How bad is sugar?
The term sugar comes from the Sanskrit word sarkara, meaning sweet. And sugar does indeed taste sweet - and provides energy. But not all sugars are the same.
Saccharides - as sugar is known in technical jargon - are categorised into monosaccharides, disaccharides and polysaccharides based on the number of building blocks. Simple sugars consist of only one sugar building block. There are three of these: glucose, fructose and galactose.
The sugars must always be broken down into simple sugars so that the body can absorb them. Malt sugar and lactose are disaccharides. This also includes table sugar, which consists of one part glucose and one part fructose. It is usually obtained from beet or sugar cane. A polysaccharide is starch, which is found in potatoes and cereal products, for example. This polysaccharide has many sugar building blocks. «Here, the glucose molecules are linked in a long chain,» explains Stephanie Graf. According to the nutritionist at the paediatric clinic at Inselspital Bern, these starch supplements are broken down very slowly and thus provide the body with long-term energy.
Turning glucose into energy
«The most important thing for the body is glucose,» says the nutritionist. Two hormones regulate its absorption in the body: insulin and glucagon. Both are released depending on the blood sugar concentration.
Insulin has a kind of key function and transports glucose from the blood into the cells. Liver and muscle cells can store this as glycogen or convert it into energy. «This regulatory mechanism is complex and depends on the energy status,» says Dr Isabelle Herter, nutritionist at ETH Zurich. It also controls the feeling of satiety. In diabetes, the mechanism is disrupted: in type 1, insulin is missing, in type 2 it does not work properly or too little of it is produced.
Fructose becomes fat
«Unlike glucose, fructose is metabolised independently of insulin,» says Isabelle Herter. This means that the regulatory mechanism is missing. In contrast to glucose, which is necessary for energy production in the cells, fructose is not actually needed by the body. However, the body is supplied with it as it is contained in fruit, vegetables and household sugar.
«Unlike glucose, fructose cannot be broken down into glycogen,» explains Stephanie Graf. While only excess glucose is converted into fat, fructose is converted directly and stored in the fat deposits.
Isabelle Herter and her team were able to prove this effect in a study: «Our test subjects were given drinks sweetened with glucose, fructose or household sugar,» says the nutritionist. The fructose had a negative effect on fat metabolism. The specialist therefore advocates restrained consumption of sweet drinks sweetened with fructose: «The best thing is to drink water or tea.» However, she is not in favour of a ban. The occasional Fanta or cola won't hurt. Nutritionist Stephanie Graf also emphasises that sweet drinks are also included in the food pyramid(www.sge-ssn.ch/lebensmittelpyramide), albeit at the top: «It depends on the amount consumed.»
Hidden sugars make you fat
Fructose is almost twice as sweet as glucose, intensifies the flavour and is cheap to produce. This is why it is used in the food industry: chocolate bars, ketchup, soft drinks and much more are now sweetened with it. However, fructose does not curb the appetite because it blocks the feeling of fullness. Isabelle Herter believes that products are sweetened too much: «For example, there could be less sugar in fruit yoghurts and they would still taste good.» According to the scientist, the love of sweetening is trained: «You could change this by drinking spritzer or plain water instead of apple juice, for example.»
Not least because of the energy balance, Stephanie Graf also recommends paying attention to hidden sugars: «On the product descriptions, the order of the ingredients is listed depending on the quantity.» If muesli contains sugar in second place after oatmeal, it also contains a large amount of sugar - and a correspondingly high number of calories. However, light products are not a substitute. However, they can be useful in individual cases for a change in diet, for example in the form of light drinks, because they reduce calorie consumption. They should be limited, especially for children.
According to Isabelle Herter, the harmfulness of sweeteners has not yet been proven. She refers to a study that documented a greater feeling of hunger after consuming sweetened drinks before eating, but the subsequent energy intake was not greater. Isabelle Herter argues in favour of a normal approach to sugar, as it is the overall energy balance that counts. Nutritionist Graf agrees: «Healthy children don't need bans, they need to learn a healthy approach to sugar.»