Time- and dose-dependent effect of psyllium on serum lipids in mild-to-moderate hypercholesterolemia: a meta-analysis of controlled clinical trials.
Level 1 - systematic review of randomized trials
Meta-analysis of 21 randomized controlled trials
PubMed 18985059 · doi:10.1038/ejcn.2008.49
What was done
A meta-analysis of 21 randomized placebo-controlled trials (both double-blind and open-label) evaluated the dose-response and time-dependent effects of psyllium supplementation in adults with mild-to-moderate hypercholesterolemia. The dataset comprised 1,717 participants (1,030 receiving psyllium and 687 receiving placebo). Evaluated daily psyllium doses ranged between 3.0 and 20.4 g/day, with intervention periods exceeding 2 weeks, diet lead-in periods ranging from 0 to 8 weeks, and any dietary background permitted. Random-effects meta-regression was used to model dose and time relationships.
What was found
Compared with placebo, psyllium significantly decreased serum total cholesterol by 0.375 mmol/l (95% CI: 0.257 to 0.494 mmol/l) and LDL cholesterol by 0.278 mmol/l (95% CI: 0.213 to 0.312 mmol/l). Meta-regression confirmed a significant dose-response relationship for doses between 3 and 20.4 g/day for total cholesterol (model: -0.0222 + 0.2061 x log (dose+1)) and LDL cholesterol (model: 0.0485 + 0.1390 x log (dose+1)). Significant time effects were also observed for total cholesterol (model: 6.3640 - 0.0316 x treatment period) and LDL cholesterol (model: 4.3134 - 0.0162 x treatment period), indicating total cholesterol decreased more rapidly than LDL cholesterol.
Why it matters
This review establishes clear mathematical dose-response and time-dependent dynamics for psyllium's lipid-lowering efficacy. It provides quantitative backing for using psyllium as a structured dietary adjunct in managing hypercholesterolemia.
Limits
The analysis combined double-blind trials with open-label studies, introducing potential performance and reporting biases. Dietary backgrounds were unrestricted, and diet lead-in durations varied widely (0 to 8 weeks). The abstract reports no data on HDL cholesterol, triglycerides, patient adherence, or gastrointestinal adverse effects.
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