Daily Intake of Sulforaphane‐Rich Broccoli Sprouts Normalizes Bowel Habits in Healthy Human Subjects
Authors: Yanaka Akinori 
Published: November 2023

Background & Aims

Sulforaphane (SFN), rich in broccoli sprouts (BS), enhances nrf2‐keap1‐mediated anti‐oxidant systems, thereby protects cells and organs from various oxidative stress. Defecation is regulated by various functions of lower GI tract, and by intestinal microflora. Extensive oxidative stress impairs lower GI functions, thereby disrupts regular defecation. We have previously shown that intake of SFN prevents overgrowth of small intestinal anaerobic microflora, and protects the mucosa from oxidative injury. In this study, we examined whether daily intake of SFN‐rich BS affect intestinal microflora, and alter defecation habit in human healthy subjects.

Objects & Methods

This study was designed as a placebo‐controlled semi‐open labelled intervention trial, in order to examine whether daily intake of BS alters defecation habits in healthy humans. The study protocol was approved by the research ethics committee in Hitachi General Hospital (Approval Number 2015‐63). Forty‐eight healthy subjects, recruited from the hospital staff, agreed to participate in this study with written informed consents, All the participants showed more than 2 points by a constipation scoring system (CSS) (Dis Colon Rectum. 1996 Jun;39(6):681–5), in which the following factors were included, (1) frequency of bowel movements, (2) painful evacuation, (3) incomplete evacuation, (4) abdominal pain, (5) length of time per attempt, (6) assistance for evacuation, (7) unsuccessful attempts for evacuation per 24 hours, and (8) duration of constipation. The 48 subjects were divided into either the broccoli sprouts (BS) group (n=24), or the alfalfa sprouts (AS) group (n=24). The subjects assigned to BS/AS group were requested to eat either raw BS/AS 20 g every day for 4 weeks, respectively. BS contains 3.2 mg/g sulforaphane glucosinolates (SGS), a precursor of SFN, while AS contains no SGS. There was no significant difference in composition of other nutrients, minerals, vitamins, or dietary fibers between BS and AS, used in this study. All the participants were asked to answer the CSS‐based questionnaires. Collection of the questionnaires, blood and stool samples were made three times, just before, at the end, and at 4 weeks after cessation of the intervention trial. Blood samples were used to analyze complete blood count, biochemical indices, glucose, HbA1c, and thyroid hormones. Stool samples were used to measure ammonia concentration, and to evaluate distribution of major intestinal microflora. Percentages of the Bifidobacterium, Lactobacillales, Bacteroides, Prevotella, Clostridium[cluster IV, IX, XI, XIVa, XVIII, and others in the stool samples were assessed, using a T‐RFLP flora analysis,.

Results

All the participants were examined as per protocol during the 4 weeks intervention period, with neither the adverse reactions or nor the abnormal laboratory findings.

Intervention with BS, but not AS, showed a significant increase in defecation frequency, a decrease in length of time to attempt, and a decrease in CSS score.

Intervention with either BS, or AS, did not alter distribution of intestinal microflora or ammonia content in stool samples.

Conclusions

Daily intake of BS improves bowel habit in healthy human subjects. The beneficial effects of BS appear to be mediated by enhancing nrf2‐dependent antioxidant responses by SFN.

Support or Funding Information

This study was condcuted as a financially‐supported collaborative research with Murakami Nohen, Co.Ltd.