The present study is the first to report the hypocholesterolemic effect of chitosan on humans. When 3-6 g/day of chitosan was given in the diet to 8 healthy males, total serum cholesterol significantly decreased, and when the ingestion was stopped, the value increased to the level before ingestion. Serum HDL-cholesterol was increased significantly by the ingestion of chitosan. The excreted amounts of primary bile acids, cholic acid and chenodeoxycholic acid, into the feces was significantly increased by the ingestion of chitosan, and the amount of cholic acid excretion decreased significantly after the ingestion was stopped. These facts suggest that chitosan combined bile acids in the digestive tract, and that the combined product was excreted into the feces. This, in turn, deceased the resorption of bile acids, so that the cholesterol poool in the body was decreased and the level of serum chrolesterol consequently decreased.Chitin is a polysaccharide contained in the cuticle of Crustacea and insects, and in the cell walls of some kinds of mold. Chitosan is the general name for the dilute acid-soluble group of deacetylated chitin. The chemical structure of chitosan is similar to that of cellulose in dietary fiber. Chitosan is not hydrolyzable by the digestive enzymes in humans, so it can be classed as one of the dietary fibers of animal origin. However, it is a cationic polymer having an amino group in its chemical structure, which is a characteristic greatly different from those of other dietary fibers.Many functions of chitosan attributable to its amino group are known. Among them, the most noticeable is its hypocholesterolemic effect,l -6) and several studies on its mechanism have been reported. 5, 7) According to these reports, it has been said that chitosan is .dissolved in the digestive tract under acidic conditions, combines bile acid with its ion-exchanging function, and excretes the combined bile acid outside the body; consequently, it decreases the cholesterol pool in the body. However, all of these studies on the hypocholesterolemic effect of chitosan so far reported have used animals,1-6) and there is no report on a study of the effects on humans. Moreover, data for elucidating the mechanism were obtained mostly by in vitro studies,7) and the proposed mechanism based upon animal studies is not entirely clear.The present study is the first to report the hypocholesterolemic effect of chitosan on humans. The results obtained are particularly useful for the effect of chitosan on the metabolism of serum cholesterol and its possible mechanism of action.. Materials and MethodsTest subjects. This study was performed in conformity with the spirit of the "Declaration of Helsinki". The test subjects were 8 healthy male volunteers between 20 and 23 years of age, who were informed of the details of the aims, contents and methods of the study, and after giving their consent, decided to participate in the study of their own free will. All of them were university studuents, and Table I shows the background factors f...

The metabolic syndrome is a constellation of risk factors, including atherogenic dyslipidemia, impaired fasting glucose, hypertension, and central adiposity, predisposing to higher risks of oxidative stress, type 2 diabetes and atherosclerotic cardiovascular disease. [1][2][3][4] In particular, an enhancement in oxidative stress by reactive oxygen species (ROS) has been proposed as a common pathomechanism by which cardiovascular risk factors affect the vessel wall to induce and amplify vessel and organ injury. Thus, an appropriate evaluation and reduction in oxidative stress in the circulating blood is important from the viewpoint of protecting vascular endothelium and vascular smooth muscle cells against oxidative stress.5-7) Dietary modifications, which include the use of antilipidemic supplements, are one of the key elements in the management of these metabolic abnormalities. For example, chitosan has been proposed as a safe and efficacious dietary supplement that can contribute to weight loss by reducing the amount of dietary fat absorbed, thereby improving calorie balance. 8)Chitosan, a cationic polysaccharide produced by the Ndeacetylation of chitin under alkaline conditions, contains a linear sugar backbone, composed of b-1,4-linked glucosamine units. It exhibits a wide variety of biological activities except for cholesterol-lowering effects.9-11) A property of particular interest for this study is the antioxidant properties of chitosan. Santhosh et al. reported that the administration of chitosan to rats that had been treated with isoniazid or rifampicin inhibited the oxidation of hepatotoxic lipids.12) It had also been reported that chitosan, when injected, inhibited glycerol-induced renal oxidative damage in rats.13) Because of the numerous in vitro and in vivo antioxidant studies that have appeared, chitosan has attracted considerable attention from researchers. In spite of this, however, relationships between molecular weight (MW) and antioxidant activity have not been extensively investigated in in vivo studies.In this study, we examined the effect of high and low MW chitosan supplements (HMC; 1000 kDa and LMC; 30 kDa) on oxidative stress in normal and metabolic syndrome model rats, in an attempt to better understand the potential role for HMC and LMC as an antioxidant in the systemic circulation. Oxidative stress was evaluated by monitoring oxidized serum albumin levels, a sensitive marker for protein oxidation, in the systemic circulation.14,15) We also investigated the role of HMC and LMC as a chelator, to develop a better understanding of the mechanism of the antioxidant activity of HMC and LMC in metabolic syndrome model rats. MATERIALS AND METHODSMaterials LMC (MWϭ30 kDa) and HMC (MWϭ1000 kDa) were obtained from Nippon Kayaku Food Techno Co., Ltd. (Gunma, Japan). All other chemicals were of the highest grade available and were obtained from commercial sources.Animals and Treatment Male (6 weeks old) Wistar Kyoto rats as a normal model (Normal-rats) and spontaneously hypertensive rat/ND mcr-cp ...

The effects of chitosan (CS) intake on faecal microbiota and faecal metabolites were studied in eight healthy volunteers who consumed a mixed free choice diet (control diet) for 2 wks before and after CS intake (CN-1 and CN-2 period, respectively), and the same diet with an additional 3 g CS/day for 1 wk (CS-1 period) and 6 g CS/day for 1 wk (CS-2 period). During CS intake, there was no detectable change in the concentrations of the microorganisms examined throughout the experimental periods. However, the frequency of occurrence of lecithinase-negative clostridia decreased significantly (P<0.05). Faecal concentrations of ammonia, phenol, p-cresol and indole were significantly reduced (PC0.05). The values of total volatile fatty acid showed a significant increase (P

No abstract

No abstract