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Fatty acid composition of serum lipid fractions in relation to gender and quality of dietary fat.

UNLABELLED: The fatty acid compositions of serum lipid fractions are believed to reflect the quality of dietary fat, but only a few cross-sectional studies have examined these relationships in a representative free-living population. We related the composition of dietary fat obtained by 7-day food records from 84 free-living middle-aged married couples, on their habitual diets, to gas chromatographic analyses of the percentage compositions of fatty acids in three lipid fractions of fasting sera. Dietary polyunsaturated fat had Pearson's correlation coefficients of 0.63, 0.73 and 0.44 with n-6 polyunsaturated fatty acids in serum cholesteryl esters, triglycerides and phospholipids, respectively. Intake of fish showed correlations of 0.60, 0.36 and 0.52 with the percentage of eicosapentaenoate in the respective fractions. Dietary saturated fat had correlations of 0.57 and 0.54 with saturated fatty acids in serum cholesteryl esters and triglycerides, respectively. Dietary monounsaturated fat did not correlate positively with monounsaturated fatty acids in any serum lipid fraction. There were some small but significant gender differences in the serum fatty acid compositions. CONCLUSIONS: of the three serum lipid fractions, triglycerides appear to be the best reflectors of dietary polyunsaturated and saturated fat, but the intake of monounsaturated fat is poorly reflected in all serum lipid fractions. Intake of fish is mirrored in all serum lipid fractions, best in cholesteryl esters and phospholipids.

Adult↗

Associations between HDL-cholesterol and polymorphisms in hepatic lipase and lipoprotein lipase genes are modified by dietary fat intake in African American and White adults.

Polymorphisms in genes involved in HDL-cholesterol (HDL-C) metabolism influence plasma HDL-C concentrations. We examined whether dietary fat intake modified relations between HDL-C and polymorphisms in hepatic lipase (LIPC-514C-->T), cholesteryl ester transfer protein (CETP TaqIB), and lipoprotein lipase (LPL S447X) genes. Diet (food frequency questionnaire), plasma lipids, and LIPC, CETP, and LPL genotypes were assessed in approximately 12,000 White and African American adults. In both races and all genotypes studied, minor allele homozygotes had highest HDL-C concentrations compared to the other genotypes (P<0.001). However, main effects were modified by usual dietary fat intake. In African Americans - women somewhat more strongly than men -LIPC TT homozygotes with fat intake >or=33.2% of energy had approximately 3-4 mg/dL higher HDL-C concentrations than CC and CT genotypes. In contrast, when fat intake was <33.2% of energy, TT homozygotes had HDL-C concentrations approximately 3.5mg/dL greater than those with the CC genotype but not different from those with the CT genotype (P(interaction)=0.013). In Whites, LPLGG homozygotes had greatest HDL-C at lower total, saturated, and monounsaturated fat intakes but lowest HDL-C at higher intakes of these fats (P(interaction)<or=0.002). Dietary fat did not modify associations between CETP and HDL-C. In conclusion, these data show that plasma HDL-C differs according to LIPC, LPL, and CETP genotypes. In the case of LIPC and LPL, data suggest dietary fat modifies these relations.

Black or African American↗

Role of dietary fat in blood pressure control.

Three controlled intervention studies were carried out in North Karelia to study the possible role of dietary fat in the control of human blood pressure. All studies included middle-aged free-living couples (families) and a baseline (BS, 2 weeks), an intervention (IN, 6-12 weeks) and a switch-back (SB, 4-6 weeks) period. During IN the families were instructed to eat low fat (less than 25 en% instead of 39 en%), high P/S ratio diet (0.4-1.1 instead of 0.2). Salt and energy intake and other lifestyles were kept constant. In the first study the P/S ratio of the IN diet was 1.1. Both systolic and diastolic blood pressures decreased significantly during IN and increased back again during SB. The same results were obtained in the second study at P/S level 0.9 when a randomized group with 60% salt reduction and a control had little change in their blood pressure levels. In the third study the blood pressure reduction was again repeated during a 12 week IN period. The reduction was similar in two randomized groups with P/S 0.4 and 0.9, when both group had less than 25 en% of total fat. The results strongly support the hypothesis that dietary fat is related to human blood pressure, and that modification of dietary fat should be considered in the non-pharmacological prevention and management of hypertension.

Adult↗

The association between leisure-time physical activity and dietary fat in American adults.

Relations between leisure-time physical activity and dietary fat were examined in a population-based probability sample of 29,672 adults in the 1990 Behavioral Risk Factor Surveillance System. Consumption of 13 high-fat food items and participation in physical activities were measured, and fat and activity scores were calculated. Dietary fat and physical activity were strongly and inversely associated. This association was independent of nine other demographic and behavioral risk factors. Etiologic researchers should consider that diet and physical activity can potentially confound each other, and creators of public health messages that target one behavior should consider including the other.

Adolescent↗

Comparison of the effect of the amount and degree of unsaturation of dietary fat on plasma low density lipoproteins in vervet monkeys.

The effects of the degree of unsaturation and of the amount of dietary fat on low density lipoprotein (LDL) concentration and composition were determined in vervet monkeys. Diets with fat contents of 41, 31 and 18% energy, each with a low and a high polyunsaturated to saturated fatty acid ratio (P/S; 0.27-0.38 and 1.13-1.47) were fed to six female vervet monkeys for two months. Another six females were given a low fat, high P/S diet for the same period of time, to serve as a reference. The cholesterol contents of the diets were low (21-33 mg per day) and relatively constant. LDL cholesterol concentrations decreased significantly (P < or = 0.01) when the dietary fat content decreased from 31 to 18% of energy. The dietary P/S ratio only affected LDL cholesterol concentrations during moderate (31% of energy) fat intake, where LDL cholesterol increased (P < or = 0.01) with a decrease in dietary P/S. Substantial individual variations were observed in LDL cholesterol concentration responses to dietary fat changes. The changes in LDL cholesterol concentrations were the result of changes in the concentration of LDL particles, as the molecular composition did not differ significantly between dietary periods. The high density lipoprotein cholesterol and the plasma triacylglycerol concentrations were not influenced by the dietary fat changes. During the high P/S diets, the percentage of 18:2 (linoleic acid) increased (P < or = 0.01) and that of 18:1 (oleic acid) decreased (P < or = 0.01) in LDL esterified cholesterol, as compared to the low P/S diets. In adipose tissue triacylglycerol the percentage of 18:2 was three times higher (P < or = 0.01) during the high P/S diets than during the low P/S diets.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗

The metabolic use of energy from dietary fat in broilers is affected by fatty acid saturation.

1. Two experiments were performed to evaluate the effect of dietary fat on performance and fat and protein accretion in broiler chickens according to the degree of saturation. 2. The first experiment was designed to test 2 sources of dietary fat and 3 levels of dietary energy using a factorial (2x3) experimental design. The foods were formulated to maintain a constant ratio of energy to protein (and other nutrients). There were no significant differences in weight gain, intake, final body weight or food to gain ratio between broilers fed on diets differing solely in the degree of fat saturation. Broilers fed on diets containing animal fat showed higher whole-body fat retention (P=0.02) and lower protein accretion (P=0.03) than those fed on diets containing vegetable oils. 3. In the second experiment, only 1 concentration of fat (tallow, lard or sunflower oil) was incorporated into the experimental diets, providing different energy to protein ratios. The carcase protein content was not affected by dietary fat source, while total fat accretion (P=0.01) and energy retention (P=0.14) were highest in broilers fed on a diet containing tallow. 4. The findings suggest that the degree of saturation of dietary fats affects their metabolic use and fat accumulation in broiler chickens.

Animal Feed↗

Effect of dietary fat source on lipoprotein composition and plasma lipid concentrations in pigs.

Most studies of the effects of dietary fat sources on plasma lipid components have used diets with extreme fat compositions; the current study was designed to more nearly mimic human dietary fat intake. Young growing pigs were fed diets containing either 20 or 40% of energy as soy oil, beef tallow or a 50/50 blend of soy oil and tallow. Different dietary fats did not affect concentrations of cholesterol, triacylglycerol or protein in plasma or major lipoprotein fractions. The concentration of phospholipid was less in plasma and in very low density lipoproteins with soy oil feeding than with tallow feeding. The weight percentage of cholesteryl ester in the low density lipoprotein fraction tended to be greater with 40% than with 20% tallow and tended to be less with 40% than with 20% soy oil. Phospholipid as a weight percentage of low density lipoprotein was least in pigs fed soy oil. Tallow feeding increased the percentage of myristic, palmitic, palmitoleic and oleic acids in plasma, relative to both other groups. Soy oil feeding increased the percentage of linoleic and linolenic acids. These moderate diets were not hypercholesterolemic, but they did alter plasma fatty acid composition and phospholipid concentrations in plasma and very low density lipoprotein.

Animals↗

Cytotoxicity of fecal water is dependent on the type of dietary fat and is reduced by supplemental calcium phosphate in rats.

The effects of the type of dietary fat (180 g/kg diet) and of calcium phosphate (CaHPO4) supplementation (25 vs. 225 mmol/kg diet) on luminal solubility of fatty acids and bile acids, cytotoxicity of fecal water and intestinal epitheliolysis were studied in rats. In rats fed the low and high calcium phosphate diets, fecal excretion of fatty acids diminished in the order palm oil > milk fat > corn oil. Palm oil also caused the highest concentration of fatty acids measured in fecal water followed by milk fat and corn oil when fed at both calcium phosphate levels. The differences in concentrations of luminal surfactants in fecal water of rats fed the three fat diets resulted in a fat type-dependent cytotoxicity of fecal water, with that of palm oil-fed rats the most cytotoxic. The concentrations of fatty acids as well as bile acids in fecal water were, however, significantly lowered by calcium phosphate supplementation in rats fed all types of dietary fat. This reduction in concentration of fecal water surfactants resulted in a lower cytotoxicity of fecal water. The concentration of surfactants in fecal water and cytotoxicity were correlated by multiple regression analysis (R = 0.89). Intestinal epitheliolysis measured as alkaline phosphatase activity in fecal water was lowered comparably to the reduction in cytotoxicity by supplemental calcium phosphate. Intestinal epitheliolysis and cytotoxicity of fecal water were correlated (r = 0.92, P < 0.001). The type of dietary fat and the amount of dietary calcium phosphate influence the concentrations of surfactants in fecal water and consequently affect cytotoxicity of fecal water and intestinal epitheliolysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗

A meta-analysis of studies of dietary fat and breast cancer risk.

There is strong evidence that breast cancer risk is influenced by environmental factors, and animal experiments and human ecological data suggest that increased dietary fat intake increases the incidence of the disease. Epidemiological evidence on the relationship of dietary fat to breast cancer from cohort and case control studies has however been inconsistent. To examine the available evidence we have carried out a meta-analysis to summarise quantitatively the large published literature on dietary fat in the aetiology of breast cancer. After assembling all of the published case control and cohort studies, we extracted the relative risk in each study that compared the highest to the lowest level of intake. We then calculated a summary relative risk for all studies. The summary relative risk for the 23 studies that examined fat as a nutrient was 1.12 (95% CI 1.04-1.21). Cohort studies had a summary relative risk of 1.01 (95% CI 0.90-1.13) and case control studies a relative risk of 1.21 (95% CI 1.10-1.34). Summary estimates of risk for specific types of fat excluded unity for only saturated fat. For the 19 studies that examined food intake, the summary relative risks were 1.18 (95% CI 1.06-1.32) for meat, 1.17 (95% CI 1.04-1.31) for milk, and 1.17 (95% CI 1.02-1.36) for cheese. Summary relative risks for total fat intake were examined for several potential modifying factors. Regression analysis showed that European studies were more likely than studies done in other countries to show an increased relative risk associated with dietary fat and breast cancer, after taking into account potential modifying factors that included study design and quality.

Animals↗

Prior exercise increases subsequent utilization of dietary fat.

PURPOSE: Exercise appears to offer protection against weight gain, perhaps related to its effects on fat metabolism. Previous work in rats has shown that interventions resulting in a negative energy balance lead to alterations in the trafficking of dietary fat. This study was undertaken to determine whether exercise after an overnight fast would alter the partitioning of dietary fat between oxidation and storage. METHODS: Seven female subjects (age = 26 +/- 1 yr, BMI = 21 +/- 1 kg x m(-2); mean +/- SEM) were recruited for three visits: rest, light, and heavy exercise. Stationary cycle exercise sessions were calculated to use 1,250 kJ and were done in a whole-body calorimeter. Dietary fat oxidation was calculated from the recovery of (13)C-oleate corrected for acetate sequestration and d(31)-palmitate given in a liquid meal 30 min after the completion of exercise. RESULTS: Cumulative oxidation of (13)C-oleate at 11.5 h postdose was significantly greater during the heavy exercise (49 +/- 4%) trial than both the light exercise (39 +/- 4%) and the rest trials (34 +/- 4%) (P < 0.005). Oxidation of d(31)-palmitate recovery at 11.5 h postdose was not different during the heavy exercise (12 +/- 1%), light exercise (11 +/- 1%), and rest trials (10 +/- 1%). CONCLUSIONS: These data illustrate that exercise has the ability to alter the trafficking of dietary fat. Furthermore, the effect of exercise is dependent on the type of fatty acid.

Adult↗

Effect of dietary fat on fluoride absorption and tissue fluoride retention in rats.

The effect of dietary fat on fluoride toxicity was investigated in rats fed isoenergetic diets with graded levels of fat (0, 10%, 30% or 50% of energy) containing 400 ppm fluoride. Growth rate was depressed in all groups receiving fluoride but most severely in the 50% dietary fat group. Plasma, liver and femur fluoride concentrations were increased by increasing dietary fat. This was apparently due to increased absorption of fluoride, since urinary fluoride increased and fecal fluoride excretion decreased as fat intake was elevated. The enhancement of fluoride absorption by fat is believed to be due to the delaying effect of fat and fluoride on gastric emptying, thereby allowing more time for the fluoride to be absorbed from the stomach.

Absorption↗

Influence of different dietary fats on triacylglycerol deposition in rat adipose tissue.

It has been demonstrated that triacylglycerol (TAG) mobilization from adipose tissue is selective and depends on fatty acid (FA) chain length, unsaturation and positional isomerism. The present study was performed to determine the influence of dietary fat on the composition of TAG stored in rat perirenal and subcutaneous adipose tissues. These results may provide information on the susceptibility of stored TAG to hydrolysis and further mobilization, and may help to establish an interrelationship between dietary composition and the FA efflux from adipose tissue. TAG molecular species and FA composition were determined by HPLC and GLC respectively. No significant differences were found in either FA or TAG composition between perirenal and subcutaneous adipose depots. The major FA in the dietary fats were present in the adipose tissues of the animals; in most cases, in similar proportions. However, differences were found between dietary and adipose tissue content of minor FA, which suggests that dietary FA composition is altered between ingestion and deposition in adipose tissue. The TAG molecular species of rat adipose tissue were enriched with the FA characteristic of each dietary fat. Dietary sunflower oil was responsible for enrichment with the most polar TAG. This finding may suggest easier mobilization of stored TAG. In conclusion, the process of fatty acid and TAG deposition in rat adipose tissue is selective, and depends on the composition of the diet.

Adipose Tissue↗

Effects of dietary fat source and subtherapeutic levels of antibiotic on the bacterial community in the ileum of broiler chickens at various ages.

The effect of dietary fat source (soy oil or a mixture of lard and tallow) and dietary supplementation with antibiotics (a combination of avilamycin at 10 mg kg of feed(-1) and salinomycin at 40 mg kg of feed(-1)) on the bacterial community in the ileum of broiler chickens at different ages (7, 14, 21, and 35 days) was studied using PCR with denaturing gradient gel electrophoresis (DGGE) analysis and bacteriological culture. The bacterial origin of fragments in DGGE profiles was identified by sequencing. Bacterial enumeration results, together with PCR-DGGE profiles, showed that the composition of the microflora was age dependent and influenced by dietary fat source and antibiotic supplementation. An increased incidence of streptococci, enterobacteria, and Clostridium perfringens with age of the chickens was demonstrated. Lactobacilli and C. perfringens were the bacterial groups most strongly affected by the dietary treatments. Moreover, different strains (clonal variants of the alpha-toxin gene) of C. perfringens type A were detected in response to age, dietary fat source, and dietary supplementation with antibiotics.

Age Factors↗

Dietary-induced obesity: effect of dietary fats on adipose tissue cellularity in mice.

1. Male and female mice, 4 weeks old, were fed ad lib. diets containing various amounts of lard (0-300 g/kg) or various kinds of dietary fats (300 g/kg) for 13 weeks. Fat cell number and size were determined by a histological method in three different adipose sites. 2. Lard at 200 g/kg diet (43% energy from lipids) was sufficient to promote fat cell hyperplasia in the parametrial fat. Hyperplasia was also observed in the subcutaneous fat in males. The relationship between fat cell hypertrophy and the level of lard in the diet was dependent on site and sex. 3. Obesity was produced whatever the kind of dietary fat eaten: lard, beef tallow, sunflower oil or soya-bean oil. In the subcutaneous depot of males given lard, fat cell size and number were increased, but only cell hypertrophy was observed in those given soya-bean oil. In the female groups of mice fat cell hyperplasia or hypertrophy or both were related to the adipose site but not the kind of dietary fat. 4. It is concluded that dietary fats of different origin can induce obesity in mice. The effects on adipose tissue cellularity depend on the levels and kind of fat eaten, the adipose site and sex.

Adipose Tissue↗

Dietary fat intake does affect obesity!

There is a difference of opinion about whether the percentage of dietary fat plays an important role in the rising prevalence of overweight and in its treatment once it has developed. We believe that ample research from animal and clinical studies, from controlled trials, and from epidemiologic and ecologic analyses provides strong evidence that dietary fat plays a role in the development and treatment of obesity. A reduction in fat intake reduces the gap between total energy intake and total energy expenditure and thus is an effective strategy for reducing the present epidemic of obesity worldwide. A review of the results from 28 clinical trials that studied the effects of a reduction in the amount of energy from fat in the diet showed that a reduction of 10% in the proportion of energy from fat was associated with a reduction in weight of 16 g/d. We thus conclude that dietary fat plays a role in the development of obesity. To reduce the prevalence of obesity, there must be an increase in energy expenditure, a reduction in total energy intake, or both. This goal can be facilitated by reducing the amount of fat in the diet.

Animals↗

The relationship of dietary fats to prostaglandin biosynthesis.

The direct and indirect evidence that the fatty acid composition of dietary fat is involved in the regulation of prostaglandin biosynthesis was reviewed. Direct evidence included effects of essential fatty acid deficiencies and excesses on endogenous tissue levels and production rates of prostaglandins by several tissues. Indirect evidence included lipolytic, platelet aggregatory, hypertensive, inflammatory and immune responses. In general, composition of dietary fat did not affect prostaglandin biosynthesis unless a biochemical essential fatty acid deficiency was induced or the linoleate to saturated fatty acids ratio of the dietary fat was greater than 5. Most results were interpreted in light of changing fatty acid composition; however, very few direct measurements have been made.

Adipose Tissue↗

Dietary fat saturation modifies the metabolism of LDL subfractions in guinea pigs.

The effects of dietary fat saturation on the metabolism of low-density lipoprotein (LDL) subfractions were measured in adult male guinea pigs fed semipurified diets containing 15% (wt/wt) corn oil (CO; 58% linoleic acid), lard (24% palmitic/14% stearic acid), or palm kernel oil (PK; 52% lauric/18% myristic acid). Animals fed the CO diet had lower plasma total cholesterol levels than guinea pigs fed the PK or lard diets (P < .01). Plasma LDL-1 (d = 1.019 to 1.05 g/mL) concentrations were 3.5- and 2.4-fold higher in animals fed the PK diet compared with the CO and lard groups, respectively, while LDL-2 (d = 1.05 to 1.09 g/mL) concentrations were not different among groups. For all dietary fat groups LDL-1 had a higher molecular weight and a larger diameter than LDL-2. LDL fractional catabolic rates (FCRs) varied, depending on both the diet and the LDL subfraction. Animals fed the polyunsaturated CO diet had a more rapid LDL FCR than animals from the other two groups (P < .01). Within the same diet group, LDL-2 exhibited a slower turnover rate than LDL-1 in animals fed the PK diet, while no differences in LDL subfraction FCR were found in the CO and lard groups. Animals fed the PK and lard diets did not exhibit significant modifications in the density distribution of LDL subfractions over a period of 33 hours. In contrast, animals fed the CO diet exhibited a shift of more buoyant to denser LDL particles, suggesting that differences in LDL intravascular processing are mediated by dietary fat saturation. In vitro LDL binding to hepatic membranes confirmed the in vivo data with an increased expression of apolipoprotein B/E receptors (Bmax) in animals fed the CO diet (P < .01). Hepatic apolipoprotein B/E receptors exhibited less affinity for LDL-2 in the PK group, a result consistent with the less rapid turnover of LDL-2 in PK-fed animals. The results suggest that dietary fatty acids varying in saturation and composition have distinctive atherogenic potentials. The lowest plasma LDL cholesterol concentrations mediated by CO intake could in part be explained by induced changes in the composition and processing of LDL subfractions, resulting in faster LDL turnover rates in addition to increased expression of hepatic apolipoprotein B/E receptors.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗