IBS and its ugly cousin, Fructose Malabsorption
What is Fructose Malabsorption
Fructose malabsorption, formerly called dietary fructose intolerance, occurs when cells on the surface of the intestines are not able to break down fructose efficiently via the GLAT-5 receptors.
Fructose is a type of sugar found in fruits, vegetables, and honey. Fructose is also found in high-fructose corn syrup, which is an artificial sweetener used in sodas, canned fruits, and packaged desserts, as our food supply evolves, we are now consuming more fructose than ever before. Concerning stats show that the consumption of fructose from high fructose corn syrup has increased over 1,000 percent just from 1970–1990. It’s possible that this rise in consumption has led to an increase in fructose malabsorption and intolerance. Fructose malabsorption occurs as a result of the sugar fructose not being fully absorbed in the small intestine. As a result, the undigested fructose makes its way into the large intestine where it is set upon and fermented by intestinal bacteria. This metabolism of fructose causes unwanted gas, bloating, diarrhea, and stomach pain in the sensitive and reactive bowels of people with IBS. Fructose malabsorption is thought to affect approximately 40 percent of individuals in the Western hemisphere; its cause is unknown, but studies have shown that If you have certain gut disorders such as IBS, Crohn’s disease, colitis, or celiac disease, you’re more likely to have Fructose malabsorption and/or Fructan intolerance.
What is Irritable Bowel Syndrome
Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders and is also known as spastic colon, irritable colon, mucous colitis, and spastic colitis. About 11% of the population in most countries is assumed to have IBS, in saying this, IBS is considered a blanket term for unknown ongoing gastrointestinal issues. The symptoms of this disorder include recurrent abdominal pain or discomfort related to bowel habit changes that continue for 6 months, causing heavy burden on the quality of life of some affected persons. The mechanism behind IBS is considered to be multifactorial, including altered motility, visceral hypersensitivity, altered gut microbiota, and dysfunction of the brain-gut axis and the immune system.
Possible causes include an overly sensitive colon or immune system. Postinfectious IBS is caused by a previous bacterial infection in the gastrointestinal tract. The varied possible causes make IBS difficult to prevent. More often, certain foods can be common triggers for many people with IBS. However, some foods may have a greater effect on you than on others. It may help to keep a food diary for a while to learn which foods are triggers for you. Some foods that you may to limit or exclude include: beans, onions and some other vegetables, fruits, certain dairy foods, certain carbohydrate and foods that contain sorbitol, mannitol, or xylitol
Research on the Connection to IBS
Research backs up the identification of Fructose Malabsorption as a cause of intestinal distress, as well as its possible link to IBS.
One study made a comparison between healthy individuals and people who were self-identified as suffering from fructose intolerance based on the fact that they experienced bloating and flatulence after eating certain fruits. The self-identified patients had higher breath hydrogen levels and did experience more bloating and flatulence as a result of drinking the fructose solution than did healthy individuals.
Another study that looked specifically at fructose intolerance in 80 adults diagnosed with IBS found that up to one-third of patients with suspected IBS had dietary Fructose Malabsorption.
Interestingly, of these 80 patients, 26 participated in a follow-up assessment one year later. Upon follow-up, 14 of these patients reported that they were able to comply with a fructose-restricted diet, and these participants experienced significant improvement in the symptoms of pain, belching, bloating, indigestion and diarrhea. The patients who did not comply with the fructose-restricted diet continued to have symptoms.
Diagnosing Fructose Malabsorption
A hydrogen breath test is a common test used to diagnose issues with digesting fructose. It’s a simple test that doesn’t involve a blood draw. You’re required to limit carbohydrates the night before and fast the morning of the test. Failing to do this can alter the results, often leading to false positives/negatives.
At your doctor’s office, you’re given a high fructose solution to drink, and then every 20 to 30 minutes for several hours your breath is analysed. The whole test lasts about three hours. When fructose is unabsorbed, it produces higher amounts of hydrogen in the intestines. This test measures how much hydrogen is on your breath from this malabsorption.
Of note, the fructose intolerance breath test is similar to the lactose intolerance test, except that your breath is analysed for hydrogen gas after consuming fructose dissolved in water (and not a lactose-containing beverage).
With the fructose intolerance breath test, a high level of hydrogen gas in your breath indicates that the fructose in the solution has been fermented by bacteria in the large intestine. This suggests that your small intestine is having difficulty absorbing the fructose.
Differential Diagnoses
In addition, small intestinal bacterial overgrowth (SIBO) is a possible diagnosis when the hydrogen breath test is positive. Your healthcare provider must determine whether that SIBO or fructose intolerance is the proper diagnosis to describe your condition.8 The diagnosis of SIBO can be confirmed with a hydrogen breath test analysed after drinking a sugar solution containing glucose or lactulose (not fructose).
Eliminating fructose from your diet is another way to tell if you have fructose malabsorption. With the help of a registered dietitian, you can develop a plan to effectively remove any foods containing fructose and see if your symptoms resolve. This is often referred to as the FODMAP elimination diet. More information about this process can be found here: Monash FODMAP
Different people have different tolerances for fructose. Some may be more severe than others. Keeping a food journal can help to track the foods you’ve eaten and any symptoms you have.
Research suggests that this condition, called fructose malabsorption, may contribute to or even cause the symptoms of intestinal distress seen in some patients with irritable bowel syndrome (IBS). In fact, the identification of fructose malabsorption is a key component of the theory behind the use of a low-FODMAP diet for IBS. If you suspect fructose is the problem for your IBS, reduce your fruit intake to just three a day, avoid particularly high fructose fruits (Apples, watermelon, cherries, mango and pears), limit your intake of fruit juice to a small glass (100ml) and avoid foods containing high fructose corn syrup, fruit juice concentrates and honey. Of note Fructan (a longer sugar chain of Fructose) can also contribute to similar symptoms, Fructan is found in high levels in foods such as garlic, onions, artichokes, beans and grains. Often people suffering from Fructose malabsorption, also have a sensitivity to Fructan.
Treatment of Symptoms
While there is no cure for IBS or Fructose malabsorption, but there certain steps you can take to reduce your symptoms.
Xylose isomerase is an enzyme that converts fructose to glucose in the small intestine.
Alpha-d-galactosidase is an enzyme used to digest complex carbohydrates and Fructan in foods and helps in digestion. It also prevents the formation of gas or bloating.
Probiotics are “good” bacteria that may ease the belly pain and gas you get with IBS. There aren't specific recommendations on how much you should take, which kinds, or how often. Studies have shown there is a potential for benefit, but more research is needed.
Prebiotics: These sugars serve as food for “good” bacteria and can help them grow.
Avoiding the following foods may bring some relief:
Milk
Milk and other foods that contain lactose, like cheese and ice cream, can cause gas and bloating in people who are lactose intolerant. About 70% of adults worldwide do not produce large amounts of lactase, an intestinal enzyme that helps break down the sugar in milk. Without this enzyme, the small intestine cannot absorb lactose, which passes undigested into the colon, where bacteria ferment and cause gas. Even though dairy products are the major culprits of discomfort for some IBS sufferers, yogurt proves to be an exception. The live cultures in the yogurt break down the lactose, so it's less likely to cause gassy symptoms.
Foods High in Fructose
High fructose corn syrup is a main ingredient in processed foods, commercially prepared sweets, snacks and soft drinks, and these items can aggravate IBS symptoms. But they are not the only source of blame (or bloat).
It turns out some very healthy foods like apples, pears and dried fruits are naturally high in fructose, which when ingested, can trigger some of the same side effects as undigested lactose. Fruits lower in fructose, such as berries, citrus and bananas, may be a better choice for people with IBS.
Carbonated Beverages
Because the bubbles in beverages like soda and seltzer can produce a similar fizzy effect in the GI tract, stick with water and lactose-free milk to quench your thirst. And before you think about adding juice to that list — remember that fruit-based drinks are frequently high in fructose!
Caffeine
Caffeine can increase diarrhea, another major symptom of IBS. High sources of caffeine include coffee, tea, cola drinks, chocolate and some over-the-counter pain relievers designed for headache relief — check labels carefully.
Sugar-free Chewing Gums
Many sugar-free gums are made with artificial sweeteners such as sorbitol and xylitol, which have been shown to cause diarrhea. In addition, chewing gum leads to more swallowed air and gassiness.
In Conclusion
IBS is often a mild condition that can be well-managed by diet and other lifestyle improvements, but it may significantly impact your quality of life and can be stressful to manage. Some people develop depression and anxiety, migraine, fibromyalgia and/or chronic fatigue syndrome.
If IBS is causing you to feel down, anxious or upset, there are IBS-specific psychological support services. Talk to your GP about whether they are right for you.
For more information and support, try these resources:
Monash University FODMAPs and Irritable Bowel Syndrome.
The Continence Foundation of Australia — National Continence Helpline.
