If you're like many people who have started on the low FODMAP diet, you've been feeling a lot better as a result, and have realized that FODMAPs are to blame for the digestive symptoms you’ve suffered with for years. You may have even started to think of FODMAPs as "evil" or "bad." Many people start feeling so much better on the elimination phase of the diet that they don’t want to go through the re-introduction process because they know it will induce symptoms again.
However, it's not advisable to stay on the elimination phase of the diet until the end of time. Sometimes this message gets lost when doctors just tell their patients to start on the diet but don't explain that there is a second and third phase to the diet (they often don't know this themselves).
Though there aren’t enough studies yet to know the long-term health effects of being strictly low FODMAP, we do know that it alters the gut microbiome. And being on a restrictive diet can put a real damper on one's social life (in case you haven't noticed).
So what do FODMAPs have to do with the microbiome? Well the gut microbiome is made up of trillions of microorganisms including bacteria, fungi, and yeast. Your microbiome is the unique set of microorganisms that inhabit your gut specifically. Having the right balance and types of microorganisms is an important part of our overall health, and research indicates that the diversity of our microbiome can be related to many health problems from autism to obesity! Our microbiome diversity is affected by our diet, among other factors.
When you are on the elimination phase of the Low FODMAP diet, you are restricting fructans and galacto-oligosaccharides, which have prebiotic effects. Prebiotics are certain fibers needed to stimulate the growth of beneficial bacteria including probiotics. Therefore, if you're restricting prebiotics, you may be reducing good bacteria. Of particular concern is that certain strains of the good bacteria Bifidobacteria, are often found to be decreased in the feces of people on a low FODMAP diet. Bifidobacteria has some important roles in our overall health. For one thing, it produces Short Chain Fatty Acids (SCFA) including Butyrate. Butyrate is an especially important SCFA because it is believed to have a role in colon cancer prevention, the immune system, and our overall health status.
Besides the potential microbiome alterations, there's the social isolation of being on a restricted diet. Seeing as how pretty much all of our social events take place around food, it can be difficult and isolating to be on a restricted diet. Though there are ways to manage this and work around it, these social occasions will certainly be more enjoyable with less food restrictions.
It can also be difficult to get adequate nutrition when you are on a restricted diet. Some areas of possible nutrition concern with the low FODMAP diet are calcium, fiber, iron, and protein. A varied diet is necessary for overall good health and digestive function. It's possible to have adequate variety while doing low FODMAP, but most people have a hard time doing this on their own without the guidance of a trained dietitian.
Though there is no evidence that I know of to support this statement just yet, it seems that FODMAP intolerances may get worse the longer that someone is on the elimination diet, at least anecdotally. So if you've been on the strictest version for years, you may have a stronger reaction when you reintroduce FODMAPs than someone who has only been on it for a few weeks or months. Again, this has not been proven but something I've observed from years of working with patients and have heard from other dietitians.
So what do you do if you go through the whole re-introduction phase of the diet and find that you really can’t tolerate any FODMAPs? Though this is not very typical, it does happen sometimes. First, make sure you followed the reintroduction process correctly. Sometimes people do the process wrong and jump right to a huge serving of a high FODMAP food or choose a food that contains multiple FODMAPs and don’t tolerate it. It’s important that you start with only one FODMAP group, in a small amount, and gradually increase it to learn what your individual threshold is. Also, be mindful of what else is going on in your life at the time of challenges. If you are in the midst of a huge life stressor, like moving, starting a new job, going through a divorce, or dealing with a personal crisis, it would be better to wait until life settles down to start your challenges because stress can definitely impact your symptoms.
You may find that you can tolerate a small amount of onion or garlic during the challenge phase, which is useful to know because having some in your diet is likely better than none as far as prebiotic benefits. And it is certainly more convenient if you tolerate some vs. none, because small amounts of garlic and onion are in most pre-packaged and restaurant-prepared foods.
Sometimes people with certain medical conditions, like colitis, celiac disease, or SIBO, may have a harder time tolerating high FODMAP foods. Hopefully before you started on this diet, you got some thorough testing to ensure there were no serious underlying conditions. If you haven't done so, and you find you are reacting to all FODMAPs, it's worth circling back around with your healthcare provider for evaluation.
I hope this helps you understand why it's not a good idea to stay on the low FODMAP diet indefinitely. It's important not to "demonize" FODMAPs and to understand the valuable role they play, for all the reasons mentioned above. If you've tried to re-introduce and find yourself stuck, please stay tuned for my next post. I'll cover what to do if you've failed all the FODMAP challenges and can't get off the elimination phase of the low FODMAP diet.