Abstract and Introduction
Abstract
Probiotics are living microorganisms that, upon ingestion in high amounts, exert health effects beyond inherent basic nutrition. To date, some studies have shown that dietary intake of probiotics is effective at lowering plasma cholesterol. The aim of this article is to summarize the current knowledge on the underlying mechanism(s) that affect(s) the cholesterol-lowering action of probiotics. The accepted mechanism responsible for the cholesterol-lowering effect of probiotics is the inhibition of intestinal cholesterol absorption and the suppression of bile acid reabsorption. Recent research has indicated that several sites within the cholesterol metabolism, such as the NPC1L1 protein, 3-hydroxy-3-methylglutaryl-CoA reductase and 7α- and 27α-hydroxylase, have been suggested where regulation may take place after oral administration of probiotics, but these mechanisms are still imperfectly understood. Human metagenomic studies examining the possible mechanisms by which probiotic ingestion can be used to treat hypercholesterolemia should be carried out in the future.
Introduction
Coronary heart disease (CHD) is currently a leading cause of death worldwide; this disease is still increasing and has become a true pandemic that respects no borders.[1] Although there are multiple risk factors for CHD, hypercholesterolemia remains a major determining factor for this pathology. To decrease the incidence of CHD, it is therefore necessary to reduce the level of serum cholesterol in hypercholesterolemic subjects. Both pharmacological and nonpharmacological interventions can reduce cholesterol concentrations in serum. Many patients prefer nondrug treatments for hyperlipidemia for many reasons, including the adverse effects of antilipid drugs, contraindications to drugs or personal preference for natural or alternative therapies.[2] In addition, dietary prevention methods are important to the general population, including those without dyslipidemic symptoms. Multiple approaches to dietary therapy have been suggested to improve hyperlipidemia, such as the inclusion of ω3 fatty acids,[3] soy,[4] vitamin C,[5] nonsoy legume[6] and red yeast rice[7] in the diet.
Probiotics are defined as 'living microorganisms, which upon ingestion in certain numbers, exert health effects beyond inherent basic nutrition'.[8] Lactic acid bacteria, predominantly selected from the genera Lactobacillus and Bifidobacterium, constitute a significant proportion of probiotic cultures in nutritional supplements, pharmaceuticals and functional foods.[9] Since Mann and Spoerry first reported the hypocholesterolemic activity of fermented milk in the Maasai tribe of Kenya in 1974,[10] many scientists have used animal models or humans to evaluate the effects of probiotics on serum cholesterol levels, whose benefits have been emphasized over the past 40 years. Cell and animal models have also been used to determine the effects of probiotic interventions on metabolic processes and gene expression related to cholesterol regulation, with the purpose of understanding the mechanisms of cholesterol-lowering effects by probiotics. The aim of this article is to review clinical outcome and potential mechanism(s) of the cholesterol-lowering effects of probiotics in the past few decades.
Clin Lipidology. 2012;7(5):501-507. © 2012 Future Medicine Ltd.