What is Fructose intolerance?

You might have heard of it before, but did you know there are different types of fructose intolerance?

Fructose is a sugar, and fructose intolerance is a condition that affects how the body processes sugar. When someone has fructose intolerance, their body cannot break down or absorb fructose from food causing various symptoms.

While there is no cure, there are ways to manage the condition and lead an everyday life. Read on to learn about fructose intolerance and how to live with it.

What's the difference between dietary fructose intolerance and hereditary fructose intolerance?

There are two types of fructose intolerance; the first one is called dietary fructose intolerance, and the other is called hereditary fructose intolerance.

Dietary Fructose Intolerance

Dietary fructose intolerance is not a disease but a condition that affects how the body processes fructose from food. The body cannot break down fructose or absorb it.

Fructose is a well-known trigger on the low FODMAP diet; fermentable carbohydrates cause common symptoms for people with Irritable Bowel Syndrome (IBS). Fructose malabsorption causes undigested fructose to attract water through osmosis; this causes distension and additional abdominal pain.

Hereditary fructose intolerance

Hereditary fructose intolerance is a genetic disorder where the body completely lacks the enzyme needed to metabolize fructose and absorb fructose properly in the small intestine. You have a 25% chance of developing hereditary fructose intolerance if both your parents have the gene that causes the aldolase B enzyme not to work.

If you have hereditary fructose intolerance, you may feel nauseous or experience bloating, abdominal pain, diarrhea, vomiting, and low blood sugar levels (hypoglycemia) after consuming fructose.

Eating fructose too often can lead to kidney and liver damage. This damage can cause your skin and the whites of your eyes to turn yellow (jaundice), an enlarged liver (hepatomegaly), and chronic liver disease (cirrhosis). In extreme cases, people with hereditary fructose intolerance can die from liver failure or kidney failure.

Because the symptoms caused by eating fruits and juices with fructose are so severe, most people with this condition stay away from fructose-containing foods altogether.

What are the symptoms of fructose intolerance?

The symptoms of dietary fructose intolerance usually range from mild to severe. Fructose intolerance symptoms can range from bloating and gas to stomach pain and diarrhea.

Other symptoms can include fatigue, headaches, dizziness, and difficulty concentrating. Symptoms may worsen if the person eats or drinks high-fructose foods.

What does a fructose intolerance look like, and is it the same for each person?

Fructose intolerance can look different for each person. Some people may experience mild symptoms, while others may have severe reactions.

Some people's intolerance might only show up if they eat a large number of fructose foods or after drinking certain drinks with added sugar. Other people might experience reactions when they eat small amounts of fructose.

How much fructose onset symptoms can be determined with a fructose elimination diet. Here you test small amounts of fructose dissolved in food and monitor your response.

A registered dietitian can help you determine how much fructose your body can tolerate and create a long-term nutrition plan accordingly.

Fructose intolerance vs. fructose allergy: what's the difference?

They may sound similar, but they are two different diagnoses with distinct symptoms and treatments.

Fructose intolerance

Fructose intolerance is the inability to digest the sugar fructose properly in the gastrointestinal tract. The undigested fructose causes symptoms in your digestive tract, such as abdominal pain, bloating, gas, diarrhea, or constipation.

Fructose allergy

When you're being allergic to fructose, your body reacts as if it were an allergen and produces an immune response against it. Resulting in an allergic reaction and is an autoimmune disease.

Symptoms include skin reactions such as hives, itching, swelling, redness, and respiratory issues. In some cases, an allergic reaction can cause anaphylaxis which requires immediate medical attention.

Is fructose malabsorption common?

Fructose malabsorption is quite common, with estimates suggesting that up to 30% of the population suffers from it [Trusted Source].

It is more common in women and those with existing gastrointestinal issues. Those who have had gut surgery may also be more likely to suffer from fructose malabsorption.

How common is a fructose allergy?

Fructose allergies are relatively rare compared to other food allergies, affecting an estimated 0.2-0.5% of the population in the U.S. and Europe.

However, this number may be higher due to underdiagnoses or misdiagnoses of fructose intolerance because of the similarities between the two conditions.

What causes (sudden) fructose intolerance?

Several factors can cause sudden fructose intolerance. In some cases, fructose intolerance may be caused by a genetic predisposition or environmental factors such as changes in diet and lifestyle. Finally, it is possible for the body to suddenly become intolerant to fructose after taking certain medications such as antibiotics.

How is fructose intolerance diagnosed?

Diagnosing dietary fructose intolerance is typically done through a hydrogen breath test. This test measures the level of hydrogen in your breath after consuming certain drinks or food containing fructose.

Another standard method of diagnosing dietary fructose intolerance is through an elimination diet. Temporarily you remove fructose from your diet. Once symptoms are gone, you reintroduce them again in small amounts and monitor your symptoms to see if they return and at what intake level. A trained registered dietitian can support you in this medical nutrition therapy intervention.

How do I know if I have hereditary fructose intolerance?

The only way to determine if you have hereditary fructose intolerance is to get tested. Your doctor may order a blood test or a genetic test to check for the specific mutated gene responsible for hereditary fructose intolerance.

How do you treat fructose intolerance?

The best way is to limit your intake of fructose and eliminate all beverages containing high-fructose corn syrup to avoid ingesting fructose and causing trouble.

How do you reverse fructose intolerance?

There isn't a cure, but you can follow a low-fructose diet to avoid digesting fructose in your system and causing trouble.

Follow a low-fructose diet and maintain a healthy lifestyle. You could improve your tolerance of fructose over time. Eating smaller amounts throughout the day may also help mitigate symptoms.

It is essential to also pay attention to any other underlying health conditions that could be causing your fructose intolerance, as they may need to be addressed for you to reverse the condition.

For example, suppose small intestinal bacterial overgrowth (SIBO) or functional gastrointestinal disorders such as irritable bowel syndrome (IBS) contribute to your fructose intolerance. In that case, it is essential to seek medical advice to address that underlying condition.

It is also important to note that a strict low-fructose diet may not be enough for those with severe cases, and they will need to avoid any foods containing fructose altogether. In these cases, supervision from a registered dietitian can help you find the proper diet that works best for you.

Finally, it is crucial to understand that reversing fructose intolerance may not always be possible. For some people, the only way to manage their symptoms is through long-term dietary changes and lifestyle modifications.

What foods to avoid if you are fructose intolerant?

Fructose is a simple sugar; some fructose-containing foods are certain fruits, vegetables, honey, table sugar, and agave nectar.

Avoid high fructose foods such as fruit juices, fruit purees, apples, pears, mangoes, watermelons, pineapple, dried fruits, fruit juices, or smoothies with added sugar.

Some foods to avoid with hidden sources of fructose include some condiments, salad dressings, and many processed foods.

Other foods like candy, cookies, cakes, and desserts also contain fructose, artificial sweeteners, sugar alcohols, or added sugars such as high-fructose corn syrup and are high in fructose.

How do you know if a food is high in fructose?

Fructose-containing foods are not always obvious. It is important to read food labels carefully and avoid products that list "fructose" and "high-fructose corn syrup" as ingredients.

Some manufacturers may use sucrose, glucose, or corn syrup.

How can a registered dietitian help me?

Fructose intolerance can be challenging to manage, but by avoiding to digest fructose, you can reduce symptoms. It can become much more manageable with the proper guidance to understand your food intolerances and make personalized dietary modifications.

In summary

If you think you have fructose intolerance, seek support to get diagnosed and manage your condition.

There is no cure for fructose intolerance, but through dietary changes, most people can manage their symptoms and live a relatively everyday life.

Talk to your dietitian for more information on avoiding foods and keeping adequate nutrition. They can provide personalized dietary advice based on your medical history, eating habits, and specific needs.