Effects of rice-based and wheat-based diets on bowel movements in young Korean women with functional constipation

Constipation, a common digestive disorder, is often linked to insufficient dietary fiber intake. While dietary fiber is known to improve bowel movements, the effectiveness varies, and high-fiber supplements can cause discomfort. This study aimed to evaluate the effects of rice-based (brown rice and white rice) and wheat-based diets on bowel movements in young women with functional constipation. The researchers hypothesized that diets rich in whole grains (brown rice and wheat) would improve bowel function more effectively than a diet based on refined grains (white rice). This is important because grains are a primary food source, and identifying effective and natural ways to improve bowel function is crucial for managing constipation. Current recommendations for dietary fiber intake are often unmet, leading to a need for effective and palatable strategies to increase fiber consumption. The study focuses on comparing rice-based and wheat-based diets, as previous studies often lack direct comparisons between these common dietary sources.

Existing research indicates a correlation between dietary fiber intake from various grains and improved bowel movements. However, studies directly comparing the effects of rice-based and wheat-based diets on bowel function are scarce. Several studies have explored the impact of specific fiber supplements and types of whole grains on constipation, with varying results regarding efficacy and side effects. Some studies have shown that increased fiber intake, even from whole grains, doesn't always result in improved stool consistency. There's a need for more research on the comparative effects of different whole grain sources on bowel function in various populations. This study aims to address this gap by directly comparing rice-based (brown rice and white rice) and wheat-based diets.

This open, randomized, controlled, parallel-group study included 39 young Korean women (aged 19-30) diagnosed with functional constipation according to Rome III criteria. Participants were randomly assigned to one of three groups: brown rice-based diet (BRD), white rice-based diet (WRD), or wheat-based diet (WD) (13 subjects per group). Each group received a pre-defined diet for four weeks, with the daily caloric intake around 2100 kcal, containing an average of 30 g of dietary fiber per day. The BRD and WRD groups differed only in the type of rice used (brown vs. white). The WD group consumed wheat-based foods like breads, noodles, and cereals. Dietary compliance was monitored, and subjects were instructed to maintain their usual physical activity level. Primary outcome measures were total colonic transit time (TCTT), measured using radiopaque markers and abdominal X-rays. Secondary outcomes included number of bowel movements, fecal weight, short-chain fatty acid content, and fecal enzyme activity. Data was analyzed using appropriate statistical methods, including linear mixed-effect models and paired t-tests.

After four weeks, the BRD and WD groups showed a statistically significant reduction in TCTT compared to the WRD group (p = 0.028 and p = 0.022, respectively). Specifically, the BRD group experienced a significantly greater reduction in TCTT than the WRD group (-16.5 ± 8.1 vs + 6.8 ± 2.1 hours). Similarly, the WD group also displayed a significantly lower TCTT than the WRD group (-17.1 ± 11.9 vs + 6.8 ± 2.1 hours). The BRD group also exhibited a statistically significant decrease in left colon transit time (p = 0.030) and total colon transit time (p = 0.032). While the study mentions secondary outcome measures (number of bowel movements, fecal weight, short-chain fatty acids, and fecal enzyme activity), the specific numerical data for these measures is not detailed in the provided abstract and excerpt. The provided table shows baseline characteristics of the participants and does not show differences among the groups before the intervention.

The findings suggest that diets rich in whole grains, whether brown rice or wheat, can improve bowel function in young women with functional constipation compared to a diet based on refined white rice. The significant reduction in TCTT in the BRD and WD groups indicates faster movement of stool through the colon, thereby alleviating constipation. This study highlights the potential benefits of choosing whole grains over refined grains for improving bowel health. Further research is needed to elucidate the specific mechanisms underlying these effects and to explore the optimal levels and types of dietary fiber for maximizing benefits. The impact of other dietary factors and lifestyle interventions on bowel function should also be investigated.

This study demonstrated that brown rice-based and wheat-based diets are superior to white rice-based diets in improving bowel function in young women with functional constipation, as measured by reduced total colonic transit time. The findings support the inclusion of whole grains in dietary strategies for managing constipation. Future research could explore the long-term effects of these diets, examine different types of whole grains, and investigate the underlying mechanisms involved in the improvement of bowel function.

The study's relatively small sample size and the open-label design are limitations that could affect the generalizability of the results. The four-week intervention period might be too short to assess long-term effects. The study also focused exclusively on young Korean women, limiting the applicability of the findings to other populations and age groups. The lack of detailed data on secondary outcomes also limits a full analysis of the results.