IBS--Free at Last!

Polyols 101

Many of my clients tell me that even a few small pieces of sugar-free candy or gum cause diarrhea. Ditto for the well-know effect of prunes or cherries. What do these foods have in common? They contain polyols, also known as "sugar alcohols".

Technically, they are FODMAPS carbohydrates, and they are sweet! Most polyols are poorly absorbed, and wind up in the large intestine when they are consumed. In the large intestine, polyols are fermented by gut bacteria. They are also capable of drawing water into the large intestine. Together, the excess gas and excess fluid can cause distension of the colon, which cause bloating, flatulence and looser stools for the IBS sufferer. In a double whammy, eating or drinking sugar alcohols worsens fructose intolerance!

Some sugar alcohols, such as sorbitol, occur naturally in fruits such as apples, pears, and the "stone fruits," which include plums, prunes, apricots, peaches, cherries and so on. Sugar alcohols are often used to sweeten "sugar-free" foods (such as candy, gum, low-carb items, and bubbly water) and liquid medications. They can be recognized on the food label's list of ingredients by the ending "-ol". Examples are xylitol and maltitol.

Note that erythritol seems to be an exception. Studies have shown it is well absorbed and unlikely to cause GI symptoms.

Fructose 101

Fructose is known as "fruit sugar". It is present in fruits, some vegetables, honey, granulated sugar, agave syrup and high-fructose corn syrup. In the past, the human diet was lower in fructose than it is today--think of how hard it was to get honey in the wild, for example, or what a treat it would have been in the past to have fruit out of season, much less a never-ending supply of ketchup, cookies, candy and other sweets. Now it seems as though fructose is everywhere in our food supply.

Our capacity to absorb fructose is easily overwhelmed; it is almost considered normal to experience abdominal pain, flatulence, bloating or diarrhea when we overdo the amount of fruit or fruit juice we consume--many people have experienced this phenomenon. But some of us experience symptoms with much smaller intakes of fructose. And most of us overlook the impact that large portions of sugary sweets, baked goods and soft drinks can have. And what about those honey or fruit juice concentrate-sweetened energy bars? Interestingly, apples are part of the traditional BRAT diet sometimes recommended to fight diarrhea. Umm...maybe apples and apple juice aren't such a good idea for some people with diarrhea.

Diagnostic dietary fructose intolerance tests are available, but are not ordered as frequently in the US as they are elsewhere. If you suspect you don't tolerate fructose very well, try cutting back on soft drink and other sweets. Limit tomato paste. Choose small portions of fruits that are lower in fructose, such as kiwi, berries, citrus fruits, and bananas. Read labels, and avoid or limit portion sizes of foods sweetened with honey, fructose, high-fructose corn syrup, agave syrup and fruit juice concentrates.  See if you feel better!

Fructose malabsorption can occur on its own, or it can be part of the larger IBS picture.The FODMAPS elimination diet in IBS--Free at Last! can help you figure out how fructose fits into your IBS scenario.

It is important to distinguish dietary fructose intolerance, described in this posting, from hereditary fructose intolerance, which is a serious, hereditary disorder requiring a truly fructose-free diet.

Click here for more details about dietary fructose intolerance and how it causes GI symptoms.

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Fructose Malabsorption and Depression

Do an internet search for the terms "fructose malabsorption" and "depression" and you will find a lot of buzz over the possibility that the two are linked. Google returned over 6,800 hits on this combination. The idea seems to be taking on a life of its own, and is treated as fact on a number of web sites and blogs. I wondered if there was any of that pesky old evidence on the subject.

I've spent several evenings poking around the internet, reading abstracts and peer-reviewed research reports, most of them published in Europe. In fact there are a number of interesting published research reports that suggest there may be a link worthy of further study. It is far from proven, however. The handful of studies that have been done, most by a particular workgroup at the University of Innsbruck, Austria, included a very small number of study subjects. The researchers have tried to discover whether there was an association between fructose or lactose malabsorption and depression. They did find such an association, but only in females. But the studies simply weren't designed to prove that fructose malabsorption causes depression. It is intriguing, though, isn't it?

The researchers did some more small scale studies to explore possible mechanisms for the fructose or lactose malabsorption-depression link. They have discovered that there may be an association between fructose malabsorption and lower levels of tryptophan, zinc and folate in the blood. It is the job of scientists to speculate about how these observations could all fit together, and speculate they do. Could these nutrients be poorly absorbed because the fructose malabsorption causes diarrhea and reduces contact time between the contents of the GI tract and the absorptive surfaces of the small intestine? Could unabsorbed sugars be interfering with the absorption of tryptophan? Could fructose malabsorption be encouraging small intestinal bacterial overgrowth (SIBO)? Could the lower serum levels of tryptophan, zince and folate cause depression?

There are far more questions than answers, here. Scientists are choosing their words with care, using the terms "may" and "suggest" and "associated with," and they point out that further studies are needed.

What is the take-away message here for people with fructose and/or lactose malabsorption? If you're a woman, removing excess amounts of these sugars from your diet might make you feel better mentally as well as physically! That's all, folks.

The report that started it all? Fructose malabsorption is associated with early signs of mental depression, Ledochowski M, Sperner-Unterweger B, Widner B, Fuchs D. Eur J Med Res. 1998 Jun 17;3(6):295-8.

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Lecture by Satish Rao, MD at FNCE

At the American Dietetic Association (ADA) Food and Nutrition Conference and Expo (FNCE), I attended an excellent lecture by Dr. Satish Rao from the University of Iowa Hospital and Clinics. His topic was primarily dietary fructose intolerance (DFI). Consumption of fructose in the US is on the rise, yet our capacity to absorb fructose in the small intestine is limited, and varies from person to person. Dr. Rao explained that dietary fructose intolerance is far more prevalent than commonly recognized, and can explain gas, pain, bloating and diarrhea in some individuals. He recommends individuals be tested for dietary fructose malabsorption.  His group's research shows that reducing the amount of free (or excess) fructose in the diet can improve fructose intolerance symptoms.

He referred to FODMAPS in his talk.  FODMAPS stands for Fermentable Oligo-, Di- and Mono-saccharides and Polyols.  Fructose is the "M" or monosaccharide in FODMAPS. When malabsorbed in the small intestine, it proceeds to the colon.  Fructose is osmotically active (capable of pulling fluid into the colon) and rapidly fermentable by the colonic flora, causing gas and bloating.

Those wishing to perform a fructose-only elimination diet could use my upcoming book IBS--Free at Last! to do so. The book includes menus and a shopping list that are low fructose (in addition to being low FODMAPS overall). There are lists of allowed fruits, which do not contain excess fructose.  Extensive label reading tips are provided, since fructose in many forms is a common food additive. Write to me at patsycatsos@gmail.com if you would like me to notify you when my book is available in print!

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