An Effective Dietary Approach: The FODMAP Diet for Irritable Bowel Syndrome (IBS)
Irritable Bowel Syndrome (IBS) is one of the most common functional disorders of the digestive system, affecting approximately 10–15% of the population. Main symptoms include bloating, gas, abdominal pain, diarrhea and/or constipation, often with a significant impact on quality of life.
In recent years, the low FODMAP diet has emerged as one of the most effective non‑pharmacological interventions for relieving these symptoms.
What Are FODMAPs?
The term FODMAP stands for:
Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols — a group of short‑chain carbohydrates that are poorly absorbed in the small intestine and reach the colon, where they are fermented by gut microbiota.
This process causes:
- gas production (hydrogen, methane),
- increased osmotic pressure (drawing water into the bowel),
- symptoms such as bloating, gas, pain and diarrhea.
Examples of High‑FODMAP Foods
| Category | Examples |
| Oligosaccharides | Wheat, onion, garlic, lentils, beans |
| Disaccharides (lactose) | Milk, yogurt, ice cream |
| Monosaccharides (fructose) | Apples, pears, honey |
| Polyols | Sorbitol, mannitol, xylitol (in gums, sugar‑free products) |
How Do FODMAPs Affect the Gut?
FODMAPs are not fully digested in the small intestine and reach the colon almost intact. There:
- they are fermented by gut bacteria, producing gas,
- they increase osmotic water retention, causing diarrhea,
- they irritate intestinal receptors, causing pain and distension.
This mechanism explains why people with IBS experience intense symptoms after consuming certain foods.
The Three Phases of the FODMAP Diet
The low‑FODMAP diet is not a “trend”, but a scientifically designed protocol applied under the supervision of a gastroenterologist and dietitian. It includes three phases:
-
Elimination Phase (6–8 weeks)
Complete avoidance of high‑FODMAP foods to relieve symptoms.
Goal: reduce daily FODMAP intake below 3 grams.
This phase must be done with professional supervision to avoid nutritional deficiencies.
-
Reintroduction Phase
Gradual reintroduction of foods, one at a time, to identify which type and quantity triggers symptoms.
Each food is tested for 2–3 days and the reaction is recorded.
-
Personalization Phase
Based on the results, a personalized dietary plan is formed, where the patient knows which foods they tolerate and which to avoid.
The goal is not permanent restriction, but finding balance.
What Do Studies Show?
The effectiveness of the FODMAP diet is supported by multiple studies:
- In a review by Nanayakkara et al. (2016), 86% of IBS patients showed improvement in bloating, gas and abdominal pain.
- Böhn et al. (2015) showed that the FODMAP diet is as effective as traditional dietary guidelines, with greater pain reduction.
- A meta‑analysis by Altobelli et al. (2017) demonstrated a significant reduction in pain and bloating in patients following a low‑FODMAP diet.
A recent study (Hillestad et al., 2024) in patients with IBS‑D and IBS‑M showed that a strict FODMAP diet:
- significantly improved quality of life (QoL),
- reduced symptoms by 80%,
- without major nutritional deficiencies.
Patient Example
34‑year‑old male with chronic bloating, abdominal pain and alternating diarrhea–constipation.
Investigations (endoscopies, blood tests) showed no organic disease.
With a diagnosis of mixed‑type IBS, he started a low‑FODMAP diet with medical and dietary supervision.
Within 6 weeks:
- Reduced gas and bloating,
- Less abdominal pain,
- Better quality of life and sleep.
This targeted intervention highlighted the importance of personalization and medical follow‑up.
Limitations and Precautions
The FODMAP diet is effective, but not for everyone.
Factors such as stress, anxiety, psychological tension or depression influence the response.
The gut‑brain axis plays a critical role in symptom regulation.
Prolonged food restriction without guidance can lead to:
- lack of fiber, vitamins and micronutrients,
- alteration of gut microbiota,
- increased risk of nutritional deficiency.
Therefore, the diet must be followed only under medical and dietetic supervision.
What Is the FODMAP‑Light Approach?
For patients with mild to moderate symptoms, a more flexible version — FODMAP‑Light — can be used.
Instead of complete restriction of all high‑FODMAP foods, it focuses on a few main triggers such as:
- onion, garlic, legumes,
- certain fruits high in fructose,
- dairy products with lactose.
This approach is more realistic for everyday use and allows greater social and dietary flexibility, while maintaining symptom reduction.
The Role of Psychology and Lifestyle
IBS management is not limited to diet alone.
Effective treatment includes:
- stress reduction (e.g. mindfulness, gentle exercise),
- improved sleep,
- balanced hydration,
- regular meal timing.
A combined approach (diet + psychological support) increases success rates.
In Summary
The low‑FODMAP diet:
- Significantly reduces bloating, gas and abdominal pain,
- Improves bowel function and quality of life,
- Requires follow‑up by a specialized gastroenterologist and certified dietitian,
- Is not a permanent diet, but a diagnostic and therapeutic tool.
The FODMAP‑Light approach is a simpler, more sustainable solution for patients who find the full protocol difficult to follow.
Consult a Gastroenterologist
If you experience bloating, alternating diarrhea and constipation, or abdominal pain, you may be suffering from Irritable Bowel Syndrome.
Proper diagnosis and personalized dietary guidance can make a difference.
Book an appointment with Dr. Argyropoulos Theodoros,
Gastroenterologist – Hepatologist,
Consultant Gastroenterologist at GNA “G. Gennimatas”
& Scientific Director of the Affidea Peristeri Gastroenterology Center.
