Fructose

Fructose (fruit sugar) is a simple sugar that occurs naturally in fruit, honey and some vegetables – and today it's also added in large quantities to processed foods. Table sugar is half fructose and half glucose. The name is misleading: “fruit sugar” on a pack doesn't make a product any healthier.

The difference lies in the packaging nature provides. In an apple, fructose comes together with water, fibre, vitamins and phytochemicals – you chew, you feel full, and the sugar enters the bloodstream slowly. That's why the German Nutrition Society (DGE) explicitly recommends two portions of fruit a day. Press three apples into juice and the sugar stays while the fibre is gone – and the glass is empty in seconds. According to the WHO, juice, smoothies and fruit syrups count as free sugars.

Fructose is metabolised differently from glucose: almost exclusively in the liver. Large amounts from sugary drinks and syrups promote fat formation there and can contribute to fatty liver disease. On top of that, fructose barely triggers any satiety signals. Added sweeteners such as glucose-fructose syrup, agave syrup (up to 90% fructose) or claims like “sweetened with fruit” are therefore no better than sugar.

Some people don't tolerate fructose well (fructose malabsorption): bloating, stomach ache and diarrhoea after fruit, juice or honey. A breath test at the doctor's can clarify this – please don't cut out fruit on your own, especially not for children.

For families, this means: fruit, yes – two handfuls a day is great; juice diluted with sparkling water and only as an exception; dried fruit in small amounts; and check products labelled “no refined sugar” just as critically as sweetened ones.