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[Behavior of certain parameters of lipid and energy metabolism. 5. Effects of high-fat and low-fat diets on certain biochemical parameters in rat livers before and after change of diet].

Typical metabolic patterns are detectable in the livers of growing rats after feeding diets with high (25%) or low (2%) fat contents. In view of the elucidation of problems related to the regulation of the metabolic processes, it is of interest to know in what way these metabolic patterns change after short-time change from the one diet to the other and if there are hierarchies. Within 2 days after change of diet, the enzymes glucose-6-phosphate dehydrogenase, NAD-malate dehydrogenase, lactate dehydrogenase, citrate synthase and fatty acid synthase were affected, only the 3'.5'-c AMP-splitting phosphodieterase showed no change. The metabolites lactate and pyruvate also changed, inversely to lactate dehydrogenase activity, the lactate-pyruvate ratio remaining almost constant. Acetyl CoA also responded in a characteristic manner. The single parameters were differently affected by the kind of the change of diet (from high-fat to low-fat diet or inversely). For example, glucose-6-phosphate dehydrogenase responded very rapidly to the change from the high-fat to the low-fat diet, malate dehydrogenase behaved inversely, and citrate synthase responded to both changes. Consequently, the regulatory processes after change of diet start from different sides. It is thinkable that this behaviour is related to the different roles of the determined parameters in fat and energy metabolism.

3',5'-Cyclic-AMP Phosphodiesterases↗

Effect of ingestion order of the fat component of a solid meal on intragastric fat distribution and gastric emptying assessed by MRI.

PURPOSE: To develop an MRI technique to investigate how varying the ingestion order of nonfat and fat components of a solid meal influences three-dimensional intragastric distribution and gastric emptying (GE). MATERIALS AND METHODS: Eight healthy subjects were studied twice in randomized order. On one occasion (condition F-NF), the fat component (40 g mayonnaise on toast) was served before the nonfat component (270 g pasta, 200 g tomato sauce, 100 mL water); on the other (condition NF-F), the ingestion order was reversed. GE and intragastric distribution of both components were assessed by MRI for 180 minutes. RESULTS: During condition F-NF, GE of fat was significantly faster than during condition NF-F (T(25) [min]: F-NF: 20 +/- 9; NF-F: 40 +/- 7; P < 0.05), a larger amount of fat was observed in the antrum during condition F-NF, and more fat layering occurred. No differences were observed in total GE between the two conditions. CONCLUSION: Meal ingestion order influences GE and intragastric distribution of fat, which can be assessed by MRI techniques, providing new insights into the physiology of gastric processing and intragastric distribution of different meal phases.

Adult↗

Blood glucose and plasma insulin responses to fat-free milk and low-lactose fat-free milk in young type 1 diabetics.

The blood glucose and plasma insulin responses to test milk samples were studied in eight insulin-dependent diabetics. After an overnight fast, the subjects (aged 20-45 years) were given a breakfast containing two Weetabix biscuits (20 g carbohydrate) with 500 ml of either regular (S) fat-free milk (25 g lactose) or 500 ml of a new low-lactose (D) fat-free milk (3.75 g lactose and 4.25 g fructose). The regular morning insulin dose was omitted. Mean basal plasma glucose level was slightly higher before S milk (11.4 vs. 10.1 mmol/l). The peak increment in plasma glucose was higher in S milk (9.4 vs. 6.6 mmol/l). The rise was 83% above basal (S) vs. 65% (D). Although the final mean plasma glucose concentration was not significantly higher 3 h after S milk compared with D milk (17.9 vs. 14.3 mmol/l) the incremental area under the plasma glucose curve was much greater (p less than 0.001) with S milk than with D milk (1266 +/- 295 units vs. 909 +/- 242 units). No galactose was detectable in any sample and there was no difference in plasma beta-hydroxybutyrate levels. The results suggest that the low-lactose fat-free milk (D) may be suitable for diabetic diets and weight reducing diets due to the lower contribution of energy. The results suggest that fat-free milk does not exert a fast action on blood glucose concentration and therefore fat-free milk and especially low-lactose fat-free milk may also prove to be suitable for diabetic diets.

Adult↗

Influence of heated and nonheated partially hydrogenated dietary fats on ileal chyme fat and fatty acid composition of ileal mucosa in pigs.

In this study the effects of partially hydrogenated chemically processed fats (CPF) and non-CPF on the ileal chyme fat and the fatty acid (FA) profile of the ileal mucosa and the subcutaneous tissue were analyzed. Samples were collected via an ileocutaneous fistula. For three months pigs were fed a control meal or diets containing either non-CPF high on 16:0, non-CPF high on 18:2 n6, CPF with 50% trans-18:1 or 20% trans-18:1. The latter fat was used after heat treatment. With both CPF diets, the fat content in the ileal chyme was three times higher than with non-CPF. In contrast to subcutaneous tissue reflecting dietary composition, changes in FA profile of ileal mucosa were restricted. Each non-CPF resulted in an increase of the characteristic major dietary FA. Both CPF increased the mucosal trans-FA percentage from 0 to 12% on average, although dietary composition was different. This study suggests: (1) less effects of trans-FA on the regulation of intraluminal fat load compared to saturated and cis-polyunsaturated FA, and (2) higher mucosal incorporation of trans-FA with heated CPF. This may play a role in the development of epithelial lesions in the ileum, which are known following ingestion of these fats.

Animals↗

Lactation curves and effect of pup removal on milk fat of C57Bl/6J mice fed different diet fats.

Groups of C57Bl/6J mice, fed either a cis (C-Diet) or trans diet (T-Diet) were milked without preconditioning at 6, 8, 10 and 12 days postpartum. On day 10, groups of mice were also milked 4, 6 and 18 h after separation of the pups. Except for the 18-h separation, all T-Diet fed animals produced milk of lower fat content than did the C-Diet animals (P < 0.001) throughout the lactation period measured. In the C-Diet mice, the 6-h separation period resulted in a decrease (P < or = 0.03) in fat, but the diet-depressed milk fat of T-Diet animals was not decreased further until the 18-h separation period. Milk volume increased as lactation progressed and was greatly increased as a result of preconditioning (P < or = 0.001), even at 4 h of separation when fat was not reduced, and was always greater for T-Diet animals. Within diet groups, fatty acid composition was similar throughout the lactation period studied and was not affected by preconditioning except in the 18-h separation period, when de novo fatty acids were significantly reduced (P < or = 0.05). The data are consistent with the hypothesis that preconditioning results in lowered milk fat values and that preconditioning techniques can explain discrepancies in literature values for murine milk fat.

Animals↗

Energy balance and brown fat activity in rats fed cafeteria diets or high-fat, semisynthetic diets at several levels of intake.

The object of the study was to determine the relative effects of hyperphagia and diet composition on energy balance and thermogenic activity in rats fed highly palatable cafeteria diets. Three types of diet were used: a pelleted stock diet, a cafeteria diet composed of a variety of human food items, and semisynthetic diets with nutrient compositions similar to the stock and cafeteria diets. Feeding rats a high-fat semisynthetic diet (similar to the cafeteria diet) at a energy intake equivalent to that of stock-fed controls (approximately 2.5 times maintenance) resulted in greater body energy gains and energetic efficiencies. These effects were probably due to the reduced energy costs of fat synthesis associated with high-fat diets. No effect of dietary composition on body energy gain was seen in animals fed below 2.5 times maintenance. Animals fed four cafeteria food items each day, or the high-fat semisynthetic diet, at 2.5 times maintenance showed significantly greater thermogenic responses to norepinephrine, increased brown adipose tissue (BAT) mass, and greater BAT mitochondrial GDP binding than controls on the same intake. Injection of propranolol reduced oxygen consumption in all groups, but the effect was greater in animals on higher intakes and was highest in the cafeteria groups. Thus, increasing fat intake, either by presenting cafeteria food items or by feeding a high-fat semisynthetic diet at the same level of intake as controls, stimulates the sympathetic nervous system and BAT activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue, Brown↗

Simultaneous assessment of fat maldigestion and fat malabsorption by a double-isotope method using fecal radioactivity.

[14C]Triolein and [3H]oleic acid are useful tracers of dietary triglycerides and free fatty acids. The combustion/liquid scintillation counting technique was found a practicable method of estimating the fecal activity of these tracers. When ingested with the nonabsorbable marker 51CrCl3, the fecal excretion of 14C and 3H could be estimated accurately from samples of two stools. This technique was investigated as a test of lipid assimilation in a prospective, blind study of 84 consecutive patients suspected of malassimilation. The fecal excretion of 14C was a useful alternative to fecal fat: the patients with "normal lipid assimilation" excreted less than or equal to 10.4% of the dose ingested, whereas 25 of the 26 patients with steatorrhea ("unequivocal malassimilation") excreted greater than 10.4%. Fecal fat was normal in 18 patients who exhibited other signs of malassimilation ("equivocal malassimilation"); in 5 of these patients fecal excretion of 14C was greater than 10.4%. Lastly, there was a significant correlation between fecal 14C and fecal fat (r = 0.82, p less than 0.001). The fecal 14C/3H ratio was found useful as an index of pancreatic digestive function, being less than 1.3 in patients with "normal" lipid digestion and greater than or equal to 1.3 in 18 of the 19 patients with pancreatic steatorrhea and in 19 of the 27 patients with severely reduced exocrine pancreatic function. The test result was found widely independent either of the amount of carrier fat or the quality of the fecal collections and was therefore useful as an outpatient test. As it provided information about the pathogenesis of malassimilation and was at least as sensitive and specific as a fat "balance study," the test may be a useful alternative to fecal fat measurement.

Carbon Radioisotopes↗

Effect of a controlled high-fat versus low-fat diet on insulin sensitivity and leptin levels in African-American and Caucasian women.

African-American women have been shown to be more insulin-resistant than age- and weight-matched Caucasian women, but the reasons for this difference are unclear. The purpose of the present study was to determine whether experimental manipulation of dietary fat intake has differential effects by race on insulin sensitivity (S(I)) in 20 African-American and 11 Caucasian women. Additionally, leptin levels before and after 3 weeks of an isocaloric high-fat ([HF] 50% fat, 35% carbohydrate, and 15% protein) or low-fat ([LF] 20% fat, 55% carbohydrate, and 15% protein) diet were compared. African-American and Caucasian women did not differ significantly in the body mass index (BMI) or percentage body fat at baseline. S(I) (adjusted for BMI) decreased on the HF diet and increased on the LF diet in both races combined relative to the baseline control (control, 2.42 +/- 0.22; HF, 2.29 +/- 0.22; LF, 2.75 +/- 0.21 x 10(-4) min(-1)/microU x mL; main effect of diet, P = .04). There was a 6% decrease in S(I) on the HF diet compared with the control in women of both races, while the LF diet increased S(I) by 6% in African-American and 20% in Caucasian women. Leptin levels increased by 14% on the HF versus control diet in African-Americans (35.2 +/- 3.0 v 30.8 +/- 3.0 ng/mL, P < .01), but did not change with diet in Caucasian women. Glucose and insulin administration had no effect on leptin levels. We conclude that a HF diet consumed over several weeks reduces S(I) in healthy women of both races; however, the magnitude of increase in S(I) on a LF diet is greater in Caucasian women. The HF diet significantly increased leptin levels in African-American women, although there were no other influences of diet, insulin, or race on serum leptin.

Adult↗

Comparison of fat retainers in accelerated solvent extraction for the selective extraction of PCBs from fat-containing samples.

Five types of fat retainers were investigated for the lipid-free extraction of PCBs from fat-containing matrixes using accelerated solvent extraction: florisil, basic alumina, neutral alumina, acidic alumina, and sulfuric acid-impregnated silica. All of the fat retainers generated fat-free extracts when the fat/fat retainer ratio was 1:40. Sulfuric acid-impregnated silica and florisil were the only retainers that gave completely clear extracts, and the former was the only not to show any reaction when treated with sulfuric acid after the extraction. Using sulfuric acid-impregnated silica as fat retainer, on-line cleanup of fat-containing matrixes was possible, as demonstrated for naturally contaminated fish meal as well as certified cod liver oil (CRM 349).

Animals↗

Effect of some fat replacers on the release of volatile aroma compounds from low-fat meat products.

The effect of fat content and carbohydrate fat-replacers on the release of volatile odor compounds from beefburger, salami, and frankfurter has been investigated. The reduction in fat content in any of the three meat products studied resulted in a tendency toward an increase in the quantities of volatiles released in the headspace. Tapioca starch and maltodextrin appear to delay the release of certain classes of compounds selectively; for instance, tapioca starch appears to slow the release of some Maillard products while maltodextrin has a similar effect on terpenes. In contrast, oat fiber decreases the release of most of the compounds analyzed. Thus, the addition of carbohydrate fat-replacers to low-fat meat products could assist the flavor qualities of low-fat meat products by slowing down the release of odor compounds.

Dietary Fats↗

Inhibitory effects of chondroitin sulfate prepared from salmon nasal cartilage on fat storage in mice fed a high-fat diet.

OBJECTIVE: Chondroitin sulfate is an acidic polymer consisting of repeating D-glucuronic acid and D-N-acetylgalactosamine units, and the N-acetylgalactosamine is substituted with the sulfate at either the 4' or 6' position, with approximately one sulfate being present per disaccharide unit. The present study assessed the effects of chondroitin sulfate on the activity of pancreatic lipase and lipid uptake into brush border membrane vesicles of the rat small intestine in vitro, and on the degree of fat storage induced in mice by the oral administration of a high-fat diet for 8 weeks. DESIGN AND MEASUREMENTS: Experiments were carried out to clarify whether or not chondroitin sulfate inhibited pancreatic lipase activity in assay systems using triolein emulsified with phosphatidylcholine or gum arabic. In addition, the effects of chondroitin sulfate on lipid absorption by brush border membrane vesicles were examined. Moreover, mice were fed a high-fat diet and treated with chondroitin sulfate for 8 weeks. RESULTS: Chondroitin sulfate dose-dependently inhibited the pancreatic lipase activity in an assay system using triolein emulsified with phosphatidylcholine. In addition, chondroitin sulfate inhibited the palmitic acid uptake into the brush border membrane vesicles of the rat jejunum. Chondroitin sulfate caused the reduction of body weight and parametrial adipose tissue weight, and prevention of fatty liver and hyperlipidemia in mice fed a high-fat diet. CONCLUSION: The reduction of fat storage and the antihyperlipidemic action of chondroitin sulfate might be due to the inhibition of small intestinal absorption of dietary fat through the inhibition of pancreatic lipase activity and fatty acid uptake through brush border membrane.

Adipose Tissue↗

Fat supplementation to the gestation diet of older sows and its effect on maternal and fetal fat metabolism.

Sows that had had 3 previous litters were fed either a diet with no added fat (low fat) which was rich in linoleic acid (56.7% 18:2n-6), or a high fat diet containing lard, high in total saturates (28.9%) and oleic acid (37.8% 18:1n-9) during gestation. Backfat build-up in the sows on the high fat diet was accelerated compared to the low fat group. On day 110 of gestation, fetuses were removed. The fat content of the diet had no significant effect on sow weight gain during gestation, and the number or body weight of fetuses. Activities of sow liver and adipose and fetal liver malic enzyme, glucose-6-phosphate dehydrogenase (G-6-P) and acetyl-CoA-carboxylase (ACoABx) were measured. Only fetal liver ACoABx and sow adipose G-6-P were significantly affected by the sow's diet.

Acetyl-CoA Carboxylase↗

Effect of increased intake of dietary animal fat and fat energy on oxidative damage, mutation frequency, DNA adduct level and DNA repair in rat colon and liver.

The effect of high dietary intake of animal fat and an increased fat energy intake on colon and liver genotoxicity and on markers of oxidative damage and antioxidative defence in colon, liver and plasma was investigated in Big Blue rats. The rats were fed ad libitum with semi-synthetic feed supplemented with 0, 3, 10 or 30% w/w lard. After 3 weeks, the mutation frequency, DNA repair gene expression, DNA damage and oxidative markers were determined in liver, colon and plasma. The mutation frequency of the lambda gene cII did not increase with increased fat or energy intake in colon or liver. The DNA-adduct level measured by 32P-postlabelling decreased in both liver and colon with increased fat intake. In liver, this was accompanied by a 2-fold increase of the mRNA level of nucleotide excision repair (NER) gene ERCC1. In colon, a non-statistically significant increase in the ERCC1 mRNA levels was observed. Intake of lard fat resulted in increased ascorbate synthesis and affected markers of oxidative damage to proteins in liver cytosol, but not in plasma. The effect was observed at all lard doses and was not dose-dependent. However, no evidence of increased oxidative DNA damage was found in liver, colon, or urine. Thus, lard intake at the expense of other nutrients and a large increase in the fat energy consumption affects the redox state locally in the liver cytosol, but does not induce DNA-damage, systemic oxidative stress or a dose-dependent increase in mutation frequency in rat colon or liver.

Animals↗

Failure of dietary fat intake to promote fat oxidation: a factor favoring the development of obesity.

Seven young men spent three nights and 2 d in a respiration chamber where their rates of energy expenditure and substrate oxidation were continuously measured by indirect calorimetry. During the first 24 h they ingested a mixed maintenance diet containing 35% of calories as fat. An additional amount of 106 +/- 6 g fat/24 h (means +/- SD) was added to this diet during the following 36 h. The fat supplement (987 +/- 55 kcal/d) did not alter 24-h energy expenditure (2783 +/- 232 vs 2820 +/- 284 kcal/d) and failed to promote the use of fat as a metabolic fuel (fat oxidation 1032 +/- 205 vs 1042 +/- 205 kcal/d). The overall energy balance was closely correlated with the fat balance (r = 0.96, p less than 0.001) but not with the carbohydrate balance (r = -0.12, NS). These data indicate that substantial imbalances between intake and oxidation are much more likely for fat than for carbohydrate.

Adult↗

Pentadecanoic acid in serum as a marker for intake of milk fat: relations between intake of milk fat and metabolic risk factors.

BACKGROUND: The fatty acid composition of the diet is known to be partially reflected by the fatty acid composition of serum lipids. OBJECTIVE: We examined whether pentadecanoic acid (15:0) in serum lipids can be used as a marker for intake of milk fat, the major dietary source of 15:0. We also investigated the relations between intake of milk fat and cardiovascular disease risk factors. DESIGN: Sixty-two 70-y-old men completed 7-d dietary records. The intake of milk products was studied in relation to the proportions of 15:0 in serum cholesterol esters and phospholipids, as well as to the clinical characteristics of these men, by using Spearman's rank correlation. RESULTS: The proportions of 15:0 in serum cholesterol esters were positively related to butter intake (r = 0.36. P = 0.004) and to the total amount of fat from milk products (r = 0.46, P < 0.0001): 15:0 in phospholipids was related to the amount of fat from milk and cream (r = 0.34, P = 0.008) and to the total amount of fat from milk products (r = 0.34, P = 0.008). Inverse associations were found between intake of milk products and body mass index, waist circumference, LDL-HDL ratio, HDL triacylglycerols, and fasting plasma glucose, whereas relations to HDL cholesterol and apolipoprotein A-I tended to be positive. CONCLUSIONS: The results suggest that 15:0 in serum can be used as a marker for intake of milk fat. The explanation for the inverse associations between the intake of milk products and certain cardiovascular risk factors is not known.

Aged↗

Milk fat depression in C57Bl/6J mice consuming partially hydrogenated fat.

Mice of the C57Bl/6J strain were maintained on diets in which the unsaturated fatty acids were all cis fatty acids (CFA) or a mixture of CFA and trans fatty acids (TFA). The fats used were mixtures of corn oil, olive oil, cocoa butter, margarine and shortening blended to yield similar fatty acid compositions, except for the ratio of the CFA to TFA and the percentage of linoleic acid (EFA). Regardless of the level of fat (20 or 40 energy %) or the level of EFA (2 to 12 energy %), diets with TFA decreased the percentage of fat in mouse milk. When lactating females raised on the CFA diets were crossed to the TFA diets, TFA appeared in the milk at 12 h postcross, and within 4 d postcross the percent of milk fat was decreased to levels similar to that of nursing females raised continuously on the TFA diets. Conversely, lactating females crossed from TFA to CFA diets produced milk with percentage fat values and fatty acid compositions that approached those seen in nursing females fed the CFA diets continuously. The possible involvement of TFA in the classical milk fat depression phenomenon in ruminants and its potential relevance in human lactation are discussed.

Animals↗

Pork fat and chicken fat similarly affect plasma lipoprotein metabolism in cynomolgus monkeys fed diets with adequate levels of linoleic acid.

The effects on plasma lipoprotein metabolism of replacing pork fat (PF) with chicken fat (CF) (formulated as part of currently recommended prudent diets) was evaluated in 10 male cynomolgus monkeys. Monkeys were rotated through three dietary periods, (each of 10-wk duration), during which total cholesterol (TC), triacylglycerol (TG) and HDL-cholesterol (HDL-C) were measured (7, 8 and 9 wk) and in vivo lipoprotein metabolism evaluated (after 9 wk). Initially, all monkeys were fed a high-fat, high-cholesterol reference diet [38% of energy (en) from fat, 18%en saturated fatty acids (SFA), 10%en monounsaturated fatty acids (MUFA), 10%en polyunsaturated fatty acids (PUFA), 0.045 mg cholesterol/kJ diet]. Subsequently, monkeys were rotated through two test diets (30%en fat, SFA/MUFA/PUFA 1:1:1, 0.004-0.005 mg cholesterol/kJ diet), in which 80% of the fat was either PF or CF, with the remaining 20% derived from high-linoleic safflower oil. There was no significant difference between the two test diets for TG, TC, nonHDL-C, HDL-C or the ratio of TC/HDL-C. Lipoprotein composition, LDL apolipoprotein B pool size, fractional catabolic rate and transport rate were also not significantly different when monkeys consumed the two test diets. These data suggest that when incorporated into diets following current guidelines and containing adequate PUFA ( approximately 7-9%en), PF and CF similarly affect plasma lipids.

Animals↗

Dietary fat type influences total milk fat content in lean women.

Trans fatty acids (TFA) are found naturally in some foods (e.g., dairy products) as well as many processed foods made with partially hydrogenated vegetable oils (PHVO). Data from a growing literature suggest that some TFA decrease milk fat in lactating animals. Because the physiologic effects of TFA in lactating women are unknown, this study was designed to investigate the effects of TFA consumption on human milk fat. A randomized, crossover design (n = 12) was used to study the effect of 3 dietary treatments: high PHVO (regular margarine), low PHVO (low TFA margarine), or low PHVO but high in naturally occurring TFA (butter) on milk fat. Treatments were administered for 5 d, with 7-d washout periods. Maternal adiposity was estimated by dual-energy X-ray absorptiometry. Milk and blood were collected on d 5 of each intervention period. In general, milk and serum fatty acid concentrations mirrored those of the dietary treatments. There were significant interactions between treatment and maternal adiposity on milk fat and infant milk consumption, as well as on serum glucose and nonesterified fatty acid (NEFA) concentrations. Consumption of regular margarine, compared with low TFA margarine, resulted in lower milk fat in leaner, but not in more obese women. Consumption of either regular or low TFA margarine, compared with butter, elevated serum NEFA concentrations in the more obese women. In summary, consumption of regular margarine, compared with low TFA margarine, decreased milk fat in lean women. Further studies are required to determine whether infant milk consumption might compensate for this potentially important change in milk composition.

Absorptiometry, Photon↗