This systematic review and meta-analysis is aimed to assess the effect of commonly consumed viscous fibers on blood lipids including LDL-C, non-HDL-C, and ApoB.

Medline, Embase, CINAHL, and the Cochrane Central databases were searched through May 13, 2019. Three independent reviews extracted data and assessed risk of bias. Randomized controlled trials that assessed the effect of barley b-glucan, oat b-glucan, konjac glucomannan (KJM), psyllium, guar gum, and pectin, with a study duration of ≥ 3 weeks, in adults with or without hypercholesterolemia were included. Data were pooled using the generic inverse variance method with random effects models and expressed as mean differences with 95% confidence intervals. Heterogeneity was assessed by the Cochran Q statistic and quantified by I2 statistic. Overall quality of the evidence was assessed using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) approach.

Inclusion Criteria:

• Must be a randomized controlled clinical trial with either a parallel or cross-over design
• have a treatment period of at least 3 weeks
• Hypercholesterolemic or normocholesterolemic adults, overweight and obese individuals or individuals with diabetes were all acceptable
• Sources from β-glucan oats, β-glucan barley, konjac, psyllium, guar gum, and pectin were accepted
• The amount of soluble fiber must be reported or measured or must be computable.
• Must be appropriately controlled.
• Must measure one of LDL-C, non-HDL-C or ApoB. These lipid measures can be either primary or secondary outcomes.
• Enough information must be provided to calculate the magnitude of effect, i.e. end of treatment measures and/or change from baseline measures

Exclusion Criteria:

• If the study was insufficiently controlled, i.e. the control was another soluble fiber
• If the soluble fiber was a combination supplement or in whole food sources where the amount of soluble fiber could not be isolated
• If the outcome measures did not include LDL-C, non-HDL-C or ApoB
• If the treatment period was less than 3 weeks
• If the study was from a non-adult population
• If the study provided insufficient information to calculate a magnitude of effect
• Secondary information such as reviews, editorials, commentaries, were excluded
• If the dose was less than 0.4g/day

Hypercholesterolemic or normocholesterolemic adults, overweight and obese individuals or individuals with diabetes