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Fructose Overload: Can You Get Too Much Fruit Sugar?
Sugar is continually blamed for adding empty calories and causing obesity, but there’s something else to consider: it can also make you sick to your stomach. Sure you remember those tummy aches after too much candy, or your mother not wanting to spoil your appetite with dessert, but there's more to too much sugar’s ill effect. Newer research is exposing the cause of discomfort may be too much fructose. Dietary fructose intolerance, now called fructose malabsorption (FM), is getting more public attention.
What is It?
Sugar consumption is a major concern in America where we consume over 131 pounds of caloric sweeteners of which about 49 pounds is high fructose corn syrup. Too much fructose, which naturally occurs in some fruits, vegetables, and honey and is also a component of refined sugar, including table sugar and high fructose corn syrup, causes gastrointestinal symptoms. The reason is there is no digestive enzyme to absorb fructose. Rather, an equal amount of glucose is needed to digest fructose in the small intestine. Too much fructose without enough glucose is what defines FM. Like lactose intolerance, it causes gas, bloating, diarrhea, nausea and constipation.
Because of lack of awareness and proper testing, the prevalence of fructose malabsorption among Americans is hard to define. However, small scale studies have found an alarming rate of FM in otherwise healthy subjects. Published in Clinical Gastroenterology and Hepatology, one study gave subjects 10% solutions of 15, 25, and 50 grams (g) of fructose. While minimal FM was observed at 15 and 25 g, breath tests showed 80% affected at the 50 g serving. Another study, led by Susan Shepherd, M Nut Diet, APD, published in the Journal of the American Dietetic Association, treated patients with irritable bowel syndrome(IBS) and found almost a third had FM. Yet another reported over 60% of IBS sufferers also have it.
Diagnosis and Testing
Fructose malabsorption can be asymptomatic, but if you’re experiencing symptoms, ask your doctor or dietitian to be tested. Gases from the large intestine created by undigested fructose cause an increase in hydrogen and methane which can be detected by a breath test. Because testing is not standardized however, diagnosis may differ among practitioners. If you are diagnosed, unlike hereditary fructose intolerance, FM is not life-threatening, and can be treated with changes in your diet.
Treatment and High “Free Fructose” Foods
Treatment does not require a complete removal of foods that contain fructose. Shepherd’s dietary treatments suggest ingesting glucose with foods, limiting total fructose consumption at each meal, and limiting foods that contain high levels of “free fructose,” noted by >0.5 g/100 g fructose in excess of glucose, or foods with significant fructan content. In addition to honey, dried fruit, fruit juices, and foods that use high fructose corn syrup, fructose and fruit juice concentrate, as a major sweetening ingredient, the following is a partial list of “unfavorable foods” for fructose malabsorption according to her study: apple, pear, honeydew melon, mango, papaya, cherry, grape, and watermelon. Shepherd also lists “indulgent quantities” of sucrose sweetened soft drinks and confectionary.
Do you think you’re eating too much fructose?