Effect of Oat β-Glucan Supplementation on Chronic Kidney Disease: A Feasibility Study.

Objective: Dietary supplementation with grains containing high β-glucan fiber has been shown to attenuate the progression of chronic kidney disease (CKD) and vascular calcification in animal models. The aim of this study was to investigate the feasibility of consuming an oat β-glucan supplement and to assess its effects on certain uremic toxins and markers of mineral metabolism in patients with CKD.

Design: This is a 20-week, nonrandomized, single-center, pretest-posttest study. Twenty-eight subjects with CKD stages 3-4 were enrolled. The mean age was 67.6 ± 8.9 years, and the mean estimated glomerular filtration rate was 35 ± 14 mL/min/1.73 m. Subjects received a dietary supplement containing 3 g of oat β-glucan per day for 12 weeks. The 4-week period before the start of the intervention was used as a baseline comparison for each subject. The primary outcome was pre-post supplement changes in plasma levels of two uremic toxins: trimethylamine N-oxide (TMAO) and asymmetric dimethylarginine. Secondary outcomes were pre-post supplement changes in serum calcium, phosphorus, and Klotho levels. Repeated-measures analysis of variance was used to test the differences in outcomes over the three-month-long intervention.

Results: Serum levels of TMAO decreased by a median of -17% (interquartile range: -46%, 7%) at the end of the intervention. A nonstatistically significant change was observed for asymmetric dimethylarginine (median -0.6% [-12%, 20%]) and serum Klotho (median -3% [-8%, 7%]). There were no changes in serum levels of calcium and phosphorus. One month after discontinuation of β-glucan therapy, TMAO levels increased by a median of 16% (-12%, 36%) but remained slightly below the pretreatment levels. Eight subjects experienced side effects and discontinued the treatment.

Conclusion: A diet supplemented with β-glucan is safe and potentially efficacious in lowering serum concentrations of TMAO in patients with CKD. Larger trials with longer follow-up times are needed to determine whether such reductions translate into clinical benefits.