Nutritional evaluation of crude palm oil in rats.

Edible-grade crude palm oil (CPO: from Elaeis guineensis) is one of the richest natural sources of beta-carotene (7500 mumol/L) and is cheaper than other edible oils, making it a promising source of vitamin A in a deficient population. Nutritional studies were conducted on weanling albino rats of the Wistar/NIN strain for 28 and 90 d. Diets contained 10% of either CPO, groundnut oil (GNO), or refined palm-olein oil (RPO) and adequate amounts of all other nutrients. No adverse effects were observed as judged by growth rate, feed-efficiency ratio, protein-efficiency ratio, net protein utilization, digestibility, fat absorption, nitrogen balance, phosphorus and calcium retention, serum enzymes, and blood hematology, which were comparable with control values. Lipid profiles of the animals of the 28-d study indicated that CPO and RPO had higher amounts of cholesterol and triglycerides than did GNO although tissue lipids were comparable. In the 90-d study, however, lipid concentrations were comparable with control values. These results suggest that CPO has adequate nutritional quality compared with GNO and RPO.

Reproductive toxicology and nutritional studies on mahua oil (Madhuca latifolia).

Mahua (Madhuca latifolia, Sapotaceae) seed oil is a common ingredient of hydrogenated fat in India. It is obtained from the seed kernels (which contain 45% oil, w/w), and is a pale yellow, semi-solid fat at room temperature. It has palmitic (19%), stearic (15%), oleic (42%) and linoleic (24%) as a major fatty acids. The physicochemical parameters of the oil are similar to those of other edible oils. The unsaponifiable fraction contains several unidentified polyenes. Nutritional studies were carried out in groups of 15 weanling albino rats of each sex, fed for 14 wk on a 20% protein diet, adequate in all vitamins and minerals, containing 10% mahua oil. A similar (control) group was simultaneously maintained on the same basic diet containing 10% groundnut oil. The growth, fat absorption, and retention of nitrogen, calcium and phosphorus were similar in the two groups, as were the lipid profiles of the serum, liver and heart. Multigeneration reproduction studies in groups of 15 rats of each sex, fed a diet containing 10% mahua oil, as used in the above study, indicated poor reproductive performance in the second generation. All the male rats became sterile. Histological studies indicated bilateral testicular atrophy with degenerative changes in the seminiferous tubules in the affected animals. On withdrawal of mahua oil from the diet and rehabilitation, the male animals regained their fertility. These results indicate temporary male sterility on feeding mahua oil to rats. No other adverse toxicological effects were found.

Mutagenicity tests of cashewnut shell liquid, rice-bran oil and other vegetable oils using the Salmonella typhimurium/microsome system.

In view of the shortage of edible oils in India, nutritional and toxicological evaluations have been carried out on some unconventional oils to determine whether they might be safe for human consumption. As part of these evaluations, eight unconventional oils were tested by the Ames mutagenicity assay, using Salmonella typhimurium strains TA98 and TA100 with and without metabolic activation with S-9 mix prepared from the livers of rats pretreated with sodium phenobarbitone or Aroclor 1254. Of the oils tested, metsa oil (Hibiscus sabdariffa) and cashewnut shell liquid were mutagenic with and without metabolic activation with S-9 of either source. No mutagenic activity (with or without S-9 of either source) was observed with any of the other oils tested (rice-bran oil, Cleome viscosa oil, mango-kernel oil, mahua oil, kapok oil and neem oil).

Effect of red palm oil on some hepatic drug-metabolizing enzymes in rats.

Red palm oil (RPO) from Elaeis guineensis is being considered for use as an edible oil in India as it is one of the richest natural sources of carotenoids. The effect of RPO on the host detoxification system, which is a vital mechanism in cancer prevention, was studied in three separate batches of Wistar/NIN inbred albino rats, and compared with controls, groundnut oil (GNO) and refined bleached deodorized palmolein oil (RBDPO). The first batch of 36 rats (12 from each group) comprised the adult males (26 wk old) of the third generation (F2b) from a multigeneration reproduction study in which three groups were fed 10% GNO or RPO or RBDPO for three generations continuously. Phase II glutathione-S-transferase (GSH-T) activity was measured in the liver cytosol of these rats after they had twice completed the process of mating, gestation, lactation and weaning, because GSH-T is one of the principal detoxifying enzymes involved in conjugating reactions of phase II metabolism. The fourth generation (F3b) weanling rats of the three groups, receiving GNO, RPO or RBDPO, were continued on the 10% oil diet for 9 wk, after which cytosolic GSH-T activity was measured. In the second experiment, eight male weanling Wistar/NIN inbred albino rats, 5 wk old, weighing 100-120 g, were fed 10% GNO, RPO or RBDPO for 4 wk in a 20% protein synthetic diet. Liver cytosolic GSH-T, reduced glutathione, microsomal total cytochrome P-450, aminopyrine N-demethylase and ethoxyresorufin-O-deethylase activity were measured to elucidate the effect of RPO on some phase I and phase II reactions. Significantly higher levels of GSH-T were observed in F2b and F3b rats given RPO than in those given GNO or RBDPO. In the second experiment, GSH-T induction was also noted, together with increased levels of reduced GSH. Phase I enzymes and total cytochrome P-450 levels were comparable between groups, indicating that no induction attributable to RPO had occurred. Thus, enhancement of one of the detoxifying phase II enzymes, in conjunction with the lack of induction of those activating phase I enzymes that are known to metabolize phenobarbitone and polycyclic aromatic hydrocarbons, suggests that RPO affords protection against chemical carcinogens, probably because of its carotenoid content.

Multigeneration studies on red palm oil, and on hydrogenated vegetable oil containing mahua oil.

Edible grade red palm oil (RPO; Elaeis guineensis) is being considered for use an an edible oil in India since it is one of the richest natural sources of carotenoids. Earlier chemical and nutritional evaluations in rats indicated no adverse effects. Multigeneration breeding studies in rats have now been carried out. Mahua oil (MO; Madhuca latifolia) is used in hydrogenated vegetable oil (HVO) for human consumption. Earlier studies on MO indicated adverse effects on the male reproductive system. Hence, a study was undertaken to evaluate the safety of HVO containing 30% MO (MO-HVO) in terms of reproductive performance. A three-generation study was conducted with groups of 12 male and 12 female Wistar/NIN/inbred albino rats fed, at 10% in the diet (20% protein), groundnut oil (controls), RPO, refined, bleached and deodorized palmolein (RBDPO), or MO-HVO. Reproductive parameters including percentage conception, birth weight, litter size, weanling weight, sex ratio at birth and weaning, preweaning mortality and number of days from introduction to mating, were recorded. Behavioural and reflexological tests were conducted on preweaning animals. Adult animals were subjected to weekly observation. No significant differences were found between the RPO and MO-HVO groups in comparison with groups fed GNO or RBDPO in any of the above parameters. However, certain indications of reduced fertility were observed in the MO-HVO group in the first and third generations. The results indicate that RPO did not produce any adverse effect on reproductive performance or other toxicological parameters studied, and therefore it can be considered as safe for consumption. On the other hand, HVO containing 30% MO needs further testing with a larger number of animals.

Immune studies with T-2 toxin: effect of feeding and withdrawal in monkeys.

Ingestion of T-2 toxin, a product of Fusarium fungi, has been reported to have a variety of effects leading to morbidity and mortality in animals and humans. Semi-purified T-2 toxin was given to monkeys by gastric intubation at a level of 100 microgram/kg body weight/day for 4-5 wk and the haematological and immune parameters were studied before and after the treatment. Leucocyte counts were depressed at the end of wk 4 of treatment. The immunological studies studies showed suppression of the bactericidal activity of neutrophils, of cell-mediated immune status as assessed by T-cell number and lymphocyte transformation, and of humoral immunity as reflected in B-cell number and IgG and IgM levels. However serum complement (CH50) did not show any change. Investigations carried out 5 months after withdrawal of the toxin indicated that these parameters had returned almost to the initial, pretreatment levels. These data suggest that the greater incidence of infection seen in mycotoxin-ingesting animals may be due to immune suppression. Withdrawal of the mycotoxin results in improvement of haematological and immune functions.

Urinary porphyrin pattern in liver damage.

Known techniques were used with slight modification to analyse and quantify porphyrins in the urine samples of normal human subjects, of clinically established jaundice cases and of women taking oral contraceptives. The results indicate that the urinary porphyrin pattern can be a useful tool in the detection of early liver injury.

PIP: This study used modifications of methods developed by Harmsen and Strik for total porphyrin and for porphyrin metabolites to investigate porphyrin patterns in urine samples from clinically established jaundice cases, women taking oral contraceptives (OCs), and healthy human subjects. Determination of urinary porphyrin patterns was carried out by use of thin-layer chromatography. The ranges of total porphyrins (20-120 mcg/liter), uroporphyrin (6-45 mcg/liter), and coproporphyrin (9-63 mcg/liter) in urine samples from normal subjects were within the limits reported in the literature. As expected, total porphyrins were higher in the jaundiced patients. There was a slight but not statistically significant increase in total porphyrin xcretion and a slight decrease in the coproporphyrin/uroporphyrin ration in OC users. Recoveries using this technique were 80-85% and reproducible. These results suggest the value of this method in monitoring for occupational and environmental exposure to xenobiotics. Future screening is planned to detect liver injury in childred with Indian childhood cirrhosis or kwashiorkor.

Ames mutagenicity tests of repeatedly heated edible oils.

Six cooking oils with different levels of unsaturation were each heated at 180 +/- 3 degrees C for 6 hr on each of four consecutive days and cut potatoes were fried in the oils at hourly intervals. Samples of the heated and unheated oils were tested in the Ames mutagenicity assay. None of the oil samples (taken before or after 24 hr heating) showed any mutagenicity in the Ames test with or without metabolic activation.

Toxicological studies on debitterized Neem oil (Azadirachta indica).

Azadirachta indica, popularly known as 'Neem' in India, is widely grown all over the tropics. The seed contains 45% oil and is a minor oil of considerable potential. Neem oil is bitter and inedible. Recently, a method has been developed to completely remove the bitter and odoriferous principles and leave a bitterless, odourless and colourless oil. The nutritional and chemical evaluation of debitterized neem oil (NO) was reported earlier (C. Rukmini, Food Chemistry 1987, 26, 119). We report here a three-generation study, carried out according to WHO/FDA protocol in groups of 15 male and 15 female rats fed a diet containing 10% NO or groundnut oil (GNO). Reproductive toxicology was monitored for three generations. The results obtained in both the matings in all the three generations did not show any adverse effects on the reproductive parameters studied in rats fed NO and were similar to those observed in rats fed GNO. The mean organ weights and the histopathological evaluation of all the organs were similar to those of the control (GNO-fed) rats. A mutagenicity test of NO was also found to be negative in Ames test as reported earlier (K. Polasa and C. Rukmini, Food and Chemical Toxicology 1987, 25, 763). These studies indicate that NO devoid of all the bitter and odoriferous principles, may be recommended as safe for consumption by humans.

Rice bran oil and hypocholesterolemia in rats.

Rats fed rice bran oil at 10% level for a period of eight weeks showed significantly lower levels of total cholesterol, low density lipoprotein and very low density lipoprotein cholesterol, both on cholesterol-containing and cholesterol-free diets. High density lipoprotein cholesterol was increased but triglyceride showed a decrease that was not statistically significant. Liver cholesterol and liver triglycerides were also reduced. Fecal excretion of neutral sterols and bile acids was increased after ingestion of rice bran oil.

Nutritional significance of rice bran oil.

India is the second largest producer of rice in the world and has the high potential to produce rice bran oil (RBO), a by-product of the rice milling industry. Since RBO is, an unconventional oil, the chemical composition, nutrient evaluation and toxicological safety were assessed. The fatty acid composition RBO is very close to that of groundnut oil (GNO). Though RBO has high unsaponifiable matter (4.2%), it is rich In minor constituents such as phytosterols, triterpene alcohols, tocopherols and tocotrienols. Experimental as well as human studies have demonstrated the hypolipidaemic effects of RBO. Further, It was established that minor constituents present in unsaponifiable fraction of RBO were responsible for its hypolipidaemic effects. Nutritional evaluation studies, carried out with 10 per cent RBO and 20 per cent protein, indicated that growth, feed efficiency and mineral balance were comparable to GNO-fed animals. Toxicological studies had shown that there were no abnormalities In animals fed either RBO or GNO. The reproductive performance was also found to be normal as compared with that of GNO-fed animals in all three generations. In addition, neither RBO nor the foods deepfried in it showed any mutagenicity as judged by Ames test. In view of its safety and hypolipidaemic activity, RBO could be considered as an alternative source of edible oil.

Nutritional and biochemical aspects of the hypolipidemic action of rice bran oil: a review.

In this paper, we review the effects of rice bran oil (RBO), an unconventional oil recently introduced onto the Indian market for human use. RBO contains oleic acid (38.4%), linoleic acid (34.4%), and linolenic acid (2.2%) as unsaturated fatty acids, and palmitic (21.5%) and stearic (2.9%) acids as saturated fatty acids. The unsaponifiable fraction (4.2%) has total tocopherols (81.3 mg%), gamma-oryzanol (1.6%), and squalene (320 mg%). Oryzanol is a mixture of ferulic acid esters of triterpene alcohols such as cycloartenol (CA) (106 mg%) and 24-methylene cycloartanol (494 mg%). Studies on experimental rats demonstrated a hypolipidemic effect of RBO. The unsaponifiable fraction of RBO lowers cholesterol levels. Feeding phytosterols, CA, and 24-methylene cycloartanol in amounts present in RBO to hypercholesterolemic rats for 8 weeks indicates that CA alone reduces cholesterol and triglyceride levels significantly. Endogenous sterol excretion increases in animals given CA. The accumulation of CA in the liver inhibits cholesterol esterase activity, which in turn leads to reduction in circulating cholesterol levels. CA is structurally similar to cholesterol and may compete with the binding sites of cholesterol and sequestrate cholesterol, which is metabolized to its derivatives. RBO, which is rich in tocopherols and tocotrienols, may improve oxidative stability. Tocotrienols inhibit HMG CoA reductase, resulting in hypocholesterolemia. The hypolipidemic effect of RBO has also been established in human subjects. Thus, RBO could be a suitable edible oil for patients with hyperlipidemia.

Lipid profile of rats fed blends of rice bran oil in combination with sunflower and safflower oil.

This study was undertaken to assess the effect of blended oils, i.e., polyunsaturated fatty acid (PUFA) rich vegetable oils like safflower oil (SFO) and sunflower oil (SNO) with the unconventional and hypocholesterolemic rice bran oil (RBO) on the serum lipid profile of rats. Rats fed RBO+SNO/SFO at 70:30 ratio for a period of 28 days showed significantly (p < 0.05) lower levels of total cholesterol (TC), triglycerides (TG) and low density lipoprotein (LDL) cholesterol and increased high density lipoprotein (HDL) cholesterol in animals fed a high cholesterol diet (HCD) and cholesterol free diet (CFD). Liver total cholesterol (TC) and triglycerides (TG) were also reduced. Fecal excretion of neutral sterols and bile acids was increased with use of RBO blends. RBO, which is rich in tocopherols and tocotrienols, may improve the oxidative stability of the blends. Tocotrienols are known to inhibit 3-hydroxy, 3-methyl, glutaryl CoA (HMG-COA) reductase (rate limiting enzyme in cholesterol biosynthesis), resulting in hypocholesterolemia. In addition to improving the lipid profile by lowering TC, TG and LDL-C and increasing HDL-C, blending of RBO with other oils can result in an economic advantage of lower prices.