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FODMAPs – Your Guide to a Superior Digestive Tract

by drgangemi on August 30, 2011

Your digestive tract is said to be your second brain. It’s where many or your brain chemicals such as serotonin are made and is home to over half of your immune system in the form of healthy bacteria and gut associated lymphatic tissue. You don’t want to mess around with your gut, though many people do, often every time they put something in their mouth.

Digestive problems are a common complaint for most people. Whether it’s heartburn, bloating, gas, indigestion, constipation, or even more serious symptoms associated with diseases such as Crohn’s, ulcerative colitis, or diverticulitis, often food plays a major role. Unhealthy bacteria, yeast, other types of fungus, parasites, and inflammation can result in an unhealthy immune system, and a poorly functioning body, including your brain. So yes you are what you eat, and your physical and mental performance relies heavily on what you consume.

Although food allergies and sensitivities exist in many people due to an immune reaction to the protein of a food, there are other types of reactions present that cause gut problems. One such problem is perhaps even more prevalent than food allergies, and perhaps the reason for many food allergies as well as a host of gut problems including dysbiosis. This sensitivity has to do with the carbohydrates (sugars) in foods that create bacterial overgrowth.

Small Intestine Bacterial Overgrowth (SIBO) is a chronic bacterial infection of the small intestine.  The infection is often of the bacteria that normally live in the gastrointestinal tract but have abnormally overgrown in a location not meant for so many bacteria. Often SIBO occurs because of dysbiosis – where there is an imbalance of the beneficial bacteria (as well as yeast) with other types of harmful bacteria, yeast, and sometimes even parasites – but also because those bacteria are living off what you’re feeding them.

This healthy bacteria overgrowth in our gut can interfere with normal digestion and absorption of food. Leaky gut syndrome is a name given when there is damage to the membrane of the digestive tract which leads to malabsorption of nutrients such as iron, vitamin B12, vitamins A & D, as well as other nutrients. The bacteria consume and literally live off food unable to be absorbed in the digestive tract, so it grows and grows and as they do, they expel gas which causes abdominal bloating and pain, constipation, and diarrhea. Undigested food particles can enter through the gut lining causing an immune reaction resulting in food allergies and sensitivities. Auto-immune reactions such as Celiac disease and rheumatoid arthritis may be a result of poor digestion from food allergies or SIBO in some people. The gut bacteria can also enter the bloodstream, burdening other areas of the body and creating a toxicity resulting in pain, fatigue, and a host of other symptoms including those neurological, such as memory problems, dementias, and learning disabilities.

FODMAPs refers to Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols. These are a collection of molecules found in food that can be poorly absorbed by some people. When the molecules are malabsorbed in the small intestine of the digestive tract, they then continue along their journey along the digestive tract, arriving at the large intestine, where they act as a food source to the bacteria that live there normally. The bacteria then digest/ferment these FODMAPs and can cause a host of symptoms as noted previously.

Fermentation of undigested food happens normally in the colon, and although there is a gradient of bacterial colonization in the small intestine, significant fermentation in the small bowel is abnormal and results in SIBO. Since bacteria eat the starch contained in all grains, SIBO offers an explanation why avoiding all grains, not just gluten grains, helps many people even though they may not be “allergic” to gluten. And also, many people omit gluten from their diet and eat “gluten-free” foods, but see no change in their symptoms. This could possibly be because many gluten-free products contain bean and lentil flours, which is a basically switching one FODMAPs (galactan) for another (fructan).

FODMAPs, especially free fructose, may contribute to SIBO. Fructose malabsorption is defined as the incomplete absorption of fructose in the small intestine, followed by the delivery of fructose to the distal small intestine and colon, where it contributes to rapid fermentation and resultant abdominal bloating. The absorptive capacity of fructose varies from person to person.

The allowed foods are mainly those foods that people ate before agriculture began, and one I recently discussed in the Paleo-Type diet. The diet we evolved to eat over millions of years was predominantly one of meat, fish, eggs, vegetables, nuts, low-sugar fruits. Our modern diet including starches, grains, pasta, legumes, and breads has only been consumed for a mere 10,000 years. In the last hundred years the increase in complex sugars and chemical additives in the diet has led to a huge increase in health problems ranging from severe bowel disorders to obesity and brain function disorders. We have not adapted to eat this modern diet as there has not been enough time for natural selection to operate. It therefore makes sense to eat the diet we evolved with.

Here’s where FODMAPs are found:

  • Oligosaccharides (Fructans and Galactans)
    • Fructans are oligosaccharides made of fructose molecule chains that are completely malabsorbed because the small intestine lacks hydrolases to break their fructose-fructose bond. For this reason, fructans can contribute to bloating, gas, and pain. Wheat accounts for the majority of people’s fructan intake. Other high fructan foods are globe artichokes, Jerusalem artichokes, asparagus, beetroot, chicory, dandelion leaves, garlic (in large amounts), leek, and onion.
    • Inulin and fructooligosaccharide (FOS) are also sources of fructans, and are added to many foods to enhance their fiber content and also to many probiotic supplements to encourage the growth of friendly gut bacteria. Interestingly though it has a negative effect for many people unknowingly. I rarely use probiotics with FOS or inulin because so many people react to these products.
    • Galactans are oligosaccharides containing chains of the sugar galactose. The human body lacks the enzymes to hydrolyze them into digestible components, so they are completely malabsorbed. Dietary sources of galactans include lentils, chickpeas, kidney beans, black-eyed peas, broccoli, and soy-based products.
  • Disaccharides (Lactose, Sucrose)
    • Lactose is milk sugar so all cow, goat, and sheep milk should be avoided as well as those products made from them which still has some sugar content, such as yogurt. Butter is okay since it’s just the milk fat. Cheese will vary per individual based off tolerance and sugar content. (The bacteria in the dairy convert the milk sugar lactose to lactic acid during fermentation into cheese.) Low-lactose cheeses including Swiss, Parmesan, Gouda, Colby, provolone, cheddar, Edam, Muenster, and Monterey Jack may be okay for some. **Interestingly, there can be a few different problems with cow milk. Many people are allergic to the protein (casein, rather than the whey) in dairy, giving them various symptoms. Other may be lactose intolerant where they lack the enzyme lactase to break down the milk sugar, lactose, often resulting in the common digestive complaint of diarrhea. And yet another problem may be the FODMAPs relationship as the bacteria in the gut eat the lactose, fermenting the sugar and giving the person a host of symptoms. Damn dairy!
    • Sucrose is table sugar (the white stuff) and should be limited or removed based upon individual tolerance. This includes brown sugar, raw sugar, turbinado, and cane and beet sugars.
  • Monosaccharides (Fructose, rather than glucose, in this case)
    • Higher fructose (fruit sugar) content is found apples, mango, pears, watermelon, peaches, sugar snap peas, canned fruit, dried fruit, and fruit juice. This is where you should investigate your individual tolerance to certain fruits and find your threshold level. In other words, you may be able to eat one apple, but not two apples or an apple with another FODMAPs food, such as cheese. High fructose corn syrup and agave should always be avoided due to their excessive fructose levels. Honey may or may not be a problem in the FODMAPs diet, especially in low dietary amounts and depending on the source and quality of the honey. Honey with higher fructose content tends to crystallize more than honey with less fructose and more glucose.
  • Polyols are also known as sugar alcohols (Sorbitol, Mannitol, Maltitol, Xylitol and Isomalt). Most are too large for simple diffusion from the small intestine, creating a laxative effect on the GI tract. They are found naturally in some fruits and vegetables and added as sweeteners to sugar-free gums, mints, cough drops, and medications. Polyols will produce osmotic diarrhea when consumed in quantities above an individual’s personal threshold, (especially when they are added as a sweetener), or in combination with other FODMAP sources. Apples, apricots, avocado, cherries, raspberries, longan, lychee, nectarines, peaches, pears , plums, prunes, mushrooms, cauliflower, mushrooms, snow peas, and almonds all contain somewhat higher levels of polyols (xylitol). The added sugar alcohols should be removed 100% from the diet.

Omitting FODMAPs from your diet if you feel you are sensitive can have dramatic effects on your entire health. Energy levels often increase, sleep improves, blood sugar becomes more balanced, (since an overgrowth of bacteria in the gut is no longer consuming many of your carbohydrates for energy), mood improves, and many other symptoms improve as your gut heals. Ideally you should refrain from all the FODMAPs for at least a couple weeks, longer if your symptoms are not fully resolved by then, but continue to improve. After a good two weeks of being symptom-free you can try adding in various FODMAPs foods to check your sensitivity and tolerance levels to certain foods. You may find that you can’t eat a food such as wheat at all, but perhaps can handle some dairy periodically such as a particular cheese, for example. In essence, you figure out your FODMAPs threshold – the point at which your symptoms return but you must first clear them out of your diet one hundred percent!

Some physicians recommend using herbs, supplements, and even medications (antibiotics) to help rid the body of bacteria overgrowth quicker than just refraining from the foods that feed it. I have seen this beneficial, but also see it to be very individualized. In some patients I have found they respond well to herbs such as Uva Ursi and Goldenseal, whereas other patients supplements such as biotin and betaine hydrochloride work well. However, whatever the case, total omission of FODMAPs is necessary – the supplements just tend to help resolve symptoms quicker especially if they “accidently” snuck a FODMAPs food into their diet.

* Here’s a great list of the FODMAPs foods from http://www.eat-real-food-paleodietitian.com.

30 Comments

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  1. Thanks for this post. I have been gluten free for eight years and paleo for 1.5 but still have a lot of bloating and rheumatoid arthritis symptoms (even on autoimmune protocol). Maybe this is the next step.

  2. D Moore permalink

    Thanks for your clear explanation. I’m trying to implement a low-FODMAPs diet and having difficulty finding consistent explanations of what FODMAPs are and which foods to avoid.

    I have SIBO and my naturopath has me on herbal antibiotics, which are predominantly concentrations of garlic. Do you know if garlic in this dried, concentrated form is a big source of inulin? I’m concerned that taking the herbal antibiotics while doing a FODMAPs elimination would be counterproductive.

    • I just added a FODMAPs list – check the bottom of the article. I am not sure on the dried garlic if you’d react or not but you’re right if it does then it will feed the SIBO. If you’re not feeling better on the garlic, that would be one indication.

  3. brendan permalink

    I’m assuming that all of the vegetables within the first two columns of your list are all good to eat if you are on the two week test?

  4. Michelle permalink

    Dear Dr. Gangemi,
    Thank you for your informative posts. Very much appreciated. Could you recommend some strains of bacteria that one should look for in a probiotic supplement (minus FOS)?

    • Sorry I can’t. I recommend them per patient based off what they show a need for; I don’t make general recommendations.

  5. Kim permalink

    Doctor, what medical tests would you recommend for a person who experiences great bloating, intestinal gurgling, cramps, especially after eating sweets such as cake, cookies, etc…I am going to do the FODMAPs diet but would like to be checked first. Thanks!

    • I can’t personally guide you there. Medical tests don’t check for these things. They look for pathology, not a functional issue. No medical test is going to say you need to be, or not need to be, on a FODMAPS diet. Actually many GI docs don’t think diet has anything to do with gut health. If you find that hard to believe it’s because it is. I see patients all the time from “great” hospitals such as UNC and Duke, both close to my office, and the GI docs don’t ever discuss diet. Actually I’m see a woman right now who I’m helping to keep from having her entire colon removed. Her GI doc said that the foods she was eating had absolutely nothing to do with her scarring, inflammation, and massive gut destruction. She’s already over 60% better on a FODMAPs Diet and some other therapies.

      • Kim permalink

        Thanks again Doctor Gangemi! Two things….1) I was tested back in 2009 because of these stomach symptoms. One test was a Transglutamiase IgA Autoantibodies…and the other was a stool test. It came back saying I had no yeast but my Klebsiella was at 4+. Doctor just said “don’t worry about it”. Would you agree with that?

        and 2) I decided to do my own mini experiment over the last 3 days…..all lean protein and veggies, plain yogurt, blueberries, some white rice, whole wheat pasta, a few crackers, a nectarine and an apple and just water to drink…..and…..I have basically had no bloating at all. But today I added some cookies….and oh boy!! I look 6 months pregnant….again!! So, could it be JUST sugar that I am not digesting well….not just simple carbs in general??

        Thanks very much,
        Kim

        • Just because your transglutamiase IgA was neg doesn’t mean you don’t have a gluten problem. Could be wheat that was processed in the cookies, could be sugar.

          Sure, a +4 for any bacterial on a stool test should be a concern.

  6. Jackie permalink

    Hello

    I got an IGG food intolerance test and found out that I am intolerant to the whole dairy category including casein and whey. I am also very intolerant to eggs. I have noticed that I have an extremley hard time digesting carbs. I want to take the 2WT, but also go on the FODMAPs diet. Right now all fruits make me feel sick, should I wait for 2 weeks before eating the fruits that are listed in the safe category in the FODMAP diet? I also don’t know what to eat for breakfast considering I can’t eat any eggs or cheese.

    Also, if I go on the FODMAPs diet and it seems to help my symptoms, should I stay on this diet or will it be bad to not have the carbs in it? Also, how long into this diet should symptoms after drinking alcohol stop occuring (if ever)?

    • Yes I’d try the 2WT and then include the carbs on the FODMAPS when you start the 3rd week. See if you can tolerate some of those foods then.

      Alcohol issues could resolve via these diets or could be an entirely different problem – liver detox issue.

  7. Jackie permalink

    Okay thanks! How come it only says white rice in the test, is brown rice usually not tolerable? or what about quinoa? Also, are fiber suppliments bad to take during this test since fiber is considered a carb? I was looking at a 100% acacia fiber powder with nothing else added. If someone has carb intolerance does that mean they can’t digest fiber either? (example flax seeds).

    If taking enzyme pills should it help digest carbs easier or if you are truly carb intolerant will this not help the issue at all?

    Thanks for your help!

    • Bit too many questions to answer here. FODMAPs diet is not a “test”, it’s a type of diet. I don’t subscribe to fiber supplement use (usually) or enzymes either. There are articles on this site regarding both; use the search tab. :)

  8. Tanya permalink

    Hi Doc
    I stumbled across your site by accident and am planning to take the TWT, however, I don’t want to waste my time, as I have with so many other things concerning my stomach.

    I have had what was diagnosed as IBS, since the age of 12. I am now 42. In those days, as today, diet was NEVER a factor. By the age of 21, I would have an attack every month, sending me to hospital for valoid and pain injections, it was that bad. I had a colonoscopy and gastroscopy, and all they said was that I had an elongated colon and not to eat pizza and tomatoes.

    After being on numerous different diets (I have been wheat free, sugar, free, dairy free and alcohol free for 3 months, and symptoms did not change , although I did not have bad attacks ), having all the tests, being gluten free for the past 15 years, it is not fixed. I know I am not expecting a cure, but it seems to be getting worse.

    I have been following the GTNP diet for the past 4 years (food combining) , and taking probiotics for the past 3 years. This has definately helped, however, I have had 3 very bad attacks in the past 6 months and I cannot pinpoint it. The attacks also always seem to come when I have my period. My doctor has put me on HRT (natural ) and I have seen a slight difference.

    I have always suffered from constipation, since a child. Eating gluten free flours seems to make it worse.

    My diet for the past 6 months has been no glutens, bake with almond flour only, eat rice and potatoes maybe once a week, hardly any fruit, always cook with garlic, no fruit juice, stevia in my herbal tea, I make cheese with raw, organic milk, I make my own yoghurt using this milk, wine every night, mostly chicken, cream, butter, olive oil, and sugar in the occassional mud pie and usually a small piece of chocolate at night. I have tried even omitting chocolate from my diet for a month, and nothing changed. I admit to not eating many vegetables, although I do love them. Basically, I live on a lot of almond crackers, eggs, cheese.

    I still get bloating and that feeling where I know that I will get an attack, so I immediately stop eating (even if I have prepared a meal ) and live on tins of Ensure for a while, until my gut feels ready to take solids again.

    So , in a nutshell. Would trying out this diet work for me ? I am sorry this is so long, you may edit it . I am just desperate.

    • It sure won’t hurt :)

      • Tanya permalink

        Hi Dr. G . Thanks for replying, and I think it is truly amazing that you do reply to all these posts. However, your reply to my post does not instill any confidence in me that I should actually try this diet, based on my already 98 % grain free diet, and still symptoms.

        Thanks

        • I cannot give you specific advice. You asked if the FODMAPs diet may help you; that’s a lot more than being “grain-free”. You eat almond flour, dairy, garlic and probably many other high FODMAPs foods.

          • Tanya permalink

            I did think of the almonds and garlic, as I had read through the TWT foods (I just pulled a fresh new batch out of the oven !! ). Ok, so I should perhaps try the TWT test first, and then if I am feeling better, go onto the FODMAPS diet ?

            I am confused between this and the Paleo diet.

            Thanks

          • TWT – most limited/restricted
            FODMAPS = TWT type foods plus some fruits and starches (potatoes, rice). A few foods, like almonds and avocados, would be okay in the TWT but not FODMAPS.
            PALEO = FODMAPS with less restriction – more of a variety of fruits, veges, nuts

          • Tanya permalink

            Thanks so much !!! All very clear now.

          • Tanya permalink

            Hi Dr.G
            I had a trial run today before I start my TWT. Just wanted to know if feta cheese and halloumi cheese are okay to eat ? I make it myself. Regarding mayonnaise, mine is the most natural I can buy but it is 2g per serving. Should I be making my own ?

            Thanks

          • TWT questions/comments should go on the TWT post. I no longer answer them though as there are too many and they’ve all pretty much been answered. You’ll have to read through/search all those comments :)

  9. jackie permalink

    I would like to try the betaine hydrochloride pills to help digestion. I was just wondering if there are any brands you recommend and also does this help get rid of SIBO? And is brown rice or quinoa allowed or just white rice? And what about fries cooked at home with good fats?(canola oil)

  10. nikos charonitakis permalink

    Hi and thanks for the article.

    raspberries are in the safe side in the list from
    http://www.eat-real-food-paleodietitian.com.

    you mentioned the opposite in your polyols section.

    Which is right?

    Thanks in advance

    Nikos

  11. Muris permalink

    Hi DrG, what would u use to reduce klebsiella numbers in stool? Mines at 3+ causing some gut issues/food intolerences. Tried using golden seal to reduce numbers but not much effect. Any ideas?

    • Could be a number of things. Many other herbs such as Olive Leaf, Noni, Neem, and Oregano would be on the top of my list. But if you’re harboring a 3+ then most likely something is creating an unhealthy environment – inflammation, foods sensitivities, and general poor gut health.

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