Fructose Malabsorption

Assessment of Dietary Fructose Intake

The hydrogen breath test is the foundational diagnostic assessment for identification of dietary fructose malabsorption.^[26] One description of this test comes from a study conducted by Choi et al of 183 patients with unexplained chronic abdominal pain.^[27] Subjects were asked to refrain from consuming foods containing high fat, lactose, or fructose for 1 day prior to testing and to fast after midnight. Subjects were asked to blow into a modified bag in order to collect a 50 mL end-expiratory breath sample. The sample was injected into a gas chromatography analyzer to measure baseline values for hydrogen and methane. The subjects were then asked to drink a 33% fructose solution. Breath samples were analyzed at 30-minute intervals for 5 hours. Based on the amount of fructose that escaped absorption in the small intestines, commensal flora in the large intestines metabolized the fructose and released hydrogen and methane consequently.^[28] A positive breath test was inferred in subjects with a rise in breath hydrogen and/or methane of at least 3 parts per million (ppm) over three consecutive breath samples from the baseline value or from having a value 20 ppm above baseline.^[27]

The pitfall of the hydrogen breath test in diagnosis of fructose malabsorption is that 28% of the population does not expel hydrogen through the lungs and/or does not have hydrogen-producing bacteria inhabiting the GI tract.^[14] In such patients, fructose malabsorption is often undiagnosed due to lack of an alternative diagnostic test.

In the Choi et al study, fructose malabsorption was discovered in 39% of the 183 patients who had consumed 25 g of fructose and in 66% of the patients who had consumed 50 g of fructose, with 73% of total patients having a positive hydrogen breath test.^[27] To put these quantities of fructose in perspective, depending on the type of corn syrup sweetener used, one 22-oz soft drink contains approximately 30 to 40 g of fructose.

Table 1. Common Symptoms of Fructose Malabsorption
Gas Bloating Abdominal discomfort Nausea Disturbed bowel function Gastroesophageal reflux (occasionally)

Source: Reference 13.

Table 2. High-Fructose Foods and Alternatives
High-Fructose Foods	Alternatives
Fruits: apple, cherries, coconut milk, grapes, guava, honeydew melon, lychee, mango, pear, persimmons, pomegranate, quince, watermelon Dried fruit/bars: apple, apricot, currant, date, fig, mandarin orange, raisins, pear, prune, tangelo	Stone fruits: apricot, nectarine, peach, plum Berries: blackberry, blueberry, boysenberry, cranberry, raspberry, strawberry Citrus fruits: grapefruit, kumquat, lemon, lime Others: jackfruit, kiwi, passion fruit, pineapple, rhubarb, tamarillo
Vegetables: artichoke, asparagus, dandelion greens, endive, onion family	Any vegetable without fructans; cook with but do not consume (use whole in soups then remove)
Condiments: barbecue sauce, chutney, honey, plum sauce, relish, sweet-and-sour sauce, tomato pastes	Golden syrup, jam, jelly, maple syrup, marmalade, peanut butter, treacle, yeast extract spreads
Wheat-based products: bread, breadcrumbs, breakfast cereals, cakes, cookies, crackers, noodles, pasta, pastries	Rye, barley, and oat bread or crackers; gluten-free pasta, rice, or noodles; cereals low in dried fruit and honey; almond meal cakes and cookies
Drinks: fruit juice, chicory-based coffee, fortified wines, port, sherry, sucrose-sweetened soft drinks	Glucose-sweetened sports drinks (e.g., Gatorade), unsweetened teas, coffee in moderation
Sweeteners: fructose sweeteners (e.g., fruit sugar or levulose), high-fructose corn syrup	Sucrose in moderation (e.g., table sugar, cane sugar), glucose sweeteners (e.g., dextrose or grape sugar)

Source: Reference 19.

Table 3. Fructose Content of Common Foods
Food	Fructose (g) per 100 g raw	Low-Fructose substitutions	Fructose (g) peer 100 g raw
	Fresh Fruits
Grapes	8.1	Apricots	0.9
Apples	5.9	Nectarines	1.4
Pears	6.2	Peaches	1.5
Bananas	4.9	Strawberries	2.4
	Fresh Vegetables
Carrots	1	Celery	0.5
Onions	2	Peas	0.4
Asparagus	1	Spinach	0.1
Sweet potatoes	0.7	Mushrooms	0.2
	Beverages
Brandy	16	Whiskey	8
Cola	6.1	Gatorade	0.2
Apple juice	5.7	Iced teaa	0
Sprite	5.2	Coffee	0
Orange juice	2.2	Hot tea	0

^a Unsweetened. Source: Reference 33.

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Fructose Malabsorption

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