The effects of feeding conjugated linoleic acid (CLA) on rat growth performance,serum lipoproteins and subsequent lipid composition of selected rat tissues

Four groups of 12 albino rats (six males and six females), at 4 weeks of age, were fed for 60 days a semi‐synthetic diet containing graded amounts of conjugated linoleic acid (CLA; 0.0, 0.5, 1.0 and 1.5%) to determine its effect on growth performance and serum lipoprotein profiles and its incorporation into abdominal and muscle lipids. Rats fed CLA responded by significantly improved body mass gains; however, this effect was observed only with the 1.0% CLA‐supplemented diet. It was also true for feed conversion efficiency. The changes in serum total cholesterol (TC) and HDL cholesterol concentrations were insignificant and showed an opposite pattern. However, the resulting HDL cholesterol/TC ratio was significantly (P ≤ 0.01) increased. At the same time, serum triacylglycerol (TAG) concentrations were significantly (P ≤ 0.01) elevated, thus counteracting the potential antiatherogenicity of the improved HDL cholesterol/TC ratio. Feeding CLA to rats resulted in its substantial incorporation into both abdominal and muscle lipids. Generally, tissue lipids were enriched with CLA at the expense of long‐chain polyunsaturated fatty acids, eg linoleate and arachidonate. This effect is likely to correspond with reduction of arachidonate‐derived eicosanoid synthesis. These data together suggest that CLA has a potent effect on lipid transport and metabolism in rats. Also, they confirm the potential of nutritional methods to provide CLA‐enriched functional animal products, especially meat, for human consumption. © 2000 Society of Chemical Industry     

膳食蛋白质与大鼠脂质代谢关系的研究

通过给予SD种Ⅱ级雄性大鼠4种不同蛋白质的高脂合成饲料,研究不同来源膳食蛋白质对脂质代谢的影响及其机理探讨。结果显示,大豆蛋白组和谷豆混合蛋白组血清TC、LDL-C、(VLDL-C+LDL-C)/TC明显低于酪蛋白组(P＜0.05),而血清HDL-C、HDL-C/TC明显高于酪蛋白组(P＜0.05)。谷类蛋白组LDL-C也明显低于酪蛋白组(P＜0.05),HDL-C明显高于酪蛋白组(P＜.05)。谷类蛋白与大豆蛋白混合后,其生物利用率提高,调节血脂的作用增强。提示大豆蛋白尤其谷豆混合蛋白有预防AS形成作用。     

A meta-analysis of randomized, double-blind, placebo-controlled trials for the effects of garlic on serum lipid profiles

BACKGROUND: Inconsistent results were obtained for the lipid‐regulating effects of garlic in clinical trials. With increasing interest in complementary medicine for hyperlipoidemia, it is important to explore the real effects of garlic. This meta‐ analysis was performed to investigate the influence of garlic on serum lipid parameters. RESULTS: A total of 26 studies were included into meta‐analysis. Overall, garlic was superior to placebo in reducing serum total cholesterol (TC) and triglyceride (TG) levels. Compared with the placebo groups, serum TC and TG levels in the garlic group were reduced by 0.28 (95% CI, ? 0.45, ? 0.11) mmol L^?1 (P = 0.001) and 0.13 (95% CI, ? 0.20, ? 0.06) mmol L^?1 (P < 0.001), respectively. The effects of garlic were more striking in subjects with long‐term intervention and higher baseline TC levels. Garlic powder and aged garlic extract were more effective in reducing serum TC levels, while garlic oil was more effective in lowering serum TG levels. In contrast, garlic did not influence other lipid parameters, including low‐density lipoprotein cholesterol, high‐density lipoprotein cholesterol (HDL‐C), apolipoprotein B, and TC/HDL‐C ratio. CONCLUSION: Garlic could reduce serum TC and TG levels, and garlic therapy should benefit patients with risk of cardiovascular diseases. Copyright © 2012 Society of Chemical Industry     

Effects of defatted dried roselle (Hibiscus sabdariffa L.) seed powder on lipid profiles of hypercholesterolemia rats

BACKGROUND: In vivo investigations were made of the effect of defatted dried roselle seed powder (DRS) on the lipid profiles of rats with induced hypercholesterolemia. The two‐batch sample consisted of 23 and 20 Sprague‐Dawley male rats randomly divided into four groups and fed with four different diets. The first batch of rats was fed with normal, hypercholesterol, hypercholesterol + 10 g kg^?1 (w/w) DRS and hypercholesterol + 20 g kg^?1 (w/w) DRS diets. The second batch of rats was fed with normal, hypercholesterol, hypercholesterol + 50 g kg^?1 (w/w) DRS and hypercholesterol + 150 g kg^?1 (w/w) DRS diets. Treatments were given for a total of 5 weeks. RESULTS: Results indicated that the addition of 10 g kg^?1 and 20 g kg^?1 of DRS did not significantly lower the plasma total cholesterol (TC) levels. In contrast, 50 g kg^?1 and 150g kg^?1 DRS significantly lowered (P < 0.05) the TC and low density lipoprotein cholesterol (LDL‐C) levels. CONCLUSION: The addition of 50 g kg^?1 and 150 g kg^?1 DRS showed potential hypocholesterolemic effects. Furthermore, these findings indicated that protein, lipid and dietary fibre were high in the seed powder. Copyright © 2008 Society of Chemical Industry     

Inhibitory effects of Hibiscus sabdariffa L extract on low‐density lipoprotein oxidation and anti‐hyperlipidemia in fructose‐fed and cholesterol‐fed rats

Hibiscus sabdariffa L extract (HSE) is an aqueous extract of Hibiscus sabdariffa L flowers that is used as a local soft drink and medical herb in Taiwan. Oxidation of low‐density lipoprotein (LDL) has been shown to increase the incidence of atherosclerosis. In this study, we determined the antioxidative activity of HSE on LDL oxidation by examining relative electrophoretic mobilities (REM) and thiobarbituric acid‐reactive substances (TBARS). The data revealed an inhibitory effect of HSE on Cu²⁺‐mediated REM and TBARS. HSE exhibited a remarkable ability to reduce cholesterol degradation and ApoB fragmentation. Overall, HSE showed a high potency to inhibit the production of oxidized LDL induced by copper and, specifically, to reduce serum triglycerides in high‐fructose diet (HFD) fed rats and serum cholesterol in high‐cholesterol diet (HCD) fed animals. The levels of LDL and the ratio of LDL‐cholesterol (LDL‐C) to HDL‐cholesterol (HDL‐C) were reduced by HSE in both hyperlipidaemia models. Based on these findings, we suggest that HSE may be used to inhibit LDL oxidation and to prevent various types of hyperlipidaemia in HFD‐ or HCD‐fed rats. Copyright © 2004 Society of Chemical Industry     

Dietary calcium decreases plasma cholesterol by down‐regulation of intestinal Niemann–Pick C1 like 1 and microsomal triacylglycerol transport protein and up‐regulation of CYP7A1 and ABCG 5/8 in hamsters

Scope: It has been shown that calcium supplementation favorably modifies plasma lipoprotein profile in postmenopausal women. The present study investigated the interaction of dietary calcium with genes of transporters, receptors and enzymes involved in cholesterol metabolism. Methods and results: Forty‐eight ovariectomized hamsters were fed one of the four diets containing 0, 2, 6 and 8 g calcium per kg. Plasma total cholesterol (TC), triacylglycerols (TG), and non‐high density lipoprotein cholesterol were dose‐dependently decreased, whereas high‐density lipoprotein cholesterol (HDL‐C) was dose‐dependently increased with the increasing dietary calcium levels. Dietary calcium had no effect on protein mass of hepatic sterol regulatory element binding protein‐2 (SREBP), liver X receptor‐alpha (LXR), 3‐hydroxy‐3‐methylglutaryl‐CoA reductase (HMGR), LDL receptor (LDLR) and cholesterol‐7α‐hydroxylase (CYP7A1). However, dietary calcium up‐regulated the mRNA levels of hepatic CYP7A1 and intestinal ATP binding cassette transporters (ABCG5/8) whereas it down‐regulated the intestinal Niemann‐Pick C1 like 1 (NPC1L1) and microsomal triacylglycerol transport protein (MTP). In addition, dietary calcium increased the activity of intestinal acyl coenzyme A: cholesterol acyltransferase 2, while it decreased plasma cholesteryl ester transport protein (CETP). Conclusion: Beneficial modification of lipoprotein profile by dietary calcium was mediated by sequestering bile acid absorption and enhancing excretion of fecal cholesterol, via up‐regulation of mRNA CYP7A1 and intestinal ABCG 5/8 with down‐regulation of mRNA NPC1L1 and MTP.     

Healthy aspect of low‐cholesterol ghee on modulation of lipid profile of rats

Low‐cholesterol ghee (LCG) feeding did not show any significant increase in total plasma cholesterol level from day 0 (56.8 ± 6.8 mg/dL) to day 90 (59.5 ± 0.8 mg/dL). Plasma HDL cholesterol (HDL) levels increased by 59.9%, whereas LDL cholesterol (LDL) showed a reduction of 74.8%. Total plasma triacylglycerol (mg/dL) did not show any significant change within or between groups. Relative contribution of lipoprotein fraction HDL was 69% vs 47% in control. Atherogenic Index was low (0.47 ± 0.05) vs 1.03 ± 0.2 in the control. Deposition of cholesterol in arteries and liver was also less (0.423 mg/g tissue) than in control (0.648 mg/g tissue). Feeding LCG improved the lipid profile of rats.     

The Role of Dietary Cholesterol in Lipoprotein Metabolism and Related Metabolic Abnormalities: A Mini-review

Cholesterol plays a vital role in cell biology. Dietary cholesterol or “exogenous” cholesterol accounts for approximately one-third of the pooled body cholesterol, and the remaining 70% is synthesized in the body (endogenous cholesterol). Increased dietary cholesterol intake may result in increased serum cholesterol in some individuals, while other subjects may not respond to dietary cholesterol. However, diet-increased serum cholesterol levels do not increase the low-density lipoprotein/high-density lipoprotein (LDL/HDL) cholesterol ratio, nor do they decrease the size of LDL particles or HDL cholesterol levels. Elevated levels of LDL cholesterol, reduced HDL cholesterol levels, and small, dense LDL particles are independent risk factors for coronary artery disease. Dietary cholesterol is the primary approach for treatment of conditions such as the Smith–Lemli–Opitz syndrome. Recent studies have highlighted mechanisms for absorption of dietary cholesterol. These studies have help understand how dietary and/or pharmaceutical agents inhibit cholesterol absorption and thereby reduce LDL cholesterol concentrations. In this article, various aspects of cholesterol metabolism, including dietary sources, absorption, and abnormalities in cholesterol metabolism, have been summarized and discussed.     

Choosing hamsters but not rats as a model for studying plasma cholesterol‐lowering activity of functional foods

Rats and hamsters are commonly used rodents to test the efficacy of cholesterol‐lowering functional foods. In general, a diet containing 1% cholesterol for rats whereas a diet containing 0.1% cholesterol for hamsters is used to induce the hypercholesterolemia. The present study was carried out to compare hamsters with rats as a hypercholesterolemia model. Golden Syrian hamsters and Sprague Dawley rats were randomly divided into four groups and fed one of the four diets containing 0–0.9% cholesterol. Results demonstrated that serum total cholesterol (TC) in hamsters was raised 73–81% higher than that in rats fed the same cholesterol diets. Unlike rats in which HDL‐C accounted very little for serum TC, the lipoprotein profile in hamsters was closer to that in humans. We investigated interaction of higher cholesterol diets with 3‐hydroxy‐3‐methylglutary‐CoA (HMG‐CoA) reductase, low‐density lipoprotein receptor (LDL‐R) and cholesterol‐7α‐hydroxylase (CYP7A1), sterol regulatory element binding protein‐2 (SREBP‐2), and liver X receptor (LXR‐α). Results showed hamsters and rats metabolized cholesterol differently. In view that hamsters synthesize and excrete cholesterol and bile acids in a manner similar to that in humans, it is concluded that hamsters but not rats shall be chosen as a model to study efficacy of cholesterol‐lowering functional foods.     

Hypocholesterolemic Action of Fermented Brown Rice Supplement in Cholesterol-Fed Rats: Cholesterol-lowering Action of Fermented Brown Rice

Fermented rice products have been implicated in vascular injury and atherosclerosis in recent animal and human studies. In the current study, whether consumption of differently processed brown rice diets may change the cholesterol metabolism was evaluated in male Spraque Dawley (SD) rats after 28 d of treatment with diets containing 1% cholesterol. The experimental diets include corn starch alone as control diet (CO) or a diet containing a 50% substitute of CO; uncooked brown rice (UB), cooked brown rice (CB), lactic acid bacteria (LAB), brown rice mixed with LAB (BLAB), and fermented‐brown rice by LAB (FB), respectively. Among them, FB group elicited significantly lower levels of plasma and hepatic triglycerides, plasma total cholesterol, low‐density lipoprotein cholesterol (LDL‐C), and very low‐density lipoprotein cholesterol (VLDL‐C) by 33% to 50%, whereas higher levels of HDL‐C were elicited by 227% compared with the CO group (P < 0.05). These amelioration action on lipid profile in FB group appeared to correspondent to the higher excretions of fecal weight, triglyceride (TG), total cholesterol (TC), and bile acid (P < 0.05). Furthermore, sensory properties such as flavor liking, taste liking, and overall acceptability of the diet were significantly improved by the addition of fermented brown rice. Conclusively, fermented‐brown rice may have a potent cholesterol‐lowering benefits with sensory quality improvement of the diet.     

低聚果糖降血脂作用的动物研究

为探讨低聚果糖对高脂动物血脂的影响,以高脂饲料诱发大鼠为高脂动物模型,同时给予高脂饲料与低聚果糖28d后,与高脂模型组比较.0.5、1.5、2.5g/kgBW低聚果糖可显著降低大鼠血清总胆固醇(TC)和甘油三脂(TG)的水平(P＜0.05);但对高密度脂蛋白胆固醇(HDL-C)的水平无显著影响.结果表明低聚果糖可降低高脂动物血脂水平.     

Plant starches and oils. Their influence on digestion in rats

The purpose of the present study was to determine the interaction effect of starch and fat of such products over blood parameters (cholesterol, triglycerides), and to evaluate starch and fat digestibility. Experiments were carried out in eight groups of Sprague-Dawley rats that were under the following diets: four of the groups were fed with a mix of 14% palm oil and 58% of each one of the starches (rice, corn, manioc and green plantain); the other four groups were fed a mix of 14% of corn oil and 58% of each one of the same starches under study. No significant differences were found in liver weight or fat digestibility among the groups of study. Significant differences were found on the starches digestibility, the green plantain starch being the one with the lowest digestibility (83–97%). The statistical differences showed an interaction between the starch and oil that affects the starch present in faeces and the starch digestibility. The evaluation of the blood parameters (cholesterol and triglycerides) showed significant differences when different starches were fed, but no so, when oils were changed. Animals that were fed manioc starch showed a higher concentration of cholesterol and triglycerides (244–150 mg dl⁻¹), while animals that ingested green plantain starch showed the lowest concentration (93–150 mg dl⁻¹). Our results suggest that the levels of cholesterol in rats was probably influenced by the digestibility of the starches present on the diet. The statistical analysis showed a high interaction starch vs oil over plasmatic triglycerides concentration. The green plantain starch has the same effect as some of the resistant starches. © 1998 SCI.     

The effect of leaf protein concentrate from red clover on plasma cholesterol level in rats

The effect of native and defatted leaf protein concentrate (LPC) from red clover on plasma cholesterol level in rats was studied. Fat-free casein was used as a control protein. The native LPC contained 212 g kg^?1 of ether extract and oleic acid (C_{18: 1}) was its main fatty acid. LPC protein was relatively poor in sulphur-containing amino acids. Each protein studied was given to rats with or without soya bean oil. It was found that total cholesterol level in plasma of rats fed with the oil-containing diets was higher than that of rats fed with the oil-free diets. Original fat present in the native LPC though rich in unsaturated fatty acids had no hypocholesterolaemic effect. LPC was hypocholesterolaemic compared with casein in diets not containing added soya bean oil, although the difference did not reach statistical significance.     

藻油及其与火麻仁油混合物辅助降血脂功能

研究了藻油及其与火麻仁油混合物的辅助降血脂作用。将84只SPF级雄性SD大鼠分为7组,其中6组喂养高脂高胆固醇饲料2周以建立高脂血症模型,造模成功后即进行4周干预实验,阴性对照组与模型组给予0.85％生理盐水,药物组每日灌胃3.33 mg/kg立普妥,混合物组每日灌胃800 mg/kg藻油混合物,藻油干预组每日分别灌胃150、300、600 mg/kg藻油。实验过程记录大鼠的体重、进食量与饮水量,实验结束后采集大鼠的血液、附睾脂肪、肝脏,检测大鼠的血脂四项血清总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白胆固醇(HDL-C)及低密度脂蛋白胆固醇(LDL-C),并进行肝脏与附睾脂肪病理检测。结果表明：造模后高脂血症大鼠的TC、TG、LDL-C水平显著上升;中、高剂量藻油及其混合物均可使大鼠血清TC（混合物除外）、TG、LDL-C水平显著降低,藻油呈现剂量依赖;藻油及其混合物干预后大鼠肝脏中含脂滴的肝细胞和多灶性泡沫细胞聚集例数减少。说明藻油及其混合物对高脂高胆固醇饮食导致的肝细胞脂肪变性、脂肪堆积有一定改善作用,藻油及其混合物均有辅助降血脂作用。     

Technical note: Characterization of ceramide in bovine lipoproteins

The hepatic synthesis and export of ceramide is enhanced in diabetic monogastrics. Moreover, ceramide in lipoproteins can mediate the development of insulin resistance. We have previously demonstrated that circulating ceramide increases during the progression of insulin resistance in postpartum dairy cows. Considering that the origins of circulating ceramide required investigation, our objective was to develop a method to characterize the ceramide profile of lipoprotein fractions collected from dairy cows. Serum was collected from 4 nonpregnant and nonlactating Holstein dairy cows. Serum lipoproteins were isolated using size exclusion chromatography by fast protein liquid chromatography (SEC-FPLC). Measurement of triacylglycerol (TAG), phospholipid, total cholesterol, and protein was performed using standard colorimetry practices. Following lipid extraction, fractions were analyzed using electrospray ionization tandem mass spectrometry. Data were analyzed as repeated measures using a mixed model. Lipoprotein isolation using SEC-FPLC and subsequent colorimetric analyses confirmed the presence of 4 distinct fractions: TAG-rich, low density (LDL), and large (buoyant) and small (dense) high density lipoprotein (HDL) subclasses. As expected, the fraction representing mixed very low density lipoproteins and chylomicrons primarily contained TAG. Low density lipoprotein fractions were equally enriched with cholesterol and phospholipid. Buoyant HDL contained elevated levels of cholesterol, phospholipid, and protein. In contrast, the fraction containing dense HDL primarily contained protein. Our method revealed that LDL are enriched with ceramides. Ceramides were also compartmentalized to a lesser extent within both HDL subclasses and TAG-rich lipoproteins. Comparable to whole serum, C16:0-ceramide was the predominant ceramide quantified in all lipoprotein subclasses. Interestingly, the proportion of C24:0-ceramide to total ceramide was elevated in TAG-rich lipoproteins, relative to all other lipoprotein subclasses. We conclude that SEC-FPLC coupled with mass spectrometry is a means to quantify ceramides in lipoprotein fractions. Moreover, ceramides are enriched within bovine LDL, and lipoprotein ceramide profiles reflect levels observed in whole serum. Future investigation will need to determine the biological importance of lipoprotein ceramides with distinct C-chains at amide residues.     

Dietetic and hypocholesterolaemic action of black soy peptide in dietary obese rats

To investigate the effect of peptides from black soy (rat's eye) bean (Rhynchosia volubilis Lour.) on weight gain and lipid composition, Sprague–Dawley male rats were fed either a black soy peptide (BSP; 2, 6 or 10% of energy)‐containing diet or a casein control diet (20% of energy) enriched with 36% fat and 1% cholesterol for 28 days. Compared with the casein group, the BSP groups showed significant attenuation of body, liver and epididymal adipose tissue weight gains (P < 0.05). Moreover, rats that consumed BSP had a lower total cholesterol concentration and low‐density lipoprotein/high‐density lipoprotein (LDL/HDL) ratio in serum and a lower level of hepatic triglycerides as well as higher excretion of faeces compared with those fed only casein (P < 0.05). Molecular weights of peptides from black soy were mainly below 10 kDa, and Arg/Lys and Gly/Met ratios in BSP were five and three times of those in casein respectively. It is concluded that BSP can be a potent nutraceutical component for anti‐obesity and hypolipidaemic benefits. Copyright © 2007 Society of Chemical Industry     

Effects of dietary fibre‐ and polyphenol‐rich grape products on lipidaemia and nutritional parameters in rats

The aim of this work was to evaluate the effects of three dietary fibre‐ and polyphenol‐rich materials obtained from grapes on serum cholesterol, lipoprotein and triglyceride concentrations as well as on body weight, fat and protein digestibility in adult Wistar rats fed on cholesterol‐free and 10 g kg⁻¹ cholesterol‐added diets. Dietary fibre content of materials ranged from 540 to 590 g kg⁻¹. Intake of grape products increased stool weight and the amount of fat and protein excreted in faeces, but did not affect negatively animal growth or protein efficiency of the diet in Wistar rats. Studied grape fractions lower serum total cholesterol and LDL cholesterol concentrations in hypercholesterolemic rats. These results could be taken into account in potential applications of these products as a food ingredient. © 2000 Society of Chemical Industry     

Dietary effects on growth,plasma lipid and tissues of rats fed with non‐conventional oil of Telfairia occidentalis

The nutritional value of Telfairia occidentalis seed and seed oil available in local market was studied in rats. The average values of the proximate analysis on dry matter basis were 203 g kg^?1 crude protein, 536.3 g kg^?1 fat, 39 g kg^?1 ash, 95 g kg^?1 crude fibre and 43.7 g kg^?1 carbohydrate, while the moisture content was 75 g kg^?1. The mineral analyses showed that T occidentalis seeds contain potassium (3280 mg kg^?1), sodium (1230 mg kg^?1), magnesium (60.8 mg kg^?1), calcium (60.8 mg kg^?1) and iron (13.0 mg kg^?1). The oil extracted from the seed sample showed physicochemical properties that suggest its suitability for edible and industrial uses. The oil contained high levels of unsaturated fatty acids, oleic and linoleic, which accounted for 63.22% of total fatty acids recovered, while palmitic acid (27.4% of the oil by weight) was the most prevalent saturated fatty acid in the oil. No trace of eleostearic acid was detected in the oil. The effect on physical appearance, weight gain, organ weight, tissue and plasma cholesterol and triacylglycerol levels was determined in rats fed a diet containing 5% T occidentalis oil. These were compared with those of rats fed a control diet (0% T occidentalis oil) over an 8 week study period. Weekly monitoring of the rats showed good physical appearance and steady weight increase. The test rats were not anaemic and no mortality was recorded. While there was a significantly higher (p < 0.05) level of cholesterol in the heart of test rats compared with the control, there was a significantly lower (p < 0.05) plasma cholesterol level, suggesting that T occidentalis seed oil can be used to lower plasma levels of cholesterol. Histological examination of the sections of the heart, liver, kidney and spleen of the test rats revealed varying degrees of pathology. These include artherosclerotic changes in the walls of vasa vasori and lymphatics in the heart and hyaline degeneration of myofibrils, fatty infiltration of hepatocytes, and glomerular and tubular degeneration in the kidneys. These lesions may have been due to the effect of fatty acids, especially erucic acid, in the seed oil, which at 1.24% (less that the 5% conventional allowable limit for edible oils) may be intolerable for rats and may be unsuitable for human consumption. The seed oil may be used for industrial purposes such as soap making, lubrication and cosmetics for which it is well suited. Copyright © 2004 Society of Chemical Industry     

共轭亚油酸对小白鼠身体组成的影响

饲料中添加不同剂量共轭亚油酸喂养 4周龄小白鼠 4周。实验结果表明 ,血清中Chol、HDL和LDL含量的平均值随着共轭亚油酸添加量的增加而升高 ,而Chol/HDL的比值则几乎保持不变。饲料中添加 0 .5 %的共轭亚油酸对血清中甘三酯浓度影响不大 ,基本上类似于对照组的含量 ;当共轭亚油酸的添加量达到 1%时 ,与对照组间差异较大。共轭亚油酸对血清中免疫球蛋白含量影响不大。小白鼠身体水分和蛋白质含量分析结果表明 ,饲料中添加共轭亚油酸增加了水分和蛋白质含量。此外 ,共轭亚油酸能显著降低小白鼠身体的脂肪含量 ,这主要通过抑制LPL活性和增加肉碱棕榈酰转移酶活性来实现 ;同时通过抑制肝脏中硬脂酰辅酶A去饱和酶mRNA的表达来改变其脂肪酸组成。