Fed Coconut Oil Research Articles

Differential changes in the fatty acid composition of the main lipid classes of chick plasma induced by dietary coconut oil

For a better understanding of the hyperlipidemic function of saturated fat, we have studied the comparative effects of diet supplementation with 10 and 20% coconut oil on the main lipid classes of chick plasma. Changes in fatty acid composition of free fatty acid and triglyceride fractions were parallel to that of the experimental diet. Thus, the increase in the percentages of 12:0 and 14:0 acids may contribute to the hypercholesterolemic effects of coconut oil feeding. Plasma phospholipids incorporated low levels of 12:0 and 14:0 acids whereas 18:0, the main saturated fatty acid of this fraction, also increased after coconut oil feeding. The percentage of 20:4 n-6 was higher in plasma phospholipids than in the other fractions and was significantly decreased by our dietary manipulations. Likewise, minor increases were found in the percentages of 12:0 and 14:0 acids in plasma cholesterol esters. However, the percentage of 18:2 acid significantly increased after coconut oil feeding. Our results show a relationship between fatty acid composition of diets and those of plasma free fatty acid and triglyceride fractions, whereas phospholipids and cholesterol esters are less sensitive to dietary changes.

The effect of dietary menhaden, olive, and coconut oil fed with three levels of vitamin E on plasma and liver lipids and plasma fatty acid composition in rats

The effect of dietary fats with varying degree s of unsaturation in the presence of different concentrations of vitamin E on tissue lipid levels was studied in rats. Rats were fed either menhaden oil, olive oil or coconut oil at 15% level s with either 0.1, 0.3 or 0.6 mg/g of vitamin E as α-tocopherol for four weeks. Rat serum and liver were analyzed for total cholesterol, HDL-cholesterol, triacylglycerol and phospholipids. In addition, fatty acid composition of serum lipids was also analyzed. Serum total cholesterol and triacylglycerol were significantly lower in rats fed menhaden oil than in those fed olive or coconut oil, while the HDL-cholesterol was significantly higher in serum of rats fed menhaden and olive oil than in those fed coconut oil. Levels of vitamin E in the diet had only a significant effect on serum cholesterol and liver phospholipids. The Pearson correlation coefficient showed a significant positive relationship between serum triacylglycerol and total cholesterol, and a negative correlation between triacylglycerol and HDL-cholesterol, and between total and HDL-cholesterol. In the liver, total cholesterol was significantly higher in rats fed coconut oil than in rats fed menhaden oil. Total liver phospholipids were lower in rats fed either coconut oil or olive oil compared to those fed menhaden oil, especially with higher levels of vitamin E intake. Higher levels of vitamin E in the diet appear to increase triacylglycerol and phospholipids in livers of rats fed menhaden oil. In the liver a significant negative correlation was observed between phospholipids and cholesterol. The type and degree of unsaturation (polyunsaturated fatty acids in menhaden oil, monounsaturated fatty acids in olive oil and saturated fatty acids in coconut oil) significantly affected plasma and tissue lipids.

Changes in the chemical composition of surfactant-like particles secreted by rat small intestine in response to different dietary fats.

Consumption of dietary oil, viz., corn, fish, coconut, or olive, induced the secretion of surfactant-like particles (SLP) in rat intestine. These lipoprotein particles differ in (i) levels of alkaline phosphatase activity, (ii) lipid composition, and (iii) FA composition in response to feeding of different oils. The secreted particles had similar buoyancy (1.07-1.08 g/mL) and cholesterol/phospholipid molar ratios (0.61-0.72) except that feeding coconut oil to rats produced SLP with a low (0.18) cholesterol/phospholipid molar ratio compared to control animals. It is concluded from these observations that feeding different oils induces the secretion of lipoprotein particles in rat intestine with different chemical compositions.

Changes in plasma lipid composition induced by coconut oil. Effects of dipyridamole

The comparative effects of 10-20% coconut oil feeding on fatty acid composition of the main lipid classes of chick plasma have been studied with and without simultaneous treatment with dipyridamole in order to clarify the hypolipidemic role of this drug. Coconut oil drastically increased the percentages of lauric and myristic acids in free fatty acid and triacylglycerol fractions, whereas these changes were less pronounced in phospholipids and cholesterol esters. The percentage of arachidonic acid was higher in plasma phospholipids than in the other fractions and was significantly decreased by coconut oil feeding. Linoleic acid, the main fatty acid of cholesterol esters, was drastically increased by coconut oil feeding. Changes induced by the simultaneous administration of dipyridamole were more pronounced in the phospholipids and cholesterol esters than in the other fractions. The fall observed in linoleic acid levels after dipyridamole treatment may be of interest for a lower production of its derived eicosanoids, especially in plasma phospholipids and cholesterol esters.

Exocrine Pancreatic Secretion Is Stimulated in Piglets Fed Fish Oil Compared with Those Fed Coconut Oil or Lard

An experiment was conducted to study the effect of feeding diets containing fat sources with different fatty acid composition (fish oil, coconut oil or lard, 10 g/100 g diet) on exocrine pancreatic secretion in piglets after weaning. A total of 16 barrows were weaned at 4 wk of age; 3 d later, they were surgically fitted with a catheter in the pancreatic duct for continuous collection of pancreatic juice. Collections of pancreatic juice were made every other day starting 4 d postsurgically. Piglets fed the fish oil diet secreted a significantly greater volume of pancreatic juice than piglets fed the coconut oil or lard diets. The output [U/(h. kg(0.75))] of lipase was higher in piglets fed fish oil than in piglets fed lard or coconut oil. The output of colipase was greater in piglets fed fish oil and coconut oil than in those fed lard. The dietary treatments did not affect the output of carboxylester hydrolase. The output of trypsin was significantly lower in piglets fed lard than in piglets fed fish oil or coconut oil diets and the output of carboxypeptidase B was greater in those fed the fish oil diet. Protein, chymotrypsin, carboxypeptidase A, elastase and amylase outputs did not differ among the dietary treatment groups. The apparent digestibilities of nutrients and energy were measured in feces and did not differ among groups. Thus, the greater output of lipase in fish oil-fed piglets did not result in a greater digestibility of fat in this diet.

Response of common carp ( Cyprinus carpio) larvae to different dietary levels and forms of supply of medium-chain fatty acids

The effects of dietary medium-chain fatty acids (MCFA) on survival, growth and fatty acid composition of first-feeding carp larvae were investigated in two 21-day feeding trials. In trial 1, one diet CO was supplemented with 10% coconut oil, two diets, M1 and M2 with 1.7 or 4.2% interesterified medium-chain triacylglycerols (MCT), and two other diets T1 and T2 with 1% tricaprylin and 0.7% tricaprin, or 2.5% tricaprylin and 1.7% tricaprin. The five diets were made isolipidic (18% of dry diet) with triolein and compared to a control diet without MCFA. With a low dietary level (1% of dry diet) of caprylic acid (C8:0), final survival and mean weight of larvae fed CO, M1 and T1 were not significantly different from those of control (68 ± 6% and 62 ± 8 mg, respectively). In contrast, with a high dietary C8:0 level (2.5% of dry diet), final survival and mean weight of larvae fed M2 and T2 were markedly decreased (23 ± 2% and 40 ± 8 mg, respectively), without effect of the form of supply. In trial 2, larvae were fed six diets with graded tricaprylin contents (from 0 to 10% in diet). Survival was not significantly affected but growth was decreased by C8:0 levels higher than 2% of dry diet. Fatty acid composition of larval total lipids revealed high levels of lauric and myristic acids in larvae fed coconut oil. Deposition of C8:0 and capric acid (C10:0) was low after MCT feeding, but depended of the form of supply, being higher with pure than with interesterified MCT. Relatively high amounts of C8:0 and C10:0 were recorded in total lipids of larvae fed 10% tricaprylin. It is concluded that high levels of caprylic acid decrease growth but that low levels are well utilised by carp larvae, irrespective of the form of supply.

Effect of energy source and xylanase addition on energy metabolism, performance, chemical body composition and total body electrical conductivity (TOBEC) of broilers.

Three diets containing either no supplemented fat (LF), 12% soybean oil (SO) or 12% coconut oil (CO) were fed to broilers to examine energy utilization in two experiments. Heat production and energy retained as fat and protein were measured in the first experiment using a respiration technique in combination with C- and N-balance and controlled (pair-fed) feeding conditions. Growth performance, carcass composition, chemical body composition and total body electrical conductivity (TOBEC) were evaluated in a second experiment under ad libitum feeding conditions (from hatching to day 35). Moreover, each of the three diet types was tested with or without the addition of a xylanase-containing enzyme preparation in the growth experiment. Energy utilization (experiment 1), expressed as the ratio between total retained energy and metabolizable energy intake, amounted to 0.33, 0.36 and 0.39 in LF-, SO- and CO-fed groups, respectively. Applying ad libitum feeding conditions in the second experiment caused a significant reduction in feed intake and weight gain in broilers fed the CO-diet. The feed-to-gain ratio was significantly lower in birds given the fat-supplemented diets. The highest degree of fatness as indicated by the highest percentage of abdominal and visceral fat and by highest total fat content was found in birds fed the CO-diet. The higher the body protein content and the lower the body fat content, the higher the TOBEC value should be. This was confirmed when LF-fed broilers were compared to their CO-fed counterparts. However, fat type seemed to be related to TOBEC values since SO-fed broilers had similar TOBEC values as CO-fed birds, whereas chemical body composition was comparable to LF-fed broilers. Xylanase addition significantly increased weight gain up to 21 days of age and decreased the feed-to-gain ratio slightly, whereas none of the other parameters were influenced by this treatment. An interaction between energy source and enzyme supplementation was not observed. It is concluded that feeding of coconut oil was most effective in terms of energy retention, but failed to induce an adequate performance under ad libitum feeding conditions due to a reduced voluntary feed intake. TOBEC measurements in relation to chemical body composition were rather inconclusive.

Serum lipoprotein cholesterol and triglyceride concentrations in pigs fed diets containing fish oil, milkfat, olive oil and coconut oil

Eight-week-old pigs (6 pigs per group) were fed diets containing either fish oil, milkfat, coconut oil, olive oil or cornstarch at an inclusion rate of 4% (w/w) for 3 weeks. Serum total cholesterol concentration was significantly higher in pigs fed coconut oil than in pigs fed cornstarch or fish oil ( p < 0.05). Pigs fed coconut oil, olive oil and milkfat had a significantly higher HDL cholesterol concentration than those fed cornstarch or fish oil. There were no significant differences in LDL cholesterol concentrations between groups. The serum triglyceride concentrations were higher in pigs receiving coconut oil and milkfat. This study showed that dietary fats that have a hypercholesterolaemic effect in humans tended to raise HDL cholesterol rather than LDL cholesterol concentrations in pigs. These findings suggest differences in lipoprotein metabolism between humans and pigs and caution is warranted when making inferences about human lipoprotein metabolism from porcine studies.

Serum Aminopeptidase A Activity of Mice Is Related to Dietary Fat Saturation

A high intake of monounsaturated fat has been proposed to be a dietary factor that can decrease the incidence of cardiovascular disease and hypertension. In addition, increasing dietary fat saturation has been shown to increase plasma total cholesterol and elevate systolic and diastolic blood pressures. We demonstrated previously that cholesterol selectively increases in vitro aminopeptidase A activity, which is related to angiotensin metabolism. In this study, we investigated the effect of different degrees of dietary fatty acid saturation on serum aminopeptidase activities in vivo. Serum total cholesterol concentrations were also measured. Five groups of male Balb/C mice were fed for 10 wk diets containing 2.4 g/100 g of sunflower oil, fish oil, olive oil, lard or coconut oil. We measured alanyl-, arginyl-, cystinyl-, pyroglutamyl-, aspartyl- and glutamyl-specific aminopeptidase activities using arylamides as substrates. Serum total cholesterol levels were higher in mice fed diets containing saturated oils (lard and coconut) than in those consuming sunflower oil, which is unsaturated. Two of the serum aminopeptidase A activities (aspartyl and glutamyl aminopeptidase) increased progressively with the degree of saturation of the dietary fatty acids; activities were significantly greater in mice fed coconut oil than in those fed sunflower or fish oil. Therefore, the substrates hydrolyzed by this activity as well as their functions may be similarly affected. These results may have some implication for the treatment of cardiovascular disease.

Dietary fatty acids influence the production of Th1- but not Th2-type cytokines

C57B16 mice were fed for 6 weeks on a low-fat diet or on high-fat diets containing coconut oil (rich in saturated fatty acids), safflower oil [rich in n-6 polyunsaturated fatty acids (PUFAs)], or fish oil (rich in n-3 PUFAs) as the main fat sources. The fatty acid composition of the spleen lymphocytes was influenced by that of the diet fed. Thymidine incorporation into concanavalin A-stimulated spleen lymphocytes and interleukin (IL)-2 production were highest after feeding the coconut oil diet. Interferon (IFN)-gamma production was decreased by safflower oil or fish oil feeding. IL-4 production was not significantly affected by diet, although production was lowest by lymphocytes from fish oil-fed mice. The ratio of production of Th1- to Th2-type cytokines (determined as the IFN-gamma/IL-4 ratio) was lower for lymphocytes from mice fed the safflower oil or fish oil diets. After 4 h of culture, IL-2 mRNA levels were higher in cells from mice fed coconut oil, and IFN-gamma mRNA levels were higher in cells from mice fed coconut oil or safflower oil. After 8 h of culture, IL-2, IFN-gamma, and IL-4 mRNA levels were lowest in cells from mice fed fish oil. The ratio of the relative levels of IFN-gamma mRNA to IL-4 mRNA was highest in cells from mice fed coconut oil and was lowest in cells of mice fed fish oil. The influence of individual fatty acids on IL-2 production by murine spleen lymphocytes was examined in vitro. Although all fatty acids decreased IL-2 production in a concentration-dependent manner, saturated fatty acids were the least potent and n-3 PUFAs the most potent inhibitors, with n-6 PUFAs falling in between in terms of potency. It is concluded that saturated fatty acids have minimal effects on cytokine production. In contrast, PUFAs act to inhibit production of Th1-type cytokines with little effect on Th2-type cytokines; n-3 PUFAs are particularly potent. The effects of fatty acids on cytokine production appear to be exerted at the level of gene expression.

Menhaden oil feeding increases lipolysis without changing plasma membrane order in isolated rat adipocytes

Alterations in dietary fatty acid composition can influence the regulation of metabolism in adipose tissue. To study the effect of dietary fatty acid composition on lipolysis we fed rats diets containing menhaden oil (MO) or coconut oil (CO) for 4 weeks. After 4 weeks on the diets body weight was similar in both groups although epididymal, retroperitoneal and mesenteric fat pad masses were significantly elevated (∼30%) in rats fed the CO diet. Epinephrine-stimulated lipolysis was elevated at concentrations >1M in epididymal adipocytes isolated from the MO group. The addition of insulin (10nM) to 1M epinephrine decreased lipolysis to a similar level in both groups. Plasma membrane fatty acid composition was altered to reflect the respective diets. Membranes from the CO fed group were enriched in saturated fatty acids (C10–16) and 18:1n9 and devoid of long chain n3 fatty acids compared to the MO fed group. To examine the effect of altered plasma membrane fatty acid composition on membrane physical properties we used Fourier transform infrared spectroscopy (FTIR). Membrane order was determined in adipocyte plasma membranes from −20°C to +58°C. Peak CH 2 symmetric and asymmetric stretching frequencies indicated that below 31°C membrane order is increased in CO fed animals. When temperature was increased above 31°C, there were no differences in membrane order between groups. The results of this study suggest that membrane order is not responsible for the lower rate of lipolysis in animals fed coconut oil when both variables are measured at 37°C.

Elevated hepatic apolipoprotein A-I transcription is associated with diet-induced hyperalphalipoproteinemia in rabbits

Past studies have shown that a high saturated fatty acid diet containing coconut oil elevates plasma HDL cholesterol and apolipoprotein A-I (apoA-1) in rabbits through a mechanism involving increased synthesis. We have extended those studies by investigating expression of the hepatic apolipoprotein A-I gene and other lipid related genes in that model. Rabbits fed a diet containing 14% coconut oil for 4 weeks showed HDL-C elevations of 170% to 250% over chowfed controls with peak differences occurring at 1 week. Plasma apoA-I levels were also increased over this time frame (160% to 180%) reflecting the HDL-C changes. After 4 weeks, there were no differences in plasma VLDL-C or LDL-C levels in chow versus coconut oil-fed rabbits. Hepatic levels of apoA-I mRNA in coconut oil-fed animals were elevated 150% after 4 weeks compared to chow-fed controls; hepatic mRNA levels for ten other genes either decreased slightly (apoB, LCAT, hepatic lipase, albumin, ACAT, and HMG CoA reductase) or were unchanged (CETP, apoE, LDL-receptor, and acyl CoA oxidase). Nuclear run-on transcription assays revealed that coconut oil feeding for 4 weeks caused a 220% increase in hepatic apoA-I transcription rate compared to controls; no change was observed for CETP and apoE. Treatment of cultured rabbit liver cells with various saturated fatty acids and sera from chow-fed and coconut oil-fed rabbits did not alter apoA-I mRNA levels as observed in vivo. These data demonstrate that coconut oil elevates plasma HDL-C and apoA-I by increasing hepatic apoA-I transcription while expression of other genes involved in lipid metabolism are reduced or unchanged in response to coconut oil feeding.

Zinc deficiency and the activities of lipoprotein lipase in plasma and tissues of rats force-fed diets with coconut oil or fish oil

The present study was performed to investigate the effect of zinc deficiency on the activities of lipoprotein lipase in postheparin serum and tissues of rats fed diets containing either coconut oil or fish oil as dietary fat, using a bifactorial experimental design. To ensure an adequate food intake, all the rats were force-fed by gastric tube. Experimental diets contained either 0.8 mg zinc/kg (zinc-deficient diets) or 40 mg zinc/kg (zinc-adequate diets). The effects of zinc deficiency on the activities of lipoprotein lipase in postheparin serum and postprandial triglyceride concentrations and distribution of apolipoproteins in serum lipoproteins depended on the type of dietary fat. Zinc-deficient rats fed the coconut oil diet exhibited a reduced activity of lipoprotein lipase in postheparin serum and adipose tissue, markedly increased concentrations of triglycerides in serum, and a markedly reduced content of apolipoprotein C in triglyceride-rich lipoproteins and high density lipoproteins compared with zinc-adequate rats fed coconut oil. By contrast, zinc-deficient rats fed the fish oil diet did not exhibit reduced activities of lipoprotein lipase in postheparin serum and adipose tissue and increased concentrations of serum lipids compared with zinc-adequate rats fed the fish oil diet. This study suggests that a reduced activity of lipoprotein lipase might contribute to increased postprandial concentrations of serum triglycerides observed in zinc-deficient animals. However, it also demonstrates that the effects of zinc deficiency on lipoprotein metabolism are influenced by dietary fatty acids.

Dietary fats affect macrophage-mediated cytotoxicity towards tumour cells.

In the present study, the effects of feeding mice diets of different fatty acid compositions on the production of TNF-alpha and nitric oxide by lipopolysaccharide-stimulated peritoneal macrophages and on macrophage-mediated cytotoxicity towards L929 and P815 cells were investigated. C57Bl6 mice were fed on a low-fat (LF) diet or on high-fat diets (21% fat by weight), which included coconut oil (CO), olive oil (OO), safflower oil (SO) or fish oil (FO) as the principal fat source. The fatty acid composition of the macrophages was markedly influenced by that of the diet fed. Lipopolysaccharide (LPS)-stimulated macrophages from FO-fed mice showed significantly lower production (up to 80%) of PGE2 than those from mice fed on each of the other diets. There was a significant positive linear correlation between the proportion of arachidonic acid in macrophage lipids and the ability of macrophages, to produce PGE2. Lipopolysaccharide-stimulated TNF-alpha production by macrophages decreased with increasing unsaturated fatty acid content of the diet (i.e. FO < SO < OO < CO < LF). Macrophages from FO-fed mice showed significantly lower production of TNF-alpha than those from mice fed on each of the other diets. Nitrite production was highest for LPS-stimulated macrophages from mice fed on the LF diet. Macrophages from FO-fed mice showed significantly higher production of nitrite than those from mice fed on the OO and SO diets. Compared with feeding the LF diet, feeding the CO, OO or SO diets significantly decreased macrophage- mediated killing of P815 cells (killed by nitric oxide). Fish oil feeding did not alter killing of P815 cells by macrophages, compared with feeding the LF diet; killing of P815 cells was greater after FO feeding than after feeding the other high fat diets. Compared with feeding the LF diet, feeding the OO or SO diets significantly decreased macrophage-mediated killing of L929 cells (killed by TNF). Coconut oil or FO feeding did not alter killing of L929 cells by macrophages, compared with feeding the LF diet. It is concluded that the type of fat in the diet affects macrophage composition and alters the ability of macrophages to produce cytotoxic and immunoregulatory mediators and to kill target tumour cells.

Fish oil reduces cholesterol and arachidonic acid levels in plasma and lipoproteins from hypercholesterolemic chicks.

The value of fish oil for prevention and/or treatment of human atherosclerosis has not been fully established. This study shows that replacement of saturated fat in young chick diet with menhaden oil produced a significant reversion of the hypercholesterolemia previously induced by coconut oil feeding. Fish oil also produced a clear decrease of plasma triacylglycerol levels. Coconut oil increased the percentages of 12:0 and 14:0 fatty acids, while menhaden oil increased those of 20:5 n-3 and 22:6 n-3. Percentages of 20:4 n-6, 18:2 n-6 and 18:1 n-9 significantly decreased by fish oil addition to the diet. Total cholesterol, phospholipid and protein contents of high and low density lipoproteins increased by coconut oil feeding. When coconut oil was replaced by menhaden oil, total cholesterol was significantly reduced in high, low and very low density lipoproteins. All chemical components of VLDL were decreased by menhaden oil feeding. Our results show a strong hypocholesterolemic effect of menhaden oil when this fat was supplemented to hypercholesterolemic chicks. The clear decrease found in arachidonic acid content of chick plasma and lipoproteins may contribute to the beneficial effects of fish oil consumption by lowering the production of its derived eicosanoids.

Dietary n-3 fatty acids, curcumin and capsaicin lower the release of lysosomal enzymes and eicosanoids in rat peritoneal macrophages.

Male Wistar rats (12 rats/group) were fed a diet containing 8 wt % coconut oil or groundnut oil or cod-liver oil for a total period of 8 weeks. The diets were also supplemented with 2 wt % groundnut oil for providing essential fatty acids. During the last 2 weeks, 6 rats form each group were additionally given curcumin (30 mg/kg body wt/day) or capsaicin (5 mg/kg body wt/day) in 1 ml groundnut oil. The peritoneal macrophages from rats fed cod-liver oil diet secreted lower levels of lysosomal enzymes collagenase, elastase and hyaluronidase as compared to those from rats fed coconut oil or groundnut oil diets. Curcumin and capsaicin significantly lowered the secretion of these lysosomal enzymes from macrophages in animals given coconut oil or groundnut oil diet. Macrophages from rats fed cod-liver oil secreted lower amounts of prostaglandin E2, 6-keto PGF1alpha, leukotrienes B4 and C4 and also incorporated lesser amounts of [3H]-arachidonic acid as compared to those given coconut oil or groundnut oil diets. Curcumin and capsaicin lowered the secretion of these eicosanoids and decreased the incorporation of [3H]-arachidonic acid in macrophage lipids. However curcumin and capsaicin significantly increased the secretion of 6-keto PGF1alpha in all the groups of animals. These studies indicated that dietary cod-liver oil (rich in n-3 fatty acids), and spice principles curcumin and capsaicin can lower the secretory functions of macrophages in a beneficial manner.

Differential effects of dietary fat on chick plasma and liver composition and HMG-CoA reductase activity

The comparative effects of diet supplementation with 10% saturated fat rich in 12:0 and 14:0 fatty acids (coconut oil), without and with 1% added cholesterol, and with 10% unsaturated fat rich in n-3 polyunsaturated fatty acids (menhaden oil) on cholesterol metabolism in neonatal chicks were examined to clarify the different mechanisms of their hyper- and hypolipidemic action. Supplementation of coconut oil produced a significant hypercholesterolemia after 7 days of treatment, with a similar increase in the amount of both free and esterified cholesterol. Supplementation of coconut oil plus cholesterol produced a higher increase of plasma cholesterol levels (approximately two to three times higher than those found with standard diet). However, supplementation of menhaden oil induced a significant decrease in total cholesterol after only 2 weeks of treatment. Levels of plasma triglycerides did not change by coconut oil addition to the diet, but a significant increase was observed after coconut oil plus cholesterol feeding. Menhaden oil produced a transient decrease in plasma triglycerides. Hepatic 3-hydroxy-3-methylglutaryl-CoA reductase activity did not change with coconut oil treatment. However, both coconut oil plus cholesterol and menhaden oil supplemented diets drastically decreased reductase activity after 1 week of dietary manipulation. These results show that different nutrients with the same inhibitory effect on reductase activity produced opposite effects on plasma cholesterol content, suggesting the existence of important differences in the regulatory mechanisms implied in cholesterol biosynthesis and its accumulation in plasma.

Cholesterol and triglyceride reduction in rats fed Matthiola incana seed oil rich in (n-3) fatty acids.

Seeds of Matthiola incana contain oil rich (55-65%) in (n-3) linolenic acid. Selected lines were developed and evaluated for their agronomic and chemical parameters. Extracted oil was fed for 6 weeks to rats, which were compared with rats fed a diet containing coconut oil or sunflower oil. Cholesterol levels were significantly lowest in rats fed diets rich in M. incana oil (27% reduction), and triglycerides were significantly lower in rats receiving either M. incana or sunflower oil (36% reduction). The contents of arachidonic acid and other (n-6) fatty acids were significantly the lowest in the liver and plasma of rats that had received M. incana oil. The levels of (n-3) fatty acids were significantly greater in both the liver and plasma of rats fed M. incana oil. The ratio of (n-3)/(n-6) long-chain fatty acids in the plasma was 7 times higher in rats fed with M. incana oil than in those fed with sunflower oil and 6 times higher than in those fed coconut oil. The results demonstrate for the first time a beneficial effect of dietary M. incana oil in reducing cholesterol levels and increasing (n-3) fatty acid levels in the plasma. This new, terrestrial plant source of (n-3) fatty acids could replace marine oils and thereby contribute beneficially to the human diet.

Production of a rapid hypercholesterolemia in young chick by feeding coconut oil from two different sources and fatty acid composition

In this work, we have studied comparatively the effects of supplementation to a standard diet with the same proportion (20%) of saturated fat (coconut oil) from two different commercial sources and with clear differences in their fatty acid composition. Both experimental diets produced a rapid (24 h) and significant hypercholesterolemia in 14-day-old chicks. However, plasma cholesterol levels were higher in animals fed a diet supplemented with coconut oil for commercial cooking use (“Pastry”) than in those fed a diet with coconut oil for pharmaceutical use (“Pharmacy”). Both dietary manipulations rapidly (24 h) increased the percentages of the more hypercholesterolemic fatty acids (12:0 and 14:0) in plasma. This increase was higher after “Pastry” than after “Pharmacy” diet feeding. Likewise, the percentages of the hypocholesterolemic fatty acids (18:1 n-9 and 18:2 n-6) were lower in plasma from treated animals than in control, especially after feeding the “Pastry” diet. All these differences may be implied in the high hypercholesterolemic effects showed by “Pastry” diet. The hyper-cholesterolemia was not accompanied by changes in the levels of liver cholesterol.

Coconut kernel protein modifies the effect of coconut oil on serum lipids.

Feeding coconut kernel along with coconut oil in human volunteers has been found to reduce serum total and LDL cholesterol when compared to feeding coconut oil alone. This effect of the kernel was also observed in rats. Since many plant proteins have been reported to exert a cholesterol lowering effect, a study was carried out on the effect of isolated kernel protein in rats. Feeding kernel protein resulted in lower levels of cholesterol, phospholipids and triglycerides in the serum and most tissues when compared to casein fed animals. Rats fed kernel protein had (1) increased hepatic degradation of cholesterol to bile acids, (2) increased hepatic cholesterol biosynthesis, and (3) decreased esterification of free cholesterol. In the intestine, however, cholesterogenesis was decreased. The kernel protein also caused decreased lipogenesis in the liver and intestine. This beneficial effect of the kernel protein is attributed to its very low lysine/arginine ratio 2.13% lysine and 24.5% arginine.