Could fructose be causing your IBS and gluten intolerance?
Fructose is a dietary sugar found in many fruits and vegetables. Fructose Malabsorption is an underdiagnosed cause of irritable bowel syndrome causing symptoms like gas, bloating, cramping, constipation and/or diarrhea. It is a close relative of lactose intolerance, because both are caused by an inability to digest a specific form of sugar.
Like lactose intolerance the laboratory test is a breath test. After consuming a fructose solution, you breathe in to a special collection bag and the breath is analyzed for hydrogen and/or methane levels. If the levels are elevated you did not absorb fructose in the small intestine. There is no pill to treat fructose intolerance, and individual tolerance of this sugar varies widely.
The initial treatment phase involves limiting high fructose foods. I have found in practice that people start to feel better in as little as three days. High fructose foods include apples, watermelon, asparagus(!), honey, mango, sugar snap peas, peaches and pears. High fructose corn syrup (HFCS) is also a major issue for people with fructose malabsorption. Make sure to read labels for fructose and HFCS, they are often found in baked goods, soft drinks, candy and many processed foods.
The fructose molecule is also part of a type of carbohydrate called fructans. Foods containing fuctans can also cause symptoms for those who are maldigesting fructose. Wheat is high in fructans and may be the cause of “gluten intolerance”. As well as the foods mentioned above, other foods high in fructans include artichokes, zucchini, pineapple, onions, garlic, leeks, shallots and grapes.
Polyol is another potentially problematic carbohydrate. Sorbitol, which is used as a sweetener but is also found naturally in some foods falls in to this category. Foods high in polyols include apples, pears, apricots, peaches, plums, cherries, nectarines. The following sweeteners are also pylyols: mannitol, isomalt and xylitol.
There are lower fructose fruits and vegetables, which can be consumed in moderation for many people with fructose intolerance. These include strawberries, raspberries, blueberries, lemons, limes, oranges, mandarins, banana, rhubarb, honeydew melon, rockmelon, kiwi, passion fruit, tomatoes, green peppers, leafy greens, lettuce, celery, potatoes (both sweet and regular), green beans, cucumbers, pumpkin, alfalfa sprouts, chives and corn.
In practice I find a trial of this diet eliminating all the high fructose, fructan and polyol containing foods can dramatically improve digestive symptoms quickly. I have people do a trial for a week and if they see an improvement in their symptoms they continue on the diet until their gut has stabilized which can take a month to six weeks. Over time they can slowly challenge higher fructose foods to determine their individual tolerance for serving size and particular foods.
Thank you to Melinda Dennis, RD, MS, LDN from Delete the Wheat, Beth Israel Celiac Disease center in Boston and Dr. Doherty’s co-author of the supplements 101 chapter in the book Real Life with Celiac Disease for this great information.