Author: Dr. Stephen Chaney
Can the FODMAP diet help reduce gas, bloating, diarrhea, and constipation? Everyone suffers from one or more of these symptoms, but nobody talks about them. For some they represent an annoyance. For others they can be incapacitating.
When the symptoms become frequent and start to affect quality of life, the medical community starts to give them names. When the symptoms occur at least 3 days/month for at least 3 months and there are no known diseases causing the symptoms, it is called irritable bowel syndrome (IBS). If the symptoms are also associated with inflammation, it is called inflammatory bowel disease (IBD). The principle forms of IBD are Crohn’s disease and ulcerative colitis.
A Primer On IBS And IBD
IBS is fairly common. Between 10-15% of the US population has been diagnosed with IBS, but experts estimate that as much as 25% of the population experiences symptoms consistent with IBS.
It is also important to understand that IBS is a collection of symptoms, not a disease. The only difference between IBS and the gas, bloating, and diarrhea (or constipation) that many people experience on a fairly regular basis is the frequency and severity of symptoms – and that is an arbitrary distinction. Someone experiencing those symptoms an average of 2 days/month is not significantly different than someone experiencing those symptoms 3 times/month.
While severe IBS can be incapacitating, it does not appear to cause lasting damage to the intestine or predispose to other diseases. Finally, the causes of IBS are largely unknown. Stress, obesity, and food sensitivities may all play a role.
IBD is much less common (0.4% of the US population), but much more severe. It can cause permanent damage to the intestine and can predispose to several diseases, including cancer. For that reason, you should always consult with your physician if you have severe, chronic gastrointestinal issues.
Standard treatment of IBS and IBD has traditionally consisted of recommendations to:
- Reduce weight if overweight
- Increase exercise
- Reduce stress
- Limit caffeine and alcohol
- Limit fatty foods
- If diarrhea is the primary symptom, limit dairy products, fruits, and sweeteners such as sorbitol and xylitol.
- If constipation is the primary symptom, increase dietary fiber
These interventions generally provide only partial relief of the symptoms, so medications are frequently prescribed to control the symptoms. Unfortunately, many of those medications have significant side effects.
Fortunately, research over the past decade suggests that there is a natural, holistic approach that can significantly reduce the symptoms associated with IBS and IBD, thus decreasing the reliance on medications to treat those diseases. It is something called the FODMAP diet. The FODMAP diet is rapidly becoming the standard of care for IBS and IBD, and the same diet also appears to significantly improve symptoms in people who merely experience gas, bloating, and diarrhea more frequently than they would like. More importantly, the principles behind the FODMAP diet can help almost everyone who experiences occasional gas, bloating, diarrhea and/or constipation.
What Is The FODMAP Diet?
The FODMAP diet was devised over a decade ago by a group of scientists in Australia. Basically, they identified all of the kinds of foods that were known to cause gas, bloating, diarrhea, and/or constipation in susceptible people and put together a diet that was low in all of them.
FODMAP is an acronym that stands for:
- F – fermentable carbohydrates
- O – oligo-saccharides
- D – di-saccharides
- M – mono-saccharides
- P – polyols
Of course, that statement comes under the “Aren’t you glad you asked?” category. It is meaningless to most people. A better way to understand this is to look at foods in the FODMAP category. They include:
- Lactose, found in milk and milk products (especially for people who lack the enzyme lactase)
- Fructose in high concentrations, found in foods like apples, pears, honey and agave syrup. (30-40% of individuals have problems absorbing fructose).
- Fructans, found in foods like wheat, onions and garlic.
- Galacto-oligosaccharides, found in foods like beans, lentils, and soybeans.
- Polyols such as sorbitol and mannitol, found in fruits such as cherries, apricots, and apples, and as sweeteners added to many “sugar-free” foods.
These are all foods that are poorly digested or poorly absorbed, so they are fermented by intestinal bacteria. It is the fermentation of these foods by intestinal bacteria that causes the gas, bloating, and diarrhea.
Does The FODMAP Diet Work?
The evidence that the FODMAP diet is effective is pretty impressive. For example:
- One study (Gearry et al, Journal of Crohn’s And Colitis, 3: 8-14, 2009) reported that 50% of patients with IBD showed significant improvement in overall abdominal symptoms, abdominal pain, bloating, flatulence, and diarrhea.
- Another study (Ong et al, Journal of Gastroenterology and Hepatology, 25: 1366-1373, 2010) reported that the FODMAP diet reduced gas production by 75% in both healthy volunteers and in patients with IBS.
- Another study (Studacher et al, Journal of Human Nutrition And Dietetics, 24: 487-495, 2011) compared the results for patients with IBD who received standard dietary advice versus patients who were put on the FODMAPs diet. (Note: The standard dietary advice at the time was discussed earlier. It avoided some, but not all FODMAPs, so you would expect it to give partial relief).
- 86% of patients in the low FODMAPs group reported better overall symptom response compared to 49% in the standard diet group.
- 82% of patients in the low FODMAPs group reported an improvement in bloating compared to 49% in the standard diet group.
- 85% of patients in the low FODMAPs group reported an improvement in abdominal pain compared to 61% in the standard diet group.
- 87% of patients in the low FODMAPs group reported an improvement in flatulence compared to 50% in the standard diet group.
- A follow-up study (Maagaard et al, World Journal of Gastroenterology, 22: 4009-4019, 2016) of IBS and IBD patients who had been on the FODMAP diet for an average of 16 months found:
- 86% of the patients who stuck with the diet reported either a full (54%) or partial (32%) improvement of symptoms.
- The greatest improvements were in bloating (82%) and abdominal pain (71%).
- Finally, a meta-analysis (Marsh et al, European Journal of Nutrition, 55: 897-906, 2016) of 6 placebo-controlled, randomized clinical trials of patients with IBS reported that the FODMAP diet:
- Decreased abdominal pain by 81%
- Decreased bloating by 75%
- Reduced overall symptoms by 81%
- Improved quality of life by 84%
What Does This Mean For You?
On the surface, this seems to be a good news, bad news story.
The good news is that the FODMAP diet is incredibly effective at decreasing frequent gas, bloating, abdominal discomfort, diarrhea and constipation – and it really doesn’t matter whether you have been diagnosed with IBS or IBD, or you are just someone who suffers from those symptoms more frequently than you would like.
The bad news is that the FODMAP diet is very restrictive. You can appreciate that when you look at the list of high FODMAPs foods you need to avoid. That means:
- The diet is very difficult to stick to long term. In the follow up study described above only 30% of the participants were able to stick with the diet for the full 16 months.
- The diet restricts so many foods that you would really need the guidance of a registered dietitian to design a nutritionally adequate diet plan.
The reality, however,is that very few people actually need to restrict all the high FODMAP foods to enjoy significant relief from their symptoms. Clinically, most physicians test various FODMAPs in their IBS and IBD patients and only restrict the ones that cause symptoms. You can do exactly the same thing yourself. Start by reducing groups of high FODMAP foods on the list. Once you have identified which food groups cause your symptoms, you can test foods within that group one by one.
The most important news is that the FODMAP diet concept may help many people who struggle with occasional gas, bloating, and diarrhea. Let me give you one example:
- Let’s suppose you have discovered that foods made from wheat flour cause you g.i. problems. You have concluded that you are gluten intolerant and carefully avoid foods containing gluten, but you still have occasional gas, bloating and diarrhea. You might be sensitive to the fructans in wheat, not the gluten. If so, a quick glance at the FODMAPs list suggests a number of fructan-containing foods you may be sensitive to that you would never have expected if you just focused on avoiding gluten. For example:
- Vegetables: garlic, onions, asparagus, artichokes and snow peas might be causing you trouble.
- Fruits: grapefruit, nectarines, plums and watermelon could be causing you problems.
- Processed foods: Inulin, a naturally occurring fiber, found in Jerusalem artichokes, is primarily a fructan. Inulin and several other naturally occurring fructans are added to many processed foods to increase their fiber content. These foods might also be causing you trouble.
This is just the tip of the iceberg. Most of us have probably identified one or two problem foods that we know give us gas. By using the FODMAPs list we may be able to identify other foods we should avoid.
The Bottom Line
- By restricting all foods known to cause gas, bloating, diarrhea and constipation in susceptible individuals, scientists and clinicians have created something called the FODMAP diet.
- The FODMAP diet has proven to be very effective at reducing those symptoms in people with IBS or IBD, but it is also equally effective at eliminating symptoms in individuals who simply suffer from gas, bloating, abdominal pain, diarrhea and/or constipation more frequently than they would like.
- The low FODMAP diet is also very restrictive, but the good news is that most people don’t need to eliminate all of the foods in the diet. You can systematically test and eliminate the individual foods that cause your symptoms.
- Most importantly, the FODMAP concept can help us identify problem foods that we might have otherwise never suspected of giving us gas. You will find an example of how this concept works in the article above.
- Gas, bloating, abdominal pain, diarrhea and constipation can also be caused by a number of serious diseases. For that reason, you should always consult with your physician if you have severe and chronic gastrointestinal issues.
These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.