Hereditary Fructose Intolerance

Hereditary fructose intolerance, often shortened to HFI, is a rare but serious genetic disorder that affects the way your body processes a natural sugar called fructose. Unlike the more common fructose malabsorption, this isn’t just about feeling uncomfortable after eating fruit or sweets, it’s something you’re born with and it needs careful management for life.

The root of the problem is a missing or faulty enzyme called aldolase B. This enzyme normally helps your body break down fructose properly once it’s been absorbed. Without enough aldolase B, fructose builds up inside the liver, kidneys, and small intestine, causing a range of unpleasant (and sometimes dangerous) symptoms [1].

HFI usually shows up early, often when babies first move from milk to foods containing fruit, vegetables, or sweeteners. Getting the right diagnosis early on is crucial because avoiding fructose completely can help people with HFI live healthy, active lives [1].

At IBS Clinics, we are very experienced in supporting people with a range of health conditions that require management with restricted diets. Book a free 15-minute initial consultation with an online nutritionist to find out more about how we can support the management of your condition with a tailored diet and lifestyle plan for optimum health.

If you’re looking for more information on fructose intolerance, take a look at our article What is Fructose Intolerance?

What Causes Hereditary Fructose Intolerance?

Hereditary fructose intolerance is caused by a change (mutation) in a specific gene – the ALDOB gene. This gene provides the instructions for making the aldolase B enzyme, which plays a key role in breaking down fructose inside the body.

When there’s a problem with the ALDOB gene, the aldolase B enzyme doesn’t work properly, or sometimes isn’t made at all. As a result, when someone with HFI eats foods containing fructose, sucrose (table sugar), or sorbitol (a sugar substitute), their body can’t process it correctly. Instead of being broken down and used for energy, fructose builds up in the liver and other organs, leading to symptoms like low blood sugar, nausea, vomiting, and even serious liver problems if not managed carefully [1].

Hereditary fructose intolerance is something you inherit from your parents. If both parents carry a faulty ALDOB gene, there’s a chance their child will be born with the condition.

For more detailed medical information, GeneReviews offers an excellent, trusted overview of hereditary fructose intolerance, including how it’s diagnosed and managed.

What Are the Symptoms of Hereditary Fructose Intolerance?

Symptoms of hereditary fructose intolerance usually start to show up quite early in life – often just after a baby is weaned onto foods that contain fruit, vegetables, or added sugars. Until that point, babies who are breastfed or on basic formula often seem completely healthy, because they haven’t been exposed to fructose yet.

Once fructose enters the diet, the symptoms can appear quite quickly. Common signs include:

Vomiting soon after eating
Severe abdominal pain or cramping
Low blood sugar (hypoglycaemia), which can cause shakiness, irritability, or even fainting
Refusal to eat
Jaundice (yellowing of the skin and eyes)
Poor growth or “failure to thrive” as the body struggles to get enough energy
Lethargy or unusual sleepiness

It’s important to understand that these symptoms are very different from the milder digestive issues seen in fructose malabsorption. With HFI, the reaction to fructose isn’t just uncomfortable, it can become dangerous if not recognised and managed properly [1].

Early diagnosis is key to preventing long-term damage and helping children (and later, adults) with hereditary fructose intolerance stay healthy [1].

Hereditary Fructose Intolerance Test: How It’s Diagnosed

When it comes to hereditary fructose intolerance, getting a proper medical diagnosis is essential. Unlike the non-hereditary form (fructose malabsorption), which can sometimes be managed through dietary trials and symptom tracking, hereditary fructose intolerance must be formally diagnosed to protect long-term health.

The gold standard for diagnosing HFI is a genetic test. Unlike non-hereditary fructose intolerance, which is a lot more common and not genetic in origin, HFI needs to be diagnosed with genetic testing and never with fructose tolerance tests as this is unsafe for HFI [1].

Genetic testing involves analysing a sample of your blood to look for mutations in the ALDOB gene, which is responsible for producing the aldolase B enzyme. If mutations are found, it confirms the diagnosis.

In some cases, doctors might also use blood and urine tests to spot warning signs, such as low blood sugar levels or unusual by-products that suggest the body isn’t processing fructose properly. However, these are usually used as part of the initial investigation rather than for a final diagnosis.

A professional diagnosis is so important because managing hereditary fructose intolerance is a lifelong commitment. Without a clear diagnosis, people could unknowingly continue to eat fructose and risk serious liver and kidney damage over time [1].

If you suspect HFI in your child, speaking to a specialist and arranging proper testing should always be the first step.

How to Fix Fructose Intolerance: Is It Possible?

When it comes to hereditary fructose intolerance, it’s important to be clear – this condition cannot be “fixed” or cured. Because it’s caused by a genetic mutation affecting the aldolase B enzyme, there’s no way to reverse it or restore normal fructose digestion.

But the good news is that hereditary fructose intolerance can be managed very effectively for life. With the right approach, people with HFI can stay healthy, avoid complications, and live full, active lives.

The cornerstone of managing hereditary fructose intolerance is strict, ongoing dietary management and avoidance of fructose in medical products including IV fluids and pharmaceuticals [1]. This means permanently avoiding foods that contain fructose, sucrose, and sorbitol. By sticking carefully to a safe diet, people with HFI can prevent symptoms, protect their organs, and maintain good energy levels and growth.

Hereditary Fructose Intolerance Treatment

The main treatment for hereditary fructose intolerance is very straightforward in theory but it takes real commitment in practice. It involves strict, lifelong avoidance of anything containing fructose, sucrose (common table sugar), and sorbitol (a sugar substitute often found in “sugar-free” products).

Even small amounts of these sugars can trigger serious symptoms in people with HFI, so careful attention to food choices is absolutely essential. This isn’t about occasional slip-ups – it’s about making sure fructose stays out of the diet completely, every day.

Medical monitoring also plays an important role. Regular check-ups with a specialist can help ensure that growth, liver function, and overall health stay on track. Blood tests might be done from time to time to make sure nutritional needs are being met and that no hidden problems are developing.

Many people find that working with a nutritionist or functional medicine practitioner alongside their medical team makes the process much easier. Professional support can help you understand ingredient labels, plan meals, and find a way of eating that feels sustainable for life – not just restrictive.

How a Nutritionist or Functional Medicine Practitioner Can Help

Managing hereditary fructose intolerance can feel overwhelming at first, but working with a nutritionist or functional medicine practitioner can make a huge difference.

One of the biggest challenges is creating a safe, balanced diet that avoids fructose, sucrose, and sorbitol without missing out on important nutrients. A qualified practitioner can help you build meal plans that are not only safe but also enjoyable and varied.

They can also teach you how to spot hidden sources of fructose – it’s surprising how often sugars sneak into processed foods under names you might not expect. Proper guidance can make grocery shopping and meal prep much less stressful.

Beyond diet, they can also help support your gut health and address any nutrient absorption issues that sometimes come with restrictive diets. Working alongside your medical team, they’ll focus on the bigger picture, helping you stay healthy long-term, not just avoiding symptoms.

Hereditary Fructose Intolerance Diet: What to Eat and What to Avoid

Following a hereditary fructose intolerance diet means being very selective about what you eat.

What foods should you avoid if you are fructose intolerant?
For the hereditary form, the list includes:

Fruits (especially apples, pears, mangoes, watermelon, and cherries)
Fruit juices and dried fruits
Honey and agave syrup
Foods containing high-fructose corn syrup
Sucrose (found in ordinary table sugar and most sweetened foods)
Sorbitol (found in sugar-free sweets, gums, and some medications)
Vegetables high in fructose like asparagus and artichokes
Sweet sauces, syrups, and desserts

Safe foods and substitutes

There are still plenty of foods you can enjoy, such as:

Most meats, fish, and eggs
Unsweetened dairy products
Non-fructose vegetables like spinach, carrots, and potatoes
Rice, oats, and gluten-free grains without added sweeteners
Special low-fructose products recommended by your nutritionist

A nutritionist can also suggest practical substitutes, like using glucose-based sweeteners if a sweetener is needed, or choosing safe carbohydrate sources.

Practical daily living advice

Always check food and medicine labels – fructose and its relatives can hide under different names
When in doubt, stick to fresh, unprocessed foods
Prepare meals at home where you can control ingredients
Ask clear questions when eating out – restaurants are usually happy to help once they understand your needs

Living with Hereditary Fructose Intolerance

Life with hereditary fructose intolerance definitely takes some adjusting, but with good habits and the right support, it quickly becomes second nature.

Tips for everyday life

Read labels carefully every time, even on foods you think you know
Plan meals ahead, especially if travelling or eating out
Keep a small list of trusted “safe foods” for easy shopping
Find a few go-to meals and snacks you love and can prepare easily

Emotional and psychological aspects

Living with a lifelong condition can sometimes feel isolating or frustrating, especially at social events centred around food. It’s completely normal to feel overwhelmed at times. Support from a nutritionist, a functional medicine practitioner, and even online communities can make a big difference.

Conclusion

Managing hereditary fructose intolerance relies on strict dietary control, and having the right support around you makes a huge difference. Working with a qualified nutritionist or functional medicine practitioner alongside your medical team can help you create a safe, balanced diet, avoid hidden sources of fructose, and maintain good nutrition without feeling restricted.

At IBS Clinics, we understand how challenging it can feel to manage your diagnosis and the dietary restrictions that accompany it. Our team is here to support you with expert advice, personalised dietary guidance, and long-term management strategies to help you live well and confidently with HFI. If you’d like tailored support for your next steps, please don’t hesitate to contact us.

References

NCBI Bookshelf – Hereditary Fructose Intolerance, GeneReviews. Available at: https://www.ncbi.nlm.nih.gov/books/NBK333439/

Author – Tracey Randell

At IBS Clinics, Tracey Randell, a renowned Nutritional Therapist and one of the few IFM Certified Practitioners in the UK, extends her specialised knowledge and unique approach to managing and treating IBS and other gut-related conditions effectively.

Tracey’s profound understanding of Functional Medicine allows her to connect the dots for complex health conditions, identifying and addressing the root causes to curate personalised and comprehensive health plans for her patients. Her holistic approach focuses on resolving underlying imbalances and optimising gut health, enabling the body to correct other issues and attain overall well-being.

At IBS Clinics, we are dedicated to being your partner in navigating your gut-related health concerns, offering expert care and individualised treatment plans to alleviate your IBS symptoms and enhance your quality of life.

DISCLAIMER: The information provided in this article is intended for general informational purposes only and should not be construed as medical advice, diagnosis, or treatment. The products and methods mentioned are not a substitute for professional medical advice from a trained healthcare specialist. Always seek the guidance of your doctor or other qualified health professional with any questions you may have regarding your health or a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. Use of the information and products discussed is at your own risk.