Most people are aware that consuming sweets does not promote our health. However, our bodies still retain from earlier times that we need sugar to quickly obtain energy and to store it for times without food. But in today's world, with several meals a day, we hardly need these reserves.
The craving for sweets has nevertheless persisted. Studies increasingly show that not only the consumption of real sugar but also that of substitute products can be harmful. Research is still discussing the exact consequences for obesity, diabetes, cardiovascular diseases, and our gut microbiome.
What types of sugar are there and how does it affect our body?
When we say sugar, we usually mean table sugar, also known as sucrose.However, there is a large number of different molecules that fall under the category of "sugar." For even polysaccharides, such as starch from complex carbohydrates, are ultimately metabolized into simple sugars during digestion. These different options for sweetening have varying effects on blood sugar levels and insulin secretion.
Types of sugar such as glucose, fructose, and sucrose differ in their structure, absorption, and effects on the body. Glucose and fructose naturally occur in fruits, vegetables, and honey, while sucrose, a disaccharide, consists of glucose and fructose and is mainly found in table sugar and many processed foods.Let's take a closer look at the individual sugar molecules:
Simple sugars (Monosaccharides)
Glucose (Grape sugar)
- Occurrence: Glucose occurs naturally in fruits, vegetables, and honey. It is one of the most common types of sugar in our diet and is used as the body's primary energy source. Particularly high amounts of glucose can be found in bananas, grapes, oranges, cherries, as well as carrots and sweet potatoes.
- Health effects: Glucose is quickly absorbed into the bloodstream and leads to a rapid increase in blood sugar levels. Regular excessive consumption can increase the risk of Type 2 diabetes and obesity . Since glucose directly affects insulin levels, it plays a key role in metabolic diseases.
Fructose (fruit sugar)
- Occurrence: Fructose is naturally found in fruits. A particularly high content of fructose is present in apples, pears, grapes, watermelons, and mangoes. Low levels can be found z.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 to fatty liver, insulin resistance, and an increased risk of cardiovascular diseases . In contrast to glucose , fructose raises blood sugar levels less significantly, but with consistently high intake, it can damage the liver and lead to weight gain.
Fructose is almost twice as sweet as glucose and is hidden in more and more foods. Especially in the USA, the molecule is processed in many foods in the form of corn syrup, which has concerning consequences for the development of overweight. In fruits, fructose is combined with many fibers and is therefore considered healthy in moderate consumption.
Allulose
Allulose is a rare sugar that is found naturally in small amounts in foods. Examples of foods containing allulose include:
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Occurrence: figs, raisins, wheat
Although the molecule occurs in nature, allulose is often derived from corn or sugar beets for commercial purposes and used as a sugar alternative in processed foods. - Health Effects:
- Low Calorie: Allulose contains only about 0.2–0.4 calories per gram, compared to 4 calories per gram in regular sugar.
- Blood Sugar Levels: It has little effect on blood sugar and insulin levels, making it particularly suitable for people with diabetes.
- Metabolism: Allulose is mostly not absorbed and is excreted through urine, which reduces the calorie content.
- Possible Benefits: Studies show that allulose may have positive effects on liver health and improve insulin sensitivity.
These properties make allulose a popular alternative to regular sugar for health-conscious individuals and diabetics.
Galactose is a simple sugar and a component of milk sugar (lactose), which occurs in dairy products.
Disaccharides (Double sugars)
Sucrose (table sugar)
- Occurrence: Sucrose is found in sugar beets, sugar cane, and some fruits like pineapple. In its processed form (table sugar), it is widely used in confectionery and processed foods.
- Health effects: Sucrose is broken down in the body into glucose and fructose. High consumption of sucrose often leads to weight gain, cavities and an increased risk of diabetes.Sugary drinks and processed foods significantly contribute to sugar addiction as they are easily accessible sources of sugar without fiber that could slow down absorption.
Lactose (milk sugar)
- Occurrence: In milk and dairy products such as cheese, yogurt, and cream.
- Health effects: Lactose is broken down in the small intestine by the enzyme lactase into glucose and galactose. People with lactose intolerance cannot properly digest lactose, which can lead to digestive issues such as bloating, diarrhea, and abdominal pain . For people without this intolerance, lactose is harmless in moderate amounts.
Fructose, glucose, and also sucrose (regular table sugar) contain about the same number of calories (around 400 kcal or1673 kJ per 100 g)
Complex carbohydrates (Polysaccharides)
Starch:
Starch is particularly abundant in grains such as wheat, rice, and corn, but also in potatoes and legumes. Since this is a complex sugar, it is digested more slowly because the long carbohydrate chains must first be broken down. A high consumption of starchy, highly processed foods (such as white bread) can lead to weight gain and blood sugar problems .
Glycogen:
Glycogen is the storage form of glucose in the human body and does not occur directly in foods. It is stored in the liver and muscles and converted into glucose when needed. However, excess 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 cellular aging. Even with otherwise healthy eating, 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, known as Advanced Glycation Endproducts, or AGEs for short. These AGEs are also present in our food – especially highly processed foods contain particularly high amounts of them. In combination with proteins, glucose promotes a loss of activity here, which has negative consequences for cell health and thus leads to the aging process. Therefore, it is a goal to have as few AGEs as possible in the body, with Carnosine also playing a supportive role and reducing their formation.
Complex carbohydrates, however, have a different effect on the body and usually do not cause blood sugar levels to rise as sharply, as the complexity of the molecules and the fiber content result in a slower absorption.The rise in blood sugar and thus the reaction to food is very individual, which is why at this point a temporary "tracking" of blood sugar levels using a Continuous Glucose Monitor (CGM) brings clarity. This way, it can be determined how the individual blood sugar level reacts to food.
In the search for possible ways to extend the health span, the intake of berberine is a real lever among researchers. It was only a few years ago that it was thoroughly investigated for its molecular mechanism of action, and it was found that berberine can have a positive effect on blood sugar levels and increase insulin secretion.
What are sweeteners and what are sugar substitutes?
Types of sweeteners
Sweeteners are, with the exception of Stevia and Thaumatin, synthetically produced compounds that provide hardly any calories , do not promote tooth decay, and have an extremely high sweetness compared to conventional sugar. The most well-known representatives include Acesulfame K (E 950), Aspartame (E 951), Cyclamate (E 952), Saccharin (E 954), and Sucralose (E 955).
Since sweeteners are classified as food additives , they must be listed on the ingredient list. For each sweetener, there is an ADI value (Acceptable Daily Intake) set by the World Health Organization (WHO), which indicates the safe daily maximum dose.For example, the ADI value for Stevia is 4 mg per kilogram of body weight and for Aspartame 40 mg per kilogram of body weight.
A central health aspect is the question of whether these sweeteners affect the gut microbiome within the established ADI limits. Studies show that this may be the case. A study from 2021 found that even small amounts of Sucralose, Saccharin, or Aspartame can negatively alter the composition of the gut bacteria.
Sweeteners like Aspartame, Sucralose, and Stevia are significantly sweeter than sugar and contain little to no calories. These sweeteners are only needed in very small amounts, as they have a high sweetness power – for example, Sucralose is about 600 times sweeter than sugar, and Stevia around 200-300 times.Sweeteners have little effect on blood sugar levels and are therefore particularly attractive for people with diabetes.
However, research has also discovered additional properties of sweeteners. A new study from the Leibniz Institute for Food Systems Biology at the Technical University of Munich shows for the first time that during the digestion of the natural sweetener Thaumatin, bitter protein fragments (peptides) are produced in the stomach. These stimulate the acid release of human stomach cells and positively influenced inflammatory reactions in the study. Thaumatin is about 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, perceived as a sweet taste.Since they are either not fully absorbed by the body or only used in very small amounts, they provide virtually 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 amounts that aspartame contains only minimal calories. With about 200 times the sweetness of sugar, aspartame is commonly used in beverages 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 mostly excreted unchanged, which is why it is calorie-free. It has a 600-fold sweetness of sugar and is often used in reduced-calorie foods. The ADI value for sucralose is 15 mg per kilogram of body weight.
- Stevia (Steviol glycosides, E 960): Stevia is a natural sweetener derived from the leaves of the Stevia plant. It has no effect on blood sugar levels, as the sweetening compounds, the steviol glycosides, are not broken down like sugar in the body. 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, about 25% of adults regularly use products with sweeteners. From a calorie consumption perspective, this could reduce calorie intake by about 10%, according to a meta-analysis from 2020. This could in turn lead to an average weight loss of about 0.8 kg per month.
Types of Sugar Substitutes
Sugar substitutes, such as xylitol and erythritol, have a similar structure to sugar, provide like sweeteners fewer calories, and therefore have a lower impact on blood sugar levels. However, these compounds are less sweet than sugar, reaching about 60% to 100% of the sweetness. Since sugar alcohols are only partially absorbed in the small intestine, they often have fewer calories (about 2-3 kcal/g compared to sugar with 4 kcal/g). Examples of sugar substitutes include erythritol (E 968), xylitol (E 967), isomalt (E 953), sorbitol (E 420), and also the substance derived from monk fruit.
How do sugar substitutes work?
Sugar substitutes are only partially absorbed by the body.The remaining part reaches the large intestine, where it is either fermented or excreted unchanged. This leads to a lower increase in blood sugar levels and is particularly suitable for people with diabetes.
- Xylitol (E 967): Xylitol has about the same sweetness as sugar but provides only about 60% of the calories. It is commonly used in sugar-free chewing gums and dental care products, as it has been shown to prevent cavities. Studies show that xylitol can reduce the risk of cavities by up to 85%.
- Erythritol (E 968): Erythritol provides almost no calories (about 0.2 kcal/g), as it is almost completely excreted unchanged by the body. It has about 70% of the sweetness of sugar and does not affect blood sugar levels.Studies show that erythritol is well tolerated and is less laxative than other sugar alcohols.
The consumption of sugar substitutes is also increasing, especially in Europe, where they are used in a variety of foods. Studies have shown that people who regularly consume sugar substitutes like xylitol or erythritol can, on average, reduce their caloric intake by 20 %, which leads 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 widely discussed in the media and research. However, based on current scientific findings, there is no clear evidence that sugar substitutes like 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 value is 40 mg per kilogram of body weight – much more than you would normally consume.
- Sucralose: Although a study in mice showed an increased cancer risk at extremely high doses, these results were considered irrelevant for humans. The FDA and the EFSA classify sucralose as safe.
- Stevia: Natural sweetener from the stevia plant. So far, there is no evidence of an increased cancer risk.Studies show that Stevia has no carcinogenic effects.
What is better now - sugar or substitutes?
The average daily sugar consumption varies by region and country.On average, global sugar consumption is about 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 about 126 grams, which is more than five times the amount recommended by the WHO of 25 grams per day. In Europe, consumption varies widely, but in countries like Germany, it is about 90-100 grams per day. The benefits of sweeteners and sugar substitutes are clear: they allow for a reduction in sugar consumption without having to give up sweet taste. Furthermore, some studies show that they have little to no impact on blood sugar levels and insulin response, which lowers the risk of insulin resistance and diabetes.
Despite these positive properties, there are still concerns about the effects on gut health, particularly due to changes in the microbiome.
While some studies show a potentially negative effect of sweeteners on gut bacteria, the overall situation of research is not yet entirely clear. It remains important to consider individual tolerances and possible effects when using sugar alternatives.
Brand new on the sweetening horizon is the monk fruit. It consists of various carbohydrates such as fructose, glucose, and secondary plant compounds like mogrosides, which influence the sweetness of the fruit. The more it has, the sweeter the fruit is. The fruit can be about 300 times sweeter than table sugar and is now increasingly used in food products.
Sugar is a natural component of many foods and is used by our body as a quick source of energy . However, excessive sugar consumption can have negative health effects, such as diabetes, obesity, and cardiovascular diseases. Fructose and glucose, which are found in fruits and vegetables, are more natural, but can also be problematic in large amounts, especially when they are present in processed foods. Particularly fructose, which is found in corn syrup, significantly contributes to the increase in overweight.
Sweeteners like 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 impact on blood sugar and are particularly suitable for diabetics. However, they can cause digestive issues in larger amounts.
Overall, the question of whether sugar or sweeteners are better depends on individual health goals. Sugar substitutes can help reduce calories and control blood sugar, but should be consumed in moderation, as potential long-term effects, especially on the microbiome, are not yet clearly understood.
