Following the fructose-restricted diet developed by dietitians at the University of Iowa Hospitals and Clinics (UIHC) has relieved symptoms for 80% of patients diagnosed with dietary fructose intolerance. A study by Frederick Johlin, Mary Panther, and Nancy Kraft, revealed those who followed the diet 100% had symptom improvement by 75 - 100%[i]. Improvement was in direct correlation to the degree the diet was followed. Results in another study at the UIHC by Choi YK, Johlin FC, Summers RW, Jackson M, and Rao S documented that fructose intolerance is an under-recognized problem[ii].
Relief from the symptoms of Dietary Fructose Intolerance (DFI) are limited to: 1) avoiding foods containing High Fructose Corn syrup (HFCS), fructose, most fruits, some vegetables, commercially baked goods, and sorbitol; and 2) incorporating dextrose into the diet. Dextrose bonds to the free fructose in the GI tract where it can be absorbed as sucrose (common table sugar)[iii] to relieve symptoms. The future holds hope for an enzyme to break down fructose to an absorbable state.
Dextrose is a simple sugar not normally available in U.S. grocery stores. It may be found in some health food stores and at wine making supply shops. It has been found in some Asian, African or European markets in the U.S. Pharmacy grade dextrose is expensive and this quality is not necessary.
Sorbitol, a sugar alcohol food additive used as a sweetener in commercially prepared low sugar foods and gum, creates havoc in the GI tract similar to fructose. The combination of fructose and sorbitol increases symptoms and should be avoided[iv].
Restricting fructose eliminates fruits and most vegetables from the diet, and therefore the nutrients from fruits and vegetables. It is important to replace those nutrients with a daily vitamin/mineral supplement. Additional 250 mg Vitamin C tablets once or twice daily, plus a daily 200 400 mg IU natural Vitamin E complex are recommended as well.
Read the ingredient list on labels for all vitamin/mineral supplements and over-the-counter medications. If reading the label is confusing, consult the pharmacist. It is common for fructose and/or sorbitol to be used as filler in vitamin/mineral supplements or medications.
The fructose-restricted diet recommendations serve as a guideline only. Everyone experiences different levels of tolerance. The University physicians encourage following the diet strictly for four to six weeks before slowly testing tolerance of individual foods not part of the basic diet. When exploring personal tolerance, eat a questionable food no more frequently than every four days. Fructose takes three days to pass through the GI tract for most individuals[v]. Symptoms commonly continue until the offending food is eliminated. A food tolerated on day one may not be tolerated on day two or three because it remains in the colon. Foods containing fructose are often dose-dependent (small amounts may be tolerated while larger amounts are not). For best tolerance always consume a small amount of a questionable food with a recommended food.
As a young college age patient recently said and is paraphrased, I am grateful for the fructose restrictions. I have abandoned the soda, greasy hamburgers and fries of my peers. My diet is healthy and varied. I feel great. I enjoy cooking and want to learn to cook more.
Another patient proclaimed the diet is limited only by a lack of imagination.
In a nutshell, include the maximum tolerated amount of vegetables and grains, go easy on the allowed fruit, and avoid commercially prepared drinks and sweets. Take your vitamins. Go forth and enjoy life!
[i] Johlin FC, Panther M, Kraft N. A fructose restricted diet and dietary counseling in patients with dietary fructose intolerance demonstrates significant reduction in symptoms and improvement in quality of life proportionate to the amount of fructose eliminated. Gastroenterology. 2000;20(5):A-265.
[ii] Choi YK, Johlin FC, Summers RW, Jackson M, Rao S. Fructose intolerance: an under-recognized problem. American Journal of Gastroenterology. 2003;(6):1348-53.
[iii] Rumessen JJ. Fructose and related food carbohydrates: sources, intake absorption and clinical implications. Scandinavian Journal of Gastroenterology. 1992;27:819-828
[iv] Fernex-Bas F, Esteve-Pardo M, Leon R, Humbert P, Cabr, Llovet JM, Gassull MA. Sugar malabsorption in functional bowel disease: clinical implications. American Journal of Gastroenterology. 88(12):2044-2064.
[v] Brostoff J, Gamlin L. Food Allergies and Food Intolerance. Healing Arts Press. Rochester, VT.