The effects of zinc supplementation on serum zinc concentration and protein catabolic rate in hemodialysis patients.

OBJECTIVE: To examine the effect of zinc sulfate supplementation on serum zinc concentrations and protein catabolic rate (PCR) in hemodialysis (HD) patients. DESIGN: Randomized, double-blind, before-after trial. SETTING: Outpatient dialysis center in a large metropolitan city. PATIENTS: Twenty-eight maintenance HD patients were selected. Twenty (15 women, 5 men) subjects completed the study. Subjects were identified for inclusion in the study by the following criteria: a history of low PCR (<0.09 g/kg body weight), HD treatment for a minimum of 6 months, no signs of gastrointestinal disorders, and no record of hospitalizations for reasons other than access complication within the last 3 months. INTERVENTIONS: Patients consumed 7.7 pmol zinc sulfate (2,200 microg) or a cornstarch placebo capsule daily for 90 days. In addition, patients completed a 2-day food record representative of 1 dialysis day and 1 nondialysis day. MAIN OUTCOME MEASURE: Fasting, predialysis serum samples were collected on days 0, 40, and 90 to determine serum zinc concentration and PCR. Dietary parameters including intake of zinc, protein, and energy were analyzed on Days 0 and 90. RESULTS: Initial analysis at Day 0 of serum zinc concentration indicated subjects were below the normal range for serum zinc standards (12.2 micromol/L [80 microg/dL]). After supplementation, subjects in the zinc-supplemented group showed significant increases in serum zinc concentrations from 12.2 micromol/L (80 microg/dL) at Day 0 to 15.3 pmol/L (100 microg/dL) at Day 90. A significant positive correlation (r = +0.61) was shown between PCR and serum zinc concentrations at the end of the study. Reported dietary protein intake did not change with zinc supplementation. CONCLUSION: Low serum zinc concentrations are reversible with zinc supplementation. Improvement in serum zinc concentration increases the PCR of HD patients.

Cottonseed protein: what does the future hold?

Cottonseed protein has the potential to increase the world's food supply while decreasing the incidence of malnutrition among the world's hungry. Nutritionally, cottonseed flour compares favorably to other animal and vegetable protein sources, as it is low in fat and contains a substantial amount of high biological value protein. Animal studies, as well as human research, using gossypol-free glandless cottonseed flour have shown that cottonseed protein promotes growth, increased weight gain, and a positive nitrogen balance. Cottonseed protein food products have been shown to be a healthy addition to the diets of children, college-age women, and the elderly. With its light color and bland flavor, cottonseed has many uses in the food processing arena. Baked goods, snack foods and candy, as well as pet and livestock feed are just a few successful products developed utilizing cottonseed protein.

Early enteral nutrition support in patients undergoing liver transplantation.

BACKGROUND: The purpose of this study was to determine the effects of early postoperative tube feeding on outcomes of liver transplant recipients. METHODS: Fifty transplant patients were randomized prospectively to receive enteral formula via nasointestinal feeding tubes (tube-feeding [TF] group) or maintenance i.v. fluid until oral diets were initiated (control group). Thirty-one patients completed the study. Resting energy expenditure, nitrogen balance, and grip strength were measured on days 2, 4, 7, and 12 after liver transplantation. Calorie and protein intakes were calculated for 12 days posttransplant. RESULTS: Tube feeding was tolerated in the TF group (n = 14). The TF patients had greater cumulative 12-day nutrient intakes (22,464 +/- 3554 kcal, 927 +/- 122 g protein) than did the control patients (15,474 +/- 5265 kcal, 637 +/- 248 g protein) (p < .002). Nitrogen balance was better in the TF group on posttransplant day 4 than in the control group (p < .03). There was a rise in the overall mean resting energy expenditure in the first two posttransplant weeks from 1487 +/- 338 to 1990 +/- 367 kcal (p = .0002). Viral infections occurred in 17.7% of control patients compared with 0% of TF patients (p = .05). Although other infections tended to occur more frequently in the control group vs the TF group (bacterial, 29.4% vs 14.3%; overall infections, 47.1% vs 21.4%), these differences were not statistically significant. Early posttransplant tube feeding did not influence hospitalization costs, hours on the ventilator, lengths of stay in the intensive care unit and hospital, rehospitalizations, or rejection during the first 21 posttransplant days. CONCLUSIONS: Early posttransplant tube feeding was tolerated and promoted improvements in some outcomes and should be considered for all liver transplant patients.

Effect of major dietary modifications on immune system in patients with breast cancer: a pilot study.

A pilot study was conducted to evaluate the effect of diet on immune function in nine premenopausal, post-therapy patients with breast cancer. The patients were instructed on following the American Cancer Society dietary guidelines and were told to do so from day 0 to day 28. These guidelines recommend a high-fiber, low-fat diet. On day 29, the patients continued the diet but included fish high in omega-3 fatty acids until day 56. Twenty-four-hour urine and blood samples, and 3-day diet records were obtained on days 0, 28, and 56. The following parameters were monitored: lymphocyte subsets, T-cell function (proliferation and cytolytic response), and urinary prostaglandin E2 (PGE2). Results throughout the study suggested a benefit from decreasing dietary fat intake, and increasing fish intake. Helper T-cell (CD4) percentage increased from day 0 to days 28 and 56 (P = 0.048). Cytotoxic/suppressor T-cell (CD8) percentage decreased from day 0 to days 28 and 56 (P = 0.002). The CD4/CD8 cell ratio increased by days 28 and 56 (P = 0.0004). The proliferation of CD4 cells increased from day 0 to days 28 and 56 (P = 0.005). Significant changes were not found in the cytolytic activity of T cells, natural killer cells, total T and B cells, or urinary prostaglandin E2. Results suggest that patients with breast cancer may benefit from following American Cancer Society dietary guidelines and consuming cold-water ocean fish.

Effects of omega-3 and omega-6 fatty acid-rich oils on the cardiovascular system of thermally injured rabbits: changes in plasma triglycerides, plasma cholesterol, relative blood viscosity, platelet count, and bleeding time.

New Zealand white male rabbits were studied to determine how supplements of soybean oil, soybean + MaxEPA oil, or MaxEPA oil affected their cardiovascular status when they were burned. Plasma triglyceride concentrations increased at 2 hours after burn injury (28 days after supplement administration) and declined by the end of the study in all three experimental groups of rabbits. These same animals showed no noticeable differences in the plasma concentrations of total cholesterol or in the high-density lipoprotein cholesterol subfractions. Plasma low-density/very-low-density lipoprotein cholesterol levels remained unchanged at 2 hours after burn injury/sham treatment but increased by the end of the study in all three experimental groups of rabbits. The mean platelet number was significantly higher in burned/sham treated rabbits given soybean oil supplement as compared with numbers in those given either soybean oil + MaxEPA oil or MaxEPA oil supplement. Plasma relative viscosity was highest in the soybean oil-supplemented rabbits, decreased in animals fed soybean oil + MaxEPA, and lowest in MaxEPA oil-supplemented rabbits. Mean bleeding time was lowest in soybean oil-fed rabbits. The bleeding time was higher in rabbits fed soybean oil+MaxEPA oil and highest in MaxEPA oil-supplemented animals. Platelet number and plasma viscosity were highest in the soybean oil-supplemented rabbits and lowest in the MaxEPA oil-supplemented group. The reverse pattern occurred when bleeding time was established. Overall results obtained suggest that supplementation with oils rich in omega-3 and omega-6 fatty acids may have significant effects on the cardiovascular health of burned male New Zealand white rabbits.

Effects of supplemented omega-3 and omega-6 fatty acid rich oils on the cardiovascular system of thermally injured rabbits: changes in plasma and platelet fatty acids.

The effects of omega-3 fatty acid rich oil (MaxEPA oil), omega-6 fatty acid rich oil (soybean oil), and a combination of omega-3 and omega-6 oils (MaxEPA oil + soybean oil) on cardiovascular health-related parameters of thermally injured and control (sham) rabbits were determined. Plasma and platelet analyses of burned rabbits fed with MaxEPA oil revealed significantly higher concentrations of eicosapentaenoic acid and docosahexaenoic acid + myristic acid. Linolenic acid concentrations declined in animals supplemented with soybean oil + MaxEPA oil. At the end of this study the lowest concentrations of linoleic acid and arachidonic acid were found in the sham and burned groups supplemented with soybean oil + MaxEPA oil. Overall, favorable significant differences in plasma and platelet fatty acids concentrations were found in burned or sham groups supplemented with MaxEPA when compared with those of groups supplemented with soybean oil. These favorable changes in plasma and platelet lipids may have an impact on the risk of cardiovascular disease in thermally injured patients.

Resting energy expenditures measured by indirect calorimetry are higher in preadolescent children with cystic fibrosis than expenditures calculated from prediction equations.

OBJECTIVE: This study compared measured resting energy expenditures to resting energy expenditures calculated using Harris-Benedict equations (HBEs) and the Cystic Fibrosis Consensus Committee equations (CFCCEs). DESIGN: We studied 31 preadolescent boys and girls with cystic fibrosis who ranged in age from 3.25 to 12.75 years old. The patients were afebrile and not in pulmonary distress. Measured resting energy expenditures were determined using a portable metabolic measurement cart with fully automated calibration and data management. The measured resting energy expenditures obtained were compared with values obtained using HBEs and CFCCEs. RESULTS: For each patient, the measured resting energy expenditure value was above the predicted resting energy expenditure values derived from HBEs (P < or = .0001) and CFCCEs (P < or = .01). APPLICATIONS: The HBEs and the CFCCEs underestimated the energy expenditures of the study population by 13% and 8%, respectively. These findings support the usefulness of the measurement of energy expenditures in determining the energy needs of preadolescent patients with cystic fibrosis. In clinical practice, the resting energy expenditures would be multiplied by activity coefficients to determine the total daily energy expenditures of this population.

Equations for the estimation of energy expenditures in patients with burns with special reference to ventilatory status.

There are advantages to the use of easily assessed variables for the prediction of energy expenditures of patients with burns. The purpose of this study was to determine whether height, age, sex, weight, ventilatory status, and diagnosis could be correlated with measured energy expenditures of hospitalized patients. With the use of data from 200 patients, stepwise, multivariate regression analysis derived the following equations: EEE(v) = 1925 - 10(A) + 5(W) + 281(S) + 292(T) + 851(B) (R2 = 0.43); EEE(s) = 629 - 11(A) + 25(W) - 609(O) (R2 = 0.50); where EEE = estimated energy expenditure (kcal/day), v = ventilatory dependency, s = spontaneously breathing, A = age (yr), W = body weight (kg), S = sex (male = 1, female = 0), diagnosis of T = trauma, B = burn, O = obesity present = 1, absent = 0). The equations were tested on 100 patients. Measured energy expenditures were not significantly different from calculated EEE(s) or EEE(v) (paired t test, p greater than 0.25). Energy expenditures can be accurately estimated in a variety of patients, including those with major burns with the use of easily attained information.

Lack of effect of vitamin B-6 supplementation on the lipoprotein profile of post-menopausal chronic hemodialysis patients.

This study was designed to analyze the effect of vitamin B-6 supplementation on the lipoprotein profile of chronic hemodialysis patients. Individuals on chronic hemodialysis experience an acceleration of atherosclerosis, which is often accompanied by abnormal lipid metabolism. Although total plasma cholesterol is usually normal, high-density-lipoprotein (HDL) cholesterol is often low. Recently, it has been suggested that the development of atherosclerotic lesions in chronic hemodialysis patients may be the result of a decreased plasma concentration of pyridoxal 5'-phosphate (PLP) and concomitant alterations in plasma amino acid and/or lipoprotein profiles. All subjects in this study were supplemented with 0.97 mmol (200 mg) pyridoxine hydrochloride per day for 28 days; then, concentrations of PLP, total cholesterol, and lipoprotein cholesterol fractions were determined in the plasma. No significant difference was noted in PLP concentration between Group 1 (five post-menopausal women with a history of atherosclerosis who were undergoing maintenance hemodialysis therapy) and Group 2 (six subjects who were non-symptomatic). However, both groups had significant increases in PLP concentrations between the pre- and post-supplementation periods (p less than .01). In contrast, there was a statistically significant difference in total plasma cholesterol and very-low-density- and low-density-lipoprotein (VLDL and LDL) cholesterol concentrations between groups, but no significant changes in total cholesterol or VLDL and LDL cholesterol content were found during vitamin B-6 supplementation. No statistically significant differences in HDL, HDL2, and HDL3 cholesterol concentrations were observed between Group 1 and Group 2 subjects or within either group during vitamin B-6 supplementation.

Effect of aspartame on plasma amino acid profiles of diabetic patients with chronic renal failure.

A randomized, double-blind study was conducted to determine the possible effects of aspartame on the plasma amino acid profiles of 23 diabetic patients with renal failure who were undergoing maintenance hemodialysis. Subjects were given a single dose of 10 mg aspartame/kg (approximately equivalent to 25 packets of Equal [NutraSweet Consumer Products, Inc, Chicago, IL] or the amount of phenylalanine in a 300-mL glass of milk) or a placebo in a crossover study design. Three postdialysis blood samples were drawn just before and 1 and 2 h after aspartame or placebo consumption. After aspartame consumption statistically significant increases in only two amino acids, phenylalanine and tyrosine, were noted at 1 and 2 h when compared with placebo values. The increases in phenylalanine were within the normal postprandial range for healthy subjects; no other increases in essential or nonessential amino acids, except for tyrosine, were detected. This study supports the view that aspartame is safe for diabetic subjects with chronic renal failure.

Dietary cottonseed protein and cholesterol metabolism.

Low-gossypol, glandless cottonseed protein may become a major product for human consumption. In this presentation, the influence of cottonseed protein on several aspects of cholesterol metabolism will be described. Studies with rabbits and rats have shown that dietary cottonseed protein very effectively lowers the concentration of plasma cholesterol when compared to the animal protein casein. No such effect has been found in hamsters, but cottonseed protein may slightly elevate the percentage of serum total cholesterol carried by the high density lipoproteins. There is suggestive evidence that in humans the replacement of animal proteins in the diet by cottonseed protein causes a small decrease in serum cholesterol levels, but more studies are required to substantiate this. In hamsters dietary cottonseed protein effectively suppresses the formation of gallstones when compared to casein. On diets containing cottonseed protein the concentrations of both cholesterol and phospholipids in bile fluid are significantly decreased. We tentatively suggest that the consumption of cottonseed protein will have a favorable effect on cholesterol metabolism.

Effects of dietary animal and plant proteins on the cholesterol metabolism in immature and mature rats.

Three- and 9-mo-old rats were fed purified diets that contained either casein, cottonseed or soybean protein for 28 d, and plasma total and high density lipoprotein (HDL) cholesterol, lecithin cholesterol acyltransferase (LCAT) activity and excretion of fecal neutral sterols were measured. These analyses were performed in order to examine how various dietary proteins from animal and plant sources fed in a purified diet influence the changes in the cholesterol metabolism of the young and old rats. Both immature (3-mo-old) and mature (9-mo-old) rats fed purified diet containing casein maintained significantly higher plasma total and HDL cholesterol levels than their counterparts fed the same diets but containing plant proteins (soybean and cottonseed). The fractional rate of esterification (FR) of plasma free cholesterol in mature casein-fed rats was lower than that in immature rats. The FR was also lower in immature rats fed casein than in those fed plant protein. The net turnover rate (NR) of plasma cholesteryl esters (CE) tended to be higher in mature rats and in general was not affected by the dietary protein source. The rate of fecal excretion of neutral sterols was significantly higher in immature rats than in mature rats and in animals fed plant proteins at both ages than in those fed casein.

Evaluation of energy expenditures in burn patients.

Energy expenditures were estimated using the Curreri equation (CEE), the Harris-Benedict equations (HBEE), and a modification of the Harris-Benedict equations (MHBEE) and then were measured by indirect calorimetry (MEE) in 17 adult patients with burns covering 26% to 79% of their body surface areas. The mean CEE (3,831 kcal/day) was significantly greater, and the mean HBEE (1,813 kcal/day) was significantly less than the mean MEE (2,500 kcal/day). The mean MHBEE (2,720 kcal/day) and the mean MEE were not significantly different.

Effect of dietary animal and vegetable protein on gallstone formation and biliary constituents in the hamster.

A gallstone-inducing diet was utilized to examine the effect of dietary proteins (casein, soybean and cottonseed) on gallstone formation. Casein produced gallstones in 100% of the animals; however, soybean or cottonseed proteins reduced gallstone incidence to 32% and 0%, respectively. In an effort to ascertain the mechanisms responsible for gallstone formation, serum cholesterol and the 3 primary biliary constituents (bile acids, phospholipids and cholesterol) were measured. Casein produced a 4-fold increase in biliary cholesterol, whereas soybean and cottonseed yielded a 3- and 2-fold increase, respectively, when compared to a commercial diet (Purina, no. 5001). Serum cholesterol was reduced by substituting dietary vegetable protein for animal protein. This study suggests that substitution of vegetable for animal protein in the diet can decrease gallstone formation in hamsters. It is proposed that this reduced gallstone formation is due to the decreased concentrations of biliary cholesterol induced by dietary modification.

Effects of dietary protein and amino acids on the metabolism of cholesterol-carrying lipoproteins in rats.

The effect of various dietary proteins and amino acids on serum lipid metabolism was studied by using male Sprague-Dawley rats. A stock diet containing casein as a protein source was fed to control animals, whereas a vegetable protein diet (cottonseed based) was fed to one experimental group. Two other experimental diets were formulated to determine if the amino acid ratios in the protein played a role in the alteration of serum cholesterol levels. One of these diets contained casein plus enough additional arginine to make its arginine-to-lysine ratio similar to that found in cottonseed protein. The other diet contained cottonseed protein plus enough lysine to duplicate the arginine-to-lysine ratio of casein. Rats fed a diet containing protein from animal sources had greater serum and high-density lipoprotein (HDL)-cholesterol concentrations as well as increased lecithin: cholesterol acyltransferase (LCAT, EC 2.3.1.43) activities than those which had been fed a diet containing protein from plant sources. Animals fed arginine-supplemented casein diet showed a decrease in both serum and HDL-cholesterol when compared to the casein control group, whereas the addition of lysine to cottonseed protein diet caused an increase in the same two cholesterol fractions.

Food restriction as a modulator of age-related changes in serum lipids.

Fischer 344 male rats were either fed ad libitum or 60% of the ad libitum intake. The restriction of food intake markedly increased the median length of life. Postabsorptive serum cholesterol and phospholipid concentrations increase in the ad libitum-fed rats with increasing age. Life-prolonging food restriction does not influence the serum levels of these lipids in young rats but delays the age-related increase in concentrations. Postabsorptive serum free fatty acid (FFA) concentrations decrease with advancing age in ad libitum-fed rats. Life-prolonging food restriction, while not affecting the serum FFA levels in young rats, delays and possibly partially prevents the age-related decrease in concentration. Food restriction lowers postabsorptive serum triglyceride levels at all ages studied. The data on serum cholesterol, phospholipids, and FFA provide further evidence that food restriction delays age-related changes in the physiological systems of rats. This delay of physiological decline may well retard the occurrence of age-related disease processes, thus prolonging life.