# Effects of low-dose medium-chain triglycerides on bowel habit outcomes in Japanese adults prone to constipation: a randomized, double-blind, LCT-controlled crossover trial

**Authors:** Yuki Otsubo, Haruna Ishikawa, Keiichi Kojima, Shinji Watanabe, Naohisa Nosaka, Tsuneo Matsuike

PMC · DOI: 10.3389/fnut.2026.1746245 · 2026-03-11

## TL;DR

This study found that low-dose MCTs may improve bowel movements in Japanese adults who are prone to constipation.

## Contribution

The study provides new evidence on the effectiveness of low-dose MCTs for improving bowel habits in generally healthy Japanese adults.

## Key findings

- MCT intake significantly increased the number of days with bowel movements compared to LCT intake.
- MCTs also improved bowel movement frequency and stool volume in participants.
- Questionnaire-based outcomes showed changes, but differences between MCT and LCT were not always clear.

## Abstract

In Japan, many individuals experience symptoms of constipation. Medium-chain triglycerides (MCTs), composed solely of medium-chain fatty acids, have been suggested to improve bowel movements in athletes. However, most prior studies have assumed high-dose intake for ergogenic purposes, and evidence on the effects of low-dose interventions in generally healthy Japanese adults with a tendency toward constipation remains limited. In this study, we investigated the effects of consuming a small amount of MCTs on bowel movements, subjective abdominal condition, and health-related quality of life (HRQOL) in Japanese adults prone to constipation.

This randomized, double-blind, long-chain triglyceride (LCT)-controlled, crossover trial with a 2-week washout enrolled 88 healthy Japanese adults aged 20–64 years with three to five bowel movements per week. Participants ingested 2 g/day of MCTs and 2 g/day of LCTs for 2 weeks each. Bowel movement indicators, subjective abdominal condition, and HRQOL were measured.

Using a statistical model for within-participant comparisons, significant diet effects were observed for the number of days with bowel movements, bowel movement frequency, and stool volume. A post-hoc analysis further confirmed that the change from baseline in the number of days with bowel movements at week 2 was significantly greater during the MCT intake period than during the LCT intake period. By contrast, although multiple questionnaire-based endpoints showed significant pre–post changes within intervention periods, the corresponding between-diet differences were not clearly demonstrated.

Daily intake of even a small amount of MCTs, compared with LCTs, may be helpful in improving bowel movements in Japanese adults prone to constipation.

https://center6.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000060455; identifier UMIN000052997.

## Linked entities

- **Diseases:** constipation (MONDO:0002203)

## Full-text entities

- **Diseases:** abdominal condition (MESH:D000007), constipation (MESH:D003248)
- **Chemicals:** LCT (-), MCT (MESH:C000709826)

## Figures

2 figures with captions in the complete paper: https://tomesphere.com/paper/PMC13015347/full.md

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Source: https://tomesphere.com/paper/PMC13015347