Dietary beta-glucans lower the blood concentrations of cholesterol in animals and humans. Recent studies have uncovered mechanisms by which dietary beta-glucans may regulate cholesterol homeostasis. There is evidence that beta-glucans sequester bile acids in the intestine, reducing their reabsorption and return to the liver. Reducing hepatic bile acid concentrations activates the enzyme CYP7A1, which converts cholesterol into bile acids. This action leads to a reduction of hepatic cell cholesterol content, which up-regulates low-density lipoprotein (LDL) receptor synthesis and thereby accelerates the transportation of LDL-cholesterol from the blood into hepatocytes. Reduced intracellular cholesterol also up-regulates the hepatic synthesis of 3-hydroxy-3-methylglutaryl coenzyme A reductase, the rate-limiting enzyme in cholesterol synthesis. Statins inhibit 3-hydroxy-3-methylglutaryl coenzyme A reductase and could therefore provide an additive effect in suppressing hepatocyte cholesterol to that produced by enhancing its depletion with beta-glucans. Through this combination of agents, one would expect a greater clearance of LDL from the plasma with lower steady state levels of LDL-cholesterol.
"Since the production and excretion of bile acids represent the major pathway of cholesterol removal from the body, and the biosynthesis of bile acids in liver is modulated through a series of positive and negative feedback mechanisms (Andersson et al. 2002), the increased fecal removal of bile acids reduces the amount of bile acids present in the liver. The fecal effect activates cholesterol 7-␣-hydroxylase (Cohen 1999), the enzyme that catalyzes the ratelimiting step in the biosynthesis of bile acids from cholesterol, which upregulates bile acid synthesis from plasma cholesterol and ultimately leads to lowering of circulating LDL cholesterol levels (Butt et al. 2008; Chen and Huang 2009; Miettinen 1979). In 1 study, it was shown that consumption of ␤-glucan from oat bran nearly doubled the serum level of the metabolite 7␣-hydroxy-4- cholesten-3-one, which is a marker for increased bile acid secretion, within 8 h (Andersson et al. 2002). "
[Show abstract][Hide abstract] ABSTRACT: In 2010, Health Canada approved a heath claim acknowledging the link between increased oats (Avena sativa)-soluble fibre consumption and a reduction in total serum cholesterol levels. The approval also recognized the relationship between decreased total blood cholesterol concentration and a reduced risk of coronary heart disease. The functional food ingredient believed to be responsible for the hypocholesterolemic property of oats is β-glucan, a highly viscous, soluble fibre composed of d-glucose monomers linked by a combination of β-(1→4) and β-(1→3) glycosidic bonds. Found mainly in the endosperm cell wall of oats, β-glucan is thought to reduce total serum and low-density lipoprotein cholesterol by forming a viscous mass in the small intestine thus limiting intestinal absorption of dietary cholesterol as well as the re-absorption of bile acids. Given the evolution of research information with time as a result of the continual, rapid generation of new research data by laboratories around the world, it became imperative to examine the compatibility of the conclusion reached by Health Canada on the basis of the body of evidence contained in the initial petition submitted in January 2007, with newer post-2006 data. After careful evaluation, this work concludes on the basis of new research information that a dose of 3 g/day oat β-glucan consumed as part of a diet "free of saturated fatty acids" or "low in saturated fatty acids" could help to promote cardiovascular health.
"The ability of fungal polysaccharides to reduce levels of cholesterol and the lipids in blood remains one of the important pharmacological properties. Chen and Huang  conducted experiments proving the ability of β-glucans to reduce cholesterol levels in blood by partial inhibition of absorption thereof. We confirmed that exopolysaccharides from G. applanatum were able to bind in vitro cholesterol and triglycerides (Figure 7(a)). "
[Show abstract][Hide abstract] ABSTRACT: A new exopolysaccharide preparation isolated from stationary cultures of the white rot fungus Ganoderma applanatum (GpEPS) was tested in terms of its bioactive properties including its cytotoxic and immunostimulatory effect. The results indicate that the tested GpEPS (at concentrations above 22.85 µg/mL and 228.5 µg/mL) may exhibit selective activity against tumor cells (cell lines SiHa) and stimulate production of TNF-α THP-1-derived macrophages at the level of 752.17 pg/mL. The GpEPS showed antibacterial properties against Staphyloccoccus aureus and a toxic effect against Vibrio fischeri cells (82.8% cell damage). High cholesterol-binding capacity and triglycerides-binding capacity (57.9% and 41.6% after 24 h of incubation with the tested substances, resp.) were also detected for the investigated samples of GpEPS.
BioMed Research International 07/2014; 2014(1). DOI:10.1155/2014/743812 · 3.17 Impact Factor
"The supplementation of soluble fibres has been shown to increase the excretion of bile acids (Stout, 1993). Since greater amounts of cholesterol are converted into bile acids in the liver and are subsequently excreted, the supplementation of soluble fibres possibly elevates the catabolism of cholesterol (Fiordaliso et al., 1995; Kim and Shin, 1998; Chen and Huang, 2009). Consequently, lower concentrations of intracellular cholesterol stimulate the expression of LDL receptors on the plasma membrane, increasing the internalisation of LDL-c, resulting in decreased serum levels of these lipoproteins. "
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to evaluate the effect of yacon (Smallanthus sonchifolius)(Poepp.& Endl.) on clinical parameters under diabetic conditions. The aqueous extract of yacon tuberous roots (YRAE; 0.76g fructan kg(-1) body weight) was prepared at the moment of each administration. Thirty-two male rats were divided into four groups (n=8): control group (C); group that received YRAE (Y); untreated diabetic group (DM1); and diabetic group treated with YRAE (Y-DM1). The diabetes mellitus was induced by streptozotocin (60mg kg-1 body weight). The animals from Y2 and Y-DM1 received YRAE by gavage, at 7-day intervals, for 30 days. The aqueous extract of yacon roots decreased (p<0.05) the water and food intake in diabetic rats treated with YRAE (Y-DM1). YRAE treatment reduced (p<0.05) glycaemia, total cholesterol, VLDL, LDL and triacylglycerol levels in diabetic rats (YRAE). HDL, urea and creatinine levels did not differ (p>0.05) between the Y and Y-DM1 groups. YRAE normalised alanine aminotransferase (ALT) activity, when comparing DM1 and Y-DM1 rats, but had no effect on lactate dehydrogenase activity (LDH). In conclusion, YRAE was sufficient for controlling water and food consumption, hyperglycaemia and dyslipidaemia, and promote the reduction of the ALT, suggesting a hepatoprotective effect in rats with STZ-induced DM1.
Food and chemical toxicology: an international journal published for the British Industrial Biological Research Association 06/2013; 59. DOI:10.1016/j.fct.2013.05.050 · 2.90 Impact Factor
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