What Diet is Best for IBS?

If you or anyone you care about deals with irritable bowel syndrome (IBS), you understand how debilitating it can be. The painful, unpredictable, and anxiety-provoking symptoms can be a nightmare and can put a serious damper on anyone's quality of life. 

So it's understandable that many different approaches to managing IBS have been tried and explored, both by the scientific community in the form of research, and by everyday people just trying to feel better and make peace with their gut. 

Many of the approaches out there have something to do with diet. Whether we're eliminating things or adding things, these IBS diet approaches recognize that eating can often be a trigger for individuals with IBS, and that in some cases, the right foods can help, or the wrong foods can hurt. Yet these diets take many different forms, and sometimes various diets that seem to work for one individual or another might seem downright contradictory.

So I'll give you a heads-up at the outset: that headline above isn't really quite the right question. The right diet for IBS depends on you. Your symptoms, your history, your ability to control your diet in the first place, your food preferences, etc. etc. The right diet for you might actually be no diet at all. (That is, no change in your current dietary pattern. We all eat, so we're all technically on "a diet.")

With that being said, let me walk you through the range of dietary patterns that work for some individuals. There are certainly more approaches than what we'll cover here, but the below list gives an idea of some of the most popular approaches, with varying degrees of effectiveness, ease, accessibility, and practicality.

1. The Mediterranean Diet. If you've been listening to what's been going on in the health and nutrition space for the past several years, it'll be no surprise to you that this one makes the list. The Mediterranean Diet (or MedDiet, as it's popularly called) is an anti-inflammatory eating pattern that has been studied for, and has been shown to be useful for, a broad range of health conditions. It's not always the most effective for every given disease or condition or syndrome, but it almost always makes the list--clearly, it's far better than the Standard American Diet for just about everything.

Now, it's worth mentioning that what we might call the Mediterranean Diet in nutrition research doesn't necessarily line up with what people are actually eating in the Mediterranean region. That's a very large and incredibly diverse area of the world. But in general, what nutrition researchers mean when they talk about the MedDiet is:

• Lots of fruits and vegetables--likely 8-10 servings per day at least.
• Choosing whole grains, when grains are consumed.
• Several servings of legumes and pulses per week.
• Nuts and seeds daily.
• Several servings of fish per week.
• Extra-virgin olive oil, and lots of it--often 3-4+ Tablespoons per day.
• Lots of herbs and spices for flavor and nutrients.
• Limiting red and processed meats, ultra-processed snack foods, and added sugar.

The Mediterranean Diet does have some effectiveness in IBS. While it's likely not the most effective approach for those with severe symptoms, it can certainly improve IBS symptoms in some individuals, while at the same time improving overall health. Plus, it's practical and doesn't require memorizing lists or eliminating anything--just diversifying a bit and limiting the ultra-processed stuff that we're all trying to reduce, anyway.

2. The High-Fiber Diet. High-fiber diets for IBS focus especially on soluble fiber sources, things like psyllium, oats, and the flesh of fruits and vegetables. Fiber is incredibly important for gut health, whether we're dealing with diarrhea or constipation or a mixture of the two. It can help nourish the gut microbiome, keep things moving at just the right speed, and reduce symptoms of bloating and abdominal pain. In fact, the fiber in plant foods is probably one of the reasons why the MedDiet is helpful for some with IBS.

Fiber supplements like Sunfiber (PHGG) and psyllium can be really helpful, as well, and can be quite gentle options for those who have a hard time making big dietary changes.

3. The Lactose-Free Diet. Lactose is an incredibly common dietary trigger for individuals worldwide. Lactose is commonly found in milk and dairy products, such as yogurt, ice cream, and soft cheeses. Many individuals are deficient in the enzyme needed to digest lactose (called lactase). Reducing the amount of lactose we consume, or taking supplemental enzymes to replace the lactase enzyme, can dramatically reduce symptoms in those who have that enzyme deficiency. 

If you're wondering whether this is you, try switching to lactose-free dairy products and limiting most cheeses to about an ounce or so at a time. You can also try the lactase enzyme caplets when you're consuming lactose-containing dairy. If this helps your symptoms, great! If lactase doesn't help but you still feel that your symptoms are connected with dairy consumption, remember that lactose is not the only potential trigger in dairy. The form of casein in most milks in the US is also a potential trigger, so you might try milk products containing only the A2 beta casein protein as well, before concluding that milk isn't the trigger.

4. The Gluten-Free Diet. This is a popular approach with some mixed findings in the actual nutrition research. Randomized controlled trials, the gold standard in clinical research, have yielded mixed results. Many individuals do improve on GF diets, but it's hard to tell in some cases whether it's the gluten that is the real variable here, or some of the other components of these grains (things like fructans, ATIs, or lectins--particularly fructans, as we'll talk about in a few minutes).

It's difficult to say at this time, but there do seem to be some individuals with a sensitivity to gluten itself. While it may be a smaller portion than what social media might make it seem, I believe that research does confirm that this group does exist. 

For those who have noticed issues with consuming grains and wheat products wondering if going GF is right for them, I strongly encourage discussing with a dietitian or gastroenterologist first, as we really should test for Celiac disease before completely eliminating gluten. Alternate approaches may include trying replacing regular bread with long-fermented sourdough to reduce some of the problematic components, and seeing if symptoms improve.

5. The Low-Fat Diet. Some individuals notice a big link between fat intake (especially greasy foods, fried foods, foods with lots of sauces or cheese, high-fat meats like steak, etc.) and symptoms. Keeping a food journal can help to determine whether reducing fat intake might be helpful for you, or you can just try avoiding or limiting portions of the foods I just mentioned. I would especially recommend this if your stools are often greasy or floating, since this indicates possible fat malabsorption. It's also possible that fat malabsorption can result from other issues above and beyond IBS, like exocrine pancreatic insufficiency (EPI) or bile acid malabsorption (BAM) to name a few. If you're not eating large amounts of fat but struggling to tolerate even small portions, consider talking to a gastroenterologist about getting tested for these conditions.

6. The Low-FODMAP Diet. Low-FODMAP is the most evidence-based diet for IBS, but also the most complicated and the most difficult to follow. It reduces portions of some difficult-to-digest and difficult-to-absorb dietary compounds, including lactose, sugar alcohols (polyols), excess fructose, fructans (fructooligosaccharides), and GOS (galactooligosaccharides). These are some of the most common intolerances for individuals with IBS, and reducing the total load of these FODMAP foods can have a dramatic impact on symptoms. Studies suggest that approximately 70% of those with IBS experience symptom improvement on the low-FODMAP diet. 

The diet itself can be quite challenging to follow, because it's not a typical elimination approach. Foods are not generally completely off-limits; there are just specific portions that must be adhered to during the restriction phase. The types of foods that are restricted include:

• Certain grains, such as wheat
• Lactose-containing dairy products
• Certain fruits and vegetables that contain FODMAPs, such as apples, stone fruits, asparagus, garlic, and onion
• Certain nuts and legumes, such as pistachios, cashews, and pulses
• Certain food additives and sweeteners, such as sugar alcohols (sorbitol, for example), honey, high-fructose corn syrup, and inulin

However, this is far from an exhaustive list. Many nutritious foods contain FODMAPs, and support is often needed to properly follow this plan without creating nutrient deficiencies, issues for the gut microbiome, and anxiety around food. 

Following the restriction phase, if it's effective, individuals will gradually bring back the restricted food types, one at a time, to test which might produce symptoms for them. This is often the most challenging phase of the diet, as the background diet must remain low-FODMAP while the testing is going on. 

Finally, the last phase of the diet is the personalization phase, where individuals bring back all foods, in appropriate portions that they are able to tolerate. This phase of the diet is meant to be nutritionally adequate, diverse, and sustainable for the long-term.

Hungry for More?
If you ant to learn more about low-FODMAP and these other dietary patterns for IBS, plus lifestyle and supplement recommendations and guidance on making sure you've got the right diagnosis in the first place, check out my online course. You can access my IBS Mini-Course for free for a limited time, and check out my full online course Living Well with IBS for a deep dive. 

Need more personalized guidance? I'm here for you. Reach out to me via email or schedule an appointment with me.

Erica Golden, RDN, IFNCP

Dietitian, educator, and author. Gut-brain axis expert. Trauma-informed integrative nutrition therapist.