What is the FODMAP diet?

Are you one of the 60-70 million Americans affected by digestive diseases? If you’ve tried everything to help your tummy troubles with no relief, or if you’ve been given a recommendation to try a low FODMAP diet but it’s too daunting to begin, then this article is for you. FODMAPs can be confusing, but we’ll break it down for you into bite-sized pieces and give you a second chance at a happy belly.

What does FODMAP mean? What is the FODMAP diet?

FODMAP stands for Fermentable, Oligosaccharides, Disaccharides, Monosaccharides and Polyols. These are all just different types of common carbohydrates that can be difficult to absorb and are highly fermentable in your gut. While FODMAPs are beneficial food sources for your gut bacteria (which is usually a good thing), for some people they can be too much and can produce uncomfortable gastrointestinal (GI) symptoms. The FODMAP diet is a type of elimination diet that uses a systematic approach to minimizing high FODMAP foods for a period of time, then slowly reintroduces them to determine which FODMAP foods affect a person’s symptoms.

Why do the low FODMAP diet?

While we at Kroger Health believe all foods can fit a healthy lifestyle, this more traditional “diet” is a keeper…but only for some. You should always try standard nutrition advice first before embarking on a restrictive diet like this one (e.g., optimized fiber intake, regular meals, fluids, activity, etc.). If all else fails, then consider the low FODMAP diet. It’s been consistently scientifically supported to improve symptoms and quality of life for people with Irritable Bowel Syndrome (IBS). It’s effective for 70-85% of people with IBS.¹ Though more research needs to be done, it may also be useful for those with Inflammatory Bowel Disease (IBD) such as Crohn’s and Ulcerative Colitis, Small Intestinal Bacterial Overgrowth (SIBO) and “leaky gut.”

What are high FODMAP foods?

Only foods that contain carbohydrates (even trace amounts) can be FODMAPs. However, not all foods with carbohydrates are considered FODMAPs, and there are many foods that contain low enough levels of FODMAPs that they can still be eaten on the low FODMAP diet. The most common high FODMAP foods are listed below. However, this isn’t a complete list. Sometimes low and medium FODMAP foods eaten in larger portions also qualify as high FODMAP foods. Monash University is the pioneer and expert in this field, and their app is an excellent resource for further, more detailed help.

What are low FODMAP foods?

Foods that don’t contain any carbohydrates are always low FODMAP, such as plain meat, fish, eggs, butter and oils. Lactose-free dairy products are typically low FODMAP. However, ingredients or seasonings used in these foods could contain FODMAPs - a little garlic, onion or honey can make something a high FODMAP food. Some medium FODMAP foods must be eaten in smaller portions to classify as low FODMAP (see portion examples given below). The below list is not exhaustive - FODMAP expert Registered Dietitian Patsy Catsos has great resources and lists of name brand low FODMAP products. Also check out FODY Foods products.

What about gluten?

If you don’t have celiac disease or non-celiac gluten sensitivity, then you don’t need to be completely gluten-free during this trial, unless your health care provider has recommended that for you. Gluten is not a FODMAP, but wheat, rye and barley are FODMAPs (and they contain gluten), so they’re excluded in this diet. There is one exception - traditional sourdough wheat bread is low FODMAP (but not gluten-free), so you can typically eat it. It’s OK to have some gluten cross-contamination during this diet (e.g., you don’t have to buy gluten-free oats or use a separate toaster). However, you’ll likely use many gluten-free products in order to avoid wheat as a FODMAP. So be sure to check ingredient lists. Just because a product is gluten-free doesn’t mean it’s low FODMAP. There are many gluten-free breads, crackers and pastas that are still high FODMAP.

Is the low FODMAP diet right for me?

The primary purpose of adhering to the low FODMAP diet is to improve symptoms for people with severe digestive problems. The low FODMAP diet tends to be low in fiber, probiotics, prebiotics and certain vitamins and minerals. If followed long-term by someone who isn’t suffering from digestive problems, this may negatively affect their gut microbiome, especially if followed longer than intended.1 However, for people with severe digestive symptoms, using this diet to get them resolved could be healthier in the end. Be sure to only follow the diet if it’s recommended by your doctor (ideally a GI doctor), a Registered Dietitian and/or after testing to rule out other medical causes. It’s best followed if administered by a Registered Dietitian trained in FODMAPs. It’s recommended that you don’t follow any full elimination diet long-term, since elimination diets are meant to be short-term with as many foods reintroduced as possible to ensure optimal nutrient intake.

How do you start a low FODMAP diet?

A traditional low FODMAP diet follows this process:

1. Elimination. Eliminate all high FODMAP foods from your diet for 2-6 weeks. Always keep a food and symptom record. It’s helpful to rate your symptoms on a scale of 0-10 daily (10 being the worst). Only eat low FODMAP foods during this time.

• Give yourself 1 week to meal plan and shop, and 1 week to practice (it’s normal to mess up during this time). Then, aim for 2 straight weeks doing it near perfectly and with symptoms resolving.
• If your symptoms have reduced to a level of 2 or 3 out of 10 or less on the symptom scale, then that’s success and you can move to the next step. If you still have significant symptoms, reassess your diet to ensure there are no large sources of FODMAPs still being eaten, and continue for another 2 weeks. If symptoms don’t improve after 4 weeks despite not eating FODMAPs, then it’s recommended to stop the diet and consult your doctor.

2. Reintroduction. Reintroduce high FODMAP foods by introducing one FODMAP category for 2 days followed by a 3-5 day “rest” period, then repeat until all categories are trialed. Continue to monitor with the symptom scale and food diary. You’ll be trying to figure out which category causes symptoms for you and how much you can consume. By the end, you should know if you either: 1) can’t have that group at all, 2) are completely OK with that group, or 3) are okay with a small portion, but a large amount causes symptoms.

• 2-day reintroduction phase: Continue to eat only from the low FODMAP elimination diet, except for the FODMAP category foods you’re testing. On the first day, eat only a small serving of your test food (e.g., to test oligosaccharides, eat ¼ cup of onions only for the whole day). On the second day, try to eat as much of that test category as would be normal for you (e.g., eat ¼ cup onions at breakfast + 2 pieces of whole wheat bread at lunch + ½ cup cashews for a snack + ½ cup of kidney beans at dinner).
• 3-5 day “rest” phase: Eat only from the low FODMAP elimination diet and nothing else.
• There may be times when you aren’t sure if something impacted you. Did you react to the food or was there something else “off” about your day that affected you, such as stress? If this is the case, retest that group later. Don’t start a reintroduction test if you’re not feeling well to begin with.
• If you find out you don’t have symptoms with a category (e.g., lactose), you should still avoid it while you reintroduce the other groups.
• Occasionally, FODMAPs are reintroduced more gradually than this approach.

3. Liberalize and adapt. It’s important for your health that you try to eat as diverse a diet as possible with as many FODMAPs as possible once you’ve discovered which FODMAP categories affect you.

• Find nutritionally similar substitutes for the foods you avoid. For example, try lactose-free milk and yogurt in place of regular versions.
• It’s not normal for a person to not tolerate any FODMAPS. If this seems to be the case for you, consult your doctor or Registered Dietitian.
• It’s normal to have some gas, bloating and other symptoms. If they don’t bother you too much, it’s likely better to eat a more diverse diet and include a small portion of a FODMAP group that causes only minor symptoms.
• You may notice that you’re sensitive to one food in a category but not another. For example, of the oligosaccharides, you can tolerate wheat bread but not onions. Eat and enjoy the foods you can.
• Continue to re-test the FODMAP categories that cause symptoms every so often to see if you now tolerate them. Our gut microbiome and tolerance can change over time.

An alternative approach to the full elimination diet is to do what’s often referred to as “FODMAP Gentle” or “FODMAP Light.” With this approach, you avoid the major sources of FODMAPS in your diet or just cut back a little, but not completely, and then reintroduce more casually. This may be more appropriate if you’re feeling overwhelmed or if there are other factors that make this approach ideal for you (see below).

Are there any precautions around a low FODMAP diet?

A low FODMAP diet isn’t appropriate for everyone. This diet isn’t recommended for those who have a history of disordered eating; those with many dietary restrictions, limited resources or food access; and those who are at risk of malnutrition and unintentional weight loss. It’s recommended to seek medical advice prior to beginning this journey. People with GI issues should be tested for celiac disease. The diet isn’t typically recommended for children, but it can be followed if warranted, under medical supervision and by a trained Registered Dietitian.

The FODMAP diet shouldn’t be a trendy “health diet” or for someone looking for “something new,” but rather should be reserved only for those people trying to understand digestive issues to identify the source of their symptoms.

Conclusion

If you’re experiencing digestive symptoms, especially if they significantly disrupt your life, see your primary healthcare provider or a GI doctor to rule out medical causes. FODMAPs and GI issues are complex and personal. Before you embark on a low FODMAP lifestyle, see a Registered Dietitian to ensure that you’re doing it correctly, as safely as possible, and to help you include more nutrient-dense low FODMAP foods with more personalized advice for your situation. With the help of a Registered Dietitian and armed with FODMAP facts, hopefully you can spend more time enjoying great food and less time in the bathroom.

^{Disclaimer: This information is educational only and not providing health care recommendations. Please see a health care provider.}

References

1. Catsos, Patsy. The IBS Elimination Diet and Cookbook. New York: Harmony Books, 2017.
2. Monash University FODMAP Diet [App]. Version 3.0.9 (435). Melbourne, Australia: Monash Univ.