Abstract and Introduction
Abstract
Inulin has been shown to be an effective therapeutic for reducing total serum cholesterol and triglycerides in clinical trials with modest sample sizes. A systematic literature search of several databases was conducted for studies that investigated the efficacy of inulin on the plasma lipid profile of subjects. A random-effects model was used to calculate the weighted mean difference and 95% CI as the difference between the mean for the inulin and control groups. The pooled mean net changes in total cholesterol, LDL-C, HDL-C and triglycerides of hyperlipidemic and normolipidemic subjects with inulin compared with controls were calculated. The results indicate that a diet rich in inulin has beneficial effects on total cholesterol and LDL-C, as well as triglyceride concentration in the plasma of hyperlipidemic subjects, and has no effects on plasma lipids in normolipidemic subjects.
Introduction
Coronary heart disease is a major cause of morbidity and a leading cause of premature death worldwide.[1] Observational epidemiologic studies have showed that high serum lipids, including total cholesterol and LDL, are a major cause of build-up of coronary atherosclerosis and hence of the development of coronary vascular disease. Every 1% reduction in blood cholesterol concentration is associated with a 2.5% reduction in risk of coronary heart disease.[2]
Both pharmacologic and nonpharmacologic therapies can decrease the content of cholesterol and triglycerides in human plasma. Multiple nonpharmacologic approaches have been initiated to improve hyperlipidemia, such as the inclusion of vitamin C,[3] ω-3 fatty acids,[4] nicotinic acid,[5] non-soy legume[6] and red yeast rice[7] in the diet. The cholesterol-lowering effect of prebiotic products has raised much interest in recent years. Many patients prefer nondrug treatments for hyperlipidemia for reasons including the adverse effects of antilipid drugs, contraindications to drugs or personal preference for natural or alternative therapies.[8] However, nonpharmacologic therapies may not replace drugs in the treatment of hyperlipidemia in those cases where the concentrations of plasma cholesterol are very high or patients do not respond to nondrug therapy; in these cases pharmacologic therapy should be administered. Inulin-type fructans are classified as prebiotics for their physiological and nutritional effects on gastrointestinal functions. The three integral parts of inulin-type fructans are inulin, oligofructose and fructose oligosaccharides. Inulin is one of the prebiotics that has been extensively studied in the last decade, and is widely used in the food processing industry (e.g., bakery, confectionery, dairy products, beverages and seasonings) because it can be used to replace sugar, fat and flour. Functional food is a food where a new ingredient(s) has been added to a food and the new product has a novel function. As a functional food, inulin has been shown to decrease both lipogenesis and the triacylglycerol secretion rate in animals. Meir and Leitersdorf as well as Rault-Nania et al. confirmed that inulin is able to attenuate the symptoms of atherosclerosis in ApoE-deficient mice.[9,10] However, human clinical studies using inulin have yielded mixed results, with some studies finding a significant cholesterol-lowering effect[11–15] and others identifying no effect.[16,17] Therefore, the purpose of this study was to provide a comprehensive meta-analysis of randomized controlled trials to investigate the effect of inulin supplementation on total cholesterol, LDL-C and HDL-C as well as triglycerides in healthy and hyperlipidemic subjects.
Clin Lipidology. 2012;7(2):215-222. © 2012 Future Medicine Ltd.
