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PubMed1991

[The effects of body fat distribution on glucose tolerance in overweight subjects: glucose intolerance and insulin resistance induced by intra-abdominal fat accumulation].

To evaluate the pathophysiological significance of intra-abdominal fat accumulation in Japanese subjects with mild to moderate overweight, 107 subjects (56 men and 51 women, aged 16-68 years) with body mass index (BMI, kg/m2) of 17-39 (mean +/- SD, 25 +/- 4.3) were evaluated. Subjects with disorders which affect glucose metabolism, such as thyroid, adrenal, liver, and kidney diseases, were excluded. A 75 g oral glucose tolerance test (OGTT) was performed in all subjects, and venous samples were obtained before 15, 30, 60, 90 and 120 min after the glucose load for plasma glucose (PG), immunoreactive insulin (IRI) and C-peptide immunoreactivity (CPR) measurements. In 72 of the subjects, plasma free fatty acid (FFA) level at fasting was also determined. The degree of visceral fat accumulation was evaluated using a CT-scan by the method reported by Fujioka et al. (Metabolism, 36: 54-59, 1987), and intra-abdominal fat area/subcutaneous fat area (V/S ratio) was obtained. V/S ratio and BMI correlated positively in subjects with BMI less than 25 (17 men and 16 women, aged 28-62 years) but they did not correlate at all with each other in those with BMI greater than or equal to 25 (39 men and 35 women, aged 16-68 years). Based on this finding, the possible adverse effects of increased intra-abdominal fat on glucose metabolism were investigated in the subjects with BMI greater than or equal to 25. For this purpose, the correlation of V/S ratio with fasting PG (FPG), fasting IRI (FIRI), fasting CPR (FCPR), FPG/FIRI, FFA, or PG area (sigma PG) and sigma PG/sigma IRI at OGTT was analyzed. V/S ratio positively correlated with FPG, sigma PG, FPG/FIRI and sigma PG/sigma IRI but not with FFA. The correlation between V/S ratio and FIRI or FCPR was significant in the subjects with V/S ratio greater than or equal to 0.8 in men and greater than or equal to 0.4 in women. In sharp contrast to V/S ratio, BMI did not correlate at all with any of these metabolic indices. We conclude that in Japanese subjects with mild overweight to moderate obesity, intra-abdominal fat accumulation, but not the increase in the degree of obesity, accompanies worsening of glucose tolerance. Because PG elevation relative to IRI secretion is progressively greater with increasing V/S ratio, it is suggested that the deleterious effects of intra-abdominal fat accumulation can be attributed to increased insulin resistance.

Abdomen↗
PubMed1976

Concentrations of fat and plasma 5alpha-androstenone and plasma testosterone in boars selected for rate of body weight gain and thickness of back fat during growth, sexual maturation and after mating.

The levels of 5alpha-androstenone and testosterone in peripheral plasma and 5alpha-androstenone in fat collected from 18 boars selected according to thickness of back fat and rate of gain were evaluated. Sampling was started when the animals were about 100 days of age and samples were collected every 14 days until the boars were about 240 days old. The steroid profiles varied considerably between boars, although an increase in steroid levels was found in most animals with the onset of adolescence. The regression line for the level of 5alpha-androstenone in fat and the age of the animals in days was found to be y = 0.02x-1-31. High coefficients of correlation were found between the concentration of 5alpha-androstenone in peripheral plasma and fat (r = 0-78) and between levels of 5alpha-androstenone and testosterone in peripheral plasma (r = 0-64). Levels of 5alpha-androstenone in peripheral plasma above about 15 ng/ml were usually accompanied by a heavy accumulation of 5alpha-androstenone in adipose tissue. The use of four of the boars for mating resulted in increased steroid levels in peripheral plasma and fat. Significantly higher levels of 5alpha-androstenone and testosterone were found in the peripheral plasma of boars selected for fatness and a low rate of gain than in boars selected for low back-fat thickness and a high rate of gain.

Adipose Tissue↗
PubMed2004

Trunk fat and leg fat have independent and opposite associations with fasting and postload glucose levels: the Hoorn study.

OBJECTIVE: Waist and hip circumferences have been shown to have independent and opposite associations with glucose levels. Waist circumference is positively associated with glucose levels, whereas hip circumference is negatively associated. It is unclear which tissues are involved in the pathophysiological mechanism causing these associations. The main goal was to determine which tissue in the trunk and legs, fat or lean tissue, is associated with measures of glucose metabolism. RESEARCH DESIGN AND METHODS: In 623 participants of the third examination of the Hoorn Study, whole-body dual-energy X-ray absorptiometry was performed to determine fat and lean soft-tissue mass in the trunk and legs. Fasting and 2-h postload glucose levels after 75-g oral glucose tolerance test (OGTT) were determined. After exclusion of known diabetic patients, cross-sectional analyses were performed in 275 men aged 60-87 years (140 with normal glucose metabolism, 92 with impaired glucose metabolism; and 43 with diabetes) and in 281 women (148 with normal glucose metabolism, 90 with impaired glucose metabolism, and 43 with diabetes). RESULTS: Greater trunk fat mass was associated with higher glucose levels after adjustment for age, trunk lean mass, leg lean mass, and leg fat mass. Standardized beta (95% CI) in men were 0.44 (0.25-0.64) for fasting and 0.41 (0.22-0.60) for postload glucose. For women, these values were 0.49 (0.35-0.63) and 0.47 (0.33-0.61), respectively. In contrast, in the same regression models, a larger leg fat mass was associated with lower glucose levels. Standardized beta in men were -0.24 (-0.43 to -0.05) and -0.12 (-0.31 to 0.07) and in women -0.24 (-0.37 to -0.10) and -0.27 (-0.40 to -0.13) for fasting and postload glucose, respectively. In these models, larger leg lean mass was also associated with lower glucose levels but was only statistically significant in men. CONCLUSIONS: If trunk fat is taken into account, accumulation of fat in the legs seems to be protective against a disturbed glucose metabolism, particularly in women. Further research is needed to unravel underlying pathophysiological mechanisms.

Absorptiometry, Photon↗
PubMed1997

Biceps femoris and rump fat as additional ultrasound measurements for predicting retail product and trimmable fat in beef carcasses.

One hundred ninety-eight steers of Angus and Hereford breeding were evaluated ultrasonically for fat thickness over the 12-13th rib (UFAT), fat thickness over the rump (URUMP), 12-13th longissimus muscle area (UREA), and depth of the biceps femoris (UROUND) before slaughter. Carcass measurements associated with the USDA yield grade were also obtained. Carcasses were fabricated into closely trimmed (.32 cm fat), boneless subprimals. Regression procedures were used to predict weight and the percentages of retail product and trimmable fat. Final weight (FINALWT) accounted for most of the variation when predicting kilograms of retail product and trimmable fat, with R2 values of .836 and .435, respectively. As single predictors URUMP and UFAT accounted for most of the variation when predicting the percentages of retail product and trimmable fat with R2 values of .244 and .220, respectively. Adding URUMP to equations that included FINALWT, UREA, and UFAT increased R2 values for percentage of retail product from .175 to .318 and for weight of retail product from .847 to .865, whereas the addition of UROUND did not appreciably increase R2 values for the same models. Adding URUMP and UROUND to the model of FINALWT, UREA, and UFAT to predict kilograms and the percentage of trimmable fat increased R2 values from .530 to .610 and from .254 to .360, respectively. Models using live-animal measurements to predict weight and the percentage of retail product gave R2 values equal to models using the actual measurements found in the USDA Yield Grade equation.

Animals↗
PubMed1988

Fat deposition in a broiler sire strain. 5. Comparisons of economic efficiency of direct and indirect selection against fatness.

In a simulation study, selection for weight gain in a broiler sire strain was compared with 1) one and two stage index selection for weight gain and feed conversion and 2) weight gain, slaughter yield, and percentage abdominal fat. Weight gain per day was assigned an economic value of 1.138 Dutch cents (ct)1/g; feed conversion, -138.18 ct/1.0; slaughter yield, 0 or 7.55 ct/%; and percentage abdominal fat, 0 or -10 ct/%. When selection was completely or almost completely (as in two stage selection) based on weight gain, percentage abdominal fat increased; otherwise it decreased. Weight gain, feed conversion, and slaughter yield improved with all selection methods examined. Due to the high positive correlation between feed conversion and percentage abdominal fat, selection for an index of weight gain and feed conversion gave about the same reduction in percentage abdominal fat as selection for an index of weight gain, slaughter yield, and percentage abdominal fat. Selection response of the four traits was dependent more on selection methods than on sets of economic values. Based on economic values, selection for an index of weight gain and feed conversion gave 1.70 to 3.35 times the financial gain of selection for weight gain only, and selection for an index of weight gain, slaughter yield, and percentage abdominal fat gave 1.15 to 3.12 times that attained by selection only for weight gain. The extra financial gains exceeded by far the estimated additional costs of the index selection methods.

Adipose Tissue↗
PubMed1995

The association of body weight, body fatness and body fat distribution with osteoarthritis of the knee: data from the Baltimore Longitudinal Study of Aging.

OBJECTIVE: To examine the association of body weight, body fatness, and body fat distribution with osteoarthritis (OA) of the knee. METHODS: Bilateral standing knee radiographs, taken between 1985 and 1991, of 465 Caucasian men and 275 Caucasian women subjects aged 40 and above in the Baltimore Longitudinal Study of Aging were read by one investigator for grade of OA using Kellgren-Lawrence scales. Measures of obesity, assessed at same visit as the last radiograph during this interval, included body mass index, percent body fat, and body fat distribution. RESULTS: Both men and women with definite knee OA had higher age adjusted mean levels of body mass index, while women only had higher age adjusted mean levels of percent body fat. Both women and men in the highest tertile of body mass index had significantly increased odds of both definite and bilateral knee OA; women in the middle and highest tertile of percent body fat had significantly increased odds of both definite and bilateral knee OA, and men in the highest tertile of waist-hip ratio had significantly increased odds of bilateral knee OA. After adjusting for body mass index, however, the association of percent body fat and waist-hip ratio with knee OA in women and men, respectively, was no longer significant. CONCLUSION: These data further extend observations that body weight is associated with both definite and bilateral knee OA in both sexes, and support a stronger contribution of mechanical as opposed to systemic factors to explain this association.

Adipose Tissue↗
PubMed1993

Fat cell adrenergic receptors and the control of white and brown fat cell function.

Five adrenoceptor subtypes are involved in the adrenergic regulation of white and brown fat cell function. The effects on cAMP production and cAMP-related cellular responses are mediated through the control of adenylyl cyclase activity by the stimulatory beta 1-, beta 2-, and beta 3-adrenergic receptors and the inhibitory alpha 2-adrenoceptors. Activation of alpha 1-adrenoceptors stimulates phosphoinositidase C activity leading to inositol 1,4,5-triphosphate and diacylglycerol formation with a consequent mobilization of intracellular Ca2+ stores and protein kinase C activation which trigger cell responsiveness. The balance between the various adrenoceptor subtypes is the point of regulation that determines the final effect of physiological amines on adipocytes in vitro and in vivo. Large species-specific differences exist in brown and white fat cell adrenoceptor distribution and in their relative importance in the control of the fat cell. Functional beta 3-adrenoceptors coexist with beta 1- and beta 2-adrenoceptors in a number of fat cells; they are weakly active in guinea pig, primate, and human fat cells. Physiological hormones and transmitters operate, in fact, through differential recruitment of all these multiple alpha- and beta-adrenoceptors on the basis of their relative affinity for the different subtypes. The affinity of the beta 3-adrenoceptor for catecholamines is less than that of the classical beta 1- and beta 2-adrenoceptors. Conversely, epinephrine and norepinephrine have a higher affinity for the alpha 2-adrenoceptors than for beta 1-, 2-, or 3-adrenoceptors. Antagonistic actions exist between alpha 2- and beta-adrenoceptor-mediated effects in white fat cells while positive cooperation has been revealed between alpha 1- and beta-adrenoceptors in brown fat cells. Homologous down-regulation of beta 1- and beta 2-adrenoceptors is observed after administration of physiological amines and beta-agonists. Conversely, beta 3- and alpha 2-adrenoceptors are much more resistant to agonist-induced desensitization and down-regulation. Heterologous regulation of beta-adrenoceptors was reported with glucocorticoids while sex-steroid hormones were shown to regulate alpha 2-adrenoceptor expression (androgens) and to alter adenylyl cyclase activity (estrogens).

Adipose Tissue↗
PubMed1995

Long-term weight cycling reduces body weight and fat free mass, but not fat mass in female Wistar rats.

OBJECTIVE: The effects of repeated weight gain and loss, the weight cycling (WC) phenomenon, on body composition have been controversial. WC history and age are two confounding factors which may contribute to this inconsistency. In the present investigation, we examined the effects of WC on body weight regulation, body composition and feeding efficiency in a long-term study when WC history was controlled. METHOD: Six groups of female Wistar rats were used in this study. Five of these six groups were made obese by feeding a high fat (HF) diet for 11 weeks and then divided into five groups: non-cycling control group (HFCON); one group which cycled three times (HFCYC); and three one-cycle groups which cycled only once corresponding to each of the three cycles in the HFCYC group. The sixth group was fed the low fat diet without cycling (LFCON). Weight cycling (WC) was produced by feeding 50% of a HF diet with extra protein, vitamin and mineral mixture until body weight of the cycled groups reached the level of the LFCON group. After three cycles (52-56 weeks), all rats were killed. RESULTS: Results showed that repeated WC reduced final body weight and fat free mass, but not body fat mass in the HFCYC group. Repeated WC also reduced rate of weight regain. During the third cycle, the amount of fat regained during refeeding was more than the fat mass lost during restricted feeding in the HFCYC group. For the three one-cycle groups, the rate of weight regain was slower but rate of weight loss was the same in older rats as in the younger rats. CONCLUSION: Thus repeated WC may favor more body fat retention in later cycles. Aging affected rate of weight regain but not rate of weight loss, nor body composition, while repeated WC affected both rate of weight loss and regain.

Animals↗
PubMed1995

Distribution of subcutaneous fat and equations for predicting percent body fat from skinfold measurements: a comparison between Chinese females from two age cohorts.

The need to apply different regression equations in predicting percent body fat was investigated with 40 Chinese females between 20-30 years and 40-50 years in Beijing in 1993-94. Skinfolds from 10 sites at subscapular, midaxillary, pectoral, abdominal, suprailiac, thigh, triceps, medial calf, suprapatellar, and forearm were measured with a Lange caliper. The criterion test was performed with hydrostatic weighing and the Siri equation was used to calculate percent body fat. It was found that there were significant differences in the distribution of subcutaneous fat between younger and older Chinese females, with the major differences in the abdominal and subscapular skinfolds. It also appeared that the 20-30 years cohort had a more evenly distributed subcutaneous fat that the 40-50 years cohort. A general prediction equation for percent body fat with skinfolds of the forearm, pectora, subscapular, and triceps was formulated with an R of 0.95 and SEE of 2.14. Separate equations were developed for the two age cohorts. These were found to be more accurate than the general equation. The present study indicated that subcutaneous fat distribution varied with age in the female and further study in this area would be needed to better understand the relationship between fat distribution patterns, metabolic risks, and cardiovascular disease.

Adipose Tissue↗
PubMed1996

Cardiovascular risk profile in 38-year and 18-year-old men. Contribution of body fat content and regional fat distribution.

OBJECTIVE: To evaluate whether young and middle-age men differ in blood pressure and serum lipid profiles and, if so, to what extent these differences are dependent on total body fat, regional fat distribution, plasma insulin and behavioural variables. SUBJECTS: Random samples of 94 young (18 year-old) and 94 middle-age (38 year-old) healthy men matched for body mass index (BMI). MEASUREMENTS: BMI, total body fat (by bioelectrical impedance), regional fat distribution (by anthropometry), serum lipids, blood pressure, fasting insulin and some behavioural variables. RESULTS: Total body fat was similar in the two groups (mean +/- s.e.: 16.6 +/- 0.5 vs 16.0 +/- 0.6 kg and 20.8 +/- 0.5 vs 20 +/- 0.5%), while waist/hip circumference ratio (WHR) was significantly higher in middle-age as compared to young men (0.96 +/- 0.001 vs 0.92 +/- 0.003, P < 0.0001). The former also had significantly higher serum concentrations of total cholesterol (6.21 +/- 0.13 vs 4.10 +/- 0.10 mmol/l; P < 0.0001). LDL-cholesterol (4.24 +/- 0.11 vs 2.34 +/- 0.10 mmol/l; P < 0.0001), triglycerides 1.40 +/- 0.09 vs 1.02 +/- 0.06 mmol/l; P < 0.01) as well as higher systolic (134.0 +/- 1.6 vs 126.3 +/- 1.4 mmHg; P < 0.0001) and diastolic (86.8 +/- 0.9 vs 82.0 +/- 1.1 mmHg; P < 0.001) blood pressure values. HDL-cholesterol and fasting insulin concentrations were similar in the two groups (1.33 +/- 0.03 vs 1.28 +/- 0.03 mmol/l and 13.7 +/- 0.6 vs 14.7 +/- 0.7 mU/l, respectively). Significant differences in the two groups also were found in daily alcohol consumption (49.6 +/- 5.7 vs 20.0 +/- 3.4 g/day; P < 0.0001), whereas no significant differences were found in smoking and physical activity level. The comparison of subgroups (n = 41) of young and middle-age men matched for both BMI and WHR showed virtually unchanged differences in serum lipids and blood pressure. When age, BMI, WHR, fasting insulin and behavioural variables were included as independent variables in a multiple linear regression analysis in which subjects of the two groups were pooled, age was a significant predictor of total and LDL cholesterol, triglycerides and systolic blood pressure, insulin predicted HDL cholesterol and systolic blood pressure, BMI predicted triglycerides and diastolic blood pressure and WHR was not an independent predictor of any risk factor. CONCLUSIONS: These results indicate that middle-age men have a cardiovascular risk profile less favourable than young men, which is largely independent of differences in total body fat content, regional fat distribution and behavioural variables.

Adipose Tissue↗
PubMed1989

Effect of interesterified fat mixtures on certain lipid indices in experimental fat metabolism disturbance.

Groups of adult Wistar male and female rats were fed isoenergetically for a three and a six weeks period either with synthetic lipogenic diet containing 5% and 20% fat mixtures (in which sunflower oil and lard were blended according to the ratio of 35:65) or with the same synthetic diet containing the mixture of sunflower oil and interesterified lard in a similar ratio. A control group received a normal diet for 6 weeks, whereas one of the experimental groups (fed with the 20% fat mixture in the lipogenic diet for 6 weeks) was given the normal diet for an additional two weeks period. After the feeding periods had been completed serum HDL-C levels and the total lipid, triglyceride, total cholesterol, free fatty acid levels were determined in serum and liver. The distribution of fatty acids in liver and heart muscle was also evaluated. In comparison to the control values it has been found: 1. Consumption of the lipogenic diet which is known to increase the serum total lipid and total cholesterol content induced in male rats a smaller augmentation in these indices when consuming the 20% fat mixture with a P/S ratio approaching the ideal 1 values, than in case of a 5% fat mixture consumption. In case of female rats, considerable increases of the serum values, could be observed at both fat consumption levels. The serum triglyceride and HDL-C contents decreased for all experimental groups. 2. The total lipid and triglyceride content of the liver increased in a high degree, the fatty liver syndrome was developed--more rapidly in males than in females. The total lipid, triglyceride and total cholesterol contents of the liver of male rats exceeded those of females by 15-30%. 3. The interesterification of the lard component of fat mixture resulted in lipid indices similar to those without interesterification, or in certain cases, they were found to be even slightly more favourable, i.e. the biological effect of the technological change proved to be adequate. 4. After a two weeks regeneration period the serum values of the male rats approached closer the normal control values than those of the females which were decreasing from a very high level but the degree of decrease was greater for them than for the male rats. The lipid content of the liver showed similar values.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2006

Reduction of fat storage in mice fed a high-fat diet long term by treatment with saponins prepared from Kochia scoparia fruit.

The fresh fruit (Japanese name, Tonburi) of Kochia scoparia has been used as a food garnish in Japanese-style dishes from ancient times, and may prevent metabolic syndromes such as hyperlipidemia, hypertension, obesity and atherosclerosis. This study was performed to clarify whether an ethanol extract of K. scoparia fruit prevented obesity induced in mice by a high-fat diet for 9 weeks. The ethanol extract of K. scoparia fruit prevented the increases in body weight and parametrial adipose tissue weight induced by the high-fat diet. Furthermore, consumption of a high-fat diet containing 1% or 3% K. scoparia extract significantly increased the fecal content and the fecal triacylglycerol level at day 3 compared with those in the high-fat diet group. The ethanol extract (250 mg/kg) and total saponins (100 mg/kg) of K. scoparia inhibited the elevation of the plasma triacylglyccerol level 2 or 3 h after the oral administration of the lipid emulsion. Total saponins, momordin Ic, 2'-O-beta-d-glucopyranosyl momordin Ic and 2'-O-beta-d-glucopyranosyl momordin IIc isolated from K. scoparia fruit inhibited the pancreatic lipase activity (in vitro). These findings suggest that the anti-obesity actions of K. scoparia extract in mice fed a high-fat diet may be partly mediated through delaying the intestinal absorption of dietary fat by inhibiting pancreatic lipase activity.

Animals↗
PubMed2006

Conjugated linoleic acid and chromium lower body weight and visceral fat mass in high-fat-diet-fed mice.

More than half of the U.S. population has a body mass index of 25 kg/m2 or more, which classifies them as overweight or obese. Obesity is often associated with comorbidities such as diabetes, cardiovascular diseases, and cancer. CLA and chromium have emerged as major dietary supplements that reduce body weight and fat mass, and increase basal metabolic rate in animal models. However, studies show that CLA induces insulin resistance in mice and in humans, whereas Cr improves insulin sensitivity. Hence, we designed the present study to examine the combined effect of CLA and Cr on body composition and insulin sensitivity in a Balb/c mice (n = 10/group) model of high-fat-diet-induced obesity. CLA alone lowered body weight, total body fat mass, and visceral fat mass, the last of which decreased further with the combination of CLA and Cr. This effect was accompanied by decreased serum leptin levels in CLA-fed and CLA + Cr-fed mice, and by higher energy expenditure (EE) and oxygen consumption (OC) in CLA + Cr-fed mice. Serum levels of glucose, insulin, the pro-inflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6), as well as insulin resistance index (IRI), decreased with CLA, whereas CLA and Cr in combination had significant effects on insulin and IL-6 concentrations and IRI. In summary, CLA + Cr decreased body weight and fat mass in high-fat-diet-fed mice, which may be associated with decreased leptin levels and higher EE and OC.

Adiponectin↗
PubMed1997

Time course of enzyme changes after a switch from a high-fat to a low-fat diet.

This study was conducted to determine the time course of metabolic changes associated with a switch from a high-fat to a low-fat diet in rats. Adult rats, maintained on a high-fat diet (42% of energy from fat) for 4-5 weeks were switched to a low-fat diet (11% of energy from fat), and the activities of several liver enzymes were followed. Three different phases could be distinguished. The early phase, complete by 2 days after the switch in diets, included an increase in the activity of glucose 6-phosphate dehydrogenase (pentose phosphate pathway), an increase in pyruvate kinase and pyruvate dehydrogenase activities (terminal end of the glycolytic pathway) and an increase in ATP-citrate lyase and fatty acid synthetase (fatty acid synthesis pathway). The early phase also included a decrease in the activity of phosphoenolpyruvate carboxykinase (PEPCK, gluconeogenesis) and a lower branched-chain amino acid dehydrogenase activity (BCAADH, branched-chain amino acid degradation). The concentration of the allosteric phosphofructokinase regulator, fructose 2,6-bisphosphate (Fru-2,6-P2, glycolysis), decreased during the early phase. An intermediate phase could also be discerned between 3 and 10 days after the switch in diets. In this phase, the decreased Fru-2,6-P2 concentration and the decreased PEPCK and BCAADH activities observed in the early phase were reversed. The late phase occurred 10 days after the dietary switch and was characterized by an increase in the activities of glucokinase (glycolytic pathway) and glycogen phosphorylase (associated with glycogenolysis) and by a decrease in glutamate dehydrogenase, PEPCK and BCAADH activities. These measurements indicate that at least 20 days are required before metabolic changes associated with a switch in diet are complete.

Alanine Transaminase↗
PubMed1998

Varying dietary fat type of reduced-fat diets has little effect on the susceptibility of LDL to oxidative modification in moderately hypercholesterolemic subjects.

The effect of the fatty acid composition of reduced-fat diets on the in vitro oxidation of LDL was examined in 14 moderately hypercholesterolemic [low density lipoprotein (LDL) > 3.36 mmol/L] postmenopausal female and male subjects (age 44-78 y). Each subject consumed each of five reduced-fat diets [30 energy percent (E%) fat, 17 E% protein and 53 E% carbohydrate] enriched in beef tallow, canola oil, corn oil, olive oil or rice bran oil (20 E%) for 32-d periods. In vitro oxidation of LDL was assessed by incubating LDL with hemin and hydrogen peroxide, and measuring the time required for the reaction to reach maximum velocity (lag time). LDL lag times were 93.2 +/- 25.8, 95.9 +/- 26.4, 104.2 +/- 32.7, 108.0 +/- 26.6 and 113.1 +/- 24.0 min for corn oil, beef tallow, rice bran oil, canola oil and olive oil periods, respectively. When the data from all dietary phases were pooled, LDL alpha-tocopherol level (r = 0.30, P = 0.01) and plasma 18:1/18:2 ratio (r = 0.22, P = 0.08) were positively related to resistance of LDL to oxidation. Differences induced by the dietary perturbations in LDL content of beta-cryptoxanthin, lutein/zeaxanthin, lycopene, alpha-carotene or beta-carotene, and LDL particle size were not related to resistance of LDL to oxidation. In conclusion, in middle-aged and elderly moderately hypercholesterolemic subjects, the consumption of reduced-fat diets enriched in animal fat or vegetable oils with a relatively wide range of fatty acid profiles did not alter the in vitro susceptibility of LDL to oxidation. The advantages of reducing the saturated fat content of the diet were reflected in lower total and LDL cholesterol levels.

Adult↗
PubMed2000

Abdominal fat deposition and fatty acid synthesis are lower and beta-oxidation is higher in broiler chickens fed diets containing unsaturated rather than saturated fat.

We evaluated the effects of dietary fat type on fat metabolism and deposition in broiler chickens. Birds were fed diets containing either 8 g dietary saturated (beef tallow) or polyunsaturated fat (sunflower oil)/100 g for 32 d. The abdominal fat deposition of chickens fed the sunflower oil-enriched diet was significantly lower than that of chickens fed the tallow-enriched diet (2.63 +/- 0.47 versus 3.03 +/- 0.44 g/100 g live wt.; P = 0.033). The specific activities of heart carnitine palmitoyltransferase I and L-3-hydroxyacyl-CoA dehydrogenase were higher (P < or = 0.03) in chickens fed the sunflower oil-enriched diets, indicating a greater rate of beta-oxidation. Liver fatty acid synthetase activity was lower (P = 0.01) in chickens fed the sunflower oil-enriched diet, suggesting reduced hepatic lipogenesis in this group. Postprandial plasma triglyceride levels were significantly lower (P < 0.05) in birds fed the sunflower oil-enriched diet, indicating a higher rate of dietary lipid clearance from the bloodstream to tissues. In conclusion, the lower fat deposition observed in broilers fed sunflower oil-enriched diets appears to be the net result of an increased rate of lipid catabolism and lower rate of fatty acid synthesis despite higher dietary fat absorption.

Adipose Tissue↗
PubMed1999

Replacing saturated fat with PUFA-rich (sunflower oil) or MUFA-rich (rapeseed, olive and high-oleic sunflower oil) fats resulted in comparable hypocholesterolemic effects in cholesterol-fed hamsters.

Recent studies have suggested that monounsaturated fatty acid (MUFA)-rich dietary fats do not have the same plasma cholesterol-lowering effects whereby rapeseed oil was more effective than olive oil. This phenomenon could be explicable by the content of other fatty acids or plant sterols. To further evaluate the effects of different MUFA-rich oils (18:1-rich sunflower oil, rapeseed oil, olive oil) in comparison to polyunsaturated (PUFA)-rich oils (18:2-rich sunflower oil) and saturated fat (palm stearin) on cholesterol and bile acid metabolism, male Syrian golden hamsters were fed semipurified diets containing 5% fat and 0.2% cholesterol for 5 weeks. To test whether oil refining would have an impact on the cholesterol-lowering potential, unrefined and refined varieties of rapeseed and olive oil were included. After 5 weeks, plasma total cholesterol (TC) was highest with palm stearin (10.0 +/- 2.6 mmol/l) while the MUFA- or PUFA-rich fats significantly lowered TC. The lowest TC concentrations were found with refined rapeseed, cold pressed rapeseed and 18:2-rich sunflower oil (6.7 +/- 1.2; 7.1 +/- 0.7 and 7.1 +/- 0.7 mmol/l, respectively), whereas TC was 10-15% higher (not significant) with 18:1-rich sunflower, virgin and refined olive oil. Liver cholesterol concentrations were lowest in hamsters fed palm stearin or 18:2-rich sunflower oil while MUFA-rich fats increased hepatic cholesteryl ester accumulation, especially of cholesteryl oleate. There were no significant differences in the fecal neutral sterol and bile acid excretion. These data demonstrate that MUFA-rich dietary fats, e.g. rapeseed, olive and 18:1-rich sunflower oil, are comparable in their hypocholesterolemic potential and cause similar effects on plasma cholesterol as 18:2-rich sunflower oil in hamsters when the dietary cholesterol intake is moderate.

Animals↗
PubMed1994

Regulation of new fat cell formation in rats: the role of dietary fats.

Factors that stimulate formation of new adipocytes during development of obesity are yet to be identified. We examined whether diet acts directly on preadipocytes to stimulate replication and differentiation or indirectly by interacting with adipocytes to release or modify local growth factors. Male Sprague-Dawley rats were fed chow or diets high in starch (HST), saturated (HFS) or polyunsaturated (HFP) fats until 5-7 months of age. We found that, compared to other diets, HFS induced acceleration of replication of preadipocytes in primary culture (doubling time of retroperitoneal-derived preadipocytes: HFS 17 +/- 1 versus chow 32 +/- 6 and HFP 29 +/- 3 h, P < 0.05). HFS stimulated greater expansion of retroperitoneal fat than HFP even when caloric intake was equal and increased adipocyte number threefold. Preadipocyte pool size in inguinal and retroperitoneal fat pads changed relative to fat pad weight in rats fed all diets compared to chow, suggesting that the balance between the number of cells capable of replicating and those terminally differentiated was perturbed. Differentiation of preadipocytes and release of adipocyte growth factors in vitro were unaffected by diet. We concluded that dietary saturated fats induced expansion of adipose tissue mass more effectively than polyunsaturated fats and that this may, in part, be achieved by acceleration of preadipocyte replication.

Adipocytes↗