Elemental diet composition and the structure and function of rat small intestine: comparison of the effects of two diets on morphology and in vivo absorption of water

The effects of feeding elemental diets on small bowel structure and function in normal rats has been investigated, and two commercial diets Vivonex (#1) and Flexical (#2) compared. Rats were fed Diet #1 (n = 12) or Diet #2 (n = 12) for 1 month and jejunal and ileal histology compared with that of an equal number of rats fed on a normal pelleted diet. Diets #1 and #2 significantly increased villus height and decreased crypt height to villus height ratio in both jejunum and ileum (p less than 0.02 in all cases). Crypt height was also significantly reduced in the ileum but not jejunum by both elemental diets (p less than 0.05 in both cases). Segments of jejunum or ileum were perfused by an in vivo technique and water absorption measured to assess small bowel function. No significant difference in absorption was found between the rats fed Diet #1 and controls but absorption of water was depressed in both jejunum and ileum of those fed Diet #2. Small intestinal absorptive function is thus influenced by the composition of the elemental diet.

Hyperkalemia in patients on enteral feeding

The amount of potassium (K) in proprietary enteral feeds varies considerably from 2.7-9.2 mmol K+/g N. It has been suggested that up to 7 mmol K+/g N is required by the anabolic patient. The aim of this study was to determine the effect of a proprietary feed (Triosorbon MCT), containing 6.9 mmol K+/g N, on serum and urinary K in 13 patients requiring nutritional support. Serum electrolytes in all patients and urinary electrolytes in 7 were measured both before feeding commenced and when they had achieved an intake of between 2.4 and 3.0 liter/day (102-127 mmol K+/day) of full strength feed for a period of 1 wk. Ther serum K rose in all patients from 4.2 +/- 0.5 mmol/liter (mean +/- SD) before feeding to 5.1 +/- 0.5 after feeding for 1 wk (p less than 0.001; pair-difference t-test). The daily urinary K excretion rose from 37.8 +/- 24.2 mmol/day to 61.8 +/- 26.6 over the same period (p less than 0.001) The serum urea rose from 4.7 +/- 2.0 mmol/liter to 6.3 +/- 3.2 (p less than 0.05). No significant change was observed in other serum electrolytes, creatinine, or urinary electrolytes. During the whole course of feeding (range 1-11 wk) it was necessary to discontinue Triosorbon in 2 patients whose serum K concentration became elevated to greater than 6 mmol/liter. We conclude that the recommended levels of K intake may be too high and that serum K should be carefully monitored during enteral feeding.

Fecal characteristics in healthy young adults consuming defined liquid diets or a free-choice diet

Fat and nitrogen absorption and fecal characteristics were studied in 10 healthy, young adults who ingested a free-choice diet for 12 days and then isocaloric amounts of one of two nutritionally complete liquid defined formula diets during a succeeding 12-day period. Apparent fat absorption was 98 to 99% of intake with both defined formula diets and 95% of intake on the free-choice diet. Nitrogen digestibility was determined during the liquid diet period, and averaged 95 to 98% of intake. There were no statistically significant differences between the liquid diets and the free-choice diets with respect to fecal wet or dry weight, transit time, or stool frequency. Individual stool weights averaged 83 to 96 g on the free-choice or liquid formula diets and were comparable to other values reported in the literature. These results support the theory that a critical volume of feces must accumulate in the colon before defecation occurs, regardless of diet composition.

Effect of test meals of varying dietary fiber content on plasma insulin and glucose response

To assess the effect of dietary fiber on glucose tolerance four different meals of varying fiber content but identical protein fat and carbohydrate content were fed to eight healthy men aged 22 to 45. Each meal provided 75 g of carbohydrate as liquid glucose formula, as brown rice, pinto beans, or All Bran. The mean plasma glucose and insulin responses were highest following the formula, and least for All Bran and pinto beans. Rice produced nearly as great a rise in insulin and glucose as did the formula. The rank of each meal by content of neutral detergent fiber was nearly the inverse of the rank by magnitude of the insulin response evoked, fiber content being greatest in All Bran (18 g) and pinto beans (16.2 g), low in rice (2.8 g) and absent from the formula. It was concluded that dietary fiber dampened the insulin response to a high carbohydrate meal.

[Kinetic tracer studies on protein synthesis during infancy using chemically defined diets containing 15N-lysine as a tracer (author's transl)]

A four-month-old infant with exocrine pancreas insufficiency was fed exclusively on a chemically defined diet. The amino acid formulation of this diet (a supplemented casein hydrolyzate) corresponds to that of breast milk. The 15N labeled lysine tracer (97.4 atom-%) was included in the diet without changing its chemical score. A trace dose of 2.22 mg/kg body weight was applied for 5 days after the infant had been maintained on a chemically defined diet for 11 weeks. Urine was collected over a period of 170 h. The compartment theory was used to calculate the following metabolic data. Cumulative renal 15N excretion showed that nitrogen retention was 90.8%. Protein synthesis amounted to 10.34 g kg-1 d-1 compared with a protein breakdown rate of 8.97 kg-1 d-1. Net protein gain in this infant was about 5.5 g d-1 corresponding to a rate of 1.38 kg-1 d-1 or 13.3% of the synthesis rate. The metabolic pool amounted to 4.96 g N kg-1 d-1. 75.99 mg N kg-1 h-1 was metabolized, mainly to protein, and only about 10% was excreted with the urine.

Essential fatty acid status in premature newborns fed by nasoduodenal technique

The fatty acid composition of plasma phospholipids and the triene (20:3, n=9) to tetraene (20:4, n=6) ratio in the same lipid fraction have been determined, as indices of the essential fatty acid status, in a group of 22 healthy premature newborns fed by the nasoduodenal technique. Determinations have been carried out on the first and fifth day of life for all 22 newborns, and also on the tenth and 30th day of life for 12 of them. The normal plasma levels of essential fatty acids obtained indicate a satisfactory utilization of dietary essential fatty acids under these unusual nutritional conditions.

Trace element balance in adults receiving parenteral nutrition: preliminary data

There have been many recommendations regarding trace element needs of adults receiving total parenteral nutrition. Balance studies for zinc, copper, manganese, chromium, selenium, and molybdenum were carried out in 3 critically ill patients in an intensive care unit. Results indicate that the need for zinc was great in them, but that for copper and manganese was lower. Small negative chromium and selenium balances were observed. Molybdenum, iron, cobalt, and iodine balances were attempted but proved difficult to interpret. The requirement of each trace element varied from patient to patient, and was influenced by the presence of gastrointestinal fluid loss and renal function.

Determination of trace amounts of nitrites in fabricated nonmeat products

Low levels of nitrite (1-5 ppm) contributed by raw materials in new fabricated food products were successfully determined by a modification of an AOAC method for processed meats. Recoveries were greater than 90% for composite samples to which 5-10 ppm nitrite had been added. This method allows analyses of fabricated food products containing hydrogenated vegetable oils, soy proteins, and dried egg whites for low levels of nitrite.

Elemental content of predigested liquid protein products

Eight commercially available partially digested gelatin liquid products that have been used as a source of protein in dietary regimens for weight reduction and for protein supplementation were analyzed for their elemental composition. These products were prepared either by dry ashing or wet digestion techniques that were suitable for the analysis of individual elements by their respective analytical methods. Analytical methods used to assess the elemental content included inductively coupled argon plasma emission spectrometry for Ca, Mg, P, Fe, Zn, Cu, Mn, Ni, Mo, V, Be, Co, Cr, Tl, Al, Te, Sn and Sb; atomic absorption spectrophotometry for Na and K; hybride generation with atomic absorption spectrophotometry for Se and As; anodic stripping voltammetry for Cd and Pb; and ion selective electrode for F. The content of almost all of the elements in these products was extremely low compared with the amounts supplied daily for normal individuals by usual sources of dietary protein, the adult United States Recommended Daily Allowances, and typical intakes from the Total Diet Study. The following elements were not detectable in significant amounts in these products by inductively coupled argon plasma emission spectrometry: Mo, V, Be, Co, Cr, Tl, Al, Te, Sn, and Sb. The results suggest that use of these predigested liquid protein products as a sole source of nutriment will result in an inadequate intake of all of the essential elements. These products contained insignificant amounts of Ce and Pb, nonessential toxic elements.

Protein quality of supplements and meal replacements. Amino acids and calculated indicators of protein quality

The amino acid composition of several types of dietary supplements and meal replacements was measured and compared with label values when available and to published values for egg. Calculated indicators of protein quality, such as chemical score, protein calorie:total calorie ratio, individual essential amino acid:total essential amino acid ratio, and total essential amino acid:total amino acid ratio were also compared for products, egg, and the estimated pattern of adult requirements. Predigested liquid protein products were notably lower in protein quality than other products. All non-predigested products compared favorably with egg in terms of protein quality, but were more expensive and had no advantages over regular meals in terms of protein quality as reducing aids or protein supplements.

The growth of Moniliformis (Acanthocephala) in rats fed on various monosaccharides and disaccharides

Aspects of the course of infection, growth and reproductive activity of Moniliformis were studied in adult male and female rats fed on isoenergetic purified diets containing various sugars. When rats were infected and fed on experimental diets containing either 3% glucose or 3% galactose for 5 weeks, very little growth of worms and no signs of reproduction were observed. In contrast, Moniliformis grew well and showed many signs of normal reproduction when the rats were fed on diets containing either 3% fructose or 3% mannose. The ability of the worms to grow and reproduce was not lost by maintaining them first for 5 weeks in rats fed on diets containing 3% glucose and 3% galactose. When the diets of such rats were changed to ones containing 3% starch and 3% fructose, respectively, for a further 5 weeks, the worms grew and normal reproduction occurred. Similar experiments were carried out in which groups of infected rats were fed for 5 weeks on diets containing gradually increasing amounts of glucose (6-36%). It was not until the rats were fed on diets containing 24% glucose that the mean dry mass of the worms approached that of worms from rats fed on the diet containing 3% fructose; no host diet was found to be as effective a supporter of worm growth as 3% mannose. Under no circumstances, not even when the host's diet contained 36%, was galactose found to be a suitable sugar for supporting the growth and reproduction of Moniliformis. Results consistent with those recorded for worms from rats fed on the diets containing monosaccharides were obtained when infected rats were fed for 5 weeks on diets containing 3% of various disaccharides. Considerable growth and reproduction of Moniliformis occurred when sucrose was included in the host's diet, but not when lactose, maltose or trehalose was present. Several of these observations may be related to the fact that different sugars are absorbed at different rates from the intestinal tract. It is suggested that all of a given sugar, when present in the diet at a low concentration, may be removed rapidly from the anterior part of the small intestine with the result that none will be available to the parasites. Significant amounts, however, of those sugars that are absorbed more slowly may reach the region of the intestine in which the parasite normally lives.

Addition of potassium supplements to milk-based tube feeds

For an intragastric tube feeding regimen to meet the complete nutritional needs of the individual patient, it will often require the addition of extra potassium, to commercially available feeds. Potassium supplements in a suitable form can be added to milk-based feeds to concentrations of at least 175 mmol K+ per litre without any apparent coagulation. Supplements in the form of effervescent preparations are not suitable as the citric-acid content can cause severe coagulation of the feed.

[Remission spectrometric determination of vitamin D in dietetic food]

This method deals with the determination of vitamin D in dietetic food, specially in baby food. For this purpose normally 4 clean-up resp. enrichment steps are necessary (extraction, saponification, liquid-solid chromatography and TLC), followed by the determination of vitamin D by means of reflectance spectroscopy.

[Problem of using dehydrated food products in long-term space flights]

The paper discusses the results of five studies on 35 test subjects conducted to test diets of dehydrated products to be used in prolonged space flights. The studies have demonstrated that a diet consisting of only dehydrated food products can be used for a prolonged time (up to 1 year). Dehydrated foods after a 2-year storage and proton irradiation at a dose of 24,000 rad retain their biological value and assure an adequate nutritional status. On this basis a space diet composed of dehydrated foods has been developed.

A simple low-magnesium diet

Details are given of a semi-synthetic low-magnesium diet that provides adequate short-term nutrition. The diet is made up of proprietary foodstuffs and is suitable for short-term magnesium deprivation studies in man. After five days on the diet four subjects demonstrated a marked fall in urinary magnesium excretion.

A comparison of formulated liquid diets

A wide variety of formulated liquid diets are currently available on the Canadian market. Used for oral and tube feedings, they are nutritionally complete diets when offered as the sole source of nourishment for patients who are unable or unwilling to take solid food. To assist dietitians in identifying formulas most suited to patients' requirements, products are listed according to nutrient composition, caloric density, osmolality and packaging.

Very-low-calorie diet in the treatment of massive obesity: preliminary experience

Twenty-two consecutive obese patients were given very-low-calorie diet (VLCD) in the form of a casein and lactose preparation dissolved in orange juice containing 43.0 g protein, 30.4 g carbohydrate and 1.1 g lipid in a total of 317 kcal (1.3 MJ) daily. VLCD was given intermittently in eight-week periods alternating with three-week periods of conventional diet (900-1200 kcal, 3.8-5.0 MJ) to ensure recuperation of lean body mass and to establish a therapy which may facilitate indefinite patient compliance. In case of persisting hunger, diethyl-propion was given in small doses. The median observation time was nine weeks (range 1-37 weeks). The median weight loss was 15.5 kg (range 3.8-39.2 kg), and the median overweight decreased from 85.5 per cent (range 43-135 per cent) to 61.0 per cent (range 19-100 per cent). Blood glucose and cholesterol fell significantly (P < 0.01), and no major side-effects were observed.

Carnitine content of liquid formulas and special diets

Radioisotopic analyses for carnitine content were done on infant formula, formulas for tube feeding, food supplements, and chemically defined diets. The carnitine content of the diets depend on the protein source. Products whose main protein source is soy protein isolate, casein, or egg white solids contain 4 nmole carnitine per milliliter or less, with most of them containing undetectable amounts of carnitine. Products based on milk or beef contain 50 to 656 nmole carnitine per milliliter. The daily requirement of the body for carnitine is unknown. Evidence is discussed that indicates that the possible use of carnitine as a supplement to formula diets intended for long-term care needs to be considered.

Oral fluid therapy: sodium and potassium content and osmolality of some commercial "clear" soups, juices and beverages

Analysis of nearly 90 commercial "clear" fluids, including soups, juices, fruit-flavoured drinks and ices, carbonated beverages and gelatins, showed a range of 0.1 to 251 mmol of sodium and 0.0 to 65 mmol of potassium per litre; the osmolality ranged from 246 to more than 2000 mOsm/kg of water. Knowledge of these values is useful in the home or hospital management of patients for whom control of fluid and electrolyte intake is indicated. The results of the analyses are presented in tabular form for use by physicians and nutritionists when counselling patients to ingest clear-type fluids for various illnesses. Examples are given using these data to show how clear-fluid therapy can be tailored in one such illness--gastroenteritis (infectious diarrhea).