As we detailed in our report, What Is Fructose?, the fructose molecule is found in some of nature’s healthiest carbohydrate foods, including whole fruits; but it is also present in some far less-healthy carbs — such as sugar-sweetened beverages (SSBs) — which contain high concentrations of the notorious food additive, high fructose corn syrup (HFCS). If you can’t properly digest fructose, you might have the disorder known as fructose intolerance, often called “fructose malabsorption,” which can lead to a range of chronic digestive symptoms, some mimicking irritable bowel syndrome (IBS). Most adults learn to live with the disorder by trying to limit their fructose intake — which can actually benefit your metabolic health (glycemic management, especially).
What is fructose intolerance, and who gets it?
Clinicians categorize fructose intolerance as two separate conditions:
- Hereditary fructose intolerance (HFI) – fructose 1-phosphate aldolase deficiency
- Dietary fructose intolerance – often referred to as “fructose malabsorption”
The inherited type, HFI, is a rare, autosomal recessive disorder that usually manifests around 4-6 months of age when weaning is started. HFI results in infantile vomiting, liver failure and failure to thrive. Fortunately, life expectancy is normal in these individuals if appropriate precautionary measures are taken, including the dietary restriction of fructose, sorbitol, and sucrose, according to a major 2021 clinical review.
But the heart of this report will focus on dietary fructose intolerance, as it’s a far more common condition — although since quantitative population studies have not been performed, it is unclear how many people suffer from the condition, nor whether there are distinct populations of “low and high absorbers.” To distinguish it from the inherited kind, we think it’s best to refer to the more common condition by its other name, fructose malabsorption.
Interestingly, some scientists suggest that fructose malabsorption shouldn’t be categorized as a disorder or even a condition, but rather as a “common physiological state.” A 2006 research review posited:
“The vast majority of data indicate that fructose malabsorption is not abnormal, and its presence cannot be regarded as a ‘condition’ or ‘illness’. If restriction of free fructose intake does offer symptomatic control in patients with IBS, identification of patients with fructose malabsorption by breath hydrogen testing provides an opportunity to rationally introduce dietary modification with the goal of achieving better symptom control.”
Scientists also speculate that fructose malabsorption is part of the FODMAP digestive dilemma. Fermentable Oligosaccharides, Disaccharides and Monosaccharides And Polyols (FODMAPs) is a term that defines a previously seemingly unrelated group of poorly absorbed short-chain carbohydrates and sugar alcohols that have a similar fate in the distal small bowel and colon.
What are the symptoms of fructose intolerance?
In people with fructose malabsorption, eating foods high in fructose can lead to uncomfortable symptoms, including:
- Stomach pain
How do you test for fructose intolerance?
Unfortunately, diagnosing dietary fructose intolerance (malabsorption) isn’t always simple. As explained in a 2021 memorandum from The Cleveland Clinic, symptoms can sometimes overlap with other conditions, such as irritable bowel syndrome (IBS). Doctors can perform a fructose breath test to measure how much methane and hydrogen a patient breathes out after drinking a liquid with fructose, but such tests aren’t completely conclusive. Your healthcare provider will also ask about your eating patterns to look for clues.
How do you treat fructose intolerance?
If you suspect fructose malabsorption, your doctor will probably recommend an elimination diet. For several weeks, you won’t consume any fructose. Then you can slowly begin reintroducing fructose-containing foods to find out how much you can tolerate without symptoms. Fructose malabsorption has an excellent prognosis, provided the individual follows strict dietary compliance.
In our report, What Is Fructose?, we provide detailed information on the types of food that contain fructose. In summing up that analysis, it’s worth noting that a consensus of leading scientists have concluded that when attempting to restrict fructose consumption, the first target should be those highly-processed foods that contain “added sugars” — such as sugar-sweetened beverages (SSBs) — which contain high concentrations of high fructose corn syrup (HFCS).
Interestingly, one research review notes that when the fructose used as a sweetener in soft drinks is consumed at levels all too common in the U.S., this fructose consumption can quickly approach levels at which malabsorption is seen in healthy adults:
“Evidence suggests that when solutions containing 25–50 g of fructose (equivalent to >500 mL HFCS-sweetened soft drink) are used in hydrogen breath testing, >50% of healthy subjects demonstrate malabsorption of fructose and consequently experience symptoms of abdominal pain, wind and loose bowels. The high fructose content in sports drinks has also been implicated in adverse athletic performance and abdominal symptoms.”
Here’s a list of all the “worst offenders” amongst foods high in “added fructose”:
- Sugar-sweetened beverages (SSBs)
- Desserts sweetened with fructose
- Sugar-sweetened breakfast cereals
- Breads with added fructose
- Sauces and condiments with added fructose
- Hot dogs
- Potato chips
- Sweeteners such as honey, agave nectar and high-fructose corn syrup
If your medical provider diagnoses you with fructose intolerance (fructose malabsorption), and you need to restrict your fructose consumption even further, the provider may even list some natural, whole fruits and vegetables that you should restrict — even though these natural sources of fructose are not associated with cardiometabolic health risks, as concluded in a 2015 Mayo Clinic Proceedings review and a 2020 JAMA meta-analysis. Such natural, whole fructose foods include:
- Most fruits – including dried fruits, raisins and berries
- Certain vegetables – including artichoke, asparagus, broccoli, leeks, mushrooms, okra, onions, peas, red pepper, shallots and tomato products
Bear in mind that many fruits and vegetables do not contain “pure fructose”; rather, they contain sucrose, a disaccharide made of fructose and glucose. The sucrose content of most fruit and fruit juices is low, although some varieties of melons, pineapple, and tangerines contain 6–9% sucrose, and mango contains 11.6% sucrose. However, seedless raisins are much higher in fructose, as are dried dates and dried figs.
Table 1. Free fructose in selected fruits (% fresh weight basis)
|Apples, raw, unpeeled||7.6|
|Cherries, raw, sweet||6.2|
|Cherries, raw, sour||3.3|
|Grapes, raw, American||6.9|
|Grapes, raw, European||7.6|
As the above chart shows, fruits with lower fructose content include bananas, raw apricots, blueberries, and peaches. Cleveland Clinic also cites avocados, cranberries, cantaloupe, lemons and limes, oranges, and strawberries as being relatively low in fructose.
Low-fructose diets: Healthier for us all?
Ironically, fructose malabsorption can prompt you to better focus upon your overall metabolic health by embracing and adhering to a low-carbohydrate diet. Cutting way back on foods that contain high amounts of fructose and sucrose does have health benefits, especially if you are at risk for or have prediabetes or diabetes. Diets especially high in added sucrose and high-fructose corn syrup have been shown to bring on “detrimental changes in hepatic lipid, insulin sensitivity, and circulating lipids, lipoproteins and uric acid,” as stated in a 2021 parallel, double-blinded, NIH-funded study.
In other words, sugar intake in total, fructose included, is associated with the risk of developing diabetes and dying from heart disease. Furthermore, the risk of obesity rises from high-fructose consumption, increasing the risks of those same disorders and even certain cancers, as well. As we reviewed in our What Is Fructose? report, less than 10% of calories per day should come from added sugars, according to the USDA’s Dietary Guidelines for Americans 2020–2025. Yet, for American adults, added sugars account for almost 270 calories — or more than 13% — of total calories consumed per day.
Dietary fructose intolerance, or fructose malabsorption, is an uncomfortable gastrointestinal condition that often goes undiagnosed, but can be managed when found. Sufferers are often urged to follow a low-fructose diet — paying special attention to the restriction of highly processed foods containing “added fructose” in large concentrations — such as sugar-sweetened beverages (SSBs), white bread, cakes, cereals and a host of sauces and condiments. The silver lining of this treatment: embracing and adhering to a low-carbohydrate diet does have health benefits, especially if you are at risk for or have prediabetes or diabetes, as excessive consumption of sugars (including fructose) is correlated with increased risks for obesity, metabolic imbalance, cardiovascular disease and even certain cancers.