Fructose, glucose and their differences - all sugar or what?

Fructose und Glucose

Fructose, glucose, sucrose, ... - we all know these terms. But what are all these names for sugar? Is there good and bad sugar? - With the help of a little chemistry (don't worry, you don't need to dig out your dusty chemistry knowledge from school) in this article we want to explain to you the differences between fructose and glucose.

Fructose and glucose - sugar as a vital substance?

It's clear: our bodies need sugar. We think about the provision of energy, cell structure and so on. However, our body does not need sugar in the form of table sugar, but rather 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 ate and drank an average of 34.8 kilos of sugar per capita. This corresponds to almost twice the amount that the World Health Organization (WHO) has recommended for many years as the maximum amount of sugar consumed . For comparison: People in primitive tribes consume around 3 to 5 kilos of sugar per year (Wölnerhanssen, 2020). The shocking thing is that our body is not dependent 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 of sugar

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

- Simple sugars (monosaccharides)
- Disaccharides and
- Multiple sugars (polysaccharides)

The well-known table sugar ( sucrose ) consists of glucose and fructose - more precisely, 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 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 source of energy for the human body. The brain also needs glucose as a nutrient. In humans and animals, glucose is stored in the form of glycogen, and in plants it is stored in the form of starch . Fructose is also a white powder that is more easily soluble in water and sweeter tasting than glucose . You can find even more background knowledge about glucose and its different types in this video .
Both fructose and glucose have the molecular formula C6 H 12 O 6 . 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 through the blood. When consuming sucrose (table sugar), the body relies on the breakdown of the sugar into glucose and fructose. If sugar is not consumed in the form of sucrose but as glucose or fructose, these can be processed directly. But what happens to the fructose and glucose in the body?
In the human body, glucose enters the blood via the intestines 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. In addition, the absorption of glucose causes an enormous increase in blood sugar levels and the release of insulin. In addition, satiety hormones are 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 also not released (Wölnerhanssen, 2020).

Fructose and glucose in foods

Glucose is found naturally in many foods.
As the name suggests, fructose or fructose is found increasingly in fruit and honey. Fructose is also 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 amount. Therefore, less fructose is needed than glucose to sweeten a dish. Since fructose is much cheaper to produce than sucrose (table sugar), fructose has increasingly been added to processed foods in recent decades (Yudkin & Lustig, 2014, p. 43). You can find out more about fructose in processed foods and why the artificially added sweetness of fructose can be a problem in this video .

Now you ask yourself: What about fruit then? Does it contain fructose? - You're absolutely right. However, in addition to fructose and glucose, fruits and vegetables contain many other nutrients, fiber and vitamins. This means that not only glucose and fructose, but also many other nutrients are absorbed. On the other hand, the fiber it contains ensures that not so much sugar can be absorbed at once and that sugar absorption in the body is slowed down. This allows the liver to keep up with the sugar intake. Therefore, it is not so easy to consume too much sugar from natural foods such as fruits and vegetables (Lustig, 2019, pp. 171-173).

And what does a juice cleanse look like?

With a juice cleanse , you give yourself a break and consciously avoid solid food, from which you normally get the energy your body needs. The juices are your only source of nutrition and therefore your only sugar intake. With our cold-pressed I·DO juices you absorb the sugar and also the nutrients of a few portions of vegetables and fruit per day. However, sugar intake is limited during this time because the amount of juice per day is precisely defined.

Of course, no additional sugar is added to our I·DO juices . Through cold pressing, your body also benefits from the full range of nutrients and minerals from fresh vegetables and fruit - in contrast to consuming conventional pasteurized juices.


One thing is certain: not all sugar is the same. As a reminder: Sucrose is table sugar and is a disaccharide and consists of fructose and glucose. Fructose and glucose are both monosaccharides (simple sugars).

Less sugar – whether glucose or fructose
As with all nutritional components, the following applies here: balance is the be-all and end-all! A balanced diet with sufficient proportions of all important components covers the body's glucose and fructose needs. Sugar should only be consumed through foods in which it occurs naturally. So make sure you consume sugar in its naturally occurring form through fruits, vegetables, grains, etc. Because excessive consumption of sugar can have a harmful effect on the body's organ systems ( Wölnerhanssen, 2020).

You can find out more about sugar in the following magazine articles, because fructose and glucose are not the only forms in which sugar can be absorbed. There is also a lot worth knowing about other types of sugar such as cane sugar, alternatives such as agave syrup and sugar additives.

Berneis, K (2012). The search for the sweet placebo. Not all sugar is the same! Swiss Medical Forum, 12(1-2):6-7.

Lustig, RH (2019). The bitter truth about sugar – How obesity and other chronic diseases arise and how we can beat them. 4th edition. Munich: Riva-Verlag.

Wölnerhannsen, K. (2020). Refined sugar – valuable energy or physiological nonsense? Quintessence Dentistry, 71(5).

Yudkin, John & Lustig, Robert. P (2014). Pure, white, deadly: Why sugar is killing us - and how we can prevent it. Lünen: Systemed Verlag.