Fructose vs. Glucose: Is it all just sugar?

Fructose, glucose, sucrose, … we all know these terms. But what is the story behind all these names for sugar? Is there good sugar and bad sugar? With a little bit of chemistry (don't worry, you don't need to dig up your dusty high school chemistry knowledge), we want to help you understand the differences between fructose and glucose in this article.

Fructose and glucose – is sugar a vital substance?

To be clear: our body needs sugar. We think of the provision of energy, cell regeneration, and so on. However, our body does not need sugar in the form of table sugar, but the blood sugar glucose (Yudkin & Lustig, 2014, p. 43).
But how much of it do we need? The figures for Germany speak for themselves: In 2022, Germans consumed an average of 34.8 kilos of sugar per capita. This is almost double the amount that the World Health Organization (WHO) has recommended as the maximum sugar intake for many years . For comparison: people in indigenous tribes consume around 3 to 5 kilos of sugar per year (Wölnerhanssen, 2020). The frightening thing is: our body does not depend on this external supply of sugar. Sugar from additional sources is a pure luxury product that our body does not need (Lustig, 2019; Wölnerhanssen, 2020).
Reason enough to take a closer look at the matter.

Basic knowledge about sugar

The general term sugar describes many different substances in everyday language. These should, however, be named and considered separately. Basically, sugar is one of the carbohydrates. Depending on the number of sugar molecules, a distinction is made between:

- Simple sugars (monosaccharides)
- Double sugars (disaccharides) and
- Complex sugars (polysaccharides)

The well-known table sugar (sucrose) consists of glucose and fructose – specifically, one molecule of glucose and one molecule of fructose (Yudkin & Lustig, 2014, p. 43).
Fructose and glucose are both simple sugars. They are therefore each a single sugar molecule .

Glucose and fructose – what do the terms stand for?

Glucose is a white, water-soluble, and sweet-tasting powder. It is an important energy source for the human body. The brain also requires glucose as a nutrient. In humans and animals, glucose is stored in the form of glycogen, and in plants in the form of starch . Fructose is also a white powder that is more easily soluble in water and tastes sweeter than glucose . You can find even more background information on glucose and its various types in this video.
Both fructose and glucose have the molecular formula C6H12O6. However, they differ in their chemical structure and belong to different chemical groups (Lustig, 2019, pp. 258-259). No wonder there are so many differences between glucose and fructose..

Processing of glucose and fructose in the body

Basically, the human body can absorb sugar in the form of simple sugars via the blood. When consuming sucrose (table sugar), the body is therefore dependent on breaking the sugar down into glucose and fructose. If sugar is consumed not as sucrose, but as glucose or fructose, these can be processed directly. But what happens to the fructose and glucose in the body?
Glucose reaches the blood from the gut in the human body and can be converted directly into energy by the cells. Fructose, on the other hand, is mainly converted into fat in the liver and is not used directly for energy production (Wölnerhanssen, 2020).
Glucose is stored in the body in the form of glycogen. Furthermore, the intake of glucose causes an enormous increase in blood sugar levels as well as the release of insulin. Satiety hormones are also released (Lustig, 2019, pp. 156-157). In contrast, fructose does not affect blood sugar levels or the release of insulin in the body. Satiety hormones are not released either (Wölnerhanssen, 2020).

Fructose and glucose in food

Glucose is found naturally in many foods.
Fructose, or fruit sugar, occurs, as the name suggests, increasingly in fruit as well as in honey. Furthermore, fructose is found more and more in processed foods. The reason for this is that fructose has a much higher sweetening power than glucose. Fructose is twice as sweet as glucose in the same quantity. Therefore, less fructose is needed than glucose to sweeten a dish. Since fructose is much cheaper to produce than sucrose (table sugar), fructose has been added to processed foods increasingly in recent decades (Yudkin & Lustig, 2014, p. 43). You can learn more about fructose in processed foods and why the artificially added sweetness of fructose can be a problem in this video.

Now you might be asking yourself: what about fruit? Doesn't that contain fructose? - You are quite right. However, in addition to fructose and glucose, fruit and vegetables contain many other nutrients, fiber, and vitamins. Thus, not only glucose and fructose are absorbed, but many other nutrients as well. Furthermore, the contained fiber ensures that not so much sugar can be absorbed at once and the absorption of sugar in the body is slowed down. The liver can therefore keep up with the sugar intake. For this reason, it is not so easy to consume too much sugar from natural foods like fruit and vegetables (Lustig, 2019, pp. 171-173).

And what about a juice cleanse?

With an organic juice cleanse, you give yourself a break and consciously refrain from solid food, from which you would normally get the energy your body needs. The juices are your only food source and therefore also your only sugar intake. With our cold-pressed I·DO juices, you therefore consume the sugar and also the nutrients of several portions of vegetables and fruit per day. However, sugar intake is limited during this time, as the amount of juice per day is precisely determined.

Of course, no additional sugar is added to our I·DO juices. Thanks to cold pressing, your body also benefits from the full spectrum of nutrients and minerals from fresh vegetables and fruit – unlike when consuming conventional pasteurized juices.

Conclusion

One thing is certain: not all sugar is the same. Once again: sucrose is table sugar, belongs to the double sugars, and consists of fructose and glucose. Fructose and glucose are both monosaccharides (simple sugars).

Less sugar – regardless of whether glucose or fructose
As with all dietary components, the following applies: balance is the be-all and end-all! A balanced diet with sufficient portions of all important components covers the body's need for glucose and fructose. Sugar should only be consumed through foods in which it occurs naturally. Therefore, consciously ensure that you consume sugar in its naturally occurring form through fruit, vegetables, cereals, etc. Because excessive consumption of sugar can have a harmful effect on the body's organ systems (Wölnerhanssen, 2020).

In the following magazine articles, you will learn even more about the subject of sugar, because fructose and glucose are not the only forms in which sugar can be consumed. There is also plenty of interesting information to learn about other types of sugar such as cane sugar, alternatives like agave syrup, and sugar additives.

Sources
Berneis, K (2012). Die Suche nach dem süssen Plazebo. Zucker ist nicht gleich Zucker! Swiss Medical Forum, 12(1-2):6-7.

Lustig, R. H. (2019). Die bittere Wahrheit über Zucker – Wie Übergewicht und andere chronische Krankheiten entstehen und wie wir sie besiegen können. 4th edition. Munich: Riva-Verlag.

Wölnerhannsen, K. (2020). Raffinierter Zucker – Wertvolle Energie oder physiologischer Unsinn? Quintessenz Zahnmedizin, 71(5).

Yudkin, John & Lustig, Robert. P. (2014). Pur, weiß, tödlich: Warum der Zucker uns umbringt – und wie wir das verhindern können. Lünen: Systemed Verlag.