The Encyclopedia Of Nutrition And Good Health - M doc

M 411 maca (Lepidium peruvianum, Lepidium me- yenii) The dried root of a cruciferous vegetable related to the radish, maca is native to Peru, where it has been used as a food staple and a medicine by the indigenous people for thousands of years. Maca’s principle constituents include protein (about 11 percent), calcium (about 10 percent), magnesium, and potassium. Other nutrients include iron, silica, iodine, manganese, zinc, and copper. It is available in dry powder, liquid extract, and capsule form. Although unproven, claims of maca’s health benefits center on its alleged ability to balance the body’s hormone levels. Advocates say maca eases the symptoms of menopause, including hot flashes and vaginal dryness; enhances libido in both men and women; strengthens bones; promotes healthy skin, nail and hair growth; increases fertility; and elevates mood. macaroni A form of PASTA in which pieces of wheat dough are formed into various shapes and dried. Macaroni includes pasta strands (such as spaghetti), shells (conchiglie), or tubes (cannel- loni, elbow macaroni, or ziti), and it can be bent, corrugated, straight, or spiraled. Macaroni is com- posed of flour from durum wheat (a “hard wheat” rich in protein), farina (a coarsely ground endosperm of other wheats), and SEMOLINA, the coarsely milled, starchy endosperm of durum wheat after bran and germ have been removed. Semolina, farina, and durum wheat flour can be used in any combination or they can be used sep- arately. Semolina is high in protein, which gives dough the strength to hold up to the mechanical processing needed to make pasta. A small amount of disodium phosphate is added to make pasta cook more quickly. Since January 1998 all enriched pasta, flour, rice, cornmeal, and other cereal grain products in the United States have been fortified with folic acid to help reduce the incidence of neural tube defects in newborn babies. Products marked “enriched” must contain specific amounts of certain vitamins and minerals: 4 to 5 mg of THIAMIN; 1.7 to 2.2 mg of RIBOFLAVIN; 27 to 34 mg of NIACIN; and 13 to 16.5 mg of IRON per pound. Eggs are an optional ingredient in macaroni. Other pasta variations include whole wheat, beet, spinach, and soy macaroni products. (See also BREAD; COMPLEX CARBOHYDRATE; FOLIC ACID.) mackerel (Scomber scombrus) A saltwater predatory fish related to tuna, with a very stream- lined body. This important food fish is typically 14 in (35 cm) in length. The Atlantic mackerel ranges from Labrador to Cape Hatteras. The king mackerel, Scomber omovus cuvalia, is found in coastal waters from the Carolinas to Brazil. Mackerel is an oily fish and represents one of the richest sources of marine oils, EICOSAPENTAENOIC ACID and other omega-3 fatty acids. These fatty acids lower blood lipids and may reduce the risk of ATHEROSCLEROSIS, and they help reduce symptoms of autoimmune diseases like RHEUMATOID ARTHRITIS. By decreasing the tendency of blood clot formation, they lower the risk of STROKE and HEART ATTACK. The outer layers of mackerel meat are red; the interior layers are lighter in color. Most commercial mackerel is canned; fresh mackerel is very perishable. The nutrient content of 3 oz. (85 g) provides 174 calories; protein, 15.8 g; fat, 11.8 g; cholesterol, 60 mg; calcium, 10 mg; thiamin, 0.15 mg; riboflavin, 0.265 mg; niacin, 7.72 mg. (See also OMEGA-3 FATTY ACIDS ; SALMON; SEAFOOD.) macrobiotic diet A DIET emphasizing plant foods and complex carbohydrates ( STARCH and FIBER). The macrobiotic diet was introduced by George Ohsawa in the 1960s in California and it continues to be popular. The macrobiotic diet encompasses more than foods; the belief that DIGESTION and assimilation are aided by eating slowly in a peace- ful, harmonious atmosphere is fundamental. In its earliest form it was an imbalanced diet emphasizing RICE and GRAINS. Brown rice was considered an optimal balance of “yin” and “yang” forces. The rig- orous application of macrobiotic principles fre- quently caused MALNUTRITION, with ANEMIA, slowed growth, RICKETS, even kidney damage, especially in children. The modified macrobiotic diet used today, which can vary with personal needs, is wholesome and tasty and includes locally produced foods and whole grains. Animal products are used as condi- ments, rather than as main dishes. The diet varies with the climate and season, to minimize use of chemical preservation and unnecessary food processing. Meals consist of 50 percent to 60 percent whole grains. The macrobiotic diet supplies about 73 percent of total carbohydrate; only 15 percent to 20 percent of the CALORIES are fats and oils (from whole grains and vegetable oils). Brown rice, MIL- LET, OATS, RYE, BUCKWHEAT, couscous, whole WHEAT, LEGUMES, VEGETABLES, FRUITS, NUTS, and seeds com- plete the foundation. Legumes supply 5 percent to 10 percent of calories in the form of adzuki, lima, kidney, navy, mung, pinto, and soy beans. Bean sprouts are useful adjuncts. Sea vegetables like arame, hijiki, kombu, nori, and wakame provide texture, flavor, and essential nutrients. Seafood and poultry are incorporated according to dietary goals or preferences. (See also HIGH COMPLEX CAR- BOHYDRATE DIET; VEGETARIAN.) macronutrient Nutrients required by the DIET in amounts ranging from a fraction of a gram to more than a gram. The major minerals, CALCIUM, MAGNE- SIUM, SODIUM, POTASSIUM, CHLORIDE, and PHOSPHO- RUS are considered macronutrients. These balance body fluids and build bones and teeth. CARBOHY- DRATE, FAT, OIL, and PROTEIN, together with WATER, are considered other macronutrients. Together they make up the bulk of food. Fat and carbohydrate must be eaten in large amounts daily because they provide the fuel that keeps the body’s machin- ery operating. Proteins supply building blocks to replace worn out and damaged proteins. The recommended distribution of calories looks like this: For an adult requiring 2,000 calories daily, less than 600 calories (less than 30 percent of the total) should come from fat (67 grams or 4 tablespoons). How much less than 30 percent is optimal debat- able. Fifty grams of protein (1.75 oz.) supplies 200 calories (20 percent of the total). The remaining 1,200 calories (60 percent) would come from carbohydrates, preferably COMPLEX CARBOHYDRATES as found in whole grains, LEGUMES, and VEGETABLES (roughly 300 g or two-thirds of a pound). Fat is a concentrated form of ENERGY because it provides more than twice as many calories per gram as do carbohydrate or protein. The typical American diet provides about 40 percent of total calories as fat. Some 15 percent to 25 percent of calories as fat and oils may be more appropriate to reduce the risk of CANCER, HEART DISEASE, and OBE- SITY. Current dietary guidelines recommend choos- ing a diet reduced in total fat, saturated fat, and cholesterol, with oils and fats to be used sparingly. For the average American, carbohydrate supplies about 40 percent to 45 percent of the total calories, with sweeteners like SUCROSE, FRUCTOSE, and CORN SYRUP representing about half of this (about 130 to 150 pounds per year per person). U.S. dietary goals publicized in the 1970s called for cutting SUGAR consumption by two-thirds while doubling STARCH intake with whole vegetables and grains. Current guidelines are less specific. They call for eating ample amounts of vegetables, fruit, and grain products daily: with six to 11 servings of bread and grain products; three to five servings of vegetables; and two to four servings of fruits, with sweets to be used sparingly. Food supplies amino acids for building the thousands of proteins of the body. An adult needs to eat only 40 to 50 grams of protein a day, though the typical diet supplies twice this amount. The body treats surplus amino acids as excess fuel: They are either converted to fat or they are burned for energy. Drinking the equivalent of two quarts of water each day replaces water lost due to waste disposal, urine, and feces, and to perspiration. Water is essential as a coolant and as the fluid of cells and 412 macrobiotic diet tissues needed for their normal operation. (See also DIETARY GUIDELINES FOR AMERICANS; ELECTROLYTES.) macrophage See IMMUNE SYSTEM. mad cow disease See BOVINE SPONGIFORM ENCE- PHALOPATHY. magnesium A major mineral nutrient. The body contains 20 to 28 g of magnesium; 40 percent is found in tissues like MUSCLE and 60 percent occurs in BONE and teeth, where it is combined with phosphate. Among soft tissues the liver and muscles contain the highest levels. Within cells magnesium is the second most prevalent type of positively charged ion (cation) after potassium. Magnesium is required for all major metabolic processes involving ATP, the chemical energy currency of the cell. More than 300 enzymes are activated by magnesium and magnesium-ATP complexes. It functions in energy-consuming processes like bio- synthesis of protein and of DNA and RNA; sugar breakdown ( GLYCOLYSIS); and ATP-dependent transport of materials into the cell. Magnesium is essential for the transmission of nerve impulses; for electrical potentials of cell membranes; muscle contraction; ATP formation; and maintenance of blood vessels. Possible Roles in Maintaining Health Magnesium is essential for normal calcium metabolism. In muscle contraction, magnesium balances the effects of calcium, which stimulates contraction. Thus, magnesium regulates calcium uptake by cells to activate functions like heartbeat. Magne- sium may also: • protect against CARDIOVASCULAR DISEASE. It can help reduce high BLOOD PRESSURE, lower CHOLES- TEROL as LOW-DENSITY LIPOPROTEIN (LDL) and increase HIGH-DENSITY LIPOPROTEIN (HDL) cholesterol; • protect against lead poisoning; • protect against migraine and DEPRESSION; • help maintain normal heart function and prevent irregular heartbeat (cardiac dysrhythmia). The imbalance between calcium and magnesium may increase the risk of cardiovascular disease, and magnesium deficiency increases the risk of severe disruptions of cardiac rhythm; • help alleviate PREMENSTRUAL SYNDROME , when used with ZINC and VITAMIN B 6 in certain cases; • prevent KIDNEY STONES; • alleviate convulsions associated with preeclamp- sia and ECLAMPSIA, a syndrome in pregnancy characterized by high blood pressure and protein in the urine. In serious cases, eclampsia can lead to convulsions and coma. Sources Magnesium is found in MEAT (especially liver); POULTRY; FISH and SEAFOOD; green vegetables like BROCCOLI; dairy products; hard water; TOFU; AMA- RANTH; wheat germ; pumpkin seeds; instant COFFEE; PEANUTS, CASHEWS, BRAZIL NUTS; BREAKFAST CEREALS; cocoa powder; BLACKSTRAP MOLASSES; and YEAST. Magnesium is lost during FOOD PROCESSING. Requirements The adult Recommended Dietary Allowance (RDA) for magnesium is 350 mg per day for men and 280 mg for women.The typical American diet provides about 120 mg per 1,000 calories. Thus a person consuming 1,500 calories or less is likely to be magnesium deficient. Factors that increase the need for magnesium due to limited uptake or increased losses include high dietary FIBER; too much phosphate (as soft drinks) and alcoholic beverages; high psychological stress; some DIURETICS (water pills) and regular, strenuous EXERCISE. Excessive calcium in supplements may compete with magnesium. Disease and conditions that cause magnesium depletion include MALABSORPTION, MALNUTRITION, ALCOHOLISM , and intravenous feeding using nutrient mixtures that do not contain enough magnesium. Marginal deficiency is very common among teenagers and people who diet; diabetics; pregnant and lactating women; those who drink heavily; elderly persons with poor eating habits; those taking diuretics and digitalis; athletes; women with osteoporosis; and individuals with severe kidney disease and severe DIARRHEA. Early symptoms of magnesium deficiency are vague, including a loss of appetite, upset stomach, and diarrhea making diagnosis of a mild deficiency difficult. Symptoms of long-term deficiency relate to the nervous system: confusion apathy, depres- magnesium 413 sion, irritability, irregular heartbeat, muscle weak- ness, tremors, convulsions, and poor coordination, as well as a lack of APPETITE, listlessness, nausea, and vomiting. Measurement of white blood cell magnesium can be used to help assess the nutritional status of this mineral. Safety Excessive use of the home remedies Epsom salts and milk of magnesia leads to deficiencies of other minerals, even toxicity. Overdose with magnesium antacids (1,500 mg or more daily) is indicated by low blood pressure, drowsiness, nausea, slurred speech, and unsteadiness. Magnesium toxicity can occur when the kidneys cannot clear large over- loads. While magnesium appears to be safe, it should not be taken by patients with kidney disease or by those with heart problems (atrioventricular blocks). A physician should be consulted prior to using supplements. (See also TRACE MINERALS.) Seelig, M. “Review and Hypothesis: Might Patients with the Chronic Fatigue Syndrome Have Latent Tetany of Magnesium Deficiency?,” Journal of Chronic Fatigue Syndrome 4, 2 (1998): 203–205. maitake mushroom (Grifola frondosa; hen of the woods) An edible fungus indigenous to Japan also found in parts of northern Europe and North America. Its rippling shape gives it the appearance of butterflies. In Japanese, maitake means “dancing butterfly.” Some people say the fungus got its name because foragers who came upon it in the woods would dance with joy knowing they were in for a delicious treat. Maitake, which (unlike many other types of MUSHROOM ) has no cap at the end of its rippling stems, grows in clusters at the foot of mature oak trees. Individual specimens can grow to more than 50 pounds, which is why it is sometimes called the “king of mushrooms.” The flesh is firm and has a “woody” taste. Maitake has been used by herbalists in Japan for years to treat a variety of illnesses, including digestion problems, stress, and hemorrhoids. Research has shown that polysaccharides (including beta- glucan) strengthen the immune system and may be effective in fighting cancer. Some studies have shown that maitake consumption may help slow the progression of the AIDS virus. In other studies cancerous tumors in mice that were fed maitake extract decreased in size. Other animal studies indi- cate that maitake shows promise in treating high blood pressure, diabetes, and OBESITY. Maitake are often sold dried. They add an earthy flavor to soups, salads, and pilafs and can be used in almost any recipe calling for firm mushrooms. Safety data are inadequate for pregnant and breast- feeding women. Borchers, A. T. et al. “Mushrooms, Tumors and Immu- nity,” Proceedings of the Society of Experimental Biological Medicine 221, no. 4 (1999): 281–293. malabsorption Symptoms related to long-term inadequate nutrient absorption. A person can eat a BALANCED DIET and still be malnourished if the intestines cannot absorb nutrients or if DIGESTION is incomplete. The most common nutritional deficiencies involve minerals like CALCIUM and IRON, and vitamins such as FOLIC ACID, VITAMIN B 6 , or VITAMIN A. Symptoms are varied, depending on the kind of nutrient that is deficient. Fatigue and lowered resistance to infection are common indicators. Vit- amin and mineral deficiencies alter metabolism and lower immunity. Vitamin and iron deficiencies can cause ANEMIA, “tired blood.” Chronic low calcium intake leads to OSTEOPOROSIS. B complex vitamin deficiency leads to a sore tongue. Some Causes of Malabsorption • rapid transit time (diarrhea) • inadequate chewing • inadequate digestion caused by low stomach acid production ( HYPOCHLORHYDRIA), one of the consequences of aging • impaired absorption due to an unhealthy intestinal lining. Severe food allergies, sensitivi- ties and inflammation (such as CELIAC DISEASE and Crohn’s disease) injure the absorptive surface of the intestine ( MICROVILLI) • inadequate intestinal digestive enzymes. Enteropeptidase is required to activate pancreatic enzymes. Disaccharidases are required to break down sugars such as lactose (milk sugar) and sucrose (table sugar). Parasitic infection can damage the intestinal lining and decrease production of these enzymes. Lactose deficiency is 414 maitake mushroom age-related among most adults worldwide. Those of Northern European extraction often continue to make ample lactase enzyme throughout their lives • bacterial overgrowth of the small intestine, which can block absorption and limit digestion • impaired pancreatic output. Low stomach acid or more serious conditions like pancreatitis can decrease the output of digestive enzymes • lowered bile production, which reduces fat digestion and the uptake of fat-soluble vitamins (A, D, K, and E) • materials that absorb minerals and may prevent their uptake by the intestine. FIBER, PHYTIC ACID, and OXALIC ACID in VEGETABLES, GRAINS, and LEGUMES are examples; • competition by drugs. Certain drugs can block the absorption of minerals and vitamins • excessive minerals in the diet: for example, too much ZINC blocks copper uptake • inadequate INTRINSIC FACTOR. Paralleling low stomach acid production, the stomach may produce too little intrinsic factor to facilitate VITAMIN B 12 uptake. (See also BIOAVAILABILITY; DEFICIENCY, SUBCLINI- CAL; DRUG-NUTRIENT INTERACTION; GLOSSITIS.) maladaptation See TOLERANCE TO TOXIC MATERIALS. malnutrition Impaired health due to imbalanced diet or to abnormal physiologic processes required to absorb and use optimal amounts of nutrients. Thus, malnutrition can reflect the failure to obtain enough nutrients (undernutrition), or it may mean excessive amounts of nutrients (overnutrition), or both. Reliance on highly processed foods can lead to simultaneous overnutrition and undernutrition. Overnutrition The major dietary problems in the Western world reflect too much food, rather than too little. Excessive CALORIES, refined CARBOHY- DRATE, FAT, saturated fat, and sodium set the stage for modern diseases such as CANCER, CARDIOVASCULAR DISEASE , DIABETES, HYPERTENSION, and OBESITY. Undernutrition Primary undernutrition refers to ingesting inadequate amounts of nutrients to sustain normal growth or health. Populations in developing nations often suffer from chronic undernutrition. Being significantly underweight shortens the life span and takes an immense toll in human suffering. STARVATION represents severe undernutrition; the diet does not provide enough major nutrients (protein, carbohydrate, and fat) to maintain the body. The physiological results are the same as for prolonged fasting. Other symptoms include dry skin, sores that do not heal, swelling, inflamed tongue, flabby muscles, slow growth and development, and FATIGUE and apathy. Prolonged starvation wastes the body because it must literally consume itself to survive. ANEMIA and a failure to grow are severe consequences. Inadequate body stores of vitamins and minerals generally lead to a decreased immunity and a greater risk of infection. Other symptoms are common: slowed knee reflexes; abnormal pigmentation of eye membranes (conjunctiva), redness of eyes and eyelids; dull, brittle hair that is easily plucked and sometimes lighter in color than normal; swollen, bleeding gums; receded gum line; swollen parotid glands and THYROID GLANDS ; chapped, red, or cracked lips; brittle, rigid nails; rapid heartbeat; high blood pressure and enlarged liver in children. Secondary undernutrition refers to the body’s inability to efficiently use nutrients. This situation can be caused by poor digestion, inadequate uptake due to an unhealthy intestine, or by competition of nutrients with each other or with drugs. Mild malnutrition without major deficiency symptoms is much more common than severe undernutrition in the United States, but it is much harder to detect. The most common symptom is fatigue. The deaths of more than 6 million children in developing countries who are under the age of five are attributable to malnutrition. According to the U.S. Department of Agriculture’s 1994–96 Contin- uing Survey of Food Intakes by Individuals, only 3 percent of all Americans meet four of the five rec- ommendations for daily consumption of grains, fruits, vegetables, dairy products, and meats. According to a survey conducted by the Nutrition Screening Initiative, a national project to promote routine nutrition screening and better nutrition among older people, one in four elderly patients suffers from malnutrition. malnutrition 415 The elderly are prone to malnutrition because of poverty, isolation, loss of TASTE, loss of teeth and GINGIVITIS , multiple medications, constipation and MALABSORPTION, poor eating habits, reliance on PROCESSED FOODS, skipping meals, chronic disease and physical impairments that limit the ability to shop for or cook food, and a lack of concern about nutrition. Malnutrition in Children Poverty and malnutrition go hand in hand, and children suffer the most worldwide. Mild undernutrition is much more common worldwide than starvation, although famine is endemic in certain regions of Africa. Marginal intake of vitamins, minerals and/or amino acids in a child’s diet can lead to lowered immunity and a decreased ability of white cells to fight off infections, as well as slowed mental and physical development. The failure of babies to thrive most often results from an inadequate diet. MARASMUS refers to the form of starvation occurring when the diet does not supply enough calories. The skeletal image usually associated with starvation reflects marasmus. Muscle wasting supplies the body with energy. Children with marasmus adapt by slowing their growth rates, which can have severe, long-term effects on mental and physical development. KWASHIORKOR is the form of starvation occurring when the diet supplies enough carbohydrate to meet daily calorie needs, but lacks adequate PROTEIN. The starving child may appear puffy and swollen because of severe edema. Malnutrition among children of affluent, well- educated parents is a recent phenomenon in the United States. Some well-intentioned, well- educated parents apply their low-fat diets to their children to decrease the risk of childhood obesity and of heart disease later. Children grow rapidly, and low-calorie, low-fat diets can retard their growth and development. Parents should consult a specialist before putting a child on a diet. (See also BIOAVAILABILITY; CHOLESTEROL; DEFICIENCY, SUB- CLINICAL.) Salama, Peter et al. “Malnutrition, Measles, Mortality, and the Humanitarian Response During a Famine in Ethiopia,” JAMA 286 (2001): 563–571. malt A product of germinated BARLEY used in brewing beer. To prepare malt, germinated barley is bleached and dried to prevent further sprouting. During germination, seed enzymes cleave STARCH to the sugar, maltose, and split cell wall FIBER (hemicelluloses) into fermentable simple sugars. Other GRAINS, such as RYE and WHEAT , can also be malted. Malted milk is prepared by combining whole milk with the filtrate from a mixture of barley milk and wheat flour. Malt is fermented by yeast to ALCOHOL when beer is brewed. Malting and brewing were among the earliest discoveries of civilization. Egyptians have brewed beer since 5000 B.C. Beer is prepared by first warming malt and nonmalted grains (a mixture called a “mash”). Mash is then filtered to obtain a sugar-rich liquid, which is boiled with hops, then fermented by adding yeasts. Whiskey manufacture depends on fermentation of mashes without filtration, then distilling the alcohol and other volatile materials. maltase The ENZYME that digests maltose, a sugar from starch DIGESTION. The small intestine produces maltase to degrade maltose. This sugar is produced by the action of AMYLASE, the starch digestion enzyme found in saliva and in pancreatic secre- tions. Because maltose is too large to be absorbed by the intestine, it must be degraded to its building block, the simple sugar GLUCOSE, which is readily absorbed. Therefore, maltase plays a critical role in carbohydrate digestion. (See also CARBOHYDRATE METABOLISM ; LACTASE; SUCRASE.) maltol A FOOD ADDITIVE used as a FLAVOR ENHANCER . Maltol accentuates the flavor of CHOCO- LATE, VANILLA, and fruit-flavored beverages and foods. A closely related compound (ethyl maltol) is a more powerful flavor enhancer. Both are used in gelatin desserts, ICE CREAM, jams, and baked goods with fruit flavors. Because ethyl maltol tastes sweet, its use allows the sugar content of a food to be reduced by 15 percent. Ethyl maltol masks the bitter taste of the artificial sweetener saccharin. Levels of maltol added to foods range from 15 to 250 mcg per gram (parts per million); ethyl maltol is added at considerably lower levels. Small 416 malt amounts of maltol occur naturally in bread, coffee, cereals, soybeans, and malt products. Heated con- densed milk, whey, and soy sauce also produce maltol. Maltol and ethyl maltol are considered safe food additives. (See also ARTIFICIAL SWEETENERS; NATURAL SWEETENERS .) mandarin orange (Citrus reticulata) A citrus fruit with a unique sweet flavor related to the sweet orange. Mandarin oranges have a loose skin that is easily peeled. Certain red varieties are called TANGERINES , although the term tangerine is not a botanical classification. Apparently, mandarin oranges originated in Southeast Asia. Many varieties may have been developed in India, China, and Japan. Mandarin and hybrid strains are grown in most subtropical and even tropical regions throughout the world. Florida is the major domes- tic producer of tangerines. The original strains have been improved and crossbred with other citrus fruit. (For nutrient content, see ORANGE.) manganese A trace mineral nutrient. Manganese is needed for normal brain and muscle function, building bones, BLOOD CLOTTING, CHOLESTEROL synthesis, fat synthesis, and DNA and RNA synthesis. Manganese activates the enzyme responsible for the formation of urea, the waste product of protein degradation. In carbohydrate metabolism, manganese is required for the synthesis of glucose from noncarbohydrate substances ( GLUCONEOGENESIS). Manganese assists the action of SUPEROXIDE DISMU- TASE, which degrades superoxide, a free radical and a highly damaging form of oxygen. In addition, manganese is required to synthesize components of mucopolysaccharides ( GLYCOSAMINOGLYCANS), components of connective tissue. A manganese-dependent enzyme of the brain synthesizes the AMINO ACID , GLUTAMINE, as a way of removing AMMONIA,a toxic product of nitrogen metabolism. Conditions possibly associated with manganese deficiency include OSTEOPOROSIS, RHEUMATOID ARTHRITIS, LUPUS ERYTHEMATOSUS , allergies, ALCOHOLISM, and diabetes. Sources Good sources of manganese are NUTS, TEA, whole grains, BRAN, dried fruit, and leafy green vegetables. Their manganese content varies, depending on the manganese content of the soil. Eighty-six percent of manganese is lost in prepared white flour. DAIRY PRODUCTS, FISH, MEAT (other than organ meats), and POULTRY are poor sources of manganese. Inadequate absorption of manganese from plant sources may be a problem because digestion of plant food releases only a small fraction of the manganese it contains. Manganese supplements are best taken as a balanced multi-mineral preparation. Requirements The body contains low levels of manganese, and only minute amounts are required each day to maintain this level. The manganese concentration in tissues is stable primarily due to carefully con- trolled excretion. There is no RECOMMENDED DIETARY ALLOWANCE for manganese. Instead, the Food and Nutrition Board has estimated a safe and adequate daily intake as 2 to 5 mg for adults. Symptoms of manganese deficiency in experimental animals include pancreatic pathology and diabetes-like symptoms, impaired growth, reproductive abnormalities, skeletal abnormalities, convulsions, and ataxia (abnormal muscle movements). Certain groups might be deficient in manganese: women, especially those on weight loss diets; anyone on a calorie-restricted diet; aged people; and VEGETARIANS. Safety While manganese is relatively nontoxic, too much manganese can interfere with the absorption of other minerals like IRON. High manganese intake can cause nerve damage, immune system malfunc- tion, and damage to PANCREAS, LIVER, and KIDNEY. Excessive calcium supplements can interfere with manganese and iron uptake because they all use the same entry mechanism into intestinal cells. (See also ALLERGY, IMMEDIATE FAT METABOLISM.) mango (Mangifera indica) A tropical FRUIT with an oval shape, produced by a tropical evergreen. Mangoes are green when unripe; the ripened fruit is yellow-orange and the juicy pulp is sweet and tangy. Although not a popular fruit in North Amer- ica, mangoes are an important fruit crop in the mango 417 tropics, and they rank seventh among the most popular fruit crop worldwide. Mangoes seem to have originated in the broad region between Thai- land and India, and they have been cultivated since 5000 B.C. They are now grown in most tropical countries. India remains the largest producer of mangoes. The ripe fruit is eaten raw or used in jams, pre- serves, and juices; unripened fruit is used in chut- neys, a popular condiment in India. Mangoes can be seasoned with turmeric for this purpose. Nutri- ent content of one mango, raw (207 g), is 135 calories; protein, 1.1 g; carbohydrate, 35.2 g; fiber, 2.9 g; folic acid, 0.6 g; potassium, 323 mg; vitamin A, 806 retinol equivalents; vitamin C, 57 mg; thiamin, 0.12 mg; riboflavin, 0.12 mg; niacin, 1.21 mg. manioc See CASSAVA. mannitol A NATURAL SWEETENER used in chewing gum, soft candy, BREAKFAST CEREALS, frosting, and sugarless diet foods. It is also used as an antistick- ing agent for chewing gum because it does not absorb moisture. It occurs naturally in ASPARAGUS, OLIVES, PINEAPPLES, and SEAWEED. Commercially it is synthesized from the simple, common sugar GLU- COSE. Mannitol is classified as a sugar alcohol, but is not a sugar. It is not used efficiently by the body, nor does it raise blood sugar rapidly. Mannitol supplies only about half the calories of glucose and has about 70 percent of the sweetness of table sugar, and is considered a safe FOOD ADDITIVE. It is not metabolized to acids by oral bacteria. Tooth decay is caused by these organic acids, and, therefore, this additive may help prevent tooth decay. Mannitol’s rather poor absorption by the intestine results in osmotic DIARRHEA when large amounts are ingested. It is a LAXATIVE at a dose of 10 to 20 g daily. Such huge doses can worsen kidney disease. The U.S. FDA requires that the ingredient label warn of the laxative effect with excess consumption when daily ingestion of mannitol could reach 20 g. Mannitol may increase urination because much of it is eliminated unchanged by the kidneys. It has been used to prevent the kidneys from shutting down during major surgery. (See also ARTIFICIAL SWEETENERS; DENTAL CARIES; SORBITOL.) mannose A simple SUGAR found in CARBOHY- DRATE-containing proteins. In the body, mannose is formed from glucose and is used to form short chains of sugars (oligosaccharides) that are attached to certain proteins ( GLYCOPROTEINS). When attached to certain proteins, mannose may function as a recognition marker that governs the cel- lular distribution of the protein and its metabolic rate within tissues. Mannose is much less common than glucose ( BLOOD SUGAR) and does not occur free in foods. Mannose contains six carbon atoms and belongs to an important family of sugars (the aldohexoses) of which glucose is a member. (See also MANNITOL.) MAO inhibitors Monoamine oxidase inhibitors are used to treat depression and high blood pressure. Examples include Marpian, Nardil, and Par- nate. They block a key enzyme required to form DOPAMINE and norepinephrine, synthesized by nerve cells to conduct nerve impulses between cells. Foods containing TYRAMINE, a degradation product found in fermented foods, are dangerous when taking MAO inhibitors because tyramine in the pres- ence of MAO inhibitors drastically increases blood pressure. This effect may be severe enough to cause a STROKE or a HEART ATTACK. Symptoms of tyramine–MAO inhibitor interactions include vomiting, severe headaches, and nosebleed. Tyramine-containing foods to avoid include; aged CHEESES (such as Brie, Camembert, cheddar, processed American), cured MEAT (like pastrami), anchovies, AVOCADOS, BANANAS, BEETS, caffeinated beverages, chicken liver, CHOCOLATE, canned FIGS, MUSHROOMS, pickled her- ring, RAISINS, sausages, sour cream, chianti wine, sherry, and yeast extract. (See also DRUG-NUTRIENT INTERACTION ; NEUROTRANSMITTER.) maple syrup A syrup prepared from the sap of the sugar maple tree (Acer saccharum), native to eastern North America. This sweetener contains sugars like SUCROSE, glucose, and FRUCTOSE and has a distinc- tive flavor. During winter, starch is converted to sugar in tree roots, and it is carried up the trunk in the spring. Spring sap contains 4 percent to 10 percent sugar. It is collected in spring when the sap begins to flow and before buds open. The collected 418 manioc sap is concentrated by boiling down, which devel- ops the characteristic flavor of maple syrup. The maple flavor is not present in the sap itself. The province of Quebec remains the largest producer of maple syrup (over 20 million gallons yearly). U.S. production is about 5 percent that of Quebec. In the United States, Vermont and New York produce the most maple syrup. Commercial maple syrups are often blends of maple syrup and other less expensive syrups. Maple syrup should be considered a REFINED CAR- BOHYDRATE with little nutrient content other than CALORIES. It contains only traces of CALCIUM and POTASSIUM . To prevent crystallization and molds, it should be refrigerated, but not frozen. Maple syrup can be contaminated with LEAD if it is collected in or stored in metal containers with soldered seams. Suppliers should use stainless steel during preparation. (See also NATURAL SWEETENERS.) marasmus A progressive wasting and emaciation due to chronic deprivation of PROTEIN and CALO- RIES. Symptoms include wasting of MUSCLES and body fat, dry skin, low body weight, lethargy, sunken eyes, severe DIARRHEA, MALABSORPTION, and low body temperature. Diarrhea causes DEHYDRA- TION and losses of minerals like SODIUM, POTASSIUM, and CHLORIDE, causing ELECTROLYTE imbalance. This in turn leads to brain, kidney, and heart disorders. If left untreated, death may result. Decreased immunity promotes disease. In adapting to STARVA- TION, the body consumes tissue, protein, and FAT, accompanied by reduced protein synthesis and retarded growth in many tissues. All muscles, including the heart, atrophy. Causes of marasmus include inadequate food intake; prolonged malabsorption, caused, for instance, by severe diarrhea in infants; and child neglect. Marasmus occurs in infants and children in regions of the world where low-income populations are prone to undernutrition due to an inadequate supply of protein-rich foods, especially animal protein. Dietary protein may be deficient in essential AMINO ACIDS, or the total food intake may be inadequate. In either case, consumed protein is used for energy rather than being used to supply essential amino acids for protein synthesis and maintenance. Marasmatic children need physical and emotion- al warmth as well as improved nutrition. Treatment is based on an early digested diet with meals sup- plemented with 1 gram of high-quality protein and 50 to 60 calories per pound of body weight. (See also IMMUNE SYSTEM; KWASHIORKOR ; MALNUTRITION.) margarine A nondairy product resembling BUT- TER and prepared from hydrogenated (hardened) VEGETABLE OIL . Since 1950, Americans have eaten more margarine per person a year as butter consumption has declined. Margarine is usually manufactured from CORN OIL , SAFFLOWER oil, SOYBEAN oil, COTTONSEED OIL, PALM OIL, and PEANUT oil, and the amount of saturated fat that margarines contain varies. Small amounts of animal FAT may be added by manufac- turers. Unless animal fat is added, margarine does not contain cholesterol. Margarine incorporates partially HYDROGENATED VEGETABLE OIL. Most vegetable oils contain polyunsaturated fats, which are deficient in hydrogen atoms and which are liquid at room temperature. Hydrogenation, a chemical process, adds variable amounts of hydrogen to polyunsaturates, making them more saturated and harder at room temperature. In the last steps, oil is emulsified with emulsifying agents and chilled to solidify the oil and trap water. Additives include salt, yellow coloring ( BETA-CAROTENE), VITAMIN A, preservatives, and butter flavoring. It is believed that saturated fat, rather than polyunsaturated fat, promotes clogged arteries. Although margarine is more saturated than vegetable oils like corn, safflower, and soybean oils, it is much less saturated than coconut, palm, or palm kernel oils. Margarine contains more TRANS-FATTY ACID than butter. Trans-fatty acids are by-products of hydrogenation. The molecular shape of normal unsaturated fatty acids is bent, while saturated fats are straight molecules. Trans-fatty acids are also straight. Like saturated fatty acids, they can pack together more closely, making them more solid at room temperature. Trans-fatty acids raise cholesterol and therefore increase the risk of heart disease. Fried foods, such as french fries and doughnuts from fast food chains, are often cooked with vegetable shortening. Vegetable shortening is margarine 419 laden with trans-fatty acids. Food labels do not list the amount of trans-fatty acids in foods. Margarine and partially hydrogenerated vegetable oils contribute more than 80 percent of the trans-fatty acids Americans consume. Types of Margarine Liquid margarine is the least hydrogenated and contains a high fraction of unsaturated oil. Whipped margarine contains air to increase volume and to make the product spread more evenly; the air reduces calories by 40 percent. Stick margarine is higher in saturated fat than tub margarine or liquid margarine and may contain animal fat ( BEEF TALLOW). “Diet” (low-cal) margarine contains one-half to one-third the calories of regular margarine because it contains much more water. Due to the high water content, it cannot be substituted for stick margarine or butter in recipes. Salt-free margarine is available for individuals on sodium- restricted diets. Both margarine and butter contain the same number of calories and salt. Margarine is usually colored with beta-carotene to make it look like butter, which derives its color naturally from beta- carotene. Margarine contains no cholesterol; butter contains 32 milligrams/tsp. Margarine has 2 g of saturated fat/tsp; butter has 7.5 g. Margarine has 4 g of polyunsaturated fat/tsp.; butter has a half- gram. The PROTEIN, fat, CALCIUM, SODIUM, and VITA- MIN A contents are comparable. Stick margarine contains 47 percent monounsaturated fatty acids, 53 percent polyunsaturated fatty acids and 30 percent saturated fatty acids. And margarine contains high levels of trans-fatty acids; per tablespoon, margarines contain 1 to 3 g. Cholesterol-Lowering Margarine Cholesterol-lowering margarines are the latest addition to this food category. These products contain either sterol esters (from vegetable oils, soybean, and corn) or stanol esters (from wood pulp). When used in combination with a heart-healthy diet, these margarines can help lower LOW-DENSITY LIPOPROTEIN (LDL) cholesterol (the “bad” cholesterol) in some patients. Elevated levels of LDL cholesterol are strongly linked to a greater risk of heart disease. In one study children who were geneti- cally predisposed to early heart disease and who ate margarine containing sterol esters for three months reduced their LDL cholesterol levels by 18 percent. Adult relatives of the children who participated in the study also experienced some decrease in LDL cholesterol levels. The American Heart Association does not recommend cholesterol-lowering margarine for patients who have not been diagnosed as having elevated levels of LDL cholesterol. The American Cancer Society recommends that patients eat less fat of all kinds—margarine, butter, cooking oils, vegetable shortening, or lard—to lower the risk of cancer and heart disease. Patients should avoid margarines that do not list liquid vegetable oil first on the label, and avoid those listing coconut oil, palm or palm kernel oil, or lard as ingredients in order to reduce consumption of saturated fat. Patients should buy margarines with higher levels of polyunsaturates and choose diet (“light”) margarine to reduce the intake of trans-fatty acids. Margarine labels list saturated fat content but do not include trans-fatty acids. Therefore, they reveal only a portion of the content of the fat that raises LOW-DENSITY LIPOPROTEIN (LDL) cholesterol. Nutrient content of 1 tbsp (14 g) of regular 80 percent-fat margarine, 100 calories; protein, 1.1 g; fat, 11.4 g; sodium, 153 mg; vitamin A, 140 retinol equivalents; and no water-soluble vitamins. Miettinen, T. A. et al. “Reduction of Serum Cholesterol with Sitostanol-Ester Margarine in a Mildly Hyper- cholesterolemic Population,” New England Journal of Medicine 333, no. 20 (1995): 1,308–1,312. marjoram (Origanum Majorana hortensis; sweet marjoram) An HERB of the mint family. Marjoram is related to OREGANO. It has light-green oval leaves with a mild sage-like flavor. It is used in salads, meat, game, poultry, and vegetables, and with tomato-based dishes, including lentils and beans. Marjoram has been used in folk medicine to ease cramps and stomach upsets. Wild marjoram is more commonly known as oregano. (See also SPICES.) marshmallow A spongy confection. Marshmal- lows are a common sweet in the United States. 420 marjoram [...]... fruits, and vegeta- mold 443 bles, and LIGNIN may increase excretion of calcium, potassium, zinc, and other minerals PHYTIC ACID, a phosphorus-containing compound present in the outer layers of grains, binds calcium, iron, and zinc In terms of supplementation, excessive amounts of one mineral can inhibit the uptake or upset the metabolism of another; zinc and copper, calcium and phosphorous, magnesium and. .. enzyme helpers (cofactors) Iodine is required in the formation of thyroid hormones and chromium supports the blood-lowering effects of INSULIN The daily requirements of major minerals (CALCIUM, PHOSPHORUS, SODIUM, CHLORIDE, and POTASSIUM) are thousands of times larger (See also JUNK FOOD; NUTRIENT DENSITY.) microvilli Minute, hair-like extensions of the surface of cells lining the small INTESTINE and. .. irrigation, farm animals account for a major part of the water consumed in the United States Half the antibiotics produced are used for livestock Meat contains 20 percent to 23 percent PROTEIN, variable amounts of fat and approximately 60 percent water The fat content depends on the type of meat, the nutritional state of the animal, the degree of trimming, and the method of preparation Meat and dairy products... during long-term high consumption of MILK together with alkaline substances such as ANTACIDS Excessive calcium may contribute to milligram 441 kidney stones, or it may be deposited in soft tissue and harden them Symptoms include vomiting, gastrointestinal bleeding and hypertension (See also ACIDOSIS; ALKALOSIS.) milk allergy A reaction of the immune system to milk and milk products The immune system recognizes... concentration) and blood volume The body requires at least 21 different minerals Seven of these are required in large amounts and are classified as “major” minerals, or macrominerals The amounts of macrominerals required daily range from a fraction of a gram to several grams Calcium, phosphate, and magnesium are bone builders and metabolic helpers Potassium, sodium, sulfate and chloride are the major electrolytes... Protein synthesis, which includes synthesizing enzymes and certain non-steroid hormones • Glycogen synthesis, the formation of the storage carbohydrate glycogen by muscle and liver • Amino Acid synthesis; formation of 10 of the 20 amino acids Health and maintenance of body weight require a balance between the opposing processes of anabolism and catabolism When anabolism exceeds catabolism, synthetic processes... and sugary foods and increase their consumption of lean meats, vegetables, and fruits Some foods contain compounds that have estrogen-like qualities These phytoestrogens are found in soybeans and other legumes and in lesser amounts in carrots, corn, apples, and oats By mimicking estrogen these phytoestrogens may lower the risk of menopause-related symptoms Moquette, Magee E Eat Well for a Healthy Menopause:... microgram amounts, as illustrated by the following adult RECOMMENDED DIETARY ALLOWANCES (RDAs): VITAMIN B12, 1.6–2.0 mcg; VITAMIN D, 5 mcg; VITAMIN K, 65 to 80 mcg; FOLIC ACID, 180 to 200 mcg; and IODINE, 150 mcg (See also MEASURES; TRACE MINERALS; VITAMIN.) micronutrients Nutrients that are required by the body in trace amounts—milligrams (thousandths of a gram) or micrograms (millionths of a gram)... muscle; the uvula, the cone-shaped structure hanging down from the soft palate; and 446 MSG related syndrome the tongue and its muscles, which form the floor of the mouth The teeth and the tongue are accessory structures of the mouth The tongue functions to move chewed food to the back of the mouth It has a characteristic rough surface due to small structures called papillae Taste buds are microscopic... CARBOHYDRATE, PROTEIN, MINERALS, and VITAMINS; the exact composition is affected by the season, the type of feed, the environmental temperature and the breed of dairy cattle In the typical American diet, milk provides about 10 percent of the daily allowances of ENERGY, 11 percent of fat intake, 20 percent of the protein, 72 percent of CALCIUM, 30 percent of PHOSPHORUS, and 12 percent of VITAMIN A In the United . percent water. The fat content depends on the type of meat, the nutritional state of the animal, the degree of trimming, and the method of preparation. Meat and dairy products supply half of the. components of mucopolysaccharides ( GLYCOSAMINOGLYCANS), components of connective tissue. A manganese-dependent enzyme of the brain synthesizes the AMINO ACID , GLUTAMINE, as a way of removing AMMONIA,a toxic. from a fraction of a gram to more than a gram. The major minerals, CALCIUM, MAGNE- SIUM, SODIUM, POTASSIUM, CHLORIDE, and PHOSPHO- RUS are considered macronutrients. These balance body fluids and

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