l)ysphagia 4:1~9 195 (1t)90) T

~

~

6

~e6

Ds, s [ )i lag a Npl m . e e i - V c l k l b, Ne',; ~ ntk Ira.' I')t)l~

Nutritional Assessment and Requirements Perry L. Kamel, M.D. Northwestern Universily Medical School, Chicago, Illinois, USA

Nutrition is a broad science that includes the study OFall processes by which lk~od is utilized l\~r energy and preservation of body function. Health care Workers should be thmiliar with basic nutritional requirements and be able to assess the broad nutritional status of their patients. The role of nutrilJon in health maintenance and in various disease processes has increasingly become the lk)cus of reSearch and clinical investigation. Protein and calorie malnutrition is common in both acutely and chronically ill patients and has a deleterious impact on clinical outcome [1]. However, malnutrition is not confined to hospitalized patients but can also he found in the community, especially in thc clderly and the poor. The following provides an OVerview of the fundamentals of nutritional assessment and basic requirements of knowledge lbr the health care professional.

Nutritional Assessment The presence of malnutrition has multiple manifestations, ranging l'rom behavioral abnormalities Such as decreased concentration and confusion to generalized weakness, poor wound healing, and increased susceptibility to infection. Thus, the first Step in preventing the complications oF nlalnulrition is being able to identify patients with predisposing litclors who are al risk, as well as knowmg the clinical signs and symptoms of malnutrilion. The initial evaluation should always include a llistory to elicit risk factors for mal|mtrition, which include inadequate intake, exccssive nutrient loss, Address rr requests to. Perry L. Kamel, M .D., 680 N. I.akc Shore Drive, Suilc 822, Chicago, II, 6061 I, USA

and increased rcquirements. Inadequate intake may be associated with depression, alcohol or" drug abuse, anorexia duc to medications, and chronic medical illnesses. Excessive nutrient toss may be secondary to chronic diarrhca associated with malabsorplion syndrome or inllammatory bowel discase or may bc due to chronic nausea and vorniting. Increased calorie and protein requirements are seen in the acutely ill patient with extensive burns o r infections as wcll as in pregnant patients. A Functional assessment of lhe palient's ability to fccd indcpendcntly should also bc part of the initial cwduation. This becomes especially important for the elderly, who may have chronic debilitating illnesses or neuromuscular diseases that limit their ability to prepare meals and use eating utensils. Elderly patients who have experienced strokes nmy have oropharyngeal disorders with poor ability to swallow, thus placing them at risk l\)r aspiration. Poor dentition may interfere with eating solid fl~ods and necessitate a soft or pureed diet. This Functional assessment often requires a multidisciplinary approach, with the expertise of a physician, dietician, speech language pathologist, nurse, and occupational and physical therapists. Physical examination is thc next step in the clinical evaluation and does not require a great dcal of expertise or experience. Gross evidence of protein and calorie mahmlrition is evident on physical examination and vitamin and mineral deficiency will bc evident to an astute observer. Subtle nutrient deficiencies often require laboratory evaluation lk~r confirmation. The earliest signs of protein and calorie deftciency present as changes in mental status, with apathy, irritability, poor ability to concentrate, and anorexia. These are nonspecific complaints but, taken in the context of a patient's clinical situation, may be the first clues to lhe presence of malnulri-

190

tion. Other nonspecific findings include flaking, dry skin, nail changes, cracked lips, either atrophy or a beefy red appearance of the tongue, easy bruising, poor wound healing, edema, and muscle wasting. Again, these physical findings are nonspecific but may represent signs of either vitamin or mineral deficiency. Anthropometric (body) measurements provide clues to the general nutritional state of a person. The most important and often overlooked measurement is a patient's weight, especially when a previous weight is known. A person's ideal weight may be obtained from weight-for-height tables, which are based on population studies and probably mildly overestimate the ideal body weight. Formulas for the calculation of ideal body weight based on height also provide a reasonable estimate. The presence of edema should also be noted since edema will overestimate the amount of lean body tissue present. Weight loss is a key clinical indicator of malnutrition. A loss of more than 10% of total body weight over 6 months or a weight below 90% of the ideal is associated with malnutrition [2]. Weight is also an important clinical parameter to evaluate in the process of nutritional repletion. Hydration status should also be evaluated, since water is the most common essential nutrient. Dehydration is evidenced by poor skin turgor, dry mucous membranes, and lack of axillary sweat. Mental status changes often are associated with dehydration in the elderly. Evaluation of the elderly may be more difficult due to the loss of skin elasticity with aging and the common presence of mouth breathing associated with a dry oral pharynx. A rough estimate of the body's fat stores can be made by measuring the triceps skinfoid thickness, which can be compared to reference standards [3]. This measurement is usually done with calipers for nutritional studies but it can be used as a general estimate without exact measurements. The body's protein content, which accounts for approximately 15% of the total body mass, has traditionally been divided into two compartments, representing a somewhat arbitrary dichotomy. The somatic component represents skeletal muscle and supporting connective tissue, while the visceral component represents internal organ protein and secretory protein. This distinction often does not hold up well in clinical practice. Evaluation of the muscular or somatic protein stores is important because the body tends to catabolize muscle in the presence of protein and calorie starvation to provide energy while preserving visceral proteins.

P.L. Kamel: Nutritional Assessment and Requirements

Muscular protein stores are evaluated by measuring the upper midarm muscle circumference ( M A M C ) - the midpoint between the shoulder and elbow - and comparing the value to a table of standard values [3]. Measurement of the MAMC is a gross measure of malnutrition and does not detect early protein-calorie deprivation. Severe wasting of muscle protein stores as evidenced by a decrease in the M A M C or by temporal muscle wasting is a reflection of advanced malnutrition. The last phase of the clinical evaluation of a patient's nutritional status includes a basic laboratory assessment of several hematologic and immUnologic values and measurement of various serum protein levels. Often these values are the most sensitive parameters for detecting early malnutrition, but overall they tend to c o n f r m the initial clinical impression. A diagnosis of malnutrition is best determined by an overall clinical judgement rather than a single laboratory value [4]. The laboratory tests for malnutrition include a complete blood count which provides valuable information concerning whether anemia or a decreased total lymphocyte count is present. Both suggest the presence of malnutrition. There is a rough correlation of the total lymphocyte count (TLC) and the severity of malnutrition. A TLC below 800 mm 3 indicates severe protein-calorie deprivation, 800-1200 moderate deprivation, and 1200-1500 mild deprivation [5]. Various serum proteins including total protein., albumin, transferrin, and total iron binding capacaty are measured to estimate the visceral protein stores. In starvation, these proteins are preserved to a greater extent than somatic protein storeS, presumably to preserve immunological function and wound healing ability. The correlation between visceral protein stores and serum proteins in acute illness may be poor. Total protein, which includes both albumin and globulin, is unreliable in certain chronic and acute inflammatory illnesses due to elevated serum globulin levels. Serum albUmin levels are dependent on the rate of the protein's production and destruction as well as distri" bution between intra- and extravascular space. Acute illness reflected by rapid protein loss, as seen in trauma and burn patients, may result in albumin levels that do not accurately reflect visceral protein stores [6]. However, serum albumin determination is valuable in the chronic stable patient since it is widely available and is the least expensive laboratory parameter to follow that reflects overall nutritional status. Since the half-life of albumin is relatively long (20 days), it may not reflect acute alterations in nutrition. Serum transferrin, the se-

P.L. Kamcl: Nutritional Assessment and Requirements

191

rum protein that transports iron, has a shorter half-life (8-10 days) and can be more useful in determining the acute response to changes in nutritional status. Total iron-binding capacity may be substituted for transferrin [7]. Measurement of serum electrolytes, calcium, magnesium, and phosphorus should also be ineluded in the initial laboratory evaluation, since these are a reflection of an adequate total caloric intake and an adequate vitamin and mineral intake. Anergy batteries may be used to assess whether cell-mediated immunity is intact, but these parameters do not lend themselves to long-term follow-up. The presence of nutritionally induced anergy is a Poor prognostic sign in an acutely ill patient [8].

cific and nonspecific symptoms and signs since more than one nutrient is often deficient. Nutritional diseases used to be extremely common in the general population of this country due to lack of knowledge, poverty, and unavailability of certain foods. Rickets, pellagra, and beriberi are just a few of the diseases secondary to vitamin deficiencies that were commonly seen in this country and are still seen in underdeveloped areas of the world along with protein--calorie deficiencies. Calories are the basic unit of energy expenditure. The total caloric requirement represents the sum of the basal metabolic rate (BMR) and the energy needcd for activity. The BM R is the amount of energy expended at rest, which is influenced by age, sex, weight, and height and can be estimated by the Harris-Bencdict formula:

Nutritional Requirements

B M R for adult m a l e s = 6 6 + 13.7 (wt. in kg) + 5 (ht. in c m ) - 6 . 8 (agc)

Nutritional requirements (see Table 1) can be expressed as either dietary goals or recommended dietary allowances (RDAs) [9]. Dietary goals are recommendations designed to reduce the incidence of chronic degenerative diseases [10]. Recently, dietary goals have been released by both the National Institutes of Health [11] and the National Cancer Institue [12] with the hope that these will help to reduce the incidence of coronary heart disease and various malignant diseases. R D A s are specific recommendations for dietary intake that will ensure that the vast majority of people will not suffer nutritional deficiencies. The basic nutritional requirements include adequate intake of calories, protein, essential fats, vitamins and minerals, trace elements, and fiber. Deficiencies of any of these components lead to speTable I. RDAs for essential nutrients Calorics (kcal)

Females 2000 Males 2700

Complex carbohydrates

55% of calorics

I~'at

30% of calories

EFAs

2 4 % of calorics

Protein

15% of calorics 0.8 gs/kg

Fiber

35 g/day

Water

35 ml/kg

Salt

2~, g/day

Iron

Males 10 mg/day Females 18 mg/day

Calcium

1.0 g/day 1.5 g/day (postmcnopausal women)

B M R for adult fcmalcs -- 655 + 9,6 (wt. in kg) + 1.8 (ht. in c m ) - 4 . 7 (age). The B M R can also be estimated for patients weighing between 60 and 80 kg with the formula B M R = 25 kcal/kg. The degree of activity and level of physical stress will determine the amount of extra calories needed to maintain a person at a stable weight. Typically, 400--800 extra calories are required for sedentary and light activity. The average adult man requires approximately 2700 kcai per day while the average adult woman requires 2000 kcal per day, Scvere stress associated with acute illnesses such as extensive burns and sepsis requires an increased caloric intake. Calories are principally provided in the form of carbohydrates and fats. Simple carbohydrates include sugars such as sucrose or table sugar, lactose or milk sugar, and fructose or fruit sugar, They may be in the form of disaccharides such as sucrose, which yields glucose and fructose with digestion, and lactose, which yields glucose and galactose. Complex carbohydrates are starches: essentially large molecules of repeating sugar units. Starches are found in foods such as grains, rice, legumes, and root vegetables. Each gram of carbohydrates provides 3.4 calories of energy so, contrary to general belief, carbohydrates arc not a dense source of calories and should be the mainstay of a weight reduction diet. Current dietary goals are for a decreased intake of simple carbohydrates, which represent relatively " e m p t y " calories since they do not usually provide other essential nutrients, along with an increased intake of complex carbohydrates. Total carbohydrate intake

192

should provide roughly 45-55% of a person's total daily caloric intake [10]. Dietary fats are predominantly in the form of triglycerides: a glycerol molecule attached to three long-chain faty acids of variable length. Triglycerides are calorie dense and provide 9 kcal/g: 1 oz of fat containing 28 g provides 252 calories or 10-15% of an average person's daily caloric requirement. Fats can be saturated, monosatured, or polyunsaturated, which refers to the number of double bonds present in the long carbon backbone of the fatty acids. Saturated fats do not have double bonds and are found in red meat, dairy products, and certain vegetable oils such as palm and coconut oil. Saturated fats have been associated with an increased risk of heart disease because of their cholesterol-elevating effect. Current dietary goals are to decrease the portion of saturated fats in the diet. A high intake of saturated fats has also been associated with an increased epidemiologic risk for certain malignancies such as breast, colon, and prostate cancer. Monosaturated fats have one double bond in the fatty acids, are commonly found in olive oil, and are not associated with an increased risk of coronary artery disease. Polyunsaturated fats have multiple double bonds, act to lower the cholesterol level, and decrease the risk of heart disease. Linoleic acid and linolenic acid are essential fatty acids (EFAs), which are required for maintenance of health. They are necessary precursors for the biosynthesis of arachidonic acid, which provides the backbone of various hormone-like compounds including prostaglandins and leukotrienes. The body cannot synthesize EFAs from other fatty acids, so they must be derived from the diet. EFA deficiency is usually not seen clinically since they are commonly found in vegetable oils, but may be seen in patients receiving long-term parenteral nutrition whose diet is not supplemented with EFAs. The deficiency syndrome is characterized by a dermatitis with dry, flaking skin and failure to thrive [13]. Recent attention has been focused on fish oil, which is categorized as an omega fatty acid because it contains an odd number of carbon atoms instead of the usual even number, as seen in vegetable and animal fats. These omega fatty acids are commonly found in cold water fish and are associated with a decreased risk of coronary artery disease. Current recommendations by the National Institutes of Health (NIH) and the American Heart Association (AHA) are for a decreased intake of total fat in the American diet, to increase the proportion of poly- and monosaturated fats, and to decrease the proportion of saturated fats. The recommended

P.L. Kamel: Nutritional Assessmcnt and Requirements

percentage of calories to be provided by fat in the diet is 30%, with a 1 : 1 polyunsaturated/saturated fat ratio. Cholesterol has also been linked with an increased risk of atherosclerosis, and recent clinical studies have confirmed the efficacy of lowered serum cholesterol in decreasing mortality rates from coronary artery disease. The majority of cholesterol is synthesized by the body and is vital for the formation of cell membranes, production of bile acids, and is the backbone for various steroid hormones. Dietary cholesterol contributes a relatively small but significant portion of the total serum cholesterol and the N I H and the A H A have advised limiting dietary cholesterol intake to 250~300 rag/day, which is the equivalent of the cholesterol content of one egg yolk. Diets low in saturated fats will also be low in cholesterol [11]. Protein is required for structural support of muscle and cells as well as for transport and for immunologic and enzymatic function provided by secretory and intracellular proteins. Amino acids are the basic building blocks of protein and there are eight essential amino acids that the body cannot synthesize on its own: isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptO" phan, and valine. Clinical data have recently sug" gested that histidine and tyrosine may become indispensable amino acids in certain disease states secondary to either increased demand or decreased synthesis. High-quality protein found in meat, poultry, fish, eggs, and dairy products provides all the essential amino acids in adequate amounts. Egg whites contain the optimum combination of essential amino acids and provide the standard that other proteins are compared to in terms of efficiency of converting ingested amino acids into endogenous protein. Low-quality protein has inadequate amounts of one or more essential amino acids and cannot be used by the body as efficiently to build protein. Low-quality protein from various sources can be combined to provide complementary essential amino acids, as in the case of grains and legumes. The usual daily protein requirement is 0.8 g high-quality protein/kg of body weight, which is approximately 55-60 g for the average 70 kg person. Most Americans eat far more protein per day than is required for the maintenance of good health. The excess protein cannot be stored, as is the case for carbohydrates and fats, but instead is metabolically converted to glucose by the liver to provide an energy source. Total protein intake should provide approximately !5% of the daily energy requirements at a rate of 4 kcal/g [10]. Total calorie deprivation presents with marked

P.L. Kamel: Nutritional Assessment and Requirements

fat and muscle wasting and is termed marasmus. It is usually associated with protein deprivation and other nutrient deficiencies, since adequate protein, vitamin, and mineral intake is often dependent on adquate total caloric intake. Kwashiorkor, or protein deficiency, may present without total calorie deprivation and is clinically evident as muscle wasting and edema. Vitamins are nutrients required in minute quantities that serve as coenzymes or precursors of coenzymes in various metabolic functions but are not used for energy or structural units. They are classified as either fat or water soluble and cannot be synthesized by the body, except for two fat-soluble vitamins, vitamin D and K. Fat-soluble vitamins, which include vitamins A, D, E, and K, can be stored by the body, while water-soluble vitamins, which include the B complex and vitamin C, cannot be stored and are required daily. Vitamin B 12 is the exception, since the liver can store up to a 2 year supply of B12. Vitamin deficiency is closely connected to low calorie intake or an increased metabolic need. Recommended daily allowances of vitamins are set at a level such that the majority of people should not develop clinical deficiency syndromes. Pregnant women and nutritionally depleted patients such as chronic alcoholics generally require more than the RDA. Table 2 (9) presents the R D A of each vitamin, its physiological role, and the clinical manifestations of a deficiency state. The most commonly seen vitamin deficiencies include folate and thiamine deficiency, which cause megaloblastic anemia and mental status/memory disorders, respectively, and are commonly seen in alcoholic patients. Mineral and trace elements are required for maintenance of the skeletal system, neuromuscular function, and to serve as cofactors for various enzymatic reactions. Calcium is the most abundant mineral and, along with phosphorus, forms the lat-

193

rice support of bone. Poor calcium intake early in life has been associated with postmenopausal osteoporosis, which is a great source of morbidity and mortality due to the increased risk of fractures, especially of the hip. Increased calcium intake should be stressed in high-risk groups, which include thin, white women and women with a family history of osteoporosis. The R D A for calcium in premenopausal women is 1.0 g and 1.5 g for postmenopausal women [14]. This can be provided by 4 to 6 Turns or Rolaids per day, which are inexpensive sources of calcium carbonate. Iron is required for adequate hemoglobin synthesis, especially in menstruating or pregnant women, who have an increased need for iron. Anemia is a late sign of iron deficiency; iron absorption can be increased with coadministration of vitamin C. Trace elements include magnesium, zinc, copper, manganese, and chromium. Magnesium deficiency is associated with use of diuretics and may present as generalized weakness, depression, and behavioral changes. Zinc is a cofactor for several enzymes and is required for normal wound healing and maintenance of the senses of taste and smell. Copper is needed for hemoglobin synthesis. Manganese is required for normal bone formation and nerve function. Chromium serves as a cofactor for insulin. Salt or sodium is required for maintenance of the extracellular fluid volume and contributes to the cell membrane electrical potential difference needed for nerve conduction by its differential extra- and intracellular fluid concentration. The average American's salt intake is 3-6 g/day, which is heavily influenced by sodium-laden convenience foods. Salt plays a causative role in hypertension for 10-20% of Americans with sodium-sensitive high blood pressure. Universal sodium restriction is controversial, but hypertensive patients and pa-

Table 2. Vitamins: RDAs, physiological roles, and results of nutritional deficiency Vitamin

RDA

Physiological role

Result of deficiency

A Thiaminc Riboflavin Niacin B6 Folic acid BI2 C D E K

5000 IU 1.4 mg 1.6 mg 18 mg 2.2 mg 0.4 mg 3 pg 60 mg 400 IU 10 mg None

Vision, reproduction, and immunity Coenzyme; Cardiac and nervous system Coenzyme; skin and blood Coenzymc: epithclium and CNS Coenzyme amino acid metabolism Maturation of red blood cells Maturation of red blood cells, CNS Collagen formation Calcium and phosphate metabolism Antioxidant Clotting cascade

Night blindness Beriberi, Wernicke-Korsakoff Syndrome Cheilosis and anemia Pellagra; dermatitis, diarrhea, dementia Neuropathy, cheilosis Megaloblastic anemia, diarrhea,' cheilosis Neurologic deficits, megaloblastic anemia Poor healing, bleeding gums, easy bruising Hypocalcemia, rickets, osteomalacia Neurologic deficits Hemorrhage

194

tients with a family history of hypertension should limit their salt intake to about 2 g/day [10]. Water is the most common essential nutrient and contributes over one-half of the total adult body weight. Water is required for chemical reactions and transport and has a structural role in cells. Most water comes from drinking fluids, about 1.0-1.5 l/day, and another 0.7-1.0 I are derived from food. Daily adult requirements are approximately 35 ml of fluid/kg; requirements for children are higher: 50-60 ml/kg. Fluid requirements can be markedly increascd by fever and perspiration with activity or heat. This may be a significant problem for the elderly, who often have decreased thirst and are susceptible to dehydration [15]. Fiber has also been increasingly in the public eye due to its efficacy in treating constipation and more, recently, its ability to lower serum cholesterol when taken in large quantities. Fiber actually is not a homogeneous substance and exists in several forms, which can be classified into soluble and insoluble fiber. Water-soluble fiber includes gums found in oatmeal and legumes and pectins found in strawberries, apples, and citrus fruits. Gums found in foods such as oat bran can be helpful in lowering serum cholesterol levels. Psyllium, which is found in the husks of whole grains, and wheat bran are insoluble forms of fiber and are very effective in providing bulk for the alleviation of constipation. Psyillium is also useful in lowering serum cholesterol levels [16]. Each gram of psyllium or bran increases the stool weight by 4 g, by increasing the water content and bacterial volume of the stool. There is no R D A for fiber but it is generally agreed that most Americans eat too little fiber in their diet: An intake of 25-35 g daily has been recommended by the National Cancer Institute. For fiber to be effective in treating constipation, adequate fluid intake, at least 8 10 glasses/ day, must be assured and the increase in dietary fiber should be gradual to avoid side effects such as flatulcnce. Health is not only affected by nutritional deficiencies but is also adversely affected by excess of various nutrients. The most common problem is excess caloric intake manifested as obesity, which is a major health problem in this country and may represent the most important nutrition-related problem among Americans. An estimated 25% of Americans are overweight (20% above their ideal body weight) and suffer increased morbidity secondary to a higher incidence of hypertension, degenerative arthritis, diabetes mellitus, as well as subtle and blatant social discrimination [17]. Epi-

P.L. Kamel: Nutritional Assessment and Requirements

demiologic data have recently correlated abdominal obesity with a higher morbidity and mortality rate than lower torso obesity [18]. Also, vitamins in " m e g a " dose form can be obtained at most health food stores and may result in toxic effects if taken daily. Megadoses of vitamin A in the 50,000 1U/day range are associated with liver toxicity and megadoses of vitamin D with hypercalcemia. Excessive intake of iron can lead to hemachromatosis, a syndrome of iron overload manifested by cardiac, pancreatic, and hepatic dysfunction related to tissue iron deposition. Alcohol is another " f o o d " that is abused, cauSing multiple medical problems including cirrhosis, pancreatitis, and cardiomyopathy. Alcohol is also synergisitc with tobacco in increasing the risk for oral cavity, laryngeal, and esophageal carcinoma. Alcohol abuse is the source of a huge social problem that affects a large percentage of the population. Universal dietary recommendations include moderate consumption of alcohol, not to average more than one drink per day.

Summary Nutrition plays an important role in health and disease, both in prevention and treatment. IncreaSing emphasis is being placed upon nutrition as a therapeutic tool to decrease the morbidity and mortality associated with obesity, hypertension, coronary artery disease, and cancer. Adequate r~utrition should be a concern for all health care workers because of its impact on the overall health of patients. Health care professionals should be familiar with the essentials of nutritional assesSment and basic nutritional requirements and be able to improve their patients' care in the face of nutritional deficiencies or excesses.

References 1. Apelgren K N, Rombeau J I., Twomey PL, Miller RA: Corn" parison of nulrilional indices and outcome in critically ill patients. Crit Care Med 10: 305-3(17, 1982 2. Blackburn GL, Bistrian BR, Maini BS: Nutritional and metabolic assessment of the hospitalized patient. ,I Parenter" al Fnteral Nutr I : 11-12, 1977 3. Frisancho AR: New norms of upper limb lat and muscle areas for assessment of nutritional status. Am J (flirt Nutr 34.2540 2545, 1981 4. Baker JP, Dclsky AS, Wesson DE, Wolman SL, Stewart S, Whitewell J, Langer B, Jecjeephoy KN: A comparison of clinical judgement and objcctive measurements. N Engl J M e d 3 0 6 : 9 6 9 972, 1982 5. Ilenderson CT: Nutrition and malnutrition in the elderly nursing home palienl. In Zweibel NR, Casscl CK (cds): Clinics hz Geriatric Med. Philadelphia; WB Saundcrs, 4:527 547, 1988

P.L. Kamel: Nutritional Assessment and Requirements 6. Anderson CF, Wochos DN : The utility of serum albumin in the nutritional assessment of hospitalized patients. Mayo Clin Proe 57.181 184, 1984 7. Buzby GP, Mullen JL: Nutritional assessment. In Rombeau J L, Caldwcll M D (eds):Enteral and Tube Feeding. Philadelphia: WB Saunders, 127 147, 1984 8. Twomey R, Ziegler D, Rombeau J : Utility of skin testing in nutritional assessment : a critical review. J Parenteral Enteral Nutr 6 . 50-58, 1982 9. Committee on Dietary Allowances Food and Nutrition Board, National Academy of Sciences: Recommended Dietao~ Alhm'am'es. 9th ed. Washington: National Academy of Sciences, 137-144, 1980 10. US Dept. of Agriculturc/US Dept. of Health and Ituman Services: Nutrition and Your Health. Dietary Guidelines.[or Americans, 2nd ed. Home and Garden Bullctin No. 232. Washington, DC: US Government Printing Office, 1985 11. National Institutes of t Icalth Consensus Development Conference Statement: Lowering blood cholesterol to prevent heart disease. J A M A 253 : 2080-2090, 1985 12. National Cancer Institute: Diet. Nutrition and Cancer Pre-

195 r,ention: A Guide to Food Choices. NIH Publ. No. (NCI),

85 2711, 1984 13. Bjcrve K, Mostad [L, Thorcson L: Alpha-linolenic acid deficiency in patients on long-term gastric tube feeding: estimation of linolenic acid and long-chain unsaturated n-3 l;atty acid requirement in man. Am ,I Clin Nutr 4 5 : 6 6 77, 1987 14. Hcaney RP, Gallagher JC, Johnston CC, Neer R, Parfitt AM, Whedon G P : Calcium nutrition and bone health in the elderly. Am J Cl#1 Nutr 36. 98(~1013, 1982 15. Phillips PA, Rolls BJ, Lcdingham JGG, Forsling M L, Morton J J, Crowe M, Wollner L: Reduced thirst after watcr deprivation in healthy elderly men. N ~)Tgl J M e d 311:753 759, 1984 16. Anderson JW, Zettwock H, Fcldman T, Tietycn-Clark J, Oeltgen P, Bishop CW :Cho[estcrol lowering effects of psyllium hydrophillic mucilloid Ik)r hypercholesterolemic men. Arch httern M e d 147r 1988 17. Andres R : Effect of obesity on total mortality, hTt J Obesity 4:381 386, 1980 18. Bjorntrop P: t lazards in subgroups of h u m a n obesity. Eur J Clin hwest 14: 239-241, 1984