Fructose malabsorption, 
FODMAPs and the Paleo diet

IBS and digestive problems can be due to a number of things, but what you eat probably is the most important factor. If you have been diagnosed with fructose malabsorption, one of the many possible causes of IBS, you are probably familiar with the term FODMAPs, which represents a group of short-chain fermentable carbohydrates and stands for (9; 14-16):


Download the

free PDF


food list!

What are the symptoms? 
The symptoms of fructose malabsorption are pretty much the same as IBS: bloating, abdominal discomfort, abdominal pain or cramps, gas and changes in your bowel movements (constipation, diarrhea or both). (9; 14-16) These symptoms can occur within a few hours or even after 48 hours after having consumed FODMAPs, so finding the culprit is not easy.

Fructose malabsorption is also associated with a higher risk of havingnutrient deficiencies and depression. (11-13) Studies have shown that reducing FODMAPs in your diet can alleviate gastrointestinal symptoms, Crohn’s disease and even depression. (7; 11; 17-18)

Why do FODMAPs can cause digestive problems? 
FODMAPs are found in a variety of plant-based foods, including vegetables, fruits, nuts, legumes and grains. Some people can handle FODMAPs, but if you have IBS, it is likely that something in your intestines or that your individual gut flora don’t agree with FODMAPs.

FODMAPs are, by definition, fermentable!

In other words, the bacteria in your intestines can “eat” these FODMAPs. The problem is that bacteria eat by fermenting nutrients. The fermentation of these short-chain fermentable carbohydrates results in the production of a lot of different types of gas produced in your gut. These large volumes of gas trapped in your intestines are responsible for the bloating and gas, while the pressure they create induces abdominal discomfort, pain and cramping.

Depending on the types of gas produced during the fermentation, which depends on the kind of bacteria that live in your gut, you might also experience constipationdiarrhea or alternating constipation and diarrhea.

On top of that, having small unabsorbed carbohydrates such as the FODMAPs staying in your gut attracts a lot of water from your body into your intestines by a process called osmosis. For some people, this extra water present in the gut cause extra bloating and abdominal distension, with the accompanying discomfort, pain or cramping, as well as watery diarrhea.

Think of it as having a micro-brewery in your gut… 
except that the gas produced in your intestines cannot escape that easily and affect how your intestines work!

How do I know if I react to FODMAPs?
You can either get tested or experiment with your diet.

The best test is called a hydrogen/methane breath test. You should first drink a lactulose solution to determine whether you are more of a hydrogen or methane gas producer and then test for the specific FODMAPs by taking another breath test with either fructose, lactose or sorbitol. There are currently no tests to check for fructans and galactans. These tests can usually be ordered and sent by mail and can cost anywhere between $100-200 each.

If you don’t want to spend money on these breath tests, you can easily find out if you have fructose malabsorption and an intolerance to FODMAPs by using an elimination diet protocol. The best way to accomplish this is by eliminating all high-FODMAP foods from your diet for at least 2 weeks, but some people will need at least 4-6 weeks before they see improvements. If your symptoms improve, you’ll have a pretty good clue that FODMAPs were part of your digestive problems. Then, all you have to do is to reintroduce FODMAP categories one by one to determine which one you react to.

The Paleo dietitian can help you figure out if FODMAPs are a problem for you (and more precisely what type and in what amount).

FODMAP intolerance is highly individual. Some people may be fine with fructans, but not with fructose, while some lucky ones may not be able to handle any FODMAPs at all. The amount of FODMAPs tolerated also varies a lot between people. 

--- A little bit more about FODMAPs --------

Let’s have a closer look at the individual FODMAP to better understand what they are and where they are found in your diet. You can also download a complete PDF list of low-, moderate- and high-FODMAP Paleo foods here

Download the

free PDF


food list!

★ Fructose:
Fructose is a monosaccharide, a type of sugar found in fruits and most sweeteners. If you have fructose malabsorption, you are not able to absorb fructose because you don’t have enough of the transporters that are supposed to carry fructose from inside your intestines into your body. 

Result: the unabsorbed fructose is fermented in your gut.

If you choose foods that contain equal amounts of glucose and fructose or more glucose than fructose, you may be able to absorb fructose a bit better. But if you consume sorbitol at the same meal, your tolerance to fructose will be even lower.

Foods that contain a high fructose to glucose ratio (with an excess ratio of 0.2 mg) are considered FODMAPs (19):

Fruitsapples, cherries, grapes, mango, pears, watermelon, ripe bananas, dried fruits

Vegetables: artichoke, asparagus, sugar snap peas, tomato sauces, tomato paste

Sweeteners: agave syrup, honey, high-fructose corn syrup (HFCS)

Drinks: fruit juices, soft drinks, energy drinks, sweeter wines, port wines

You should also know that even “safe” low-FODMAP fruits can also cause problems. For example, grapes may have a good ratio, but if you eat more than 10, you could be getting enough fructose to experience symptoms. For this reason, you will see that grapes are in the high-FODMAP category below. You can perhaps eat them... if you can eat less than 10 at a time!

This is also why juices and dried fruits are not recommended, because even though they may have a safe fructose to glucose ratio, their high fructose content will simply overwhelm your poor ability to properly absorb fructose. If you choose to eat low-FODMAP fruits, try to not have more than ½ to 1 serving of low-FODMAP fruits at a time and no more than 1-3 servings a day, depending on your tolerance. The same goes for “safe” low-FODMAP sweeteners.

Some people are so sensitive to fructose that they can’t even tolerate fruits or sweeteners at all. SIBO (small intestinal bacterial overgrowth) is also another condition worth looking into if you seem to experience symptoms from eating almost any type of carbs, sugars or fiber. 

★ Lactose: 
Lactose is a disaccharide produced by mammals and is therefore mainly found in dairy products. If you are lactose intolerant, it is because you lack the enzyme lactase required to break down lactose and absorb it properly. 

Result: the unabsorbed lactose is fermented in your gut!

 According to Elaine Gottschall, a biochemist specializing in gut health and author of the SCD diet (specific carbohydrate diet), the amount of lactose found in 1 oz. (30 ml) of milk can produce about ¼ cup (50 ml) of gas in healthy people. However, if you have a dysbiosis, or an imbalance in your gut flora, the amount of gas produced by the bacteria in your GI tract can reach up to 100 times that amount, which would correspond to more than a gallon (5 Liters) of gas in your intestines! (6) And that is only from the lactose found in 1 oz. of milk!

Sources of lactose: Milk has the highest amount of lactose, followed by fresh cheese and commercial yogurt. Aged cheese contains less lactose. Making your own yogurt or kefir by fermenting it for 24 hours removes all the lactose and make it a safer alternative for you if you are lactose intolerant. Raw milk is usually better tolerated because it contains enzymes that help you break down its lactose and better digest it. Heavy cream has very little lactose, while butter and ghee have none.

The Paleo diet is usually free of dairy products, although some people are able to include high-quality full-fat dairy products in their diet without any problems. 

★ Galactans: 
Galactans are mainly found in legumes (beans, lentils, soy and soy-derived products). These foods are not part of the Paleo diet because of their low nutritional value and high antinutrient content. 

★ Fructans:
Fructans are an oligosaccharide made of a chain of fructose that can be easily fermented in your intestines depending on your gut flora. More than 0.2 g of fructans in a serving of food is considered high in FODMAPs. (19) The main source of fructans in the standard American diet is wheat, but fortunately the Paleo diet eliminates all grains. Still, many other Paleo foods contain fructans and can be problematic if you have IBS.


High amounts: cabbage, garlic, Jerusalem artichoke, leeks, okra, onions, shallot, snow peas, radicchio, tomato sauce, tomato paste

Moderate amounts: beetroot, broccoli, Brussels sprouts, butternut pumpkin, fennel, green peas, sauerkraut

Other: chicory root, inulin, FOS (fructo-oligosaccharide), prebiotic, onion powder, garlic powder, pistachios, coconut sugar/nectar

***About Nuts and Coconut***
Although only limited data is currently available for nuts,
nut butter, coconut flour, coconut milk, unsweetened desiccated/dried coconut, dark chocolate and cocoa powder
, they are likely to contain fructans or other short-chain fermentable carbohydrates. Unpublished data released by Monash University in Melbourne, the leader in FODMAP analysis indicates that in addition topistachios, flaxseeds, almonds and hazelnuts are high in FODMAPs. Other nuts may be better, but I would suggest eliminating them all because they can be irritant for your gut 
and high in inflammatory omega-6.

★ Polyols: 
Polyols is a family of short-chain carbohydrates that include sorbitol, isomalt, xylitol and mannitol, which are sometimes also called sugar-alcohols. Like other FODMAPs, polyols are poorly absorbed and can become a fermentable product in your intestines. 

Sugar-alcohols are commonly used as a low-calorie sweetener in some sugar-free cookies, sugar-free chocolate sugar-free ice cream as well as in some medications and supplements, but most people are not aware that some fruits and vegetables naturally contain some polyols too. 

A food is considered high-FODMAP if it contains over 0.3 g of any individual polyol or a total of 0.5 g of total polyol per serving.  (19)


High: snow peas

Moderate: avocado (and guacamole), cauliflower, celery, mushrooms, sweet potatoes/yams


High: apricots, blackberries, cherries, stone fruits (nectarines, peaches, plums), pears, persimmon, watermelon

Moderate: longon, lychee, rambutan

Sweeteners: sorbitol, mannitol, xylitol, isomalt and other sugar-alcohols ending in -ol

Learn more about the book "Digestive Health with REAL Food" →

Why low-FODMAP diets don’t (always) work? People that react to FODMAPs also suffer from IBS and various digestive problems. The typical low-FODMAP diet may reduce FODMAPs, but it doesn’t take into account the many other factors that can irritate your gut, contribute to imbalances in your gut flora and prevent you from healing.

Many low-FODMAP foods are not healthy for you, including wheat- and rye-free grain products and many wheat- and HFCS-free sweets. Some people with fructose malabsorption even add extra dextrose (glucose) to their food to balanced out the glucose to fructose ratio, improve fructose absorption and reduce their symptoms... this is definitely not the best strategy to overcome an intolerance to short-chain fermentable carbohydrates.

Some people are able to somewhat control their symptoms on the low-FODMAP diet, but not everyone. And most people following the typical low-FODMAP diet can’t recover a normal gut function and regain a better tolerance to nutritious high-FODMAP vegetables and fruits.

Why the Paleo approach doesn’t (always) work?Some people with IBS see their symptoms improve drastically when starting on the Paleo diet, while other see no change or even a worsening. The Paleo diet eliminates many gut irritants, but if youconsume more vegetables, fruits, nuts  and coconut products than ever before, you could be experiencing a lot of GI symptoms because of the fermentation of these short-chain fermentable carbohydrates in your intestines.

Combining the Paleo and low-FODMAP approach = the Paleo-FODMAP diet!

Combining the Paleo diet with the low-FODMAP diet is the best way to remove all gut irritants, allow your intestines and gut flora to recoverand eliminate your IBS and fructose malabsorption symptoms.

The good news is that because the Paleo diet already removes a lot of short-chain fermentable carbohydrates from grains, legumes and sugar, you should have a somewhat better tolerance to other FODMAP-containing foods. Everyone has a different threshold of tolerated FODMAPs and you will have a bit more leeway for vegetables in your diet by combining the Paleo and low-FODMAP diets.

If this approach doesn’t work for you, it is very likely that you have SIBOand you choose adopt a slightly different approach to achieve a better gut health.

Why does it matter?

If you have been suffering from digestive problems, your doctor probably told you that IBS is nothing to worry about. Most health professionals are not aware of the profound impact GI issues can have not only on your quality of life, but also on your health! 
I know it firsthand. Regular bloating, abdominal pain, constipation and diarrhea can lead to a lot of inflammation in your body and can wear down your adrenal glands, hindering the good functioning of your body. If you are not able to lose weight, controlling your gut issues could be the key to your weight struggles.

Is fructose malabsorption and FODMAP intolerance curable?

Would you like to eat onions again? Or not have to bother about the type and amount of vegetables and fruits you eat? It is possible. I don't know if IBS, fructose malabsorption and other intolerances are curable, but they can definitely be improved! Following a Paleo low-FODMAP diet for a few months can help your intestines heal and recover and allow your gut flora to rebalance itself. Everybody is different, but after 3-6 months of following this protocol and controlling your symptoms, you could give high-FODMAP foods another try and you may just be able to tolerate them fine!

Adding homemade bone broth and probiotics (or sauerkraut or homemade fermented yogurt/kefir if tolerated) may also help you recover from fructose malabsorption and FODMAP intolerance.

Download the

free PDF


food list!

Learn more about the book "Digestive Health with REAL Food" →

Enter Your E-mail Address
Enter Your First Name (optional)

Don't worry — your e-mail address is totally secure.
I promise to use it only to send you the Paleo RD Newsletter.

References: (1) Eastern Health Clinical School – Monash University. The Low-FODMAP Diet: Reducing Poorly Absorbed Sugars to Control Gastrointestinal Symptoms. 2010. (2) Muir JG, et al. Fructan and Free Fructose Content of Common Australian Vegetables and FruitJ. Agric. Food Chem. 2007; 55: 6619-6627. (3) Muir JG, et al. Measurement of Short-Chain Carbohydrates in Common Australian Vegetables and Fruits by High-Performance Liquid Chromatography (HPLC)J. Agric. Food Chem. 2009, 57,554–565  (4) Shephred SJ, et al. Fructose Malabsorption and Symptoms of Irritable Bowel Syndrome: Guidelines for Effective Dietary ManagementJ Am Diet Assoc.2006; 106: 1631-1639. (5) Gibson PR, et al. Evidence-Based Dietary Management of Functional Gastrointestinal Symptoms: The FODMAP Approach. Journal of Gastroenterology and Hepatology. 2010; 25: 252–258. (6) Gottschall E. Breaking the Vicious Cycle: Intestinal Health Through Diet. 2004. (7) Shephred SJ, et al. Dietary Triggers of Abdominal Symptoms in Patients With Irritable Bowel Syndrome: Randomized Placebo-Controlled EvidenceClinical Gastroenterology and Hepatology. 2008; 6: 765-771. (8) Skoog SM and Bharucha AE. Dietary Fructose and Gastrointestinal Symptoms: A ReviewAmerican Journal of Gastroenterology. 2004; 99: 2046-2050. (9) Gibson PR and Shepherd SJ. Evidence-Based Dietary Management of Functional Gastrointestinal Symptoms: the FODMAP ApproachJournal of Gastroenterology and Hepatology. 2010; 25: 252-258. (10) Shepherd SJ and Gibson PR. Fructose Malabsorption and Symptoms of Irritable Bowel Syndrome: Guidelines for Effective Dietary ManagementJ Am Diet Associ. 2006; 106: 1631-1639. (11) Ledochowski M, et al.Fructose- and Sorbitol-Reduced Diet Improves Mood and Gastrointestinal Disturbances in Fructose Malabsorbers. Scand J Gastroenterol. 2000; 10: 1048-1052. (12) Ledochowski M, et al. Fructose Malabsorption is Associated with Early Signs of Mental Depression Eur J Med Res. 1998; 3: 295-298. (13) Ledochowski M, et al. Fructose Malabsorption is Associated with Decreased Plasma TryptophanScand J Gastroenterol. 2001; 4: 367-371. (14) Gibson PR, et al. Review Article: Fructose Malabsorption and the Bigger Picture Aliment Pharmacol Ther. 2006; 25: 349-363. (15) Barrett JS and Gibson PR. Clinical Ramifications of Malabsorption of Fructose and Other Short-Chain CarbohydratesPractical Gastroenterology. 2007; series #53; 51-65. (16) Born P. Carbohydrate Malabsorption in Patients with Non-Specific Abdominal ComplaintsWorld J Gastroenterol. 2007; 13(43): 5687-5691. (17) Gibson PR and Shepherd SJ. Personal View: Food For Thought – Western Lifestyle and Susceptibility to Crohn’s Disease. The FODMAP Hypothesis. Aliment Pharmacol Ther.2005; 21: 1399-1409. (18) Gearry RB, et al. Reduction of Dietary Poorly Absorbed Short-Chain Carbohydrates (FODMAPs) Improves Abdominal Symptoms in Patients With Inflammatory Bowel Disease – A Pilot Study. Journal of Crohn’s and Colitis. 2009; 3(1): 8-14. (19) Scarlata K. Succesful Low-FODMAP Living – Experts Discuss Meal-Planning Strategies to Help IBS Clients Better Control GI Distress. Today’s Dietitian. 2012; 14(3); 36.

New! Comments

Have your say about what you just read! Leave me a comment in the box below.
Enter Your E-mail Address
Enter Your First Name (optional)

Don't worry — your e-mail address is totally secure.
I promise to use it only to send you the Paleo RD Newsletter.
XML RSSSubscribe
read my disclaimer.

join the next REAL food challenge!

Learn more about my ebook Eating Out and Traveling on the Paleo Diet and 21 myths about the Paleo diet... debunked!