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PubMed1992

Dietary fat type and cholesterol quantity interact to affect cholesterol metabolism in guinea pigs.

Interactions of dietary fat saturation with dietary cholesterol on cholesterol homeostasis in guinea pigs were studied by feeding 15% (wt/wt) fat diets containing lard, olive oil or corn oil, with 0.00, 0.08, 0.17 or 0.33% added cholesterol. Plasma total and LDL cholesterol concentrations significantly increased with increasing dietary cholesterol, with pronounced increments occurring at the pharmacologic (0.33%) level. An interaction between fat type and dietary cholesterol was seen for HDL cholesterol concentrations. Saturated fat and the pharmacologic level of dietary cholesterol increased plasma HDL concentrations, whereas polyunsaturated fat minimized the dietary cholesterol-mediated increase. Interactions were also observed for hepatic cholesterol: dietary cholesterol increased both free and esterified hepatic cholesterol concentrations in all groups fed all the dietary fats, and fat type influenced the extent of hepatic cholesterol accumulation. Lard-fed animals accumulated the least hepatic cholesterol over the range of dietary cholesterol intakes. Dietary cholesterol suppressed hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity, with maximal suppression at all levels of cholesterol intake. Dietary cholesterol had a greater effect on plasma and hepatic cholesterol concentrations and hepatic HMG-CoA reductase activity than did fat type. The data indicated limited interactions of fat type and cholesterol quantity in altering mechanisms regulating plasma cholesterol homeostasis.

Acyl Coenzyme A↗

PubMed1999

Differential response to dietary fat in large (LG/J) and small (SM/J) inbred mouse strains.

The "large" (LG/J) and "small" (SM/J) inbred mouse strains differ for a wide variety of traits related to body size and obesity. Ninety-three LG/J and SM/J mice were divided into two treatment categories and fed a moderately high-fat diet (21% kcal fat) or a low-fat diet (12% kcal fat) from weaning to necropsy. Strain differences in obesity-related traits and differential response to dietary fat increases were analyzed using ANOVA. LG/J animals grow faster from 3 to 10 wk, have longer tails, and have heavier body weight, liver weight, and fat pad weight than SM/J animals. SM/J animals grow faster after 10 wk of age and have higher fasting glucose levels than LG/J animals. SM/J mice were more responsive to increased dietary fat than LG/J mice for growth after 10 wk, necropsy weight, liver weight, fat pad weights, and fasting glucose levels (in males). The growth from 3 to 10 wk had a much greater response in the LG/J strain, whereas tail length had no response. This pattern of dietary response is similar to that expected under the "thrifty" phenotype hypothesis. Genes affecting strain differences and the differential response of the strains to dietary fat can be successfully mapped in the intercross of the LG/J and SM/J strains. This intercross provides an excellent multigenic model for the genetic basis of complex traits and diseases related to body size and obesity.

Adipose Tissue↗

PubMed1999

Dietary fat and physical performance.

Although the relationship between dietary carbohydrate and physical performance is well described, there is much controversy about the relationship between dietary fat and physical performance. Recently, several studies have tried to clarify this relationship. Here the effects of acute fat on metabolism and performance will be discussed, as well as the effects of short-term and long-term high-fat diets.

Dietary Carbohydrates↗

PubMed1979

Relationship between amount and type of dietary fat in promotion of mammary carcinogenesis induced by 7,12-dimethylbenz[a]anthracene.

Female Sprague-Dawley rats were fed semipurified diets containing various fats, either alone or in combination, to provide different amounts of dietary fat and linoleic acid. One week before commencing the diets, each rat received an intra-gastric dose of the carcinogen 7,12-dimethylbenz[a]anthracene. Rats fed diets containing mixtures of 3% sunflower seed oil and 17% of either tallow or coconut oil developed twice as many tumors as those fed 3% sunflower seed oil or 20% of either saturated fat alone. Tumor yields in the rats fed these mixed-fat diets were comparable to those in rats fed a 20% lard diet, which provided about the same amount of linoleic acid. No further increase in tumor yield was observed in rats fed a 20% sunflower seed oil diet that contained more than five times as much linoleic acid. These results show that a certain amount of polyunsaturated fat, as well as a high level of dietary fat, is required to promote mammary carcinogenesis.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1981

Dynamic modulation of mitochondrial inner-membrane lipids in rat heart by dietary fat.

A novel longitudinal feeding design was used to investigate the controlling influence of dietary fatty acids on the dynamic incorporation of fatty-acyl chains into phosphatidylcholine, phosphatidylethanolamine and cardiolipin in inner membrane of cardiac mitochondria. Rats were fed a polyunsaturated-fatty-acid-rich oil (soya-bean oil) for 12 days, crossed-over to a monounsaturated-fatty-acid-rich oil (rapeseed oil) for the next 11 days, then returned to soya-bean oil for 11 more days. Additional rats were fed either soya-bean oil or rapeseed oil only throughout. Rats were killed serially. Regression analysis was used to represent longitudinal flux in membrane lipid fatty-acid composition occurring with change in dietary fat. The fatty-acid composition of phosphatidylcholine, phosphatidylethanolamine and cardiolipin was influenced by dietary oil in a reversible way. Maximal diet influence was achieved in the 11-day cross-over period. Soya-bean oil to rapeseed oil cross-over caused the fatty-acid composition of phosphatidylcholine, phosphatidylethanolamine and cardiolipin to resemble that of rats fed rapeseed oil only. These changes were reversed by crossing back to soya-bean oil, indicating the dynamic state and short half-life of membrane phospholipid fatty-acyl chains. This report demonstrates for the first time in the whole animal fed diets adequate in all nutrients that subcellular membrane lipids rapidly respond to change in dietary fatty-acid balance. The system may be used to assess in vivo the significance of dietary fat in determining membrane physicochemical properties and biochemical functions.

Animals↗

PubMed1997

Effects of dietary fat restriction on particle size of plasma lipoproteins in postmenopausal women.

Hypertriglyceridemia is an independent risk factor for coronary artery disease (CAD) and is also commonly associated with other coronary risk factors, ie, small, dense low-density lipoprotein (LDL) particles and low plasma levels of high-density lipoprotein cholesterol (HDL-C). Dietary fat restriction is recommended for the prevention of nutrition-related cancers. Low-fat, high-carbohydrate intake can increase plasma triglyceride (TG) and decrease HDL-C. In general, plasma TG levels are inversely related to the particle size of LDL. We investigated the effects of dietary fat restriction on the concentration and particle size of plasma lipoproteins in 14 healthy postmenopausal women (aged 61 +/- 11 years). During a 4-month period of eucaloric controlled feeding, dietary fat was reduced stepwise from a habitual intake of 33% +/- 8% to 23% and then to 14% of daily energy. Changes in the plasma lipid level and particle size of very-low-density lipoprotein (VLDL), LDL, and HDL were determined at the end of each dietary phase. Increasing carbohydrate intake without weight loss was associated with an increase in plasma TG (1.86 +/- 0.30 v 2.47 +/- 0.37 mmol/L) and decreases in total cholesterol (5.82 +/- 0.25 v 5.40 +/- 0.21 mmol/L), LDL-C (3.07 +/- 0.18 v 2.61 +/- 0.21 mmol/L), HDL-C (1.42 +/- 0.1 v 1.24 +/- 0.1 mmol/L), and apolipoprotein (apo) A1 (5.14 +/- 0.25 v 4.61 +/- 0.36 mmol/L), whereas plasma apo B did not change. The particle size of VLDL increased (42.7 +/- 1.4 v 47.0 +/- 0.9 nm). However, there was no change in either LDL (25.1 +/- 0.2 v 25.3 +/- 0.2 nm) or HDL particle size. Although at each level of dietary fat intake LDL particle size correlated inversely with plasma TG and apo B, there was no relationship between the increase in plasma TG and LDL particle size. These results show that hypertriglyceridemia caused by a eucaloric high-carbohydrate intake is not associated with a decrease in LDL particle size. Therefore, carbohydrate-induced hypertriglyceridemia may not have the same atherogenic potential as genetic hypertriglyceridemias.

Aged↗

PubMed2004

Dietary fat regulates mammary stearoyl coA desaturase expression and activity in lactating mice.

Mice in mid lactation (n=6 per group) were fed a control diet (1.19% fat), or diets containing safflower oil (25% w/w) or olive oil (25% w/w) for 7d. Mammary and liver stearoyl CoA desaturase (SCD) mRNA levels and mammary SCD activities were higher in lactating mice fed the control diet than in those fed the oil-supplemented diets. Further, mammary SCD mRNA was directly related to mammary SCD activity. Milk fat composition was influenced by dietary fat composition. The olive oil diet, high in 18:1, led to high levels of this fatty acid in milk and the safflower oil diet, high in 18:2, resulted in a milk fat with high levels of 18:2. These results show that there is regulation of SCD at the transcriptional level, associated with changes in enzyme activity and in milk fat composition.

Animals↗

PubMed2005

Dietary fat content modifies liver fat in overweight nondiabetic subjects.

BACKGROUND: Fat accumulation in the liver has been shown to be closely correlated with hepatic insulin resistance and features of insulin resistance, even independent of body weight. The reason for interindividual variation in liver fat content is unknown. Cross-sectional data suggest that dietary fat content may influence liver fat, but this possibility has not been directly tested in humans. DESIGN AND METHODS: Liver fat (proton spectroscopy), intraabdominal and sc fat (magnetic resonance imaging), and markers of insulin sensitivity (insulin, free fatty acids, and lipids) were determined in 10 normal, obese women (age, 43 +/- 5 yr, mean +/- sd; body mass index, 33 +/- 4 kg/m2; range, 27-38 kg/m2) at baseline and after two 2-wk isocaloric periods containing either 16% (low-fat diet) or 56% (high-fat diet) of total energy as fat. RESULTS: Liver fat at baseline averaged 10 +/- 7%. It decreased by 20 +/- 9% during the low-fat diet and increased by 35 +/- 21% during the high-fat diet (P = 0.014 for liver fat after low- vs. high-fat diets; P = 0.042 for change in liver fat by the low- vs. high-fat diet). Fasting serum insulin averaged 70 +/- 41 pmol/liter at baseline. It decreased to 60 +/- 24 pmol/liter during the low-fat diet (P = 0.007 vs. before low-fat diet) and increased to 81 +/- 44 pmol/liter during the high-fat diet (P = 0.040 vs. before high-fat diet; P = 0.005 for change in serum insulin during low- vs. high-fat diet). Serum lipids, free fatty acids, and intraabdominal and sc fat masses were unchanged. CONCLUSION: These data suggest that the amount of dietary fat influences liver fat content.

Adolescent↗

PubMed1992

Gender and dietary fat affect alpha-tocopherol status in F344/N rats.

For four weeks, groups of eight male and eight female F344/N rats were fed diets containing 15.5, 20, 30 or 40% of energy (en%) as fat. The fat was composed of corn oil and beef tallow with 9 en% from linoleate in all diets. Females had greater mean hepatic alpha-tocopherol levels, whereas males had greater plasma alpha-tocopherol and cholesterol concentrations. In males, the plasma ratio of alpha-tocopherol/cholesterol was significantly greater than in females (P < 0.05). Plasma alpha-tocopherol increased with increasing en% fat (r = 0.51, P < 0.001) in both sexes, but dietary fat did not alter hepatic alpha-tocopherol levels. These results suggest that plasma alpha-tocopherol may serve as a biomarker of total dietary fat intake and that in F344/N rats gender differences affect alpha-tocopherol and cholesterol status.

Animals↗

PubMed2000

Dietary fat intakes in infants and primary school children in Germany.

We report dietary fat intake data in groups of infants and children in Germany. A group of 148 healthy infants was followed prospectively from birth through the first year of life. After birth, 78.9% of infants were breast-fed; 50% were breast-fed at 3 mo and 9. 8% were breast-fed at 12 mo. Infant formula was given to 22% of infants after birth, 53% at 3 mo, and 58% at 12 mo. Complementary foods were consumed by 16% of infants at 3 mo, 97% at 6 mo, and 98-100% at 7-12 mo. In non-breast-fed infants, mean dietary fat intakes were 44.8%, 42.9%, 37.4%, and 35.7% of energy intake at the ages of 1, 4, 6, and 12 mo, respectively. Calculated energy and nutrient intakes were within recommended ranges and weight gain was normal. Therefore, we see no compelling reason to actively modify total fat intakes at this age. In 158 primary school children aged 6-11 y, 7-d checklist protocols showed 41% of energy intake as fat with approximately 50% as saturated fat. Because German children of this age are experiencing increasing rates of obesity and high serum cholesterol concentrations, a stepwise reduction of total fat and saturated fat intakes in primary school children appears desirable to improve long-term health.

Adult↗

PubMed1997

Interactions between dietary fat type and xylanase supplementation when rye-based diets are fed to broiler chickens 2. Performance, nutrient digestibility and the fat-soluble vitamin status of livers.

1. The interactions between dietary fat type and xylanase supplementation of rye-based diets were investigated using a 2 x 2 factorial design in which a rye-based diet (610 g rye/kg) was combined with 100 g/kg of soya oil or beef tallow, with or without xylanase supplementation at 3000 IU/kg, and fed to 1-d-old male broilers for 35 d. Growth, nutrient digestibility and AMEN values were determined and the vitamin status of livers assessed at various ages. 2. There were significant interactions between crude fat and xylanase supplementation on the faecal digestibility of crude fat and crude protein. Fat digestibility was improved by xylanase in both fat type groups but to a greater extent for the tallow diets. However, the effects were found to be significant only for oleic, linoleic and linolenic acids. Similarly, protein digestibility and AMEN values were significantly improved by xylanase, but only for the tallow diet. 3. Ileal digestibility of nitrogen and amino acids also were affected by enzyme for both fat type diets, the effect generally being more pronounced for the tallow diet. 4. The deposition of the fat soluble vitamins A and E in livers was significantly increased by xylanase supplementation and was also better for soya oil than for tallow. 5. Xylanase supplementation increased the digestibility of insoluble pentosans whereas for the soluble pentosans the opposite effect was noted. 6. Without xylanase supplementation the tallow-based diet caused high mortality. Liveweight gain and the efficiency of food utilisation were greatest in the soya oil-based, xylanase-supplemented diet, followed by the unsupplemented soya oil-, supplemented tallow- and unsupplemented tallow-based diets.

Amino Acids↗

PubMed1984

Dietary fat, prostaglandins and the immune response.

Events leading to the interest in dietary fat and immunity are summarized. This is followed by an account of the possible functions of prostaglandins and other eicosanoids in the immune response. Dietary studies on the influence of quantity and quality of fat on immune responses and the histopathology of lymphoid organs are critically reviewed. The next section deals primarily with work conducted in the authors' laboratories on essential fatty acid deficiency and the immune response and on the effects of varying the ratio of dietary linoleic to linolenic acids on prostaglandin synthesis by immunocompetent cells and immune functions. A brief account of a study on the influence of dietary fat on leukotriene synthesis follows. Finally the problems encountered in research on dietary fat and immunity are discussed and recommendations for design and execution of such studies are given.

Animals↗

PubMed1996

Considerations about dietary fat restrictions for children.

Expert panels recommend reduction of dietary fat and cholesterol, because excessive fat intake may lead to known health hazards. However, there are no data demonstrating beneficial effects of such diets starting in childhood for all children, including those with normal serum cholesterol levels. Dietary restrictions in early life may not necessarily induce a long-lasting decrease in blood cholesterol levels in children persisting into adulthood or reduce disease incidence. On the other hand, the result of such diets may be suboptimal growth and development. Furthermore, low fat diets may lower high density lipoprotein cholesterol levels and not specifically low density lipoprotein cholesterol. In addition, low serum cholesterol levels may be associated with increased mortality, including deaths due to accidents, which is most important in children. Recently, increased attention has been drawn to the association between short stature and/or nutritional status and deficiencies in intrauterine and early life with coronary artery disease in adulthood. Also, the problems of associated psychological consequences, family conflicts and cost should not be ignored while implementing a low fat diet. In this review, we discuss the controversies on dietary fat restrictions for children.

Child↗

PubMed1994

Hispanic/white differences in dietary fat intake among low educated adults and children.

BACKGROUND: This comparative study tests for ethnic differences in dietary fat consumption in a community-based sample of Hispanic and white adults with low educational attainment (< 12 years of schooling) and a separate sample of their children. METHODS: Data are presented for adults (age 20-64, n = 886) and youths (age 12-19, n = 170) from four California cities who participated in one of four sequential cross-sectional surveys (1981-1990). RESULTS: After adjustment for age, sex, city of residence, and time of survey, white adults were significantly (P < 0.03) more likely than Hispanic adults to have eaten high-fat foods in the last 24 hr, such as red meat (75.7% vs 68.4%), cured meats, (39.1% vs 25.8%), and cheese (41.4% vs 32.7%). Furthermore, white adults consumed significantly (P < 0.001) more fat, as measured by percentage of calories from total fat (37.7% vs 33.3%) and saturated fat (13.7% vs 11.8%), and consumed significantly less dietary carbohydrate (45.5% vs 49.7%) and fiber (17.1 g vs 26.0 g) than Hispanic adults. Ethnic differences were similar for the youth sample (except for carbohydrates), but were generally not significant. A graded relationship was found between acculturation and dietary measures, where more acculturated Hispanics (English-speaking) were intermediate between less acculturated Hispanics (Spanish-speaking) and whites in their dietary intake. CONCLUSIONS: This study illustrates the high dietary fat consumption of whites with low educational attainment, the increasing fat consumption of Hispanics at higher levels of acculturation, and the need for effective dietary interventions for low educated whites and Hispanics.

Acculturation↗

PubMed2002

Effect on body weight of replacing dietary fat with olestra for two or ten weeks in healthy men and women.

OBJECTIVE: To examine in two separate studies the effects of replacing dietary fat with Olestra on body composition and weight change in healthy young men and women. METHODS: Ten healthy, lean young men participated in Study One that was a 22-day single blind, within-subject design. After a control diet (40% fat) for eight days Study One subjects received an Olestra-substituted diet (31% metabolizable fat) for 14 days. Study Two was a randomized parallel-arm clinical trial with 15 healthy, lean and overweight young women. These subjects were randomly assigned to receive a control diet (40% fat), an Olestra-containing diet (31% metabolizable fat) or a reduced-fat diet (31% fat) for 10 weeks. All foods were provided to the subjects, and energy intakes were not restricted. The primary endpoint in both studies was change from baseline in body weight. In Study Two, body composition was measured by dual energy x-ray absorptiometry. In both studies, food intake and nutrient compensation were assessed. RESULTS: In Study One fat substitution by Olestra resulted in a significant 1.7 kg weight loss from baseline. In Study Two, change in body weight and body fat from baseline were statistically significant in all groups, but the group with Olestra lost significantly more weight from baseline (-5.0 kg) than the other two groups. In Study One there was partial compensation for the decreased energy intake, while in Study Two, compensation was seen only for those on the reduced-fat diet. CONCLUSION: Replacement of 1/3 of dietary fat with Olestra in periods of up to 10 weeks results in weight loss in men and women.

Absorptiometry, Photon↗

PubMed1988

The relationship between dietary fat, adipose tissue composition, and neoplasms of the breast.

Dietary fat has been implicated in the development of carcinoma of the breast. Because of the difficulties in obtaining accurate dietary histories, we analyzed subcutaneous adipose fatty acids to compare the quality of fat intake in three groups of patients undergoing investigations for breast masses. These included carcinoma (n = 37, avg. age 54 yrs.), fibroadenoma (n = 27, age 31 yrs.), and other types (n = 21, age 50 yrs.). Subjects in the carcinoma group were heavier, although they were not obese. A one-way analysis of variance of nine adipose fatty acids and their derived ratios [polysaturates:saturates (P:S)] did not show any systematic differences in the three groups. The quality of dietary fat does not appear to be associated with the development of neoplasia of the breast in this population, which consumes a diet of a high P:S ratio.

Adenofibroma↗

PubMed1997

The role of dietary fat in breast cancer.

Studies on experimental animals have generally supported a role for dietary fat in mammary cancer, but epidemiological studies have given conflicting results. The effects of dietary fat in animals may be due to its high energy density or to other specific effects, and may have relevance for human breast cancer.

Animals↗

PubMed2005

Dietary fat interacts with PCBs to induce changes in lipid metabolism in mice deficient in low-density lipoprotein receptor.

There is evidence that dietary fat can modify the cytotoxicity of polychlorinated biphenyls (PCBs) and that coplanar PCBs can induce inflammatory processes critical in the pathology of vascular diseases. To test the hypothesis that the interaction of PCBs with dietary fat is dependent on the type of fat, low-density lipoprotein receptor-deficient (LDL-R(-/-)) mice were fed diets enriched with either olive oil or corn oil for 4 weeks. Half of the animals from each group were injected with PCB-77. Vascular cell adhesion molecule-1 (VCAM-1) expression in aortic arches was nondetectable in the olive-oil-fed mice but was highly expressed in the presence of PCB-77. PCB treatment increased liver neutral lipids and decreased serum fatty acid levels only in mice fed the corn-oil-enriched diet. PCB treatment increased mRNA expression of genes involved in inflammation, apoptosis, and oxidative stress in all mice. Upon PCB treatment, mice in both olive- and corn-oil-diet groups showed induction of genes involved in fatty acid degradation but with up-regulation of different key enzymes. Genes involved in fatty acid synthesis were reduced only upon PCB treatment in corn-oil-fed mice, whereas lipid transport/export genes were altered in olive-oil-fed mice. These data suggest that dietary fat can modify changes in lipid metabolism induced by PCBs in serum and tissues. These findings have implications for understanding the interactions of nutrients with environmental contaminants on the pathology of inflammatory diseases such as atherosclerosis.

Animals↗