Blood Lipid Responses Research Articles

The Modifying Effects of Galactomannan from Canadian-Grown Fenugreek (Trigonella foenum-graecum L.) on the Glycemic and Lipidemic Status in Rats.

Using high sucrose-fed male Sprague-Dawley rats, a study was conducted to determine the effects of feeding Galactomannan (GAL), a soluble dietary fiber extracted from Canadian-grown fenugreek seeds, on blood lipid and glucose responses. Rats (n = 8, 175–200 g) were randomly assigned to one of three high sucrose diets containing 10% cellulose (control), 7.5% cellulose + 2.5% GAL, and 5% cellulose + 5% GAL, respectively for 4 weeks. After 3 weeks, an oral glucose tolerance test (OGTT) was performed on each rat. A week later blood samples were collected to determine the effect on blood lipids. A significant reduction in glycemic response was observed only in 5% GAL group at 120 min following OGTT, when compared with that of control and 2.5% GAL groups. The plasma level of insulin was also significantly reduced (p<0.001) in 5% GAL-fed rats but at all times during OGTT. These animals also showed a reduction in body weight gain (p<0.05) in parallel with less food intake (p<0.05). All GAL-fed (2.5% and 5.0%) rats had significantly reduced plasma levels of triglycerides and total cholesterol in association with a reduction in epididymal adipose weight. Overall, this study demonstrated that feeding GAL from Canadian-grown fenugreek seeds has the potential to alter glycemic and lipidemic status and reduce abdominal fat in normal rats.

Apolipoprotein E polymorphisms, dietary fat and fibre, and serum lipids: the EPIC Norfolk study

To investigate whether blood lipid response to dietary fat and fibre vary according to the apolipoprotein E (APOE) gene locus. Regression analysis of intake of dietary fat and lipid fractions according to APOE gene loci was assessed by Pyrosequencing and validated with restriction fragment length polymorphism in 22 915 participants of the Norfolk arm of the European Prospective Investigation of Cancer. There were significant (P < 0.001) differences in serum lipids according to genotype, highest total and low-density lipoprotein (LDL) cholesterol, and lowest high-density lipoprotein and triglycerides in epsilon4/epsilon4 individuals. There were positive associations between total and saturated fat and serum total and LDL cholesterol, and significant inverse associations (P < 0.001) between polyunsaturated fat and dietary fibre and lipid fractions overall. Associations were in the same direction for epsilon2, epsilon3, and epsilon4 expressing individuals with no significant interactions between diet and genotype group on blood lipids, except in the 3% individuals expressing epsilon2/epsilon4 (P < 0.05) in whom the associations were doubled. In this largest study to date, ApoE gene loci status does not confer exemption from population targets to reduce dietary saturated fat and increase dietary fibre in order to reduce blood lipids and risk of coronary heart disease.

Postprandial Blood Lipid Responses to Aerobic Exercise and Niacin Therapy in Men with Metabolic Syndrome

Postprandial Blood Lipid Responses to Aerobic Exercise and Niacin Therapy in Men with Metabolic Syndrome

Fasting Blood Lipid Responses to Aerobic Exercise and Niacin Therapy in Men with Metabolic Syndrome

Both aerobic exercise and niacin therapy have been shown to be effective means for reducing triglyceride concentrations. Because these lipid lowering interventions appear to work through similar and separate biochemical pathways, their combination may potentiate or dampen the independent lipid lowering effects of either strategy alone. PURPOSE: Our purpose was to compare the fasting blood lipid response to aerobic exercise before and after 6 wks of niacin therapy in men with metabolic syndrome. METHODS: Fifteen men with the metabolic syndrome (46 + 2 yrs of age; BMI = 34.0 + 0.8 kg/m2; waist circumference = 107.9 + 2.1 cm; HOMA score = 4.3 + 0.5; triglycerides = 286 + 26 and HDL-C =40 + 2 mg/dL; % fat =35 + 5; VO2max = 27.7 +5.1 mL.min-1.kg-1) expended 500 kcals by walking on a treadmill at 65% of VO2max before and after a 6-wk regimen of prescription niacin. Niacin doses were titrated by 500 mg/wk from 500 to 1500 mg/dy and maintained at 1500 mg/dy for the last 4 wks. Fasting blood samples were obtained prior to, 24 and 48 hrs after exercise. Differences in serum triglyceride, glucose and insulin concentrations and clinical indices of insulin sensitivity (HOMA and glucose/insulin ratio) were determined by multiple 2 (condition) by 3 (time) repeated-measures ANOVAs (p < 0.05 for all significant differences). RESULTS: Body weights remained stable over the experimental period. Triglyceride concentrations were reduced by 15% and 27% at 24 and 48 hrs post-exercise. Niacin lowered baseline triglycerides by 34% but attenuated the triglyceride-lowering effect of exercise. Glucose concentrations did not change with exercise alone but after 6-wks of niacin increased 10% above baseline values 24 and 48 hrs post-exercise. Insulin concentrations and the HOMA scores were 21 and 23% higher and the glucose/insulin ratio was 21% lower after niacin; however, these variables were not altered by exercise. CONCLUSIONS: A single session of aerobic exercise transiently reduced fasting triglycerides to the same degree as 6 wks of niacin therapy. However, the niacin-mediated reductions in fasting triglycerides and clinical markers of insulin sensitivity appear to attenuate the short-term triglyceride lowering effect of a single exercise session in physic ally-inactive men with metabolic syndrome.

Blood Lipid Responses after Continuous and Accumulated Aerobic Exercise

The purpose of this study was to compare blood lipid responses to continuous versus accumulated exercise. Nine participants completed the following conditions on separate occasions by treadmill walking/jogging at 70% of VO2max: 1) one 500-kcal session and 2) three 167 kcal sessions. Total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG) concentrations were measured from serum samples obtained 24 h prior to and 24 and 48 h after exercise. All blood lipid responses were analyzed in 2 (condition) x 3 (time) repeated measures ANOVAs. HDL-C increased by 7 mg/dL over baseline at 48 h post-exercise with three accumulated sessions versus 2 mg/dL with continuous exercise (P < 0.05). Triglyceride concentrations were unchanged in both conditions. These findings suggest that three smaller bouts accumulated on the same day may have a modestly greater effect for achieving transient increases in HDL-C compared to a continuous bout of similar caloric expenditure.

The Influence of Cardiorespiratory Fitness on Acute Blood Lipid and Lipoprotein Responses to Aerobic Exercise

The Influence of Cardiorespiratory Fitness on Acute Blood Lipid and Lipoprotein Responses to Aerobic Exercise

Blood lipid responses to plant stanol ester supplementation and aerobic exercise training

The purpose of this study was to determine the independent and combined effects of plant stanol ester (PSE) margarine and aerobic exercise on blood lipid concentrations and related intravascular enzymes in 26 healthy sedentary, middle-aged men and postmenopausal women (age, 53 ± 8 years; body mass index, 27 ± 1.0, % fat, 28.5 ± 2). In a stratified double-blind manner, participants were randomly assigned to either a PSE (n = 17) or a placebo (CON, n = 9) margarine group. Participants supplemented their daily diets with 42 g of margarine spread (PSE = 3 g; CON, PSE = 0 g, of approximately equal energy content) for 9 weeks. During the last 4 weeks of margarine supplementation (MS), participants expended 400 kcal on a treadmill 5 d/wk at 65% of V˙ o 2 reserve (2000 kcal/wk). Fasting blood samples were obtained before initiating and after 4 weeks of MS and after exercise training. All blood samples were analyzed for total cholesterol, low-density lipoprotein cholesterol, triglyceride, high-density lipoprotein cholesterol (HDL-C), hepatic lipase, lipoprotein lipase, and cholesterol ester transfer protein activities. Total cholesterol (−10%), low-density lipoprotein cholesterol (−13%), and triglyceride (−18%) concentrations decreased after 4 weeks of MS in the PSE group, but not in the CON group ( P < .05 for all). Four weeks of aerobic exercise increased HDL-C by 21% in the CON group ( P < .05) and by 4% in the PSE group ( P > .05). Total cholesterol–HDL-C ratio decreased significantly ( P < .05) in the PSE group, but not in the CON group. No other significant alterations were observed with either PSE or exercise. Our findings suggest that PSE is effective in reducing blood cholesterol concentrations and that exercise can increase HDL-C in middle-aged men and postmenopausal women. Our findings also suggest that PSE supplementation may attenuate the exercise-induced increase in HDL-C.

Blood lipid responses to consumption of two different very low carbohydrate diets versus a lower fat diet

Low carbohydrate diets lower fasting serum concentrations of triglycerides (TG), while increasing HDL-cholesterol (HDL-C) and LDL-cholesterol (LDL-C) in comparison to lower fat diets; however, few studies have actually fed participants and none have evaluated the potential role of the type of food consumed in these fat-rich diets. Eighteen subjects (BMI=30–38) consumed three diets in a randomized, balanced cross-over design for 4 weeks separated by 4-week washout periods. Diets provided 1600 kcals for women (n=14) and 2200 kcals for men (n=4) to promote weight loss. The diets included 61% of kcals from carbohydrate (CHO), 18% protein (PRO), and 21% fat for the low fat (LF) diet and 10% CHO, 30% PRO, and 60% fat for the very low carbohydrate (VLC) diets. One of the VLC diets was primarily plant and mushroom (170 g/d) based (VLCPM) and the other provided more fat and protein from animal foods (VLCA). Serum TG was higher for the LF trial after 4 weeks (122.1 ± 46.4 mg/dl) than the VLCA (89.9 ± 29.6) and VLCPM (93.3 ± 39.3 mg/dl) diets. TC decreased by 6.1%, 13.5%, and 15.6% for the LF, VLCA, and VLCPM diets, respectively. HDL-C decreased by 10.9% during the LF trial and remained unchanged for the other trials. No differences in LDL-C were detected at the end of the trials. These results support previous research suggesting that a VLC diets can improve blood lipid profiles during weight loss in comparison to a lower fat diet. Research is needed to determine if similar effects occur during weight maintenance. Supported by a grant from the Mushroom Council.

Blood Lipid Responses After Continuous &amp; Accumulated Aerobic Exercise

Blood Lipid Responses After Continuous &amp; Accumulated Aerobic Exercise

Blood Lipid Responses After Continuous &amp; Accumulated Aerobic Exercise

Blood Lipid Responses After Continuous &amp; Accumulated Aerobic Exercise

Acute changes in blood lipids and enzymes in postmenopausal women after exercise

The effectiveness of lifestyle intervention strategies to improve blood lipids in women may be dependent on preexisting cholesterol concentrations. We characterized the effects of cholesterol status on blood lipid, lipoprotein lipid, and lipid regulatory enzyme responses to a single session of aerobic exercise in physically active, postmenopausal women. In this study, blood samples were obtained from 12 women with high cholesterol (HC; > or =200 mg/dl) and 13 women with normal cholesterol (NC; <200 mg/dl), 24 h before (Pre), immediately after (IPE), and 24 and 48 h after an exercise session (treadmill walking at 70% peak oxygen consumption, 400 kcal). We found that repeated-measures analysis revealed the following: 1) preexercise cholesterol differences did not influence the lipid or lipoprotein lipid responses to exercise; 2) for both groups, triglyceride was significantly reduced (-8.5%) after exercise; 3) the concentration profile over time for high-density lipoprotein cholesterol was significant for both groups, first falling at IPE then rising back to Pre levels by 24 h after exercise; 4) the lecithin-cholesterol acyltransferase activity (LCATA) exercise response was group dependent, increasing modestly in the NC group at 24 and 48 h; 5) lipoprotein lipase activity (LPLA) increased at IPE (by 17%) in the HC group only and then fell at 24 and 48 h (by 21%) compared with Pre; and 6) cholesterol ester transfer protein activity was unchanged by exercise. From these findings, we conclude that in postmenopausal women, a single session of endurance exercise elicited a short-term, favorable decrease in triglycerides independent of initial blood cholesterol concentrations. However, LCATA and LPLA postexercise changes were influenced by preexercise cholesterol status.

Blood lipid and oxidative stress responses to soy protein with isoflavones and phytic acid in postmenopausal women ,

Postmenopausal women are at risk of cardiovascular disease (CVD) as a result of unfavorable blood lipid profiles and increased oxidative stress. Soy protein consumption may help protect against these risk factors. Our objective was to ascertain the effect of the soy protein components isoflavones and phytate on CVD risk in postmenopausal women. In a double-blind 6-wk study, 55 postmenopausal women were randomly assigned to 1 of 4 treatments with soy protein (40 g/d) isolate (SPI): low phytate/low isoflavone (LP/LI); normal phytate/low isoflavone (NP/LI); low phytate/normal isoflavone (LP/NI); or normal phytate/normal isoflavone (NP/NI). Blood lipids (total, LDL, and HDL cholesterol and triacylglycerol) and oxidative stress indexes (protein carbonyls, oxidized LDLs, and 8-iso-prostaglandin-F(2alpha)) were measured at baseline and 6 wk. The oxidative stress indexes were not significantly affected by either phytate or isoflavones. Phytate treatment had a minimal but nonsignificant effect in reducing protein carbonyls and 8-iso-prostaglandin-F(2alpha); the reductions were 6-8% and 4-6% in the NP/LI and NP/NI groups and 1-4% and 3-4% in the LP/LI and LP/NI groups, respectively. Similarly, circulating lipids were not significantly affected by either phytate or isoflavones. The decline in total (6%-7% compared with 2%-4%) and LDL (10%-11% compared with 3%-7%) cholesterol did not differ significantly between the normal- and low-isoflavone groups, respectively. In postmenopausal women, neither phytate nor isoflavones in SPI have a significant effect of reducing oxidative damage or favorably altering blood lipids.

Apolipoprotein E Genotype in Dyslipidemic Patients and Response of Blood Lipids and Inflammatory Markers to Alpha-Linolenic Acid

The objective of this study was to determine the effect of alpha-linolenic acid (ALA) supplementation on blood lipids and inflammatory markers, in relation to apolipoprotein (apo) E genotype. The diets of 50 dyslipidemic male patients were supplemented with 15 mL of flaxseed oil per day for 12 weeks. Retrospectively, 3 apo E genotype variants were found (epsilon2/epsilon3, n=7; epsilon3/epsilon3, n=33; epsilon3/epsilon4, n=10). No significant differences were found among apo E genotypes in any variables at baseline. ALA supplementation produced a small but significant decrease in high-density lipoprotein cholesterol (from 1.12 to 1.08 mmol/L, 43 to 42 mg/dL; p=0.008) and apo A-I levels (from 1.28 to 1.24 g/L, p=0.036) in the epsilon3/epsilon3 homozygotes. In addition, ALA supplementation resulted in a significant decrease in the serum concentration of serum amyloid A (SAA) (p=0.014), C-reactive protein (CRP) (p=0.013), macrophage colony-stimulating factor (MCSF) (p<0.001), and interleukin (IL)-6 (p=0.028). Serum SAA and MCSF were also significantly decreased in the epsilon3/epsilon4 group (p=0.005 and p=0.017, respectively). In contrast, ALA produced no effects on any of the inflammatory markers in the epsilon2/epsilon3 group. ALA may have beneficial effects on inflammation in dyslipidemic carriers of the apo epsilon3/epsilon3 and epsilon3/epsilon4 genotypes, but not in carriers of the epsilon2 allele.

Cardiovascular and Hormonal Aspects of Very‐Low‐Carbohydrate Ketogenic Diets

In recent years, restriction of carbohydrate intake for weight loss has become widespread. Our research group began studying physiological responses to very-low-carbohydrate ketogenic diets (VLCKDs) in the late 1990s because we felt there was a significant void in the literature and limited understanding of metabolic responses to VLCKDs. This launched us into a line of research examining the physiological effects of VLCKDs. In this paper, we briefly overview nine studies we have published on isoenergetic and hypoenergetic VLCKDs in men and women. These studies have focused on blood lipid responses to VLCKDs, but we have also addressed changes in body weight, body composition, and hormones. Compared with low-fat diets, short-term VLCKDs consistently result in improvements in fat loss, fasting and postprandial triacylglycerols, high-density lipoprotein-cholesterol, the distribution of low-density lipoprotein-cholesterol subclasses, and insulin resistance. These are the key metabolic abnormalities of metabolic syndrome, a problem of epidemic proportions in the United States. There is substantial variability in total cholesterol and low-density lipoprotein-cholesterol responses to VLCKD. The factors responsible for this variability are not known, and studies designed to identify methods to predict blood lipid responses to VLCKD and other dietary approaches represent critical areas for nutrition researchers. Further research is warranted to validate the physiological effects of VLCKD over longer periods of time, including studies that modify the quality of macronutrients (i.e., the type of fat and protein) and the interaction with other interventions (e.g., exercise, dietary supplements, drugs).

Effect of hypothyroidism on the blood lipid response to higher dietary fat intake in mares.

Blood lipid and lipoprotein concentrations were measured and compared between euthyroid and thyroidectomized mares on low-fat or high-fat diets to test the hypothesis that hypothyroidism alters the blood lipid response to higher dietary fat intake. Four healthy adult mares and four adult mares that had been thyroidectomized 3 to 6 mo earlier were placed on low-fat or high-fat diets according to a replicated 2 x 2 Latin square design consisting of two 5-wk feeding periods separated by a 2-wk washout interval. Plasma lipid concentrations were measured at 0, 3, 4, and 5 wk, and plasma lipase activities were measured at the end of each 5-wk feeding period. Compared with euthyroid mares (0.46 ng/mL [range 0.34 to 0.68 ng/mL T3], and 21.5 ng/mL [range 18.1 to 25.1 ng/mL T4], respectively), median serum concentrations of T3 and T4 were lower (P = 0.029 and P = 0.021, respectively) in thyroid-ectomized mares (0.26 ng/mL [range 0.23 to 0.26 ng/ mL T3], and undetectable T4). Serum T4 concentrations were below the limits of detection in thyroidectomized horses. Alterations in body weight over 5 wk did not differ between groups. Mean plasma very low density lipoprotein (VLDL) and triglyceride (TG) concentrations were higher (P = 0.045 and 0.034, respectively) in hypothyroid mares (55.42 +/- 35.05 mg/dL and 52.83 +/- 34.46 mg/dL, respectively) compared with euthyroid mares (28.28 +/- 13.76 mg/dL and 23.53 +/- 9.84 mg/dL, respectively). Mean plasma total cholesterol (TC) concentrations increased from 88.73 +/- 25.49 mg/dL at baseline to 103.93 +/- 24.42 mg/dL after 5 wk on the low-fat diet, but increased by a greater magnitude (P = 0.006 diet +/- time interaction) in mares that were on the high-fat diet (81.05 +/- 17.24 mg/dL and 123.84 +/- 32.27 mg/ dL, respectively). Mean plasma TC concentrations were higher (P = 0.099) in hypothyroid mares (116.16 +/- 32.89 mg/dL) than in euthyroid mares (89.56 +/- 14.45 mg/ dL). Higher post-heparin plasma lipoprotein lipase and hepatic lipase activities (P = 0.012 andP = 0.017, respectively) were detected in mares that were on the high-fat diet (2.66 +/- 0.91 micromol FA x mL(-1) x h(-1) and 2.95 +/- 0.49 micromol FA x mL(-1) x h(-1), respectively) vs. a low-fat diet (1.75 +/- 0.55 micromol FA x mL(-1) x h(-1) and 2.27 +/- 0.59 micromol FA x mL(-1) x h(-1), respectively). We conclude that plasma VLDL and TG concentrations are elevated in hypothyroid mares, but the blood lipid response to higher dietary fat intake is not influenced by hypothyroidism.

Differential effect of two nicotinic acid preparations on low-density lipoprotein subclass distribution in patients classified as low-density lipoprotein pattern A, B, or I

We tested the hypothesis that treatment with nicotinic acid results in a differential blood lipid response in subjects classified as having a low-density lipoprotein (LDL) pattern A or B. One hundred eighty hypercholesterolemic subjects were randomized to placebo (n = 61), immediate-release niacin (3,000 mg/day, n = 59), or extended-release niacin (1,500 mg/day, n = 60) for 14 weeks. Lipids and lipoprotein cholesterol were determined with enzymatic methods. LDL subclass distribution was determined with 2% to 16% polyacrylamide gradient gel electrophoresis. Extended- and immediate-release niacin had significant effects on the decrease of triglycerides, total cholesterol, LDL cholesterol, apoprotein B, lipoprotein(a), and apoprotein A-I and significantly increased high-density lipoprotein cholesterol. The 2 nicotinic acid compounds and doses significantly increased mean LDL peak particle diameter and percent distribution in large LDL I and IIa, with a significant decrease in small LDL IIIa, IIIb, and IVb. In patients with LDL pattern B compared with those with pattern A, extended-release niacin (1,500 mg/day) increased LDL peak particle diameter significantly more and decreased the percent distributions of small LDL IIIa, LDL IIIb, and LDL IVa significantly more. With 3,000 mg/day, immediate-release nicotinic acid in patients with LDL pattern B exhibited a significantly greater increase in LDL peak particle diameter and large LDL IIa and IIb and significantly greater decreases in small LDL IIIa, IIIb, and IVa compared with patients with pattern A. These differences in response between patients with LDL pattern A and those with pattern B were not reflected by changes in the standard lipid profile, including apoproteins A-I and B. Nicotinic acid has a significantly different effect on lipids and lipoprotein subclass distribution in subjects classified as having LDL subclass pattern A or B. Nicotinic acid has a significantly greater effect on the decrease of small LDL subclass distribution and increase in LDL peak particle diameter in pattern B versus pattern A.

THE INFLUENCE OF CIRCUIT RESISTANCE TRAINING ON BLOOD LIPID RESPONSES TO CIRCUIT RESISTANCE EXERCISE

While adhering to a physically active lifestyle has been associated with a more favorable lipid profile and a reduced risk of CHD, information regarding the optimal training modality has not been well defined. Resistance training has been recommended as an integral part of a well-rounded physical activity program for health and disease prevention. However, the beneficial influence of this mode of exercise on circulating lipoprotein-lipids remains to be established. PURPOSE To determine the effects of an 8-wk circuit resistance training program on blood lipid responses to a single session of circuit resistance exercise. METHODS Five healthy men and four healthy women underwent three supervised circuit resistance exercise sessions a wk for 8 wks. The average subject age, height, and weight was 22.8 ± 2 yr, 171.7 ± 14 cm, and 73.9 ± 18.5 kg. Serum lipid concentrations were measured before and immediately after exercise (IPE) on two different occasions corresponding to 0 and 8 weeks of training. All IPE serum lipid concentrations were adjusted for changes in plasma volume. RESULTS Circuit resistance training resulted in a 6.5% increase in VO2peak, a 24% increase in upper body strength, and a 29% increase in lower body strength (p < 0.05). Results of a univariate 2 (TRAINING) × 2 (TIME) factorial ANOVA (repeated for both factors) for TC, LDL-C, HDL-C, HDL2-C, HDL3-C, and TG were as follows: TRAINING × TIME interactions were not significant. TRAINING main effects were not significant. For TIME, only TG changes were significant (−4.6%). CONCLUSION Eight weeks of circuit resistance training did not alter the acute response of lipoprotein-lipids to a single session of circuit resistance exercise. TG levels were significantly decreased immediately after a single session of circuit resistance exercise regardless of training status. In addition to improved muscular strength, our results also show that eight weeks of circuit resistance training improves aerobic capacity.

Apolipoprotein E genotype and the response of blood lipids and blood inflammatory indices to A-linolenic acid in hyperlipidaemic subjects

Apolipoprotein E genotype and the response of blood lipids and blood inflammatory indices to A-linolenic acid in hyperlipidaemic subjects

Inulin and oligofructose: effects on lipid metabolism from human studies

Although convincing lipid-lowering effects of the fructo-oligosaccharide, inulin, have been demonstrated in animals, attempts to reproduce similar effects in man have produced conflicting findings. This may be because of the much lower doses which can be used due to the adverse gastrointestinal symptoms exhibited by most subjects consuming in excess of 15 g/d. There are nine studies reported in the literature which have investigated the response of blood lipids (usually total and LDL-cholesterol and triacylglycerol) to inulin or oligofructose supplementation in human volunteers. Three have observed no effects of inulin or oligofructose on blood levels of cholesterol or triacylglycerol, three have shown significant reductions in triacylglycerol, whilst four have shown modest reductions in total and LDL-cholesterol. Studies have been conducted in both normo- and moderately hyperlipidaemic subjects. Differences in study outcomes do not appear to be due to differences in the type or dose of oligosaccharides used nor the duration of the studies. Because animal studies have identified inhibition of hepatic fatty acid synthesis as the major site of action for the triacylglycerol lowering effects of inulin and oligofructose, and because this pathway is relatively inactive in man unless a high carbohydrate diet is fed, variability in response may be a reflection of differences in background diet or the experimental foods used.

Inulin and oligofructose: effects on lipid metabolism from human studies.

Although convincing lipid-lowering effects of the fructo-oligosaccharide, inulin, have been demonstrated in animals, attempts to reproduce similar effects in man have produced conflicting findings. This may be because of the much lower doses which can be used due to the adverse gastrointestinal symptoms exhibited by most subjects consuming in excess of 15 g/d. There are nine studies reported in the literature which have investigated the response of blood lipids (usually total and LDL-cholesterol and triacylglycerol) to inulin or oligofructose supplementation in human volunteers. Three have observed no effects of inulin or oligofructose on blood levels of cholesterol or triacylglycerol, three have shown significant reductions in triacylglycerol, whilst four have shown modest reductions in total and LDL-cholesterol. Studies have been conducted in both normo- and moderately hyperlipidaemic subjects. Differences in study outcomes do not appear to be due to differences in the type or dose of oligosaccharides used nor the duration of the studies. Because animal studies have identified inhibition of hepatic fatty acid synthesis as the major site of action for the triacylglycerol lowering effects of inulin and oligofructose, and because this pathway is relatively inactive in man unless a high carbohydrate diet is fed, variability in response may be a reflection of differences in background diet or the experimental foods used.