The information included in this post is for educational purposes only. It is not intended nor implied to be a substitute for professional medical advice. Always consult your healthcare provider to determine the appropriateness of the information for your own situation, or if you have any questions regarding your treatment plan.
By Kirin Escher, MD
You started your Whole30 expecting that it would improve your gut health and digestion, which makes sense. Many Whole30’ers report improved digestion, regular bowel movements, and less bloating as their favorite non-scale victories.
Yet you’re still experiencing troublesome gastrointestinal symptoms late into your program, or even after your Whole30 is finished. You might be experiencing bloating, flatulence, abdominal pain, diarrhea, and/or constipation, and possibly even headaches, fatigue, and mood instability. What gives?
One possible culprit is FODMAPs. I also suffer from the symptoms that can be caused by this group of foods, so I’ve had to dive in, research the science behind how FODMAPs affect digestion, and figure out what works for me. In this post I’ll share what I’ve learned; I hope the following information is both informative to you and helpful in achieving a happy, healthy tummy.
Looking for more information about gut health? Check out Melissa’s interview with Dr. Michael Ruscio on Do The Thing.
Are you planning your low-FODMAP Whole30? Download our UPDATED official low-FODMAP Grocery Shopping List.
What are FODMAPs? A primer.
FODMAP is an acronym that stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, And Polyols. These are carbohydrates (sugars) that are poorly absorbed and resistant to digestion; traveling through the intestines without being broken down. Foods containing FODMAPs may have only one of these sugars (such as onions, which contain oligosaccharides). Or, they can have a combination (such as apples, which contain both monosaccharide-fructose and polyol-sorbitol).
Here’s a quick overview of foods that fall into each category:
Oligosaccharides
Fructans – wheat, rye, onions, garlic
Galactans – lentils, beans, chickpeas, soybeans
Disaccharides
Lactose – milk (from cows, goats or sheep), soft cheese, yogurt, ice cream
Sucrose – table sugar
Monosaccharides
Fructose and glucose – mango, honey, high-fructose corn syrup
Polyols
Look for sugars with the suffix “-itol”
Sugar alcohols, such as mannitol, sorbitol, maltitol, xylitol
Some stone fruit (plums, peaches), avocados, and certain vegetables (cauliflower, mushrooms)
Foods that fall into multiple FODMAP categories
Apples, watermelon, sweet corn, pears, and coconut flour
To view a more comprehensive list (including foods the Whole30 already omits), refer to this guide by Monash University.
The human gut and its normal processes
Before we dive into the how and why behind FODMAPs and intestinal distress, I want to explain how the process of fermentation works in the digestive tract. The large bowel contains a vast number of intestinal bacteria that break down foods into energy and useable nutrients. Unused or waste products are then eliminated from the body. Fermentation is a process by which bacteria that live in the intestines break down carbohydrates. Normally, this process helps you get more nutrients and energy out of your food.
Sometimes, the fermentation process “goes wrong.” This can occur when the process happens too fast, you have damage to your microbiota or gut dysbiosis, or your body can’t absorb the byproducts properly. This can lead to gastrointestinal (GI) symptoms like flatulence, abdominal pain, diarrhea, and/or constipation, and possibly even headache, fatigue, and mood instability. Here is a more technical breakdown:
When FODMAPs are poorly absorbed in the small intestine they cannot be broken down. They pass through the small intestine and go straight to the colon. Bacteria in the colon then quickly break down these products to produce hydrogen, carbon dioxide, and methane, which are all gases. These gases can cause symptoms such as flatulence, bloating, and abdominal pain. The body tries to “dilute” these particles by drawing in more fluid to get rid of them. This process can cause diarrhea.
Every person’s ability to digest and absorb FODMAPs differs and is unique to the individual. For example, some people’s bodies do not make enough lactase. This causes lactose intolerance. However, others may make enough lactase and have limited or no symptoms when eating cheese or ice cream.
Whole30, FODMAPs and you: answering your FAQs
How do I know if I should eliminate high-FODMAP foods?
If you are mid- to late into your Whole30 or have completed 30 days of the program and you have new or continuing gastrointestinal symptoms, you could try eliminating high-FODMAP foods.
How long should I eliminate high-FODMAP foods?
At least 6-8 weeks. It can take up to 8 weeks to feel a change or decrease in symptoms. Consider working with a provider trained in low-FODMAP diets to customize your elimination and reintroduction plan.
How do I reintroduce FODMAPs after the elimination phase is complete?
Think of it like an extended Whole30 Reintroduction. After your 6-8 week elimination is completed, reintroduce FODMAPs one group at a time, just as you would reintroduce foods during your Whole30 Reintroduction.
By eliminating FODMAPs, will I miss out on crucial nutrition?
Most high-FODMAP foods are rich in vitamins, minerals, antioxidants, and fiber, but happily, there are plenty of nutrient-dense low-FODMAP foods available to you. During your reintroduction, pay attention to how each newly introduced food affects your symptoms. If you are able to eat something with no unwanted symptoms, there’s no reason to keep it out of your everyday diet.
Do I have to completely eliminate onions and garlic on a low-FODMAP diet?
Yes! Both are rich in fructans (oligosaccharide) and are some of the most responsible foods for triggering unwanted gastrointestinal symptoms. Simply removing an onion at the end of the cooking process is not enough (for example, taking the onion out of a pot of soup before eating). When onions are cooked, their FODMAPs end up in the entire dish. Be sure to check ingredients in pre-made foods for onions, too, including broths, soups, sauces. For garlic, you can still enjoy the taste by quickly infusing your cooking oil. Simply sauté a whole garlic clove for 1 minute in your desired cooking oil, then discard the clove and use the garlic-infused oil to cook your dish.
What about meat and other animal-based foods (like cooking with animal fats)?
Animal-based protein, fats, and oils do NOT contain FODMAPs. However, be sure to check ingredients in processed meats, such as sausage. They may contain onions, vegetable powders or seasonings that are high in FODMAPs.
More Resources
Need more support? Check out this article by Chris Kresser: Chris Kresser: Is a Low-FODMAP diet best for digestive disorders?
Are you planning your low-FODMAP Whole30? Download our official low-FODMAP Grocery Shopping List.
References
Harrison’s Internal Medicine
“The Complete Low-FODMAP Diet” by Sue Shepherd, PhD & Peter Gibson, MD
“The Low-FODMAP Solution” by Cinzia Cuneo, MSc
“The Low-FODMAP Diet for Beginners” by Mollie Tunitsk
