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PubMed1982

The effects of dietary corn oil on the metabolism and mutagenic activation on N-nitrosodimethylamine (DMN) by hepatic microsomes from male and female rats.

Microsomes from male and female rats fed a diet containing 10% corn oil metabolized N-nitrosodimethylamine (DMN) more rapidly than microsomes from rats fed a similar diet devoid of corn oil. The daily administration of phenobarbital for 4 days prior to harvesting the microsomes resulted in significant induction of the Vmax for N-demethylation of DMN in rats fed the fat-free diet but resulted in no induction (females) or suppression (males) of this enzyme in rats fed the diet containing corn oil. Using concentrations of DMN ranging from 12 to 100 mM, microsomes from rats fed the high fat diet activated DMN to produce mutagenesis in S. typhimurium (TA100) more rapidly than those from rats fed the fat-free diet. Phenobarbital administration induced this activation more effectively in rats fed the corn oil diet than in rats fed the fat-free diet. Phenobarbital induces DMN N-demethylation in rats fed both fat-free and 10% corn oil diets when the DMN concentration is above 10 mM and explains, at least in part, this enhanced mutagenic activation.

Animals↗
PubMed1990

Liver tumor promoting ability of corn oil gavage in B6C3F1 male mice.

In chronic carcinogenic bioassays, chemicals being tested with low water solubility have been administered via corn oil gavage. The present study examined the effect of chronic corn oil gavage on hepatic tumor formation in the B6C3F1 male mouse. Mice were initiated with diethylnitrosamine (DENA) either at 15 days of age with a single i.p. injection (5 micrograms/gbw) (protocol 1) or at 4 weeks of age via the drinking water (15 mg/l) for a duration of 3 weeks (protocol 2). At weaning (protocol 1) or 8 weeks of age (protocol 2) initiated and untreated mice were administered either corn oil at a dose of 0.15 ml via gavage (once a day, 5 days/wk) or saline (0.15 ml via gavage, once a day 5 days/wk). All mice were killed at 28 weeks of age and hepatic lesions were quantitated. Only mice exposed to DENA demonstrated hepatic tumors. Mice treated with DENA (at 15 days of age) and corn oil gavage exhibited a significant decrease in the number of hepatic adenomas compared with DENA (at 15 days of age) only treated mice. No difference was noted in the number of hepatic adenomas between mice treated with DENA (at 4 wks of age) and corn oil gavage and mice exposed to DENA (at 4 wks of age) only.

Animals↗
PubMed1996

Effect of subchronic corn oil gavage on the acute toxicity of orally administered bromodichloromethane.

Bromodichloromethane (BDCM) is a by-product of water chlorination and is the second most common trihalomethane (THM) in finished drinking water. It has been reported that delivery of THMs in corn oil can influence the site and magnitude of toxic and carcinogenic responses in rodents, perhaps by inducing metabolizing enzymes or altering tissue composition. To determine if corn oil influences the acute toxicity of BDCM, adult male F-344 rats were pretreated 5 days/week for 6 weeks with oral doses of corn oil or water at a volume of 5 ml/kg. Following pretreatment, animals were gavaged with a single dose of 0, 200 or 400 mg BDCM/kg in 10% Emulphor. Urine was collected at timed intervals over a 48-h period following BDCM administration. Rats were sacrificed at this time and organs and blood removed. Urine and serum were analyzed for indicators of toxicity. Corn oil pretreatment did not enhance the acute hepato- or nephrotoxicity of BDCM, suggesting that vehicle effects noted in previous THM toxicity and carcinogenicity studies are more likely due to pharmacokinetic differences between administration in corn oil and aqueous gavage vehicles than to altered tissue composition or physiological changes.

Administration, Oral↗
PubMed1997

Preloads of corn oil inhibit independent ingestion on postnatal day 15 in rats.

The ontogenetic development of postingestive inhibitory control of ingestion by an oil preload was examined in preweaning rats. Gastric preloads (5% b.wt) of water, mineral oil or corn oil were administered 5 min before a 30-min intake test in which pups licked milk from the floor of a test chamber. Preloads of corn oil decreased intake significantly compared with preloads of mineral oil or water on Postnatal Days 15 and 18, but not on Postnatal Day 12. Because preloads of corn oil reduced intake ore than preloads of mineral oil, it is possible that the inhibitory effect of corn oil is due to its fats rather than to its oily texture. Cholecystokinin (CCK), presumably released from the small intestine, apparently mediates part of this inhibitory effect because pretreatment with devazepide, a specific CKKA antagonist, significantly reduced the inhibition produced by corn oil.

Age Factors↗
PubMed1992

Hepatotoxicity of heated and oxygenated corn oil.

The present study was undertaken in rats to examine the hepatotoxicity of ingested heated and oxygenated corn oil. Activities of serum glutamic pyruvic transaminase markedly increased in the rats given heated and oxygenated corn oil for two weeks as compared with that of the control group. In the rats given heated and oxygenated corn oil, small fat droplets were found in the liver cells, but liver cell necrosis was not seen. Ultrastructurally, there was no conspicuous change in the liver cells, except for depletion of glycogen and dilatation of cisternae of rough and smooth surfaced endoplasmic reticulum. These experimental data show that ingestion of heated and oxygenated corn oil induces hepatic injury, and that the development of hepatic injury may relate to liver cell membrane damage due to active oxygen radicals contained in heated and oxygenated corn oil.

Alanine Transaminase↗
PubMed2002

Analysis of xanthophylls in corn by HPLC.

An HPLC method was developed using the C-30 carotenoid column to separate and identify the major xanthophylls in corn (lutein, zeaxanthin, and beta-cryptoxanthin). A photodiode array detector and a mobile phase consisting of methyl tert-butyl ether/methanol/water was used. All three xanthophylls eluted in less than 25 min. Yellow dent corn had a total xanthophyll content of 21.97 microg/g with lutein content of 15.7 microg/g, zeaxanthin content of 5.7 microg/g, and beta-cryptoxanthin of 0.57 microg/g. Commercial corn gluten meal had a 7 times higher concentration of xanthophylls (145 microg/g), and deoiled corn contained 18 microg/g, indicating that the xanthophylls are probably bound to the zein fraction of corn proteins.

Chromatography, High Pressure Liquid↗
PubMed1999

Effect of heat pretreatment on the yield and composition of oil extracted from corn fiber.

Previously, hexane extraction of corn fiber was reported to produce a unique and potentially valuable oil that contained high levels of several phytosterols (which have been noted for their cholesterol-lowering properties). Current studies revealed that heat treatment (over the range of 100-175 degrees C) of corn fiber in either a convection oven or a vacuum oven caused only a modest reduction in the levels of the phytosterol components. However, these same heat pretreatments caused a considerable increase (up to 10-fold) in the levels (increasing from 0.34 wt % to a maximum of 3.64 wt % gamma-tocopherol in the oil) and yields (increasing from 5.4 mg of gamma-tocopherol/100 g of corn fiber to a maximum of 52.1 mg of gamma-tocopherol/100 g of corn fiber) of gamma-tocopherol in corn fiber oil. The main differences between the convection oven and vacuum oven pretreatments were associated with the disappearance of free fatty acids and free phytosterols at the higher temperature pretreatments in the vacuum oven, probably due to the lower boiling points of these lipids. Microwave pretreatment was also effective but caused a much smaller increase in the levels of gamma-tocopherol.

Chromatography, High Pressure Liquid↗
PubMed2000

Digestibility of cocoa butter from chocolate in humans: a comparison with corn-oil.

OBJECTIVE: To compare, in humans, the digestibility of moderate amounts of cocoa butter (30.7 g/d) consumed in the form of chocolate as part of a normal western diet with that of a well-absorbed fat (corn oil); and hence determine whether, by virtue of its apparent low absorption, cocoa butter can be considered to be a low calorie fat. DESIGN: Randomised, two-period crossover metabolic study, conducted under free-living conditions, but with strict control over food intake. SETTING: Metabolic Unit, Nestlé Research Center Lausanne. SUBJECTS: Twelve healthy men were selected from volunteers at the Nestlé Research Center and all subjects completed the study. INTERVENTION: Two treatment periods of two weeks each: cocoa butter and control periods, with strict dietary control separated by a two week wash out period. RESULTS: No differences (P>0.05) were observed in faecal weight (wet or dry), faecal fat nor in defecation frequency between treatments (cocoa butter and corn oil). Cocoa butter at a dose of 30.7 g/d in the form of black chocolate, consumed between two meals, was found to have a similar digestibility to that of corn oil (99 % of corn oil digestibility). CONCLUSION: Cocoa butter, consumed as back chocolate within a normal mixed diet, has a high digestibility, similar to that of corn oil, and a digestible energy value of 37 kJ/g in man. Thus, cocoa butter cannot be considered to be a low-calorie fat. SPONSORSHIP: Nestec Ltd, Switzerland. European Journal of Clinical Nutrition (2000) 54, 120-125

Adult↗
PubMed1996

Comparison of ultraviolet light-induced skin carcinogenesis and ornithine decarboxylase activity in sencar and hairless SKH-1 mice fed a constant level of dietary lipid varying in corn and coconut oil.

To investigate the effect of various levels of corn oil and coconut oil on ultraviolet (UV) light-induced skin tumorigenesis and ornithine decarboxylase (ODC) activity, Sencar and SKH-1 mice were fed one of three 15% (weight) fat semipurified diets containing three ratios of corn oil to coconut oil: 1.0%:14.0%, 7.9%:7.1%, and 15.0%:0.0% in Diets A, B, and C, respectively. Groups of 30 Sencar and SKH-1 mice were fed one of the diets for three weeks before UV irradiation; then both strains were UV irradiated with an initial dose of 90 mJ/cm2. The dose was given three times a week and increased 25% each week. For Sencar mice (irradiated 33 wks for a total dose of 48 J/cm2), tumor incidence reached a maximum of 60%, 60%, and 53% for Diets A, B, and C, respectively, with an overall average of one to two tumors per tumor-bearing animal. For the SKH-1 mice (irradiated 29 wks for a total dose of 18 J/cm2), all diet groups reached 100% incidence by 29 weeks, with approximately 12 tumors per tumor-bearing mouse. No significant effect of dietary corn oil/coconut oil was found for tumor latency, incidence, or yield in either strain. The effect of increasing corn oil on epidermal ODC activity in chronically UV-irradiated Sencar and SKH-1 mice was assessed. Three groups of mice from each strain were fed one of the experimental diets and UV irradiated for six weeks. Sencar mice showed no increase in ODC activity until six weeks of treatment, when the levels of ODC activity in the UV-irradiated mice fed Diet A were significantly higher than those in mice fed Diet B or Diet C: 1.27, 0.55, and 0.52 nmol/mg protein/hr, respectively. In the SKH-1 mice, ODC activity was increased by the first week of UV treatment, and by three weeks of treatment a dietary effect was observed; ODC activity was significantly higher in mice fed Diet C (0.70 nmol/mg protein/hr) than in mice fed Diet A (0.18 nmol/mg protein/hr). Although there was no significant effect of dietary corn oil/coconut oil on UV-induced tumor incidence, the data indicate that chronically UV-irradiated hairless SKH-1 mice are more susceptible to UV-induced skin carcinogenesis than Sencar mice and that this susceptibility is correlated with increased in ODC activity, a parameter of cell proliferation.

Animals↗
PubMed1997

Corn oil enhances gamma-glutamyl transpeptidase-positive foci development in the presence of phenobarbital during hepatocarcinogenesis in rats.

We investigated the effects of type of dietary fat and phenobarbital on gamma-glutamyl transpeptidase-positive foci development. Four groups of six female Sprague-Dawley rats were initiated with diethylnitrosamine (15 mg/kg) at 24 hours of age. After weaning, they were fed nutritionally complete semipurified diets containing 15% corn oil or 5% corn oil + 10% fish oil and supplemented with 5,000 ppm vitamin E with or without phenobarbital (500 ppm) for three months. Dietary fish oil significantly increased hepatic phospholipid eicosapentaenoate and docosahexaenoate concentrations and decreased arachidonate concentration compared with 15% corn oil (p < 0.05). Corn oil (15%) significantly increased hepatic prostaglandin F2 alpha concentration compared with 10% fish oil (p < 0.05). Phenobarbital significantly stimulated glutathione S-transferase activity in both dietary fat groups (p < 0.05). In the absence of phenobarbital, type of dietary fat showed no effect on hepatic gamma-glutamyl transpeptidase-positive foci development. However, in the presence of phenobarbital, 15% corn oil significantly enhanced gamma-glutamyl transpeptidase-positive foci development compared with 10% fish oil (p < 0.05). Phenobarbital showed a strong tumor-promoting action in both dietary groups. In conclusion, there was an interaction between type of dietary fat and phenobarbital on gamma-glutamyl transpeptidase-positive foci development during hepatocarcinogenesis in rats.

Animals↗
PubMed1986

Controlled evaluation of fat intake in the Mediterranean diet: comparative activities of olive oil and corn oil on plasma lipids and platelets in high-risk patients.

Activities of low-fat diets with olive oil or corn oil on lipids and platelets were studied in 23 middle-aged patients with high atherosclerosis risk for 8 wk. The olive oil diet had a polyunsaturated-saturated ratio of 0.33 vs 1.28 for the corn oil diet. Plasma total cholesterol was reduced with corn oil, but high-density lipoprotein cholesterol levels were lower with corn oil and unchanged or raised by olive. Plasma apolipoprotein B levels were equally reduced by both diets; apolipoprotein AI and the apo AI:B ratio rose only with olive oil. Plasma-glucose levels were lowered significantly with olive oil. Changes in platelet function were characterized by a reduced sensitivity to arachidonic acid (particularly with corn oil) and to collagen (particularly with olive). An olive oil diet with a moderate fat intake (about 30% of total calories) leads to favorable plasma lipoprotein and platelet changes.

Adult↗
PubMed2001

Effects of a high-dose concentrate of n-3 fatty acids or corn oil introduced early after an acute myocardial infarction on serum triacylglycerol and HDL cholesterol.

BACKGROUND: Results of epidemiologic studies and clinical trials indicate that moderate doses of n-3 fatty acids reduce the risk of cardiovascular disease and may improve prognosis. OBJECTIVE: The objective was to evaluate the effect of a high-dose ethylester concentrate of n-3 fatty acids administered early after an acute myocardial infarction (MI) on subsequent cardiac events and serum lipids. DESIGN: Three hundred patients with acute MI were randomly assigned to a daily dose of either 4 g highly concentrated n-3 fatty acids or corn oil, administered in a double-blind manner over 12-24 mo. Median follow-up time was 1.5 y. Clinical follow-up, including the drawing of blood samples, was performed after 6 wk of treatment and later at 0.5-year intervals. RESULTS: Forty-two (28%) patients in the n-3 group and 36 (24%) in the corn oil group experienced at least one cardiac event (cardiac death, resuscitation, recurrent MI, or unstable angina). No significant difference in prognosis was observed between groups for single or combined cardiac events. Total cholesterol concentrations decreased in both groups, with no significant intergroup differences. On average, the monthly increase in HDL cholesterol was 1.11% in the n-3 group and 0.55% in the corn oil group (P = 0.0016). Triacylglycerol concentrations decreased by 1.30%/mo in the n-3 group, whereas they increased by 0.35%/mo in the corn oil group (P < 0.0001). CONCLUSION: No clinical benefit of a high-dose concentrate of n-3 fatty acids compared with corn oil was found despite a favorable effect on serum lipids.

Adult↗
PubMed1987

Digestion, absorption and effects on cholesterol absorption of menhaden oil, fish oil concentrate and corn oil by rats.

Adult male rats were surgically provided with a drainage catheter in the left thoracic lymphatic channel and an indwelling duodenal catheter for constant infusion of physiological saline-5% glucose. After an overnight fast, animals were given a single duodenal dose of an aqueous emulsion containing one of the following: oleic acid, corn oil, menhaden oil or a fish oil concentrate (FOC) and [1,2-3H]cholesterol. Digestion and absorption were estimated by recovering the total fatty acids in the thoracic duct lymph over a 24-h collection period (after subtraction of the "baseline" endogenous fatty acids in the lymph). Cholesterol absorption in the thoracic duct lymph was significantly reduced (P less than 0.05) in the presence of menhaden oil or FOC compared to that in the presence of corn oil. With various fat feedings, the major increases in lymph fatty acids were directly related to the dietary fatty acid content. The relative amounts of eicosapentaenoic acid (EPA) and arachidonic acid (AA) in the thoracic lymph were influenced by the lipid content of the emulsion. The EPA/AA ratio in control, oleic acid and corn oil feedings ranged from 0.12 to 0.25. When marine oil was administered, the EPA/AA ratio was 0.78-0.98. The total amount of fatty acids found in the lymph after marine oil feeding was significantly less (P less than 0.01) than that found after corn oil feeding. The results suggested that the digestion and absorption of menhaden oil and FOC were decreased as compared with corn oil. The EPA/AA ratio was increased in the thoracic lymph after dietary fish oil feeding.

Animals↗
PubMed1995

Corn oil, palm oil and butterfat fractions affect postprandial lipemia and lipoprotein lipase in meal-fed rats.

Our objective was to investigate the time course of postprandial lipemia and lipolytic activity in male Sprague-Dawley rats trained to eat meals containing butterfat fractions, palm oil or corn oil. Baseline and postprandial blood samples were obtained via a carotid cannula in rats fed the experimental diets for 4 wk. Rats fed saturated fats compared with corn oil showed a significantly greater peak increase in postprandial triacylglycerol concentrations. Corn oil ingestion resulted in significantly lower concentrations of cholesterol and triacylglycerol in plasma and significantly less triacylglycerol accumulation (millimoles per liter per 24 h) compared with ingestion of saturated fats. Postheparin plasma lipoprotein lipase activity and plasma insulin concentration were generally greater with ingestion of corn oil compared with palm oil or butterfat. Palm oil ingestion resulted in a biphasic plasma triacylglycerol response curve and greater postheparin plasma lipoprotein lipase activity compared with butterfat ingestion, suggesting differential effects of saturated fats on postprandial lipemia. Our results indicate that greater postprandial lipemia with ingestion of saturated fats compared with corn oil may be due in part to slower plasma triacylglycerol clearance.

Animals↗
PubMed2002

Dietary calcium phosphate promotes Listeria monocytogenes colonization and translocation in rats fed diets containing corn oil but not milk fat.

Most Gram-positive bacteria are susceptible to the bactericidal action of fatty acids and bile acids. Because dietary calcium phosphate (CaP(i)) lowers the intestinal concentration of these antimicrobial agents, high CaP(i) intake may enhance intestinal colonization of Gram-positive pathogens and the subsequent pathogenesis. In this study, we tested this hypothesis in a rat model using Listeria monocytogenes. Rats were fed diets containing low (20 micromol/g diet) or high (160 micromol/g diet) amounts of CaP(i). Dietary fat was provided as corn oil or milk fat. Rats were orally inoculated with L. monocytogenes. When rats consumed diets containing corn oil, high CaP(i) intake indeed stimulated colonization of L. monocytogenes and increased L. monocytogenes translocation and diarrhea. In addition, supplemental CaP(i) enhanced ex vivo growth of L. monocytogenes in fecal extracts of rats fed corn oil diets, suggesting that high CaP(i) intake decreased a luminal inhibitory factor. The concentrations of bile salts and fatty acids, which were highly listericidal in vitro, were indeed considerably decreased in fecal water of rats in the high calcium corn oil group. Surprisingly, dietary CaP(i) did not affect colonization and translocation of L. monocytogenes in rats fed the milk fat diet, nor did CaP(i) enhance ex vivo growth in fecal extracts. This absence of Listeria stimulation was associated with a lack of effect of dietary CaP(i) on fecal soluble fatty acids. In addition, residual soluble bile salts were higher in rats fed the high CaP(i) milk fat diet compared with the high CaP(i) corn oil diet. These results suggest that the stimulating effect of CaP(i) on L. monocytogenes infection depends on the type of dietary fat consumed.

Animals↗
PubMed2004

True amino acid availability in chinese high-oil corn varieties determined in two types of chickens.

True amino acid availability (TAAA) was determined in conventional corn (CC) and in 2 Chinese high-oil corn varieties (CHOC1; CHOC2). The CC, CHOC1, and CHOC2 contained 3.7, 6.6, and 7.5% oil (ether extract) on a dry matter basis, respectively. The CP content (% dry matter) of the corn increased from 8.6 to 12.2% as oil increased from 3.7 to 7.5%. Birds (Hy-Line roosters or Arbor Acres broilers) were given 1 of the 3 corn varieties as the sole dietary ingredient in a conventional (intubation method) TAAA assay. There was a significant (P < 0.05) effect of bird type on gut metabolic (endogenous) amino acid excretion values with the broilers having higher excretions. For all amino acids, there was also a significant (P < 0.05) effect of bird type on TAAA with the Hy-Line roosters having higher TAAA values. The mean value for TAAA calculated over all of the amino acids showed a 9.8% unit higher digestibility for roosters compared with the broilers. Differences in TAAA between the corn varieties were statistically significant for alanine and valine only. Overall, the present results indicate that TAAA is equal to or superior to that in CC and that the TAAA content is higher in CHOC compared with CC. Bird type has an important effect on TAAA results and should be considered when developing TAAA assays and interpreting TAAA values.

Amino Acids↗
PubMed2006

Sham feeding corn oil increases accumbens dopamine in the rat.

Both real and sham feeding of sucrose increase dopamine (DA) overflow in the nucleus accumbens (NAc). Fat is another constituent of foods that is inherently preferred by humans and rodents. We examined the affect of sham feeding corn oil in rats that were food and water deprived overnight. Rats were implanted with guide cannulas aimed at the NAc, as well as gastric fistulas. On alternate days, they were trained to sham lick 100% corn oil or distilled water (dH2O) for 20 min in the morning. Twenty-minute microdialysis samples were taken before, during, and after sham licking. DA and monoamines were analyzed by reverse-phase HPLC with coulometric detection. The results show that DA release in the NAc was significantly increased during sham licking of corn oil compared with the prior baseline (157.5+/-18.8%, n=12). During sham licking of dH2O, DA release in the NAc was not changed (93.0+/-4.0%, n=15). This experiment demonstrates that sham feeding of corn oil releases accumbens DA in a manner similar to ingestion of sucrose. Although both stimuli may have an olfactory component, sucrose is a gustatory, and 100% corn oil appears to be a trigeminal stimulus. Thus these data support the hypothesis that different sensory modalities produce reward using the same or closely related substrates in the forebrain.

Animals↗
PubMed1996

Red blood cell and tissue phospholipid fatty acid profiles of weanling rats fed infant formula fat blends containing soy and/or corn oil.

Soy oil or corn oil may be employed to provide essential fatty acids in infant formulas. Both of these sources are high in linoleic acid; soy oil contains modest levels of alpha-linolenic acid, while corn oil contains very low levels of this essential omega 3 fatty acid. We examined the omega 3 long-chain polyunsaturated fatty acid (LCP) accretion in red blood cells, liver, and brain phospholipids of rats on diets containing infant formula fat blends with essential fatty acids provided from soy and/or corn oil. Although modest alterations occurred in the red blood cell omega 3 LCP fatty acid status, substantially larger changes were noted in liver LCP profiles. Due to the relatively mature nature of the rats employed in this experiment, no alterations were noted in brain fatty acid profiles. In conclusion, we have observed substantial tissue differences in animals fed soy or corn oil containing diets. It appears that corn oil is inappropriate for use in infant formulas.

Animals↗