REF-981 · Lis et al., 2018 · Medicine & Science in Sports & Exercise, Vol. · Paper · PubMed

Low FODMAP: A Preliminary Strategy to Reduce Gastrointestinal Distress in Athletes

Blimited evidenceMeasured on trained athletesWritten before October 2026, being re-checked

Gastrointestinal distress in endurance athletes can resemble irritable bowel syndrome, where reducing fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) has demonstrated efficacy.

Eleven recreationally competitive runners with a history of nonclinical exercise-associated GI symptoms followed a 6-d low FODMAP and a 6-d high FODMAP diet in a randomised, single-blinded crossover separated by a 1-d wash-out, with two strenuous running sessions in each period.

Daily GI symptoms were significantly lower on the low FODMAP diet (mean difference in area under the curve -13.4), driven by flatulence, urge to defecate, loose stool and diarrhea. Symptoms during exercise did not differ between diets.

Participants

Eleven runners competing at recreational level (six women, five men; 5-km best 23:00 ± 4:02 min:s), all with a history of nonclinical GI symptoms linked to exercise.

Protocol

Design: controlled, single-blinded crossover; 6 d on a low FODMAP (LFOD) and 6 d on a high FODMAP (HFOD) diet in random order, with a 1-d wash-out between them.
Exercise in each period: two strenuous running sessions — 5 × 1000 m and a 7-km threshold run.
Measures: GI symptoms during exercise and daily; the Daily Analysis of Life Demand for Athletes questionnaire. Area under the curve for daily GI symptoms across each dietary period, compared by multilevel mixed-effects linear regression.

Key Results

Daily GI symptoms over the 6 d were significantly lower on LFOD than HFOD: mean difference in area under the curve -13.4 (95% confidence interval, -22 to -4.60; P = 0.003).
Daily symptoms significantly lower on LFOD: diarrhea (P = 0.004), flatulence (P < 0.001), loose stool (P = 0.03), urge to defecate (P = 0.04).
The diets did not differ significantly in symptoms during exercise, nor in Daily Analysis of Life Demand for Athletes answers (P > 0.05).

Practical Application

"Would a low-FODMAP diet fix my gut on runs?" In 11 recreational runners with a history of exercise-related gut symptoms (randomised single-blinded crossover, 6 d per diet), the low-FODMAP diet reduced day-to-day symptoms — flatulence, urge to defecate, loose stool, diarrhea — but symptoms during the hard running sessions were no different. The authors call the findings preliminary.
So: a short low-FODMAP period is a reasonable trial for an athlete whose problem is lower-gut symptoms through the day in heavy training; it is not shown to protect the run itself.
The comparison was against a high-FODMAP diet, not the runners' habitual diet, so the size of the benefit over normal eating is unknown.
Not from this paper; the base's own practice: a restrictive diet is a short trial with one variable changed, ideally with a dietitian, and never a route to eating less (SYNTH-54); persistent or severe bowel symptoms, blood in the stool or weight loss are a medical matter.

Limitations

n=11; one 6-d period per diet with a 1-d wash-out, which is short for a dietary crossover.
Single-blinded; symptoms are self-reported.
The comparator was a high-FODMAP diet, which may exaggerate the difference from habitual eating.
No performance outcome, no race, no effect on symptoms during exercise.
Written from the abstract and record metadata only (full text not read).
How this entry was checked and changed
Why this level

crossover, n=11