Sweet temptation or health risk? All about sugar, substitutes and co.

Most people are aware that the consumption of sweets does not promote our health. However, our bodies still remember from earlier times that we need sugar to get energy quickly and to store it for times when we don't eat. But nowadays, with several meals a day, we hardly need these reserves.

The craving for sweets nevertheless remains. Studies are increasingly showing that not only the consumption of real sugar, but also that of substitute products can be harmful. Researchers are still debating the exact consequences for obesity, diabetes, cardiovascular disease and our gut microbiome.

What types of sugar are there and how do they affect our bodies?

When we hear the word sugar in everyday life, we usually mean household sugar, also known as sucrose. However, there are a large number of different molecules that fall under the category of "sugar". This is because even polysaccharides, such as starch from complex carbohydrates, are ultimately metabolized to simple sugars during digestion. These different ways of sweetening have different effects on blood sugar levels and insulin secretion .

Types of sugarsuch as glucose, fructose and sucrose differ in their structure, absorption and effect on the body. Glucose and fructose occur naturally in fruit, vegetables and honey, while sucrose, a disaccharide, consists of glucose and fructose and is mainly found in household sugar and many processed foods. Let's take a closer look at the individual sugar molecules:

Simple sugars (monosaccharides)

Glucose (dextrose)

• Occurrence : Glucose occurs naturally in fruit, vegetables and honey. It is one of the most common types of sugar in our diet and is used as the body's primary source of energy. Bananas, grapes, oranges, cherries, carrots and sweet potatoes are particularly high in glucose.
• Health effects : Glucose is quickly absorbed into the blood and leads to a rapid rise in blood sugar levels. Regular, excessive consumption can increase the risk oftype 2 diabetes and obesity . As glucose directly influences insulin levels, it plays a key role in metabolic diseases.

Fructose (fruit sugar)

• Occurrence : Fructose is naturally contained in fruit. A particularly high proportion of fructose is found in apples, pears, grapes, watermelons and mangoes. Low levels are foundz.B. in strawberries, blueberries and also citrus fruits
• Health effects : Fructose is processed in the liver, where it is converted into glucose. Excessive consumption, especially of industrially added fructose (such as in corn syrup), can lead tolipidemia , insulin resistance and an increased risk ofcardiovascular disease . In contrast to glucose, fructose raises blood sugar levels less but when ingested at consistently high levels, it damages the liver and can lead to weight gain.

Fructose is almost twice as sweet as glucose and is hidden in more and more foods. In the USA in particular, the molecule is processed in the form of corn syrup in many foods, which has serious consequences for the development of obesity. In fruit, fructose is combined with a lot of fiber and is therefore considered healthy when consumed in moderation.

Allulose

Alluloseis a rarely occurring sugar that is found naturally in small amounts in foods. Examples of foods with allulose are:

• Occurrence: Figs, raisins, wheat
  Although the molecule occurs naturally, allulose is often extracted fromcorn or sugar beet for commercial purposes and used as a sugar alternative in processed foods.
• Health effects:
• Low in calories : Allulose contains only about 0.2-0.4 calories per gram, compared to 4 calories per gram for conventional sugar.
• Blood sugar level : It hardly affects blood sugar and insulin levels and is therefore particularly suitable for people with diabetes.
• Metabolism : Allulose is largely not absorbed and is excreted in the urine, which reduces the calorie content.
• Potential benefits : Studies show that allulose may have positive effects on liver health and improve insulin sensitivity

These properties make allulose a popular alternative to conventional sugar for health-conscious people and diabetics.

Also galactose is a simple sugar and a component of milk sugar (lactose), which is found in dairy products.

Disaccharides (disaccharides)

Sucrose (table sugar)

• Occurrence : Sucrose is found in sugar beet, sugar cane and some fruits such as pineapple. In its processed form (household sugar), it is widely used in confectionery and processed foods.
• Health effects : Sucrose is broken down into glucose and fructose in the body. The high consumption of sucrose often leads toweight gain ,caries and an increased risk of diabetes . Sugary drinks and processed foods are major contributors tosugar addiction because they are easily accessible sources of sugar without fiber that could slow absorption.

Lactose (milk sugar)

• Occurrence:In milk and dairy products such as cheese, yogurt and cream.
• Health effects : Lactose is broken down into glucose and galactose in the small intestine by the enzyme lactase. People withlactose intolerance cannot digest lactose properly, which can lead to digestive problems such as bloating, diarrhea and abdominal pain . For people without this intolerance, lactose is safe in moderate amounts.

Fructose, glucose and sucrose (normal household sugar) contain roughly the same number of calories (around 400 kcal or 1673 kJ per 100 g)

Multisaccharides (polysaccharides)

Stärke:

Starch is particularly abundant in cereals such as wheat, rice and maize, as well as potatoes and pulses. As this is a complex sugar, it is digested more slowly as the long carbohydrate chains have to be broken down first. A high consumption of starchy, highly processed foods (such as white bread) can lead to weight gain and blood sugar problems .

Glykogen:

Glycogen is the storage form of glucose in the human body and is not found directly in food. It is stored in the liver and muscles and converted into glucose when needed. However, too much glucose that is not burned is stored as fat.

What effect do the different forms of sugar have on our body?

A new study by scientists at the University of California, San Francisco, has found a link between a diet with lower sugar consumption and slower biological cell ageing. Even with otherwise healthy diets, the researchers found that every gram of sugar consumed was associated with an increase in epigenetic age .

Glucose has the effect of causing adhesions in the body, the so-called Advanced Glycation Endproducts , or AGEs for short. These AGEs are also found in our food - highly processed foods in particular contain a lot of them. In combination with proteins, glucose promotes a loss of activity here, which has negative consequences for the health of the cells and thus leads to the ageing process. It is therefore a goal to have as few AGEs as possible in the body, whereby carnosinealso has a supporting effect and reduces their formation.

Complex carbohydrates, however, have a different effect on the body and generally do not cause blood sugar levels to rise as much, as the complexity of the molecules and the fiber content cause slower absorption. However, the rise in blood glucose and therefore the reaction to food is very individual, which is why temporary "tracking" of the blood glucose level using a continuous glucose monitor (CGM) provides clarity at this point. In this way, it is possible to find out how the individual blood glucose level reacts to food.

In the search for possible ways to extend the health span, the use of Berberin is a real lever among researchers. It was only a few years ago that this was investigated more thoroughly for its molecular mode of action and they found that berberine can have a positive effect on blood sugar levels and increases the secretion of insulin.

What are sweeteners and what are sugar substitutes

Types of sweeteners

Sweeteners, with the exception of Stevia and Thaumatine , are synthetically produced compounds that provide hardly any calories, do not promote tooth decay and have an extremely high sweetening power compared to conventional sugar. The best-known representatives include Acesulfame K (E 950), Aspartame (E 951), Cyclamate (E 952), Saccharin (E 954) and Sucralose (E 955).

As sweeteners are food additives , they must be stated on the list of ingredients. For each sweetener there is an ADI value (Acceptable Daily Intake) set by the World Health Organization (WHO), which specifies the maximum safe daily dose. For example, the ADI for stevia is 4 mg per kilogram of body weight and for aspartame 40 mg per kilogram of body weight.

A central health issue is whether these sweeteners affect the gut microbiome within the established ADI limits . Studies show that this may be the case. A study from 2021 came to the conclusion that even small amounts of sucralose, saccharin or aspartame can negatively alter the composition of intestinal bacteria .

Sweeteners such as aspartame, sucralose and stevia are significantly sweeter than sugar and contain few to no calories . These sweeteners are only needed in very small quantities as they have a high sweetening power - for example, sucralose is around 600 times sweeter than sugar, and stevia around 200-300 times. Sweeteners hardly affect blood sugar levels and are therefore particularly attractive for people with diabetes.

However, research has also discovered other properties of sweeteners. For example, a new study by the Leibniz Institute for Food Systems Biology at the Technical University of Munich shows for the first time that bitter protein fragments (peptides) are formed in the stomach when the natural sweetener thaumatin is digested. These stimulate the acid release of human stomach cells and positively influenced inflammatory reactions in the study. Thaumatin is around 2,000 to 3,000 times sweeter than sucrose.

How do sweeteners actually work

Sweeteners work by activating sweet receptors on your tongue, which send a signal to your brain that is perceived as a sweet taste. As they are either not fully absorbed by the body or only used in very small quantities, they provide practically no calories.

• Aspartame (E 951) : Aspartame is broken down into its components phenylalanine, aspartic acid and methanol after consumption. These substances are released in such small quantities that aspartame contains only minimal calories. With around 200 times more sweetening power than sugar, aspartame is often used in drinks and confectionery. According to the WHO, the Acceptable Daily Intake (ADI) for aspartame is 40 mg per kilogram of body weight.
• Sucralose (E 955) : Sucralose is largely excreted unchanged, which is why it is calorie-free. It has 600 times the sweetening power of sugar and is often used in calorie-reduced foods. The ADI value for sucralose is 15 mg per kilogram of body weight.
• Stevia (steviol glycosides, E 960) : Stevia is a natural sweetener obtained from the leaves of the stevia plant. It has no effect on blood sugar levels as the sweetening compounds, steviol glycosides, are not broken down in the body like sugar. The ADI value for stevia is 4 mg per kilogram of body weight.

Studies show that the consumption of sweeteners is increasing worldwide, especially in diet drinks. In the USA and Europe, around 25% of adults regularly consume products containing sweeteners. In terms of calorie consumption alone, sweeteners could reduce this by around 10%, according to a 2020 meta-analysis. This in turn could lead to an average weight loss of around 0.8 kg per month.

Types of sugar substitutes

Sugar substitutes, such as xylitol and erythritol , have a similar structure to sugar, provide fewer calories like sweeteners and therefore have a lower impact on blood sugar levels. However, these compounds are less sweet than sugar, achieving around 60 % to 100 % of the sweetening power. As sugar alcohols are only partially absorbed in the small intestine, they often have fewer calories (approx. 2-3 kcal/g compared to sugar with 4 kcal/g). Examples of sugar substitutes are erythritol (E 968), xylitol (E 967), isomalt (E 953), sorbitol (E 420) and also the substance obtained from monk fruit.

How do sugar substitutes work

Sugar substitutes are only partially absorbed by the body. The remaining part ends up in the large intestine, where it is either fermented or excreted unchanged. This leads to a lower rise in blood sugar levels and is particularly suitable for people with diabetes.

• Xylitol (E 967) : Xylitol has about the same sweetening power as sugar, but provides only about 60% of the calories. It is often used in sugar-free chewing gum and dental care products, as it has been proven to inhibit tooth decay. Studies show that xylitol can reduce the risk of tooth decay by up to 85%.

• Erythritol (E 968) : Erythritol provides almost no calories (approx. 0.2 kcal/g) as it is excreted by the body almost completely unchanged. It has around 70% of the sweetening power of sugar and has no effect on blood sugar levels. Studies show that erythritol is well tolerated and has less of a laxative effect than other sugar alcohols.

Consumption of sugar substitutes is also increasing, particularly in Europe where they are used in a variety of foods. Studies have shown that people who regularly consume sugar substitutes such as xylitol or erythritol can on average reduce their calorie consumption by 20% , leading to better weight control in the long term.

Do sugar substitutes really cause cancer

The question of whether sugar substitutes promote the development of cancer is still the subject of much debate in the media and among researchers. However, based on current scientific findings, there is no clear evidence that sugar substitutes such as aspartame, sucralose or stevia cause cancer as long as they are consumed in the recommended amounts.

• Aspartame : Numerous studies, including a comprehensive review by the European Food Safety Authority (EFSA), show that aspartame is safe in moderate amounts. The ADI is 40 mg per kilogram of body weight - far more than you normally consume.
• Sucralose : Although a study in mice showed an increased risk of cancer at extremely high doses, these results were considered irrelevant for humans. The FDAand the EFSA classify sucralose as safe.
• Stevia : Natural sweetener from the stevia plant. So far there is no evidence of an increased risk of cancer. Studies show that stevia has no carcinogenic effects.

Which is better now - sugar or substitutes?

The average daily sugar consumption varies according to region and country. The global average sugar consumption is around 17-25 grams per day per person, but this is significantly higher in many countries:

• In the USA the daily sugar consumption per person is around 126 grams, which is more than five times the WHO's recommended amount of 25 grams per day
• In Europe , consumption varies greatly, but in countries such as Germany it is around 90-100 grams per day

The benefits of sweeteners and sugar substitutes are obvious: they make it possible to reduce sugar consumption without having to sacrifice sweet taste. In addition, some studies show that they have little to no effect on blood sugar levels and the insulin response, which reduces the risk of insulin resistance and diabetes.

Despite these positive properties, there are always concerns about the effects on gut health, particularly through changes in the microbiome .

While some studies show a potentially negative effect of sweeteners on gut bacteria, the overall research situation is not yet as clear. It remains important to consider individual tolerances and potential effects when using sugar alternatives.

The monk fruit is a brand new addition to the sweetening sky. It consists of various carbohydrates such as fructose, glucose and secondary plant substances such as mogrosides, which influence the sweetness of the fruit. The more of these it contains, the sweeter the fruit. The fruit can be around 300 times sweeter than household sugar and is now increasingly being used in food.

Sugar is a natural component of many foods and is used by our body as a quicksource of energy . However, excessive sugar consumption can have negative health effects, such as diabetes, obesity and cardiovascular disease. Fructose and glucose, which are found in fruit and vegetables, are more natural, but are also problematic in large quantities, especially when they are contained in processed foods. Fructose in particular, which is found in corn syrup, is a major contributor to obesity .

Sweeteners such as aspartame and sucralose offer low-calorie alternatives to sugar, but their long-term effects on health, especially on the gut microbiome, are not yet fully understood.Sugar substitutes , such as xylitol and erythritol, have less influence on blood sugar and are particularly suitable for diabetics. However, they can cause digestive problemsin larger quantities.