Effect of Psyllium Fiber Supplementation on C-Reactive Protein: The Trial to Reduce Inflammatory Markers (TRIM)

Randomized interventional study in overweight or obese adults with elevated C-reactive protein and no history of heart disease, conducted at the Medical University of South Carolina in Charleston, United States. Active-arm sample sizes were 51 randomized in the 14 g/day group and 54 randomized in the 7 g/day group, with fewer participants contributing to intent-to-treat and protocol-completer analyses.

Participants received oral psyllium fiber powder for 3 months. The active regimens were 14 g/day (high-fiber arm; 4 packets of 3.5 g/day) or 7 g/day (low-fiber arm; 2 packets of 3.5 g/day/day), taken between meals and mixed in water, with one daily packet taken in no-pulp orange juice to match the control procedures.

Psyllium supplementation did not significantly lower CRP or other inflammatory markers over 3 months compared with no supplementation. In intent-to-treat analyses, change in CRP was 0.98 mg/L in the 14 g/day group and -0.96 mg/L in the 7 g/day group, with no significant between-group differences versus control for CRP, fibrinogen, or white blood cell count. Among protocol completers, the 14 g/day group showed a small fibrinogen decrease (-6.30 mg/dL) and this was significant after adjustment for BMI (P = .03), but the authors judged the effect not clinically meaningful. No significant adverse events were attributed to treatment.

The trial was short, with only 3 months of follow-up, and the active-arm analysis sets were smaller than the randomized numbers. The main outcome was null, and the only notable signal was a small fibrinogen change in completers that was not consistent across analyses and was not considered clinically meaningful. Confidence intervals were not reported, and the findings may not generalize beyond overweight or obese adults with elevated CRP.