High-carbohydrate Group Research Articles

Carbohydrate versus Energy Restriction: Effects on Weight Loss, Body Composition and Metabolism

Background/Aims: To compare weight loss, body composition, and metabolic changes in response to carbohydrate versus dietary energy restriction (DER) in obese mice. Methods: One hundred C57BL/6 mice were randomized into five groups of 20. The group of high-carbohydrate (HC) mice consumed an HC diet ad libitum and the group of high-fat (HF) mice consumed an HF diet ad libitum for 14 weeks. Additional groups consumed the HF diet for 7 weeks ad libitum and during weeks 8–14 were switched to either a low-carbohydrate diet (LC) consumed ad libitum, the HC diet pair-fed (PF) to the energy intake of the LC group, or an HC DER regimen providing 70% of the energy intake of the HF group. Results: At 14 weeks, the LC and HF groups weighed more and exhibited higher percent fat mass and lower bone mineral density than the HC, PF, and DER groups. Relative to the DER group, the LC group displayed comparable serum ketone bodies but higher serum glucose, triglycerides, cholesterol, leptin, insulin, and insulin-like growth factor-1. Conclusions: In contrast to DER, the LC diet did not cause weight loss or reduce serum markers associated with obesity-related diseases other than diabetes in obese mice, suggesting that carbohydraterestriction without reduced energy intake does not induce weight loss.

Effects of diet and exercise interventions on health outcomes in women with and without metabolic syndrome (MS)

355 sedentary women (46±11 yrs, 163±7 cm; 92±16 kg; 45±4% body fat) were assigned to a control group (C); an exercise group (E); an exercise & high calorie diet (HCD) group (2,600 kcals/d); or, isoenergetic high carbohydrate (HC) or high protein (HP) diets. Diets consisted of 1,200 kcal/d for 1-wk and 1,600 kcal/d for 9 wks during the weight loss phase, During the maintenance phase, subjects ingested 2,600 kcal/d and dieted for 2-d (1,200 kcal/d) only if they gained 3 lbs. Subjects participated in a Curves fitness program 3-d per wk. Subjects were retrospectively divided into those with less than (n=196) or more than (n=159) 3 criteria for MS. Data were collected at 0, 10, and 14 weeks and analyzed by repeated measures ANOVA and are presented as changes from baseline after 10 and 14 wks for the no MS and MS groups, respectively. Subjects who had MS had greater loss of DEXA fat mass (−2.29±2.6, −2.44±3.4; −2.78±4.2; −3.1±3.0 kg, p=0.046) and SBP (−1.3±13, −2.3±14; −5.6±18; −8.4±15 mmHg, p=0.01) with no significant differences between groups in reductions in waist circumference (−2.8±6.6, −3.8±7.3; −3.2±8.3; −4.2±6.9 cm, p=0.42), glucose (−0.4±15, −2.1±15; −2.6±14; −4.1±14 %, p=0.85), triglycerides (5.6±42, 2.4±42; −5.5±33; 0.2±41%, p=0.67) or HDL (−3.9±19, −2.9±17; −0.1±19; −0.9±19 %, p=0.86). Analysis of group interactions revealed that MS subjects following the HCD lost significantly more weight than the non-MS group with results comparable to those observed in the HC and HP diet groups. Also, results in the HP group were generally better than remaining groups. Results indicate that subjects with MS may experience differential effects from adhering to various types of diets during training.

Carbohydrate metabolism during period of different diet types

Obesity became a great epidemic disease all over the world, and loosing weight is a high priority concern of most obese individuals. A low carbohydrates and a high protein diets became a popular solutions for obese people therefore, the goal of this study was to evaluate the effect of a high protein diet on body weight and glucose metabolism. Adult male Spargue-Dawely rats (300–400g) were divided into three groups; group 1, fed on standard chow pellets, group 2 fed on 75% high carbohydrates diet and 25% chow pellets, and group 3 fed on 75% high protein diet and 25% chow pellets for two weeks. Body weight, food and water intake were recorded all through the experiment. Fasting glucose and insulin values were measured using biochemical and Elisa analysis, respectively. Results showed that after two weeks there was a significant increase (P<0.05) in body weight gain in group 2 (35.20±13.17), and a significant decrease (P<0.05) in B. Wt. gain in group 3 (11.25±4.21) compared to B. Wt. gain of the control group (28.80±1.72). Food intake was increased significantly in both groups 2 & 3, whereas there was no significant difference in water intake between all groups. Fasting glucose level was increased significantly in both the high carbohydrate group (8.98±1.79), and the high protein group (9.58±1.04) compared to the control value (5.97 ± 1.00), whereas no significant differences in insulin level was detected between all groups. In conclusion consumption of a high protein diet for a short period of time caused a significant weight loss and a rise in blood glucose level that might be produced by de novo process.

Carbohydrate Restriction, Dietary Energy Restriction and Weight Loss in Obese Mice: Metabolic Insights

Our objective was to compare weight loss, body composition, and key metabolic changes in response to carbohydrate restriction (modeling the Atkins diet) relative to dietary energy restriction (DER). Male C57BL/6 mice were randomized into five groups of 20. Group HC mice consumed a high carbohydrate diet and group HF consumed a high fat diet for 14 weeks. The remaining three groups consumed the HF diet for seven weeks to induce obesity and during weeks 8–14 were switched to either: a) an Atkins-like low carbohydrate diet similar to the induction phase of the Atkins diet; b) pair-feeding (PF) with the HC diet to match the energy intake of the Atkins group; or c) a high carbohydrate DER regimen providing 70% of the energy intake consumed by the HF group. At 14 weeks, body weights of the Atkins (40.3 ± 1.1 g) and HF (40.2 ± 1.1 g) groups were greater than the HC (33.0 ± 0.8 g), PF (31.5 ± 0.8 g) and DER (22.7 ± 0.6 g) groups. The Atkins (47.3 ± 1.2 %) and HF (46.8 ± 1.2 %) groups exhibited higher percent fat mass than the HC (35.4 ± 1.1 %), PF (33.9 ± 1.8 %), and DER (19.5 ± 0.8 %) groups. The Atkins and HF groups demonstrated lower bone mineral density than other groups. Relative to the DER group, the Atkins group displayed comparable serum ketone bodies but higher serum cholesterol, triglycerides, leptin, IGF-1, glucose and insulin. In contrast to DER, the Atkins-like diet did not cause weight loss or reduce serum markers associated with obesity-related diseases in mice. Funding provided in part by the Dept. Human Ecology and by N01-CO-12400.

Reintroduction of the 2G12 epitope in an HIV-1 clade C gp120

Many clade C isolates of HIV-1 do not react with monoclonal antibody (MAb) 2G12, a broad-ranging human neutralizing MAb that recognizes high mannose carbohydrate groups attached to glycoprotein gp120. We reintroduced a partial and complete 2G12 epitope into a clade C background, HIV-1(CN54), and examined the antibody reactivity of the resulting recombinant molecules. Two glycosylation sites recovered 2G12 binding completely, but some binding was evident after the reintroduction of a single glycosylation site at Asn295.

Effect of high protein vs high carbohydrate intake on insulin sensitivity, body weight, hemoglobin A1c, and blood pressure in patients with type 2 diabetes mellitus

Background Extremely low carbohydrate/high protein diets are popular methods of weight loss. Compliance with these diets is poor and long-term effectiveness and the safety of these diets for patients with type 2 diabetes is not known. Objective The objective of the current study was to evaluate effects of less extreme changes in carbohydrate or protein diets on weight, insulin sensitivity, glycemic control, cardiovascular risk factors (blood pressure, lipid levels), and renal function in obese inner-city patients with type 2 diabetes. Design Study patients were admitted to the General Clinical Research Center for 24 hours for initial tests including a hyperinsulinemic-euglycemic clamp (for measurement of insulin sensitivity), bioelectrical impedance analysis (BIA) and anthropometric measurements (for assessment of body composition), indirect calorimetry (for measurement of REE), electronic blood pressure monitoring, and blood chemistries to measure blood lipids levels along with renal and hepatic functions. Six patients with type 2 diabetes (five women and one man) were randomly assigned to the high-protein diet (40% carbohydrate, 30% protein, 30% fat) and six patients (four women and two men) to the high-carbohydrate diet (55% carbohydrate, 15% protein, 30% fat). All patients returned to the General Clinical Research Center weekly for monitoring of food records; dietary compliance; and measurements of body weight, blood pressure, and blood glucose. After 8 weeks on these diets, all patients were readmitted to the General Clinical Research Center for the same series of tests. Intervention Twelve study patients were taught to select either the high-protein or high-carbohydrate diet and were followed for 8 weeks. Main outcome measures Insulin sensitivity, hemoglobin A1c, weight, and blood pressure were measured. Statistical analyses Statistical significance was assessed using two-tailed Student’s t tests and two-way repeated measures analysis of variance. Results Both the high-carbohydrate and high-protein groups lost weight (−2.2±0.9 kg, −2.5±1.6 kg, respectively, P<.05) and the difference between the groups was not significant ( P=.9). In the high-carbohydrate group, hemoglobin A1c decreased (from 8.2% to 6.9%, P<.03), fasting plasma glucose decreased (from 8.8 to 7.2 mmol/L, ⁎ P<.02), and insulin sensitivity increased (from 12.8 to 17.2 μmol/kg/min, P<.03). No significant changes in these parameters occurred in the high-protein group, instead systolic and diastolic blood pressures decreased (−10.5±2.3 mm Hg, P=.003 and −18±9.0 mm Hg, P<.05, respectively). After 2 months on these hypocaloric diets, each diet had either no or minimal effects on lipid levels (total cholesterol, low-density lipoprotein, high-density lipoprotein), renal (blood urea nitrogen, serum creatinine), or hepatic function (aspartate aminotransferase, alanine aminotransferase, bilirubin).

High-Protein, Low-Fat Diets Are Effective for Weight Loss and Favorably Alter Biomarkers in Healthy Adults

Although popular and effective for weight loss, low-carbohydrate, high-protein, high-fat (Atkins) diets have been associated with adverse changes in blood and renal biomarkers. High-protein diets low in fat may represent an equally appealing diet plan but promote a more healthful weight loss. Healthy adults (n = 20) were randomly assigned to 1 of 2 low-fat (<30% energy), energy-restricted groups: high-protein (30% energy) or high-carbohydrate (60% energy); 24-h intakes were strictly controlled during the 6-wk trial. One subject from each group did not complete the trial due to out-of-state travel; two subjects in the high-carbohydrate group withdrew from the trial due to extreme hunger. Body composition and metabolic indices were assessed pre- and post-trial. Both diets were equally effective at reducing body weight (-6%, P < 0.05) and fat mass (-9 to -11%, P < 0.05); however, subjects consuming the high-protein diet reported more satisfaction and less hunger in mo 1 of the trial. Both diets significantly lowered total cholesterol (-10 to -12%), insulin (-25%), and uric acid (-22 to -30%) concentrations in blood from fasting subjects. Urinary calcium excretion increased 42% in subjects consuming the high-protein diet, mirroring the 50% increase in dietary calcium with consumption of this diet; thus, apparent calcium balance was not adversely affected. Creatinine clearance was not altered by diet treatments, and nitrogen balance was more positive in subjects consuming the high-protein diet vs. the high-carbohydrate diet (3.9 +/- 1.4 and 0.7 +/- 1.7 g N/d, respectively, P < 0.05). Thus, low-fat, energy-restricted diets of varying protein content (15 or 30% energy) promoted healthful weight loss, but diet satisfaction was greater in those consuming the high-protein diet.

Effects of short-term high carbohydrate or fat intakes on leptin, growth hormone and luteinizing hormone secretions in prepubertal fat-tailed Tuj lambs.

The aim of the current study was to evaluate the effects of high carbohydrate or fat diets, fed for 15 days at the end of breeding season, on leptin, GH and LH secretions in prepubertal fat-tailed Tuj lambs. For that purpose, 9-month-old ram-lambs were divided into three groups as control group (fed with basal ration, n = 4), high carbohydrate (HC) group, basal ration plus barley, n = 4), or high fat (HF) group (basal ration plus by-pass fat, n = 4). For the measurement of leptin and GH, blood plasma samples were collected on days 1, 4, 9 and 14 of the experiment. For the measurement of LH pulse frequency, serial blood samples were collected every 15 min for 6 h on day 14. Lambs were weighed and body condition scored (BCS) on days 1 and 15. Body weight and BCS increased towards the end of the study (p < 0.05). The BCS was higher in high energy groups at the end of the experiment (p < 0.05). Diet affected plasma leptin concentrations (p = 0.002) but time did not. The GH concentrations were not affected by diet or time. The LH pulse frequency appeared to be higher in HC and HF groups but there were no statistical difference between the groups. There was a significant positive relationship between overall BCS and corresponding leptin concentrations (R2 = 0.263; p = 0.010) and between LH pulse frequency and leptin concentrations (R2 = 0.594; p = 0.003). In conclusion, the present study suggests that rather than type of energy, amount of energy intake and body energy reserves are much important regulators of plasma leptin concentrations and LH pulse frequency in fat-tailed Tuj lambs.

A Comparison of Low-Carbohydrate vs. High-Carbohydrate Diets: Energy Restriction, Nutrient Quality and Correlation to Body Mass Index

Objectives: To evaluate free-living adults’ diets that ranged from very low to high amounts of carbohydrate for their energy content, nutritional quality and correlation to Body Mass Index.Methods: Adults ages 19 years and older, who had complete dietary intake data on day-1 of the USDA’s 1994 to 1996 Continuing Survey of Food Intakes by Individuals (CSFII 1994–1996), were divided into four groups—very low, low, moderate and high carbohydrate—based on the percent total energy from carbohydrate. Mean energy, nutrient, food intakes and Body Mass Index values were compared among the groups. SUDAAN software package was used for the data analysis and pair-wise mean comparisons (p < 0.05).Results: The high-carbohydrate diet was lower in energy and energy density (number of kilocalories per gram of total amount of food consumed) than the other three diets. Macronutrient composition varied significantly among all the four groups. Nutrient density (amount of nutrient per 1,000 kilocalories of energy consumed) of vitamin A, carotene, vitamin C, folate, calcium, magnesium and iron increased and that of vitamin B12 and zinc decreased with an increase in the percent total energy from carbohydrate. The high-carbohydrate group ate more of low-fat foods, grain products and fruits. This group also had the lowest sodium intake. Adults eating a high-carbohydrate diet are more likely to have Body Mass Index values below 25.Conclusion: A study of diets of free-living adults in the U.S. showed that diets high in carbohydrate were both energy restrictive and nutritious and may be adopted for successful weight management.

Popular Diets: Correlation to Health, Nutrition, and Obesity

Objective To examine the association between a range of health and nutrition indicators and popular diets.Design The Continuing Survey of Food Intake by Individuals (CSFII) 1994–1996 data were used to examine the relationship between prototype popular diets and diet quality as measured by the healthy eating index (HEI), consumption patterns, and body mass index (BMI). The prototype diets included vegetarian (no meat, poultry, or fish on day of survey) and non-vegetarian. The nonvegetarian group was further subdivided into low carbohydrate (less than 30% of energy from carbohydrate), medium (30% to 55%), and high (greater than 55% of energy). Within the high carbohydrate group, participants were classified as having Pyramid or non-Pyramid eating patterns. The Pyramid group was defined as 30% or less of energy from fat and at least one serving from the five major food groups in the USDA Food Guide Pyramid. Finally, the non-Pyramid group was further subdivided into low fat (less than 15% of energy from fat) and moderate fat (15% to 30% of energy from fat). In addition, a review of the published scientific literature was conducted; all studies identified were included in the review.Subjects 10,014 adults, aged 19 years and older, from the 1994–1996 CSFII were included in the analyses of extant data. More than 200 individual studies were included in the review of the literature.Results Analyses of the CSFII indicate that diet quality as measured by HEI was highest for the high carbohydrate Pyramid group (82.9) and lowest for the low carbohydrate group (44.6). Energy intakes were low for the vegetarians (1,606 kcals) and high carbohydrate/low fat group (1360 kcals). BMIs were lowest for women in the vegetarian group (24.6) and the high carbohydrate/low fat group (24.4); for men, the lowest BMIs were observed for vegetarians (25.2) and the high carbohydrate Pyramid group (25.2). Review of the literature suggests that weight loss is independent of diet composition. Energy restriction is the key variable associated with weight reduction in the short term.Conclusions Diets that are high in carbohydrate and low to moderate in fat tend to be lower in energy. The lowest energy intakes were observed for those on a vegetarian diet. The diet quality as measured by HEI was highest for the high carbohydrate groups and lowest for the low carbohydrate groups. The BMIs were significantly lower for men and women on the high carbohydrate diet; the highest BMIs were noted for those on a low carbohydrate diet. J Am Diet Assoc. 2001; 101:411–420.

Nutrient oxidation and metabolic rate as affected by meals containing different proportions of carbohydrate and fat, in healthy young women.

The amount and composition of food eaten influence body weight regulation, which requires that, in the long term, energy intake matches energy expenditure and that the oxidation rate to be equal to intake for each and separate nutrients. The aim of this study was to examine the influence of two liquid formulas with different macronutrient composition, a high carbohydrate (HC) meal as compared to a high fat (HF) meal, on substrate oxidation and on thermic effect of food (TEF). Eighteen lean and healthy women which were fed a HC diet during the 3 preceding d were studied for a further 4 h after meal intake. The test meals provided fixed energy intake and whose calculated FQ were 0.77 for HF meal, and 0.96 for HC meal. The mean NPRQs were higher (P < 0.01) in the HC group than in the HF group, even with values greater than 1.00 indicating net lipid synthesis (NL), and which correlated with metabolic rate (MR) value (P < 0.05), glucose (P < 0.05), and heart rate (HR) values. Carbohydrate (CHO) oxidation was higher with the HC than with HF meal (P < 0.01) and correlated with the MR (P < 0.05). Protein oxidation rate rose above baseline (P < 0.01); this increase was accompanied by with a negative CHO balance. It is concluded that the change in fuel selection and the increase of TEF is mainly due to CHO intake and metabolism, respectively, and that surplus of dietary CHO of preceding days together with a large load of CHO can exceed the glycogen storage capacity and trigger NL.

Nutritional hepatic steatosis and mortality after burn injury in rats

To investigate the effects of diet composition and starvation on hepatic steatosis and mortality after severe burn injury in rats. Experiment 1: rats received either normal chow (55 cent of energy carbohydrates, 14 cent fat, 31 cent protein), a high-fat (40 cent carbohydrates, 40 cent fat, 20 cent protein), or a high-carbohydrate diet (81 cent carbohydrates, 4 cent fat, 15 cent protein) ad libitum for 6 days. Another three groups received these diets ad libitum for 6 days after 48|h starvation. Experiment 2: mortality after 60 cent total body surface area scald burn was determined in a control group of rats and a group with nutritionally induced hepatic steatosis. Hepatic steatosis was induced by feeding the rats a high-fat diet (40 cent carbohydrates, 4 cent fat, 15 cent protein) ad libitum for 6 days. Without starvation, liver triglyceride content (mg/g liver) increased in response to the high-fat diet (25.6'6.9) compared to normal chow (9.4'3.8; P < 0. 05); the high-carbohydrate diet had no influence on liver triglyceride content (12.4'3.7). Refeeding after starvation resulted in elevated (P < 0.05) liver triglyceride content in the high-fat (18.8'8.3) and the high-carbohydrate group (28.7'14.4 vs control 6. 7'3.7). Liver triglyceride content correlated (R2=0.72; P < 0.05) to non-protein energy intake but not to total energy intake. Burn caused 33 cent mortality in the hepatic steatosis group and no deaths in the control group (P < 0.05). Diet composition and preceding starvation independently manipulate hepatic fat content in rats. Hepatic steatosis increases mortality after burn injury. Thus, nutritional interventions to reduce hepatic fat accumulation may be beneficial.

Protein metabolism during weight reduction with very-low-energy diets: evaluation of the independent effects of protein and carbohydrate on protein sparing

The aim of this study was to assess the independent effects of carbohydrate and protein intakes in protein sparing during weight reduction. Forty-eight obese women were randomly assigned to consume isoenergetic (2500 kJ/d) liquid diets that provided the following amounts (g/d) of protein and carbohydrate, respectively, for 28 d: 50 and 10, 50 and 76, 70 and 10, and 70 and 86. The effects of carbohydrate and protein were analyzed by repeated-measures analysis of variance (ANOVA). Carbohydrate significantly affected daily urinary ammonia and total nitrogen excretion, stool nitrogen, and nitrogen balance. Protein, independently of carbohydrate, significantly affected daily urinary ammonia, urea, and total nitrogen excretion but had no effect on nitrogen balance. Cumulative nitrogen losses (mmol/28 d) were lower in the high-carbohydrate groups than in the low-carbohydrate groups (1869 +/- 392 and 3611 +/- 328, P = 0.003) but were similar in the groups receiving 50 and 70 g protein/d (3171 +/- 327 and 2326 +/- 430, respectively, P = NS). These results indicate that carbohydrate and protein have independent but additive protein-sparing effects during weight reduction.

Rat hypothalamic NPY mRNA and brown fat uncoupling protein mRNA after high-carbohydrate or high-fat diets

We measured the influence of diet composition on hypothalamic neuropeptide Y (NPY) message and brown fat uncoupling protein (UCP) mRNA using different diets. Sprague-Dawley rats ate ad libitum either chow, a high-carbohydrate (HC), an intermediate-carbohydrate (IHC), a high-fat (HF), or an intermediate-fat (IHF) diet, all with equal protein content (g/kcal). The HF and IHF groups ate less food mass and, except for HC, all groups consumed similar kilocalories during the study. After 1 wk, we killed the animals and extracted total RNA from arcuate nucleus, cortex, and brown adipose tissue (BAT). Arcuate NPY mRNA in the HF group was significantly (P < 0.001) lower than in the HC and chow group. There were no differences between groups in NPY message in cortex or NPY protein in the paraventricular nucleus. BAT UCP message levels were significantly higher (P = 0.001) in the HF group. Thus HF compared with HC and chow diet reduces expression of NPY mRNA in hypothalamic nuclei and increases expression of BAT UCP message.

Tissue specific regulation of lipogenesis by carbohydrate feeding and twenty four hour starvation in the rat

The effects of high carbohydrate (HC), low fat feeding and 24 hour starvation on lipogenesis in different rat tissues were investigated, using the incorporation of tritiated water. HC feeding stimulated lipogenesis in liver (5.5 fold) and also to a lesser extent in inner white fat depots, interscapular brown fat, kidney and heart. Tritium incorporation into lipids in large intestine was inhibited under the same circumstances. All other tissues, including lung, skin and brain were unaffected. Twenty four hour starvation diminished lipogenesis, particularly in liver, but also in brown adipose tissue, kidney, heart, lung and small and large intestines. The contribution of different tissues to total lipogenesis depended on the nutritional state. Skin and bone and muscle predominated in the starved animals, whereas liver alone contributed 56% in the HC group. TLC analysis of the labeled lipids confirmed in most cases that the tritium was incorporated into fatty acids. However HC feeding diminished cholesterol labeling in liver and in large intestine. Thus the reduction in lipogenesis in large intestines from rats on the HC diet was due to a drop in cholesterol synthesis, with fatty acids being unaffected. There is great variation in the sensitivity of lipogenesis in different tissues to nutritional manipulation, providing an interesting model for the study of tissue specific regulatory processes.

Dietary carbohydrate, muscle glycogen, and power output during rowing training

The belief that high-carbohydrate diets enhance training capacity (mean power output) has been extrapolated from studies that have varied dietary carbohydrate over a few days and measured muscle glycogen but did not assess power output during training. We hypothesized that a high-carbohydrate (HI) diet (10 g.kg body mass-1.day-1) would promote greater muscle glycogen content and greater mean power output during training than a moderate-carbohydrate (MOD) diet (5 g.kg body mass-1.day-1) over 4 wk of intense twice-daily rowing training. Dietary protein intake was 2 g.kg body mass-1.day-1, and fat intake was adjusted to maintain body mass. Twelve male and 10 female collegiate rowers were randomly assigned to the treatment groups. Training was 40 min at 70% peak O2 consumption (VO2) (A.M.) and either three 2,500-m time trials to assess power output or interval training at 70-90% peak VO2 (P.M.). Mean daily training was 65 min at 70% peak VO2 and 38 min at greater than or equal to 90% peak VO2. Mean muscle glycogen content increased 65% in the HI group (P less than 0.05) but remained constant at 119 mmol/kg in the MOD group over the 4 wk. Mean power output in time trials increased 10.7 and 1.6% after 4 wk in the HI and MOD groups, respectively (P less than 0.05). We conclude that a diet with 10 g carbohydrate.kg body mass-1.day-1 promotes greater muscle glycogen content and greater power output during training than a diet containing 5 g carbohydrate.kg body mass-1.day-1 over 4 wk of intense twice-daily rowing training.(ABSTRACT TRUNCATED AT 250 WORDS)

Nutritional Control of Rat Liver Fatty Acid Synthase and S14 mRNA Abundance

The objective of this research was to evaluate the change in abundance of S14 and fatty acid synthase (FAS) mRNAs under a variety of nutritional conditions to evaluate the hypothesis that the regulation of the S14 gene is similar to that of other proteins involved in lipid metabolism and that changes in S14 expression are comparable to those that occur in FAS expression. Livers from rats fed a high carbohydrate diet were found to contain 350- and 100-fold more S14 and FAS mRNA than livers from rats fasted for 48 h. Although feeding a high fat diet increased S14 and FAS mRNA above fasting (P less than 0.05), the level of S14 and FAS mRNAs was only 5% and 4%, respectively, of the amount in the high carbohydrate group. Both S14 and FAS mRNAs accumulated quickly upon intubation of fasted rats with a solution of sucrose. The earliest rise in these mRNAs occurred within 60 min; by 240 min after gavage, each mRNA had increased 30-fold. The rapid induction of FAS and S14 mRNAs was also observed during ingestion of a high glucose meal. Hepatic FAS and S14 mRNA decreased 80-90% and 60%, respectively, during the 21-h interval between meals. This degree of mRNA loss was estimated to require a half-life for FAS and S14 mRNA of less than 8 h and less than 12 h, respectively. Regression analysis of the three dietary studies revealed a correlation coefficient for the relationship between S14 and FAS mRNA abundance ranging between 0.88 and 0.96.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of Manganese Deficiency and Dietary Composition on Rat Pancreatic Enzyme Content

Recent studies show that manganese (Mn) deficiency increases pancreatic amylase content. Pancreatic adaptation to dietary composition also alters enzyme content. The present study investigated whether Mn deficiency alters pancreatic adaptation to diet. Weanling rats that were fed for 6 wk a high carbohydrate (HC) diet with <1 mg Mn/kg diet (Mn deficient) or 40 mg Mn/kg diet (control) were divided into three control and deficient dietary subgroups: 1) HC, 2) high protein (HP) or 3) high fat (HF). Rats were then fed these diets for 10 d. Body weights and food consumption were comparable among the groups. Pancreatic and hepatic Mn contents were significantly lower in Mn-deficient rats than in respective controls. Digestive enzymes adapted to diet in both control and Mn-deficient rats with the greatest amylase, lipase and trypsin activities in HC, HF and HP rats, respectively. Mn deficiency resulted in significantly greater amylase activity in HC and HP groups and lipase activity in only the HF group than in respective controls. These data suggest that Mn participates in the regulation of pancreatic amylase content and in the adaptive response of pancreatic lipase to dietary fat.

Contribution of 500 g naturally labeled 13C dextrin maltose to total carbohydrate utilization and the effect of the antecedent diet, in man

Exogenous carbohydrate oxidation was studied for 24 h in 14 healthy young male volunteers after ingestion of 500 g naturally labeled 13C carbohydrate. Prior to the test, the antecedent diet was high in fat (4 subjects), mixed (4 subjects), or high in carbohydrate (6 subjects). The rate of exogenous carbohydrate oxidation was greater in the high carbohydrate and mixed diet groups than in the high fat group and endogenous carbohydrate continued to contribute to total carbohydrate oxidation for approximately 10 h after ingestion of the carbohydrate load in all groups. After 14 h, 178 +/- 5 g, 241 +/- 11 g and 260 +/- 9 g carbohydrate had been utilized of which 130 +/- 8 g, 155 +/- 6 g and 180 +/- 7 g was of exogenous origin in the high fat, mixed and high carbohydrate groups respectively. At the end of the test, postabsorptive glucose oxidation was of exogenous origin whatever the antecedent diet indicating that much of basal hepatic glucose production was covered by glycogenolysis of recently synthesized labeled glycogen.

Effect of dietary lipid and carbohydrate on growth, feed conversion and body composition in young yellowtail.

Young yellowtail were fed for 30 days on fish meal diets high in protein, lipid and carbohydrate, and a control diet containing both lipid and carbohydrate. The growth, feed conversion and body composition were determined. The growth and feed efficiency were high in the control group, medium in the high protein group and the high carbohydrate group, and low in the high lipid group. The control group showed the highest retention of protein and energy. Also in the contrl group, a protein required for 100g weight gain could be spared by about 28% by dietary addition of both lipid and carbohydrate. There were no marked differences in the body composition between groups, though slight differences were found in the content of fat and glycogen in the liver. These results indicate the importance of addition of a proper amount of carbohydrate as well as lipid to the diets of carnivorous fish such as yellowtail.