Fructose Malabsorption

Are you one of the three to five million Australians who suffer Irritable Bowel Syndrome?

If so, chances are you are also a sugar malabsorber.

Catherine Naghten finds out more.

The best known form of sugar malabsorption is of course, lactose intolerance, in which sufferers have insufficient enzyme levels to break down milk sugar. Recently, however, researchers have begun to realize that fructose malabsorption may be just as serious a concern in the western world.

As Accredited Practising Dietitian Melanie McGrice, who specializes in the area explains:

“Fructose malabsorption is a condition where the body doesn’t break down fructose very well. So, the enzymes that breakdown fructose either aren’t present in as large a quantity as usual or they’re not working properly for some reason. Researchers have really just been looking into it over the last five years and now that they’ve found out that there is such a thing as fructose malabsorption, more and more research is being done into it.”

Symptoms vary between patients, however, as with lactose intolerance, the classic’ Irritable Bowel’ symptoms are the most common. These include bloating, stomach pain, irregular bowel motions and flatulence. “Some people actually don’t have any symptoms at all whereas other people will have very severe symptoms, and some people may only have one of the different symptoms. So they can really range,” notes McGrice.

Research has recently linked the condition to symptoms of pre-menstrual depression and the early stages of mental depression. It is thought that fructose malabsorption causes lower than normal tryptophan levels, a chemical needed for sleep regulation and serotonin (happy hormone) production. The condition may also play a role in low folic acid and zinc levels in older women and colic in infants who are regularly given fruit juices.

Who’s at risk?

Although it was only discovered recently, fructose malabsorption could be quite common, especially in people who eat a lot of processed foods or ‘diet’ products, and in those who already have a dietary problem such as celiac disease. One study, published in The Israel Medical Association Journal, found that out of 239 patients with Irritable Bowel symptoms, 44 per cent were in fact fructose malabsorbers.

The treatment for fructose malabsorption is simple – reduce the level of fructose in the diet- however mose sufferers are currently undiagnosed. “I think there’s still a lot of doctors that haven’t heard of fructose malabsorption,” says McGrice. “It’s very new and doctors probably diagnose people with irritable bowel syndrome without knowing what’s actually causing those symptoms.” The trouble with this, of course, is that these patients will continue to eat high-fructose foods and experience no improvement in their symptoms.

What foods?

University of Sydney researchers found that even 20 to 50 per cent of healthy subjects have some intolerance to the pure fructose used as a sweetener in many processed foods. Interestingly, though, they found that most people can digest fructose when it is combined with glucose, as is the case in most fruits and natural foods.

So, even though fructose is a fruit sugar, fructose malabsorbers don’t have to give up all fruit. “There are still a lot of fruits that you can eat so it’s choosing appropriate serves of fruit,” McGrice explains. “For example, oranges are still going to be a good choice or peaches are still foing to be a good choice.” In fact, most whole-fruits contain an adequate level of glucose, so you can still enjoy all berries, all stone fruits, citrus fruits, cantaloupe, grapes and even pineapples to name just a few. “I encourage people to eat more natural foods, such as fresh fruit and vegetables rather than foods with additives in them where possible,” says McGrice.

The real problem occurs because fructose is also used to sweeten processed products such as soft drinks, confectionary, diet products and a range of other foods. “These days it is a very common additive,” says McGrice. When we eat these foods, not only are we not getting the vitamins we’d get from a piece of fruit but we’re also getting a fructose sugar-hit that our bodies were never meant to deal with. While there only a few high-fructose fruits to reduce, people may also experience symptoms if they consume highly processed fruit, such as concentrated juices, rather than whole fruit.

The last group of foods that may cause problems are those containing fructans, or chains of fructose. The evidence on fructan foods, such as onions and wheat, is inconclusive at this stage, as they seem to product symptoms in some individuals but not in others.

Feeling better
Fructose malabsorption is diagnosed using a Hydrogen Breath Test at a hospital. This non-invasive procedure involves drinking a glass of sweet fructose and breathing into a bag at intervals over a three-hour timeframe. In normal patients, the body digests fructose efficiently, which produces no hydrogen. When the body fails to digest the sugar, it is instead broken down by bacteria in the gut, which produce hydrogen as a by-product.

There’s no cure at this stage but people with fructose malabsorption generally start feeling much better soon after the problem is identified. “It’s about treating the symptoms and also by avoiding large amounts of fructose,” says McGrice. “A lot of people experience excellent relief purely by changing their diet.” So who knows, a more natural and unprocessed diet, high in whole-foods, may not only be packed with vitamins, it might even solve those niggling health complaints and omprove your overall feeling of wellbeing.

Problem foods

Processed foods containing fructose:

• Corn syrup
• High fructose corn syrup
• FOS Fructose-oligo saccharide
• Some added sweeteners and sugars
• Many soft drinks and diet products (fructose doesn’t have to be listed on labels)
• Concentrated fruit such as fruit juices, fruit straps and dried fruit

Natural foods with more fructose than glucose:

• Honey
• Pears
• Apples
• Coconut milk
• Mangoes
• Figs

Fructans are chains of fructose. Fructan foods include:

• Wheat
• Onions
• Spring onions
• Leeks
• Asparagus