Effects of a Rice Bran Dietary Intervention on the Composition of the Intestinal Microbiota of Adults with a High Risk of Colorectal Cancer: A Pilot Randomised-Controlled Trial

Abstract

Rice bran exhibits chemopreventive properties that may help to prevent colorectal cancer (CRC), and a short-term rice bran dietary intervention may promote intestinal health via modification of the intestinal microbiota. We conducted a pilot, double-blind, randomised placebo-controlled trial to assess the feasibility of implementing a long-term (24-week) rice bran dietary intervention in Chinese subjects with a high risk of CRC, and to examine its effects on the composition of their intestinal microbiota. Forty subjects were randomised into the intervention group (n = 19) or the control group (n = 20). The intervention participants consumed 30 g of rice bran over 24-h intervals for 24 weeks, whilst the control participants consumed 30 g of rice powder on the same schedule. High rates of retention (97.5%) and compliance (≥91.3%) were observed. No adverse effects were reported. The intervention significantly enhanced the intestinal abundance of Firmicutes and Lactobacillus, and tended to increase the Firmicutes/Bacteroidetes ratio and the intestinal abundance of Prevotella_9 and the health-promoting Lactobacillales and Bifidobacteria, but had no effect on bacterial diversity. Overall, a 24-week rice bran dietary intervention was feasible, and may increase intestinal health by inducing health-promoting modification of the intestinal microbiota. Further larger-scale studies involving a longer intervention duration and multiple follow-up outcome assessments are recommended.

Colorectal cancer and microbiota modulation for clinical use. A systematic review

“…Most, if not all pro-, pre- and symbiotics can be obtained naturally through a healthy diet. Prebiotics have been isolated from mushrooms, 138 fruits, 142, 151 dairy, 140 rice, 161 and green tea 138 and probiotics from fruit skins, 117 dairy, 122 and fermented products. 146…”

“…181 In the case of rice bran, various phytochemicals in its composition have been associated with a decrease in the risk of cancer development, in particular CRC. 182 Its consumption increases levels of Firmicutes and Lactobacillus 161 and produces numerous metabolic modifications that could be related to a decrease in the risk of developing CRC. 166…”

Microbiome modulation in the prevention and management of colorectal cancer: a systematic review of clinical interventions

“…These findings were reported in healthy volunteers, as well as CRC survivors. Effects were significant in interventions as short as 4 weeks, but short-lived, for as little as 12 days post-intervention [26][27][28][29][30][31][32][33][34][35]. As Russell et al demonstrated, carbohydrates confer a protective effect in a high red-meat diet [36].…”

Therapeutic approaches to colorectal cancer via strategies based on modulation of gut microbiota

“…Shi et al, 2013;Si et al, 2021 Vegetarian diet Reducing the intake of red meat and animal protein, adequate dietary fiber, etc., which can increase the microbial diversity of the intestine. Smith et al, 2007;Sivan et al, 2015;Silveira et al, 2020;So et al, 2021…”

“…These foods have the opposite effects to "anti-inflammatory foods, " such as green leafy vegetables, dark yellow vegetables, whole grains, coffee, and fruit juice. Research has shown that dark green leafy vegetables (Fruge et al, 2021), rice bran (So et al, 2021), an increased intake of dietary indoles (Wyatt and Greathouse, 2021), vitamin D, calcium, folic acid, fruits, and other vegetables (Song et al, 2015) play substantial roles in the prevention of CRC. How does the composition of the diet prevent CRC and reduce the risk of CRC?…”