Which Dietary Recommendations Actually Work for Irritable Bowel Syndrome?

Healthy Eating

First and foremost, all patients with IBS should be provided with general advice on healthy eating. The British Dietetic Association recommends limiting potential symptom triggers such as alcohol, caffeine, spicy, and fatty foods. Patients should know to eat regularly, avoid late-night meals and large portions, eat slowly, and chew food thoroughly.

Several studies have shown that this dietary approach used as the first line of treatment for IBS can alleviate symptoms, but more research is needed to determine whether it is an effective therapeutic approach on its own. A balanced diet is certainly advisable for overall health.

FODMAP Restriction

High levels of short-chain carbohydrates, known as FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols), are found in grains, fruits, vegetables, legumes, and dairy products. These molecules are slowly fermented by gut bacteria, leading to the accumulation of water and gas in the intestines. There is growing evidence of the beneficial effects of a low-FODMAP diet in alleviating IBS symptoms. The FODMAPs that patients tolerate can be reintroduced to the diet to increase its acceptability and reduce potential harmful effects.

This diet is designed as first-line treatment combined with other methods. However, not all patients respond to it, some cannot adhere to it, and there are concerns about its long-term nutritional and gut microbiome consequences. Future research should focus on individualizing this diet.

Gluten-Free Diet

The benefits observed in patients with IBS on a gluten-free diet are likely due more to the reduction of FODMAP intake rather than the absence of gluten. A recent meta-analysis showed that there is not enough evidence to recommend this diet for IBS. However, for many patients, it is more accessible than FODMAP restriction, and they may follow it without medical advice. Patients should be warned of the risks of deficiencies in vitamins D, B₁₂, iron, zinc, and magnesium when following a gluten-free diet.

Gut Microbiome Modulation

Modulation of the gut environment through probiotic administration has shown promising results in IBS; however, it is still unclear which bacterial strains or their combinations are optimal and what the duration of treatment should be.

There is currently insufficient evidence on the benefits of prebiotics and synbiotics in IBS.

Psyllium

For patients with IBS with predominant constipation or diarrhea, the use of soluble fiber—psyllium (ground husks of the Plantago ovata seed)—is recommended based on recent meta-analysis results. However, the study did not determine the optimal dose or duration for this supplementation.

Conclusion

When recommending dietary measures for IBS, it is important to consider the patient's perspective and preferences. Establishing a good relationship and trust between the patient and the nutrition specialist is essential. Patients should be supported at least in adhering to first-line dietary recommendations.

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Source: Surdea-Blaga T., Cozma-Petrut A., Dumitraşcu D. L. Dietary interventions and irritable bowel syndrome—what really works? Curr Opin Gastroenterol 2021; 37 (2): 152–157, doi: 10.1097/MOG.0000000000000706.