Fat Quality Influences the Obesogenic Effect of High Fat Diets

High fat and/or carbohydrate intake are associated with an elevated risk for obesity and chronic diseases such as diabetes and cardiovascular diseases. The harmful effects of a high fat diet could be different, depending on dietary fat quality. In fact, high fat diets rich in unsaturated fatty acids are considered less deleterious for human health than those rich in saturated fat. In our previous studies, we have shown that rats fed a high fat diet developed obesity and exhibited a decrease in oxidative capacity and an increase in oxidative stress in liver mitochondria. To investigate whether polyunsaturated fats could attenuate the above deleterious effects of high fat diets, energy balance and body composition were assessed after two weeks in rats fed isocaloric amounts of a high-fat diet (58.2% by energy) rich either in lard or safflower/linseed oil. Hepatic functionality, plasma parameters, and oxidative status were also measured. The results show that feeding on safflower/linseed oil diet attenuates the obesogenic effect of high fat diets and ameliorates the blood lipid profile. Conversely, hepatic steatosis and mitochondrial oxidative stress appear to be negatively affected by a diet rich in unsaturated fatty acids.     

Usefulness of flaxseed oil in the limitation of diet induced metabolic disturbances

The aim of this study was to compare the effects of different fats, that is pork lard, refined soybean oil, and unrefined, cold pressed flaxseed oil, on the antioxidant status, inflammatory markers and blood lipid profile of rats fed diets rich in fructose. Four week of experimental feeding with flaxseed oil enriched diet (16%) led to a significant decrease in the degree oflipid peroxidation in liver when compared with rats fed the same amount of pork lard. Moreover the addition of soybean oil or flaxseed oil to the diet (16%) decreased significantly triglyceride and total cholesterol blood levels, as well as reduced atherogenic index of plasma. The concentration of HDL cholesterol was retained on a higher blood level in rats fed flaxseed oil enriched diet, when compared with the soybean oil group.     

Differential effects of high-fat-diet rich in lard oil or soybean oil on osteopontin expression and inflammation of adipose tissue in diet-induced obese rats

Purpose

To examine the effect of different dietary fat types on osteopontin (OPN) expressions and inflammation of adipose tissues in diet-induced obese rats.

Methods

Male Sprague–Dawley rats were randomly assigned to one control group fed standard diet (LF, n = 10) and two high-fat diet groups fed isoenergy diet rich in lard or soybean oil (HL or HS, n = 45 each). Diet-induced obese rats in HL and HS group were then subdivided into two groups either continuously fed high-fat diet or switched to low-fat diet for 8 more weeks. Fasting serum glucose, insulin, and OPN concentrations were assayed and QUICKI was calculated; the expression of OPN, IL-6, IL-10, TNF-α, NF-κB, and F4/80 in adipose tissue was determined.

Results

Both high-fat diets lead to comparable development of obesity characterized by insulin resistance and adipose tissue inflammation. Obese rats continuously fed high-fat diet rich in lard oil exhibited the highest fasting serum insulin level and adipose tissue OPN, F4/80, TNF-α, and NF-κB expression level. In both high-fat diet groups, switching to low-fat diet resulted in less intra-abdominal fat mass, decreased expression of F4/80, TNF-α, and NF-κB, while decreased OPN expression was only observed in lard oil fed rats after switching to low-fat diet.

Conclusions

Reducing diet fat or replacing lard oil with soybean oil in high-fat diet alleviates obesity-related inflammation and insulin resistance by attenuating the upregulation of OPN and macrophage infiltration into adipose tissue induced by high-fat diet.     

Dietary n-3 fatty acids affect mRNA level of brown adipose tissue uncoupling protein 1, and white adipose tissue leptin and glucose transporter 4 in the rat

We examined the effect of dietary fats rich in n-3 polyunsaturated fatty acids (PUFA) on mRNA levels in white and brown adipose tissues in rats. Four groups of rats were fed on a low-fat diet (20 g safflower oil/kg) or a high-fat diet (200 g/kg) containing safflower oil, which is rich in n-6 PUFA (linoleic acid), or perilla (alpha-linolenic acid) or fish oil (eicosapentaenoic and docosahexaenoic acids), both of which are rich in n-3 PUFA, for 21 d. Energy intake was higher in rats fed on a high-safflower-oil diet than in those fed on low-fat or high-fish-oil diet, but no other significant differences were detected among the groups. Perirenal white adipose tissue weight was higher and epididymal white adipose tissue weight tended to be higher in rats fed on a high-safflower-oil diet than in those fed on a low-fat diet. However, high-fat diets rich in n-3 PUFA, compared to a low-fat diet, did not increase the white adipose tissue mass. High-fat diets relative to a low-fat diet increased brown adipose tissue uncoupling protein 1 mRNA level. The increases were greater with fats rich in n-3 PUFA than with n-6 PUFA. A high-safflower-oil diet, compared to a low-fat diet, doubled the leptin mRNA level in white adipose tissue. However, high-fat diets rich in n-3 PUFA failed to increase it. Compared to a low-fat diet, high-fat diets down-regulated the glucose transporter 4 mRNA level in white adipose tissue. However, the decreases were attenuated with high-fat diets rich in n-3 PUFA. It is suggested that the alterations in gene expression in adipose tissue contribute to the physiological activities of n-3 PUFA in preventing body fat accumulation and in regulating glucose metabolism in rats.     

Dietary phytic acid modulates characteristics of the colonic luminal environment and reduces serum levels of proinflammatory cytokines in rats fed a high-fat diet

Dietary phytic acid (PA; myo-inositol [MI] hexaphosphate) is known to inhibit colon carcinogenesis in rodents. Dietary fiber, which is a negative risk factor of colon cancer, improves characteristics of the colonic environment, such as the content of organic acids and microflora. We hypothesized that dietary PA would improve the colonic luminal environment in rats fed a high-fat diet. To test this hypothesis, rats were fed diets containing 30% beef tallow with 2.04% sodium PA, 0.4% MI, or 1.02% sodium PA + 0.2% MI for 3 weeks. Compared with the control diet, the sodium PA diet up-regulated cecal organic acids, including acetate, propionate, and n-butyrate; this effect was especially prominent for cecal butyrate. The sodium PA + MI diet also significantly increased cecal butyrate, although this effect was less pronounced when compared with the sodium PA diet. The cecal ratio of Lactobacillales, cecal and fecal mucins (an index of intestinal barrier function), and fecal β-glucosidase activity were higher in rats fed the sodium PA diet than in those fed the control diet. The sodium PA, MI, and sodium PA + MI diets decreased levels of serum tumor necrosis factor α, which is a proinflammatory cytokine. Another proinflammatory cytokine, serum interleukin-6, was also down-regulated by the sodium PA and sodium PA + MI diets. These data showed that PA may improve the composition of cecal organic acids, microflora, and mucins, and it may decrease the levels of serum proinflammatory cytokines in rats fed a high-fat, mineral-sufficient diet.     

The effect of dietary fat and salt on blood pressure,renal and aortic prostaglandins

The pressor effects of fat and salt were examined in male Sprague-Dawley rats. Rats fed high carbohydrate (5% corn oil), high salt (8% NaCl) diets demonstrated significant elevations in blood pressure within one week of diet introduction which persisted throughout the 9 week experimental period. High saturated fat (5% corn oil-15% coconut oil) diets promoted a significant elevation in blood pressure, irrespective of the level of dietary salt. High dietary salt, as opposed to basal levels, tended to decrease the blood pressure of rats fed a diet containing all unsaturated fat (20% corn oil). The greatest percent increase in the renal vasodilator prostaglandin E₂ was measured in rats fed the high unsaturated-basal salt diet compared to all other dietary treatments. A hypervolemic effect of high levels of dietary salt was demonstrated in the high carbohydrate, all unsaturated fat and high saturated fat groups. These results demonstrate that the amount and type of dietary fat interact with the level of dietary salt to influence blood pressure in rats.     

High-fat diets affect energy and bone metabolism in growing rats

Background

High-fat diets are usually associated with greater weight (W) gain and body fat (BF). However, it is still unclear whether the type and amount of fat consumed influence BF. Additionally, dietary fat intake may also have consequences on skeletal health.

Objective

To evaluate in healthy growing rats the effects of high-fat diets and type of dietary fat intake (saturated or vegetable oils) on energy and bone metabolism.

Methods

At weaning, male Wistar rats (n?=?50) were fed either a control diet (C; fat?=?7% w/w) or a high-fat diet (20% w/w) containing either: soybean oil, corn oil (CO), linseed oil (LO), or beef tallow (BT) for 8?weeks. Zoometric parameters, BF, food intake and digestibility, and total and bone alkaline phosphatase (b-AP) were assessed. Total skeleton bone mineral density (BMD) and content (BMC), BMC/W, spine BMD, and bone volume (static-histomorphometry) were measured.

Results

Animals fed BT diet achieved lower W versus C. Rats fed high-fat vegetable oil diets showed similar effects on the zoometric parameters but differed in BF. BT showed the lowest lipid digestibility and BMC. In contrast, high vegetable oil diets produced no significant differences in BMC, BMC/W, BMD, spine BMD, and bone volume. Marked differences were observed for LO and BT groups in b-AP and CO and BT groups in bone volume.

Conclusion

BT diet rich in saturated fatty acids had decreased digestibility and adversely affected energy and bone metabolisms, in growing healthy male rats. There were no changes in zoometric and bone parameters among rats fed high vegetable oil diets.     

Recovery of rat growth and lipid profiles in adult rats subjected to fetal protein malnutrition with a fructose-rich diet

There is evidence suggesting an association between fructose consumption and the development of metabolic syndrome. In turn, protein malnutrition in utero is proposed to “program” the fetal tissues, making them more susceptible to nutritional associated disorders. To test this hypothesis, the present study was designed to analyze body growth and metabolic aspects of rats subjected to fetal protein malnutrition and subsequently fed a fructose-rich diet. Wistar rats were distributed into 4 groups: balanced (B) diet—B diet offered the entire experimental period; balanced diet/fructose—B diet until birth and fructose-rich diet (F-60% fructose) until adulthood; low-protein (L) diet/balanced—L diet until birth and B diet until adulthood; low-protein diet/fructose (F)—L diet until birth and F diet until adulthood. After nutritional recovery, there was a restoration of serum glucose, total protein, and albumin concentrations, which were reduced by fetal malnutrition, and a restoration of the liver glycogen and lipids contents, which were increased by fetal malnutrition. This restoration was independent of the diet adopted after birth. It was verified that the high fructose diet arrested body growth of the rats independently of the nutritional state during fetal life and was associated with weight reduction and decrease of the adipose in some regions of the body (P < .05). Moreover, the serum concentrations of triglycerides and total cholesterol, which are indicators of metabolic syndrome, rose in the rats that ingested the fructose-rich diet (P < .05). In summary, high consumption of fructose impairs body growth and alters the circulating lipids independently of the protein nutrition in utero.     

Oligofructose protects against the hypertriglyceridemic and pro-oxidative effects of a high fructose diet in rats

Recent findings indicate that in addition to its hyperlipemic effect, a high fructose diet has a pro-oxidant effect in rats compared with a starch-based diet. Oligofructose (OFS) has already been shown to decrease plasma lipids in rats. We assessed the impact of fructose on oxidative stress by supplementing a high fructose diet with OFS. Rats were fed either a high fructose diet or a starch-based diet, with or without supplementation of 10 g/100 g oligofructose for 4 wk. Regardless of the type of carbohydrate, OFS in the diet produced an enlargement of the cecum and led to a significant increase in the SCFA cecum pool. Fructose feeding was associated with significantly higher insulin plasma concentrations (+63%) in the control groups, whereas insulin plasma concentrations did not differ in rats fed the fructose diet supplemented with OFS. Plasma leptin concentration was significantly lower (approximately 50%) in the OFS-supplemented fructose group compared with the other three groups. Fructose feeding in rats also significantly increased plasma (P < 0.001) and liver (P < 0.001) triglyceride (TG) concentrations and the addition of OFS prevented the TG accumulation induced by fructose in the liver (P < 0.05) and hyperlipemia (P < 0.05). OFS consumption prevented (P < 0.05) the lower plasma vitamin E/TG ratio in rats fed the fructose diet. Control rats fed the fructose diet had high plasma TBARS values compared with rats fed the starch diet, whereas TBARS values remained unchanged when rats were supplemented with OFS. Control rats fed the fructose diet had higher TBARS urine values and higher heart tissue susceptibility to peroxidation compared with rats fed the starch diet, and this effect was significantly reduced by OFS consumption. Further studies are required to identify the mechanisms underlying the protective effect of OFS against the pro-oxidant effect of fructose. However, the potential nutritional benefits of OFS supplementation in fructose-rich diets are suggested.     

The type of dietary fat alters the hepatic uptake and biliary excretion of cholesterol from chylomicron remnants

The consumption of fat-enriched diets may alter the uptake and metabolism of chylomicron remnant cholesterol by the liver. To test this hypothesis, [3H]cholesterol-labelled chylomicron remnants derived from different dietary fats were studied in perfused livers both from rats fed on diets enriched in the corresponding fats and from rats fed on a low-fat diet. Livers from rats fed on each of the fat-enriched diets removed similar amounts (34-40%) of the [3H]cholesterol-labelled remnants added, whereas livers from rats fed on the low-fat diet removed significantly more labelled fish-oil and butter-fat remnants than olive-, maize- or palm-oil remnants. Significantly more remnant [3H]cholesterol was secreted into the perfusate HDL by livers from rats fed on the olive-oil, fish-oil and butter-fat diets when compared with those from rats fed on the low-fat diet or the maize-oil diet. Furthermore, the excretion of remnant [3H]cholesterol via the bile acid was increased by the olive-, maize-, palm- or fish-oil diets, and decreased by the butter-fat diet when compared with the low-fat diet, although the [3H]bile acid excreted remained less on saturated fat diets. This investigation shows that the hepatic uptake and subsequent metabolism of cholesterol from chylomicron remnants is influenced by the type of fat in the diet as well as the fatty acid composition of the particles themselves, and may help to explain some of the hyper- and hypocholesterolaemic effects of saturated and unsaturated fatty acids.     

Substitution of high-dose sucrose with fructose in high-fat diets resulted in higher plasma concentrations of aspartic acid,cystine, glutamic acid,ornithine and phenylalanine,and higher urine concentrations of arginine and citrulline

High fructose intake has been shown to increase circulating alanine transaminase in humans, which could reflect damage to the liver by fructose but could also be linked to higher level of transamination of amino acids in liver. Therefore, we hypothesized that a diet with high content of fructose would affect the amino acid composition in rat plasma and urine differently from a diet with high sucrose content. Because high intake of sucrose and fructose is often accompanied with high intake of saturated fat in the Western-style diet, we wanted to compare the effects of high fructose/sucrose in diets with normal or high content of coconut oil on individual free amino acids plasma and urine. Male Wistar rats were fed diets with normal (10 wt%) or high (40 wt%) content of sucrose or fructose, with normal or high fat content (7 or 22 wt%) and 20 wt% protein (casein). Rats fed high-fructose high-fat diet had higher plasma concentrations of aspartic acid, cystine, glutamic acid, ornithine, and phenylalanine and higher urine concentrations of arginine and citrulline when compared to rats fed high-sucrose high-fat diet. Substituting normal content of sucrose with fructose in the diets had little impact on amino acids in plasma and urine. Serum concentrations of alanine transaminase, aspartate transaminase, and creatinine, and urine cystatin C and T cell immunoglobulin mucin-1 concentrations were comparable between the groups and within normal ranges. To conclude, substituting high-dose sucrose with high-dose fructose in high-fat diets affected amino acid compositions in plasma and urine.     

Influence of Dietary Fats Upon Systolic Blood Pressure in the Rat

Studies were performed to determine whether feeding diets with differing fatty acid content and composition had an influence on systolic blood pressure in the rat. Weanling male rats were fed standard laboratory chow (2.9% fat in total), or synthetic diets (10% fat in total) containing fish oil, butter, coconut oil or corn oil, for 5 weeks. Coconut oil and butter diets were rich in saturated fatty acids, whilst fish oil and corn oil were rich in the n-3 and n-6 unsaturated fatty acids respectively. Systolic blood pressure was measured using an indirect tail-cuff method at the end of the feeding period, and compared to a group of weanling rats.

Feeding the different diets did not alter the growth of the rats, so all animals were of similar weights at the time of blood pressure determination. Control (chow fed) animals, at nine weeks of age, had higher systolic blood pressures than the weanling, baseline control group. Fish oil fed rats had similar pressures to the chow fed rats. Corn oil fed rats had significantly lower systolic pressures than the controls. The rats fed the diets rich in saturated fatty acids (butter and coconut oil) had significantly higher blood pressures than all other groups. Systolic blood pressure was found to be significantly related to the dietary intakes of saturated and unsaturated fatty acids. The dietary intake of linoleic acid was significantly higher in corn oil fed rats than in other groups. Systolic blood pressure was inversely related to linoleic acid intake. Feeding a diet rich in saturated fatty acids significantly increases blood pressure in the rat. A high intake of n-6 fatty acids, and in particular linoleic acid, appears to have a hypotensive effect. Prenatal exposure of the rats to a maternal low protein diet, abolished the hypertensive effects of the coconut oil diet and the hypotensive effect of the corn oil diet upon young adult females. The intrauterine environment may, therefore, be an important determinant of the effects of these fatty acids on blood pressure in later life.     

Interrelationship of plasma triglycerides and HDL size and composition in rats fed different dietary saturated fats

We investigated the relative effects of different dietary saturated fats on the size distribution, apolipoprotein (apo) and chemical composition of HDL in fasted rats. Male Sprague-Dawley rats (174 +/- 2 g) were fed diets containing 0.035% cholesterol and 16% fat (wt/wt) from corn oil (CO diet) or from 2% CO plus 14% butterfat (BF diet), beef tallow (BT diet), palm oil (PO diet) or coconut oil (CN diet) for 6 wk. Apparent lipid digestibility was significantly lower with the PO and BT diets vs. the CO, BF and CN diets. Plasma total cholesterol levels were significantly higher in rats fed the PO and BT diets than in rats fed the BF and CN diets but were not different among the PO-, BT- and CO-fed groups. Nondenaturing gradient gel electrophoresis immunoblot analysis indicated that HDL apo A-I and E resided on particles with significantly smaller modal diameters in rats fed all saturated fats compared with those fed the CO diet. Chemical analyses indicated that HDL generally contained proportionately less protein and more triglyceride, free cholesterol and apo E with saturated fat feeding than with CO diet feeding. Significantly higher plasma and VLDL triglyceride levels were noted with ingestion of the BT, PO or CN diet than with the CO diet. Butterfat feeding resulted in lower plasma triglycerides and HDL-esterified cholesterol than did feeding the other saturated fats. Very low density lipoprotein triglyceride concentrations were inversely correlated with HDL modal diameter of apo E containing lipoproteins (P less than 0.005). These data provide further evidence of the interrelationship of triglyceride and HDL metabolism and suggest that mechanisms independent of cholesterol ester transfer protein may mediate this response in rats.     

Intestinal lymph lipoproteins in rats fed diets enriched in specific fatty acids

Four groups of rats were fed test diets with fats providing 75% of fatty acids as palmitate, stearate, oleate or linoleate. Absorption of radiolabeled cholesterol and the specific triglyceride into intestinal lymph lipoproteins and the lipid and protein content and composition of intestinal lymph were compared. Cholesterol and triglyceride absorptions were correlated significantly and were less with the saturated fatty acid diets. The fatty acid patterns of triglyceride-rich lymph lipoproteins mirrored the diet. Exogenous cholesterol was recovered primarily in chylomicrons, except with linoleate. In contrast, radiolabeled saturated fatty acids were recovered primarily in very low density lipoproteins and unsaturated fatty acids were recovered in chylomicrons. Lymph chylomicron size and lipid content were greater with unsaturated fat diets. Triglyceride-rich intestinal lipoproteins of rats fed saturated fats were polygonal by electron microscopy, related to the cooling of lymph samples below body temperature. A-I apolipoproteins were increased in relation to C apoproteins as lipid absorption was greater. Plasma triglycerides in all groups increased compared to rats fed the stock diet. A diet enriched in one specific fatty acid has its unique effects on lymph lipoprotein formation presumably affecting some intestinal subcellular mechanisms. Diet-induced changes in plasma lipids and lipoproteins are not directly related to these as yet unknown mechanisms.     

Psyllium shifts the fermentation site of high-amylose cornstarch toward the distal colon and increases fecal butyrate concentration in rats.

We examined the combination effects of psyllium (PS) and resistant starch on large bowel short-chain fatty acids (SCFA). Rats were fed one of the following four diets: low amylose (LAS) or high amylose cornstarch diets (HAS, 50 g/kg diet) with or without 15 g PS/kg diet (LAS/PS and HAS/PS diets). HAS and/or PS were substituted for the same amounts of LAS in diets. Cecal butyrate concentrations were significantly higher in rats fed the HAS and HAS/PS diets than in those fed the LAS and LAS/PS diets. However, butyrate and total SCFA concentrations in rats fed the HAS diet decreased along the length of the colon and fecal butyrate concentration was reduced to one-third of that in the cecum. In contrast, the HAS/PS diet maintained higher butyrate concentrations throughout the large bowel. Fecal butyrate concentration in the HAS/PS diet-fed group significantly exceeded the sum of the concentrations in rats fed the LAS/PS and HAS diets. PS supplementation to the HAS diet significantly increased fecal starch excretion by 10 fold compared with that of rats fed the HAS diet. There was a positive correlation between fecal butyrate concentration and fecal starch excretion (r = 0.709, P < 0.0001). In a further experiment, ileorectostomized rats were fed the HAS and HAS/PS diets. From the difference in fecal starch excretion between normal and ileorectostomized rats, starch degradation by large bowel microflora in rats fed the HAS and HAS/PS diets was deduced to be 96% and 63%, respectively. These findings support the hypothesis that PS may delay the fermentation rate of HAS in the cecum and shift the fermentation site of HAS toward the distal colon, leading to the higher butyrate concentration in the distal colon and feces.     

Brown Seaweed Sargassum siliquosum as an Intervention for Diet-Induced Obesity in Male Wistar Rats

The therapeutic potential of Sargassum siliquosum grown in Australian tropical waters was tested in a rat model of metabolic syndrome. Forty-eight male Wistar rats were divided into four groups of 12 rats and each group was fed a different diet for 16 weeks: corn starch diet (C); high-carbohydrate, high-fat diet (H) containing fructose, sucrose, saturated and trans fats; and C or H diets with 5% S. siliquosum mixed into the food from weeks 9 to 16 (CS and HS). Obesity, hypertension, dyslipidaemia, impaired glucose tolerance, fatty liver and left ventricular fibrosis developed in H rats. In HS rats, S. siliquosum decreased body weight (H, 547 ± 14; HS, 490 ± 16 g), fat mass (H, 248 ± 27; HS, 193 ± 19 g), abdominal fat deposition and liver fat vacuole size but did not reverse cardiovascular and liver effects. H rats showed marked changes in gut microbiota compared to C rats, while S. siliquosum supplementation increased gut microbiota belonging to the family Muribaculaceae. This selective increase in gut microbiota likely complements the prebiotic actions of the alginates. Thus, S. siliquosum may be a useful dietary additive to decrease abdominal and liver fat deposition.     

Prolonged Changes in Hepatic Mitochondrial Activity and Insulin Sensitivity by High Fructose Intake in Adolescent Rats

Persistence of damage induced by unhealthy diets during youth has been little addressed. Therefore, we investigated the impact of a short-term fructose-rich diet on liver metabolic activity in adolescent rats and the putative persistence of alterations after removing fructose from the diet. Adolescent rats were fed a fructose-rich diet for three weeks and then switched to a control diet for further three weeks. Body composition and energy balance were not affected by fructose-rich diet, while increased body lipids and lipid gain were found after the rescue period. Switching to a control diet reversed the upregulation of plasma fructose, uric acid, lipocalin, and haptoglobin, while plasma triglycerides, alanine aminotransferase, lipopolysaccharide, and tumor necrosis factor alpha remained higher. Hepatic steatosis and ceramide were increased by fructose-rich diet, but reversed by returning to a control diet, while altered hepatic response to insulin persisted. Liver fatty acid synthase and stearoyl-CoA desaturase (SCD) activities were upregulated by fructose-rich diet, and SCD activity remained higher after returning to the control diet. Fructose-induced upregulation of complex II-driven mitochondrial respiration, peroxisome proliferator-activated receptor-gamma coactivator 1 alpha, and peroxisome proliferator activated receptor α also persisted after switching to control diet. In conclusion, our results show prolonged fructose-induced dysregulation of liver metabolic activity.     

Effect of dietary fat on serum and tissue lipids of adult rats.

The effect of 3 types of fat: 1) Ghee, 2) Corn oil, 3) Subsidized vegetable oil (SVO) on serum and tissue lipids was studied by using adult albino male rats mean weight 114 g. Rats fed diet containing SVO had the highest serum cholesterol and LDL-cholesterol concentrations than those fed diet containing ghee or corn oil. Serum high density lipoprotein-cholesterol (HDL) concentration was highest in animals fed the ghee and lowest with those fed the SVO diet. On the other hand phospholipids values tend to be lower when feeding diets containing oils. Also serum triglycerides levels were higher on saturated fat diet than on the unsaturated fat diets. The same trends were found for liver cholesterol as in serum cholesterol. SVO diet gave the highest liver cholesterol concentration. Also SVO gave the highest heart phospholipids values.     

Fructose consumption leads to reduced aerobic capacity and to liver injury in rats

ABSTRACT: This study aimed to evaluate the effect of chronic fructose consumption on markers of nonalcoholic fatty liver disease (NAFLD), lipid peroxidation and liver damage in Wistar rats. We separated twenty-eight rats into two groups according to diet: a control group (C) (balanced diet) and a fructose group (F) (fed a diet containing fructose as 60% of the total caloric intake). The animals were fed these diets for 60 d (d 120 to 180). We performed insulin, glucose and fructose tolerance tests as well as a minimum lactate test, for aerobic capacity evaluation, at d 120 and 180. At the end of the experiment, sixteen animals were euthanized, and the following main variables were analysed: aerobic capacity, the serum aspartate aminotransferase (AST) to alanine aminotransferase (ALT) ratio, serum and liver triglyceride concentrations, serum and liver thiobarbituric acid reactive substance (TBARS) concentrations, serum and liver catalase and superoxide dismutase (SOD) activity and haematoxylin-eosin histology (HE) in hepatocytes. The remaining twelve animals were submitted to an analysis of their hepatic lipogenic rate. The animals fed a fructose-rich diet exhibited a reduction in aerobic capacity, glucose tolerance and insulin sensitivity and increased concentrations of triglycerides and TBARS in the liver. Catalase and SOD activities were reduced in the livers of the fructose-fed animals. In addition, the serum AST/ALT ratio was higher than that of the C group, which indicates hepatic damage, and the damage was confirmed by histology. In conclusion, the fructose-rich diet caused significant liver damage and a reduction in insulin sensitivity in the animals, which could lead to deleterious metabolic effects.     

Lipid profile of rats fed high-fat diets based on flaxseed, peanut, trout, or chicken skin

OBJECTIVE: Dietary saturated fatty acids are associated with coronary disease. Conversely, dietary monounsaturated polyunsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) seem to exert a protective effect. This study evaluated the lipid profile of rats fed high-fat (HF) diets, with fat added as different sources of PUFA (flaxseed and trout), MUFA (peanut), and saturated fatty acid (chicken skin). METHODS: Adult male Wistar rats were placed into six dietary groups (n = 10): control (normal); high fat, with 1% cholesterol, 10% soy oil, and 5% lard; and four groups fed similar HF diets, with 10% lipid as trout, flaxseed, peanut, or chicken skin. After 28 d the animals were killed. Blood, livers, and adipose tissue samples were collected. RESULTS: A higher level (P < 0.05) of total serum cholesterol was observed in rats fed the normal diet (93.57 +/- 14.95 mg/dL) compared with those fed the HF diet (67.57 +/- 12.54 mg/dL). Total cholesterol levels in rats fed the flaxseed diet were lower (P < 0.05) than in rats fed the other fats. No difference was observed in cholesterol levels between groups fed the peanut and chicken skin diets (P > 0.05). Animals fed the peanut diet showed decreased body weight gain than did animals in the other treatment groups. There were large lipid and cholesterol depositions in livers of rats fed the HF diet. Lipid deposition in adipose tissue followed the same dietary fatty acid profile, i.e., high levels of omega-3 PUFA in the flaxseed group, high levels of MUFA in the peanut and chicken skin groups and high levels of omega-6 PUFA in the trout group. CONCLUSIONS: These data indicate that flaxseed is promising for dietary manipulation of hyperlipidemia.