Rice bran supplementation modulates growth, microbiota and metabolome in weaning infants: a clinical trial in Nicaragua and Mali

Abstract

Rice bran supplementation provides nutrients, prebiotics and phytochemicals that enhance gut immunity, reduce enteric pathogens and diarrhea, and warrants attention for improvement of environmental enteric dysfunction (EED) in children. EED is a subclinical condition associated with stunting due to impaired nutrient absorption. This study investigated the effects of rice bran supplementation on weight for age and length for age z-scores (WAZ, LAZ), EED stool biomarkers, as well as microbiota and metabolome signatures in weaning infants from 6 to 12 months old that reside in Nicaragua and Mali. Healthy infants were randomized to a control (no intervention) or a rice bran group that received daily supplementation with increasing doses at each month (1-5 g/day). Stool microbiota were characterized using 16S rDNA amplicon sequencing. Stool metabolomes were analyzed using ultra-high-performance liquid-chromatography tandem mass-spectrometry. Statistical comparisons were completed at 6, 8, and 12 months of age. Daily consumption of rice bran was safe and feasible to support changes in LAZ from 6-8 and 8-12 months of age in Nicaragua and Mali infants when compared to control. WAZ was significantly improved only for Mali infants at 8 and 12 months. Mali and Nicaraguan infants showed major differences in the overall gut microbiota and metabolome composition and structure at baseline, and thus each country cohort demonstrated distinct microbial and metabolite profile responses to rice bran supplementation when compared to control. Rice bran is a practical dietary intervention strategy that merits development in rice-growing regions that have a high prevalence of growth stunting due to malnutrition and diarrheal diseases. Rice is grown as a staple food, and the bran is used as animal feed or wasted in many low- and middle-income countries where EED and stunting is prevalent.

Figure 1

Study recruitment and participation based on CONSORT statement guidelines for clinical trials conducted in Nicaragua and Mali (NCT02615886, NCT0255737315). 95 infants from León, Nicaragua and Dioro, Mali enrolled after meeting eligibility criteria, randomized by sex and location to one of two study arms. The number of diarrhea episodes and reasons for withdrawal were reported for each child.

Figure 2

Anthropometric Z-scores for Nicaraguan and Malian infants in rice bran and control groups at 6, 8 and 12 months. (A) Significant LAZ (p < 0.05) at 8 and 12 months in the rice bran group compared to control for Nicaraguan infants. (B) No WAZ significant changes between rice bran and control group in Nicaraguan and Malian infants. (C) WLZ at 8 months was significantly lower for the rice bran group compared to control in Nicaragua.

Figure 3

Rice bran and control infant stool microbiota at 8 and 12 months of age in Nicaragua and Mali. Nonmetric Multidimensional Scaling (NMDS) for (A). Nicaragua and Mali all samples (B). Control groups and rice bran groups at 8 and 12 months. NMDS was used on the OTU level to assess possible trends and clustering in the microbial community structure per treatment and time point. (C) Bacterial taxa at phylum and family level in Nicaragua (top) and Mali (bottom). Bar-graphs show phylum and family relative abundance based on the resulting OTU table generated using the ggplot2 package in R. These plots were generated for the data at the phylum and the family levels and meant to describe the microbial community structure per sampled group and per time point (8 months and 12 months) under each of the treatment levels (control and rice bran).

Figure 4

Microbiota differences between Nicaragua and Mali at 8 and 12 months between rice bran and control groups. Fold differences in relative percentage of OTUs different between control and rice bran groups at 8 months and 12 months. (A) Nicaragua, and (B) Mali. OTUs with fold difference more than 2 are shown for infants at 8 months (left) and 12 months (right). Fold difference for OTUs with FDR less than 0.05 is shown with the most significant OTUs on the bottom of each graph.