients are frequently found to be thiamin deficient. Depression is one of the symptoms of chronic niacin deficiency ( PELLAGRA ). Other Causes Imbalances of the PITUITARY, HYPOTHALAMUS, THY- ROID, and/or ADRENAL GLANDS have been implicated in depression. Depression is an early symptom of hypothyroidism (low thyroid output), and adrenal gland malfunction can lead to excessive cortisol production, which can produce depression, ner- vousness, and insomnia. The brain is very depen- dent upon blood sugar (glucose) for energy, and severely emotionally disturbed patients are prone to HYPOGLYCEMIA (low blood sugar). A gradual onset of hypoglycemia can lead to depression, blunted men- tal functioning and emotional instability. Pharmaceutical Causes Depression can be induced by corticosteroids, beta- blockers, and blood pressure medications that dis- rupt the normal balance of neurotransmitters, the chemicals that convey nerve impulses. Oral contra- ceptives can induce deficiencies of VITAMIN B 6 , pre- sumably resulting in lowered serotonin production in the brain, which can affect mood. depression 191 Nutritional Approaches to Treatment Normalizing swings in blood sugar levels may help treat depression. Small, frequent meals that are high in protein and complex carbohydrates, while eliminating sweets and refined carbohydrates are useful strategies. Nutritional supplements can help ameliorate depression associated with nutrient deficiencies. Much research has focused on neurotransmit- ter imbalances associated with depression, espe- cially serotonin. Supplementing nutrients that are raw materials for neurotransmitters, particularly the amino acids tryptophan, PHENYLALAMINE and L-TYROSINE, together with vitamin B 6 , have been used therapeutically with inconsistent results. Most likely to benefit are those with bipolar disorder. These nutrients may enhance the effects of antide- pressants in some cases. The use of gram amounts of amino acids requires the supervision of a physi- cian skilled in nutrition. In 1990, the U.S. FDA withdrew tryptophan as an isolated nutritional supplement. St. John’s wort (Hypericum perforatum) has been used historically to elevate mood in cases of mild depression. Alpert, J. E., and Fava. M. “Nutrition and Depression: The Role of Folate,” Nutrition Reviews 55, no. 6 (May 1997): 145–149. Elkins, Rita. Solving the Depression Puzzle, Pleasant Grove, Utah: Woodland Publishing, 2001. dermatitis A range of skin conditions involving inflammation, with redness and swelling, itching, and other abnormalities. Contact dermatitis is caused by exposing the skin to an irritating sub- stance. Poison ivy and poison oak are classic exam- ples of agents causing contact dermatitis. Regular exposure to mild irritants can cause the skin to become red, dry, scaly, cracked, or flaking. Cosmet- ics (hair care products, colognes, antiperspirants), antibiotics, and kitchen chemicals like detergents and cleansers can be causes of contact dermatitis in susceptible people. ATOPIC DERMATITIS is associated with more severe symptoms, such as ECZEMA, with skin erup- tions, blisters, and crusts. This condition runs in families. About 3 percent of infants have atopic dermatitis, which often clears up by 18 months of age. Food allergy is often implicated as a possible cause. In adults, itchiness, redness, and swelling may worsen with STRESS and FATIGUE. An allergy to wool, excessive exposure to oils and soaps, and a deficiency of any vitamin of the B COMPLEX can cause atopic dermatitis. (See also ALLERGY, FOOD .) dessert The last meal course. In the United States, dessert is likely to be a high-sugar, high-fat food: pastry-like cookies; cakes and pies; ice cream or other frozen dessert; custards or puddings; and gelatin desserts. Cheese, tarts, and custards are favorite desserts in Great Britain. In France, meals traditionally end with fruit, cheese, and a wine. In northern Europe cakes and tarts are often desserts. In Spain and Latin America, flan is traditional. Dessert may also include milk-based sweets with fruits. In India, sweet puddings and cakes flavored with honey, nuts, and rose water are typical dessert items. In many other cuisines, fresh fruit, tea, and coffee end the meal, without a sweet course. (See also DAIRY-FREE FROZEN DESSERTS.) detoxification The chemical modification of for- eign substances and waste products in order to help the body dispose of potentially harmful substances. Detoxification refers to treatment protocols designed to help the body rid itself of waste and toxic materials. The LIVER is a key actor in detoxifi- cation. Its battery of protective enzymes can oxi- dize and inactivate toxic compounds to increase their water-solubility so they can be excreted more readily. Liver enzymes add oxygen, break bonds, remove carbon atoms, and attach highly water-sol- uble materials such as amino acids and sugar deriv- atives to a wide range of compounds. Common examples of substances detoxified by the liver include ALCOHOL, oxidized to a derivative of acetic acid, AMMONIA, the toxic by-product of amino acid degradation, converted to nontoxic UREA, steroid HORMONES, and pollutants. CYTOCHROME P450 refers to a major class of oxi- dizing enzymes of the liver, requiring IRON and RIBOFLAVIN. Cytochrome P450 enzymes can add oxy- gen atoms to otherwise very resistant compounds, including a variety of drugs and cyclic hydrocarbons. 192 dermatitis [...]... DIETING; EXERCISE; FOOD; HEIGHT-WEIGHT TABLES; HYPERTENSION; TEETH.) Nutrition and Your Health: Dietary Guidelines for Americans, Fifth Edition Washington, D. C.: U.S Departments of Agriculture and Health and Human Services, 2000 Dietary Reference Intakes (DRI) The most recent set of dietary recommendations established by the Food and Nutrition Board of the Institute of Medicine They update and expand... intake Diglycerides are composed of two FATTY ACIDS linked to glycerol, while fat and oils are TRIGLYCERIDES, containing three fatty acids bound to glycerol Diglycerides are readily digested and are considered safe food additives A variety of additives related to glycerides have been created by food technology Ethoxylated monoglycerides and diglycerides are used as dough conditioners to improve the texture... calorie-restricted diets according to FDA guidelines These products often reduce calories by incorporating ARTIFICIAL SWEETENERS that provide little or no calories (See also DIETETIC FOODS; DIETING.) diet-induced obesity See YO-YO DIETING diet-induced thermogenesis Heat produced in the body as a result of digesting food and absorbing nutrients Heat is normally produced as the body uses energy for any of. .. fiber seems to reduce the rate of glucose absorption High-fiber diets supplemented with fiber up to 50 g daily have been used to lower blood lipids and to lower blood cholesterol On the other hand, high-fiber diets can raise blood lipids and/ or blood sugar among diabetics, cause excessive insulin production and lower the desirable kind of blood CHOLESTEROL, HIGH-DENSITY LIPOPROTEIN (HDL) Therefore, a high... pounds of appropriate body weight than overweight Recent evaluations support the premise that thinner individuals (down to 10 pounds below the average weight of their group in height and build) may live longer, provided they are healthy and do not smoke Individuals with health problems, pregnant and lactating women, and children should not under- dieting 203 take self-prescribed popular weight-loss diets... converted to fat (See also CARBOHYDRATE METABOLISM; GLYCEMIC INDEX.) DHEA (dehydroxyepiandrosterone) A HORMONE made by the adrenal glands, testes, and ovaries Like other steroid hormones, DHEA is fabricated from CHOLESTEROL and is released into the bloodstream where it is the most abundant of this hormone class However, unlike the other steroid hormones, production of DHEA peaks between the ages of 25 and. .. with DSS and similar detergent-like molecules, they more easily dissolve DSS is used with thickening agents, powdered SOFT DRINK mixes, and cocoa milk beverages (to dissolve cocoa butter) DSS is also used as a detergent to clean fruit and vegetables, and in sugar manufacture The U.S FDA is considering adding DSS to a list of food additives that have a GENERALLY RECOGNIZED AS SAFE (GRAS) designation ADDITIVE... called THYMINE and CYTOSINE, ADENINE and GUANINE Their sequence defines (codes for) the sequence of amino acids in a protein Pairs of DNA chains twist about each other to form a double helix, resembling a double-railed spiral staircase with the steps composed of purine and pyrimidine extending inward The sequences of bases in each DNA strand of the double helix are complementary to each other: a base of. .. at the rate of two ounces per day The body adjusts to starvation conditions by burning stored fat for ENERGY In this process, it can overproduce KETONE BODIES, a readily transported form of fat calories Excess ketone bodies acidify the blood (ACIDOSIS) and cause dehydration and ELECTROLYTE imbalance Crash dieting can lead to YO-YO DIETING, a cycle of on-again, off-again dieting The body may respond... with reduced intake of refined carbohydrate, seems prudent Weight loss diets need to be tailored carefully for the individual A moderate reduction in daily calories (250–500) may be advised The American Diabetes Association recommends a balanced diet that follows the recommendations in the FOOD GUIDE PYRAMID Regular exercise and well-balanced meals that are low in fat and sugar help diabetics manage their . re- cent set of dietary recommendations established by the Food and Nutrition Board of the Institute of Medicine. They update and expand the RECOM- MENDED DIETARY ALLOWANCES the benchmark of nutritional. Clause and it amends the Federal Insecticide, Fungicide, and Rotenticide Act by establishing a single health- based standard for PESTICIDE residues in all foods. The new safety standard is defined. has had profound ramifications. First, the widespread use of DDT rapidly led to DDT-resistant insects. Second, DDT and other chlorinated hydrocarbons accumulate in the FOOD CHAIN because they