Effects of diets containing proteins from fish muscles or fish by-products on the circulating cholesterol concentration in rodents: a systematic review and meta-analysis

Abstract

A high circulating cholesterol concentration is considered an important risk factor for the development of cardiovascular disease. Since lean fish intake and fish protein supplementation have been associated with lower cholesterol concentration in some but not all clinical studies, the main aim of this study was to investigate the effect of diets containing proteins from fish muscles and fish byproducts on the serum/plasma TC concentration in rodents. A systematic literature search was performed using the databases PubMed, Web of Science and Embase, structured around the population (rodents), intervention (type of fish and fraction, protein dose, duration), comparator (casein as control protein) and the primary outcome (circulating total cholesterol). Articles were assessed for risk of bias using the SYRCLE’s tool. A meta-analysis was conducted in Review Manager v. 5.4.1 (the Cochrane Collaboration) to determine the effectiveness of proteins from fish on the circulating TC concentration. Thirty-nine articles were included in the systematic review and meta-analysis, with data from 935 rodents. The risk of bias is unclear since few of the entries in the SYRCLE’s tool were addressed. Consumption of proteins from fish resulted in a significantly lower circulating TC concentration when compared to control groups (mean difference -0.24 mmol/l, 95% confidence interval -0.34, -0.15, P < 0.00001), with high statistical heterogeneity (I2 = 71%). To conclude, proteins from fish muscles and byproducts show promise as a functional dietary ingredient or supplement by preventing high cholesterol concentration in rodents, thus reducing one of the most important risk factors for developing cardiovascular disease.

Effects of diets containing fish oils or fish oil concentrates with high cetoleic acid content on the circulating cholesterol concentration in rodents. A systematic review and meta-analysis

“…The circulating TC concentration is regulated by changes in the endogenous production of cholesterol in the liver, the uptake of LDL-cholesterol to the liver, the amount stored as cholesteryl esters in the liver, the secretion of VLDL from the liver and the excretion of cholesterol and bile acids in faeces, and these pathways are affected by dietary intakes of cholesterol, fats and other nutrients. We have recently shown that diets containing fish proteins prevent high cholesterol concentration in rodents, most likely by increased faecal removal of TC and/or bile acids in normocholesterolemic rodents and through down-regulation of hepatic cholesterol synthesis hypercholesterolaemic Zucker fa/fa rats ( 52 ) . It was therefore mandatory that the included articles in the present review had similar amount and type of protein in the intervention diet and the comparator diet.…”