Fructose…friend or foe?

Fructose, also called levulose, is a simple sugar found in many fruits as well as honey, wheat and some vegetables. For the chemistry empowered, fructose has exactly the same chemical formula as glucose, but the atoms are arranged in a different structure. Fructose and glucose are simple monosaccharides, while table sugar, for comparison, is a disaccharide made up of one glucose and one fructose joined together.

Normally fructose is absorbed in the small intestine; in fructose malabsorption, this absorption is impaired. Unabsorbed fructose in the small intestine can cause some rather painful abdominal symptoms. In its unabsorbed state it can move through to the large intestine where bacteria use it as a food source. When bacteria digest fructose it causes stomach bloating, wind, abdominal pain, loose stools and/or constipation. Fructose malabsorption is usually diagnosed by a hydrogen breath test, however just eliminating fructose from your diet for six weeks, and then reintroducing it will soon confirm whether fructose is a problem.

Many poor patients come to me after having received a positive diagnosis totally confused and overwhelmed about which foods they need to eliminate. That is a lot of misinformation on the net!

Take it from me the only foods high enough in fructose to cause problems are the following;
Apples, pears, honey, guava, persimmon, lychee, watermelon, mango, pawpaw, all dried fruit, coconut cream, wheat, leeks, onion (particularly high), green beans, asparagus, spring onion and chicory. Interesting to note too that psylium, often used to treat constipation is also high in fructose. Fructose is widely used as a food additive; best to check all manufactured products.

If you suspect that fructose is causing your abdominal symptoms, firstly delete all the high fructose foods for six weeks. If symptoms resolve or are minimized, fructose malabsorption can quite confidently be assumed.
You can then try each food on the above list one by one to see if it provokes a symptom. Often patients can have a small amount of some of these foods. The most problematic seem to be apples, pears, dried fruit, wheat and onions.