Fructose and IBS
Quote:
Bitter sweet
By Claire Deutsher Burke
August 03, 2008
DIGESTIVE upsets? It could be that you suffer from a condition called fructose malabsorption.
Until recently, little information has been offered in terms of possible causes or treatments for irritable bowel syndrome (IBS), the blanket term given for digestive upsets such as bloating, wind, cramping, nausea, diarrhoea and/or constipation, after more serious conditions have been ruled out.
Around one in seven Australians suffer from IBS, and many attempt to manage the condition by “eating well”. But it’s now known that, in many cases, the foods they turn to in order to improve their diet – fruits, vegetables and wholegrains – could actually be causing the irritation.
Fructose malabsorption – the inability to properly digest sugars in some fruits and vegetables – is believed to be a significant contributor to IBS symptoms.
Fructose is the naturally occurring sugar found in almost every fruit and vegetable and some grains, occurring either as a single sugar or a chain of sugars called fructans.
Fructose is generally absorbed by the small bowel, but in those with fructose malabsorption the small bowel is unable to break down the fructose, allowing it to travel into the large bowel.
The normal bacteria in the large bowel then act upon the undigested fructose and fructans, breaking it down by fermenting it.
Melbourne-based dietitian Sue Shepherd explains: “When fructose is fermented, it can cause the release of gas, which contributes to wind and bloating, and can change the whole bowel environment, which may lead to altered bowel habits such as diarrhoea or constipation, or a combination of both.” She says symptoms of IBS are common symptoms of fructose malabsorption.
Shepherd and gastroenterologist Professor Peter Gibbons, from Monash University in Melbourne, have pioneered research into fructose malabsorption in Australia.
Diagnosis of fructose malabsorption is achieved through a simple hydrogen breath test, usually over at least two sittings (the first is a control), where patients are given a sugar drink and then asked to breathe into a breathalyser device to measure the hydrogen gas produced in response to the drink.
“We don’t have hydrogen in our breath normally, but we would have it if we have malabsorbed something,” Shepherd says.
Once diagnosed, patients are advised to follow a fructose-free diet for a minimum of three months.
“If you reduce (fructose0 in the diet, three out of four people will have a marked improvement in their IBS symptoms,” Professor Gibbons says.
Fructose malabsorption can affect people of any age, although it’s more common in women than men. However, it seems that some people can spend a large part of their lives seemingly unaffected by symptoms, and then suddenly start to experience problems.
“In the majority of people, we don’t know what precipitates the problem,” Professor Gibbons says. “It could be something in the environment or stress, or it could be an infection, and the infection goes but the bowel is less well.”
Not so fruitless
Although fructose is present in almost every fruit and many vegetables and grains, fruit and vegies don’t have to be completely removed from the menu.
Foods with an even balance of naturally occurring sugars, such as fructose and glucose, are able to be absorbed normally, but if the ratio of fructose outweighs glucose, symptoms are likely.
“People with fructose malabsorption can still absorb fructose, but it has to be via a different mechanism, where glucose acts as a carrier molecule for fructose. The glucose piggybacks the fructose across the intestine and it can be absorbed that way,” Shepherd explains.
Once you’re aware of problematic foods (see box below), managing fructose malabsorption is relatively easy.
“It’s not a case of ‘I can’t ever eat fruit again’,” Shepherd says. “It’s about teaching people about the balance between fructose and glucose, and teaching them never to have too much of a fructose load at one time; not even too many ‘safe fruits’ at one time. It’s not a nutritionally inadequate diet – it’s simply identifying what the problem foods are and avoiding them.”
Unlike people with serious conditions such as coeliac disease, who must strictly steer clear of problem foods to avoid damaging their digestive system, if sufferers of fructose malabsorption are exposed to a little “bad fruit”, they may experience symptoms but won’t cause long-term damage.
Individual tailoring
While fructose malabsorption is a chronic condition, once diagnosis is established and symptoms have improved with the diet, it’s useful to experiment with fructose foods, as individual tolerance levels vary.
“There are varying degrees of severity,” Shepherd says. “Some people can handle breakouts every now and then, and others are just completely debilitated by it. That’s the individual sensitivity. Our job is to teach what the general rules are and then people can incorporate it into their diet. There may be times where you will be able to eat a bread roll or an apple and be okay, but if you were to continue to do it, you’d run into strife.”
Professor Gibbons says: “It’s all about dose, so we initially restrict stringently and, if the patient is doing well, we start easing back to see what level of restriction they need to have. The sensitivity of the bowel differs between individuals: some people don’t absorb any of the fructose they have and some people absorb some of it – it’s a very variable amount that’s absorbed, so there are various factors involved.”
• Sue Shepherd has written two recipe books for those with fructose malabsorption, Irresistibles For The Irritable (Shepherd Works) and Two Irresistible For The Irritable (Shepherd Works). Her handbook, Fructose Malabsorption Food Product Guide (Shepherd Works), provides a useful shopping guide. For more information, visit Sue Shepherd’s website at www.coeliac.com.au
A little too fruity
Problematic foods for sufferers of fructose malabsorption include:
Excess fructose
¿ Apples
¿ Pears
¿ Mangoes
¿ Watermelon
¿ Quince
¿ Fig
¿ Pawpaw
¿ Lychee
¿ Guava
¿ Persimmon
¿ Honey
¿ Fruit of any kind (even suitable fruits) in large amounts such as fruit salad, fruit juice or dried fruit.
Excess fructans
¿ Onions
(all varieties, including leeks)
¿ Asparagus
¿ Green beans
¿ Artichokes
¿ Chicory
¿ Endive
¿ Radiccio
¿ Coconut cream or milk in large amounts
¿ Inulin
¿ Wheat in large amounts (bread, pasta, cakes). Note: wheat-derived ingredients used in small amounts are suitable.
Paul’s story
Paul Richards, 26, a real estate agent from Montmorency, Victoria,
was recently diagnosed with fructose malabsorption.
“Last year I had a stomach infection. I spent five days in hospital and after I went home I was still not feeling well. I bought litres of apple juice and other things I thought were good for me, but I kept wasting away and felt horrible every day. My gastroenterologist ordered a hydrogen breath test and it turned out fructose malabsorption was the problem.
“When I think about it, before the infection I may have been a bit sensitive to fructose, but the infection made it a million times worse. I used to go to the toilet three to four times a day, but after the infection I was going 16 to 20 times a day. I lost 24 kilograms over three months. Once I had the test I stopped eating fructose and have felt progressively better.
“As soon as I eat something I shouldn’t, I get stomach cramps. At the supermarket, I check the labels on everything. I was hesitant for the first few months to go out for dinner, but now I take Lucozade with me. Because it’s pure glucose, if I eat anything that contains a bit of fructose, it helps it through my system. I’m so happy to be feeling good again.”
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