Food intolerances: Lactose intolerance and fructose intolerance

Food intolerances & sugar: overview

More and more people are becoming sensitive to certain types of sugar. This is partly due to the widespread use of sugar in processed foods and partly to individual differences in digestive performance. Particularly in focus: Lactose (milk sugar) and Fructose (fruit sugar).

Lactose intolerance - what's behind it

With the Lactose intolerance lacks Lactasethe enzyme that breaks down lactose into glucose and galactose. Lactase activity naturally decreases from childhood onwards. In addition to this "primary" form, a secondary lactose intolerance occur temporarily - for example after intestinal inflammation or other diseases of the intestinal mucosa.

Symptoms & diagnosis of lactose intolerance

If lactose is not broken down sufficiently in the small intestine, it passes into the large intestine. There, intestinal bacteria break it down, producing gases and organic acids. Frequent consequences are flatulence, abdominal cramps and soft stools. The diagnosis is often made using a hydrogen breath test. In practice, fresh milk, cream, cream cheese or quark are often less well tolerated, while fermented or matured products such as Greek yoghurt, heavy cream quark, ricotta, mozzarella, feta or hard cheese usually contain less lactose due to the manufacturing process.

Sugar alternatives for lactose intolerance (lactose-free)

Rare and functional sugars are lactose-free and can be used as part of a low-lactose diet:

• Galactoseprovides energy as pure sugar without lactose.
• IsomaltuloseDual sugar from glucose/fructose, completely absorbed in the small intestine; tooth-friendly* and low-glycemic.
• TrehalosePure source of glucose, easily absorbed; also popular in combination with galactose.
• Tagatose* & Erythritol*natural sweetening options with high or moderate sweetening power. If you have a sensitive intestine, we recommend a slow increase and an individual tolerance test.

Fructose intolerance - intestinal vs. hereditary

The most common form is the intestinal fructose intolerance: In this case, absorption via the GLUT-5 transporter in the intestinal wall is limited. Unabsorbed fructose reaches the large intestine, is fermented and can promote flatulence, abdominal cramps and diarrhea. The hydrogen breath test is also frequently used here.
Very rare is the Hereditary fructose intolerance (congenital enzyme defect in fructose metabolism). In this case, fructose must be consistently avoided in the diet.

Everyday life & product choice for fructose intolerance

Added fructose sources in processed products - e.g. sucrose (household sugar), glucose-fructose syrup or invert sugar - are challenging. Many sufferers pay attention to low-fructose choices and the ingredient lists of typical "hidden sugars" in drinks, confectionery, desserts and ready-made sauces.

Suitable sugar alternatives for fructose intolerance

Fructose-free and can be used as part of a low-fructose diet:

• GalactoseSimilar to glucose, fructose can improve the absorption of fructose in food (e.g. sprinkled over fruit or stirred into desserts).
• TrehaloseFully absorbable glucose source with low glycemic effect compared to pure glucose.
• RiboseFunctional sugar, fructose-free, can be used as a powder.
• Erythritol / Erythritol-Steviacalorie-free, almost completely absorbed in the small intestine and hardly fermented; erythritol stevia offers a sweetening power similar to household sugar and is often suitable as a 1:1 substitute in recipes. Note: Erythritol should preferably not be used together with fructose-containing foods, as it can also reduce fructose absorption.

Tagatose - special feature of fructose intolerance

Tagatose is fructose-free, but is partly absorbed passively. In normal quantities (approx. 1-2 teaspoons per meal) it is often well tolerated; if symptoms persist, careful testing in small portions is recommended.

Hereditary fructose intolerance: what is suitable?

• Suitable: Galactose, trehalose, ribose, erythritol (as well as mixtures such as erythritol-stevia).
• Not suitable: Isomaltulose (provides fructose) and tagatose (related metabolic pathways).

Practical application - short & compact

• Individual testingTry out new types of sugar in small quantities and observe your own tolerance.
• Check ingredients: watch out for sucrose, glucose-fructose syrup, invert sugar and other fructose-containing additives.
• Clever sweeteningUse galactose, trehalose, erythritol or erythritol stevia depending on the target; dose tagatose carefully.