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Dr. Advice

Sweeteners or sugar substitutes, or just sugar?

Sugar

Sugar is a colourless carbohydrate of crystalline structure. It appears white through refraction. All green plants are made up of carbohydrates, which are formed in the chlorophyll from sun energy, carbon dioxide and water through photosynthesis.

There are different types of sugars classified according to their chemical structure:

Table 3: Classification of sugar according to chemical structure:
Monosaccharides Disaccharides Polysaccharides
  • Grape sugar (glucose)
  • Fruit sugar (fructose)
  • Household, raw or beet sugar (sucrose)
  • Malt sugar (maltose)
  • Milk sugar (lactose)
  • Starch
  • Dietary fibres (such as cellulose)

Glucose plays an extra special role for people with diabetes. It is quickly absorbed into the blood from food, and can be measured as “blood sugar” using various methods (e.g. blood sugar measuring devices). When the blood sugar level in the beta cells of the pancreas rises, healthy bodies release more of the hormone insulin, enabling the glucose to be absorbed and used in the muscle cells. For people with diabetes, insulin production has either ceased (type 1) or the effect of the insulin on the muscle cells is defective (type 2). Both cases result in an increased blood sugar value. Long-lasting phases with high blood sugar levels lead to damaged organs, vessels and nerves. Treatment of diabetes mellitus with insulin, medications for reducing blood sugar levels, and systematic controlling of diet and exercise aims to achieve a blood sugar level as close as possible to that of health people to avoid subsequent damage.

Carbohydrates play a special role for controlling the diet of diabetics because of the direct correlation between food intake and the increased blood sugar level. During digestion, disaccharides and polysaccharides are initially divided into monosaccharides - only these can be absorbed into the bloodstream.

Unlike glucose, fructose is processed virtually exclusively in the liver and is not insulin-dependent, which is the main reason why it is used to replace sugar, together with sweeteners or sugar substitutes, in diabetic foods.
However, medical literature has recently shown that too much fructose can lead to unpleasant effects on health. Fructose leads to a greater gain in unhealthy stomach fat, which weakens insulin sensitivity and contributes towards raising the blood sugar level (study by the University of California, www.news.ucdavis.edu). Even though, for the purposes of the study tests, larger quantities of fructose were administered than those normally absorbed through the eating of fruit, particularly overweight people should make sure they do not consume extra quantities of fructose in food.

The division of the disaccharides and polysaccharides into monosaccharides, which can then be absorbed by the body, is clearly slower than the direct digestion of glucose (“goes immediately into the blood”). This effect is consciously capitalised on in the diets of people with diabetes. However, each intake of carbohydrates leads to an increased blood sugar level and must be taken into account when arranging treatment. Insulin-treated diabetics in particular must adjust the quantity of injected carbohydrates to the quantity of insulin injected. The so-called “bread unit” (BU) was introduced many years ago as a measurement unit enabling mutual exchange of carbohydrates. One BU corresponds to the quantity of food containing 12 g of carbohydrates. Attempts were later made to convert it to “carbohydrate units” (CU or CHU) for simplification. One CU corresponds to the quantity of food containing 10 g of carbohydrates. In German-speaking Switzerland, however, the “BU” had already been defined as 10 g carbohydrate content. The term “carbohydrate unit” has not been implemented in Germany. Even today, “bread units” are most commonly used, and defined as being 10 to 12 g of carbohydrates. There are extensive tables which list the “BU” content of food to enable exchange between them. Until well into the 1990s, this data constantly showed that food containing sugar was to be strictly avoided by diabetics. We will address this issue later.

At so-called training sessions, however, people with type 2 diabetes are often tortured with hour-long lectures about “BUs” and exchange tables, although they are unnecessary for overweight people not treated with insulin. For these people, weight loss, and therefore the consumption of low-energy foods, is the main priority. They are better off counting “calories” instead of “BUs”.

Reducing food containing carbohydrates down to “BUs“ alone is a gross simplification. Apart from the quantity of carbohydrates contained, the speed of the division and the absorption of glucose into the blood must also be taken into account when arranging treatment (so called “Glycaemic Index”). So for example, blood sugar levels rise slower with wholemeal bread than with the same quantity of carbohydrates in the form of fruit juice. But it’s not just food alone, but also its preparation or combination with other foods which influences blood sugar level increases - protein and fat have an inhibitory effect on intake, while intense crushing (e.g. potato broth instead of salted potatoes) accelerates it. Training centres, specialised diabetological practices and clinics offer extensive training options allowing insulin-treated diabetics in particular to not only be provided with knowledge, but also to perform practical exercises. Diabetics treated with blood sugar-reducing tablets or exclusively with “diet” should primarily concentrate on learning to estimate and control the energy content of food. However, food with a low glycaemic index, i.e. a slow increase in blood sugar levels after food intake, should also be given preference here.  The only sure way of losing weight is by reducing energy intake or increasing energy consumption!

Until the 1990s, guides and instructions prohibited diabetics from consuming household sugar. Consumption of food containing sugar was considered one of the “greatest sins” of the treatment. If the taste really has to be made “sweet”, it must only be done with sweeteners or sugar substitutes. This attitude has been clearly rethought in the last 10 to 15 years. Of course, it continues to be general knowledge that diabetics should not force consumption of pure sugar. But type 1 diabetics on intensified insulin treatments or insulin pump treatments can definitely incorporate a sensible, limited amount of sugar-containing food into their diet. Attention must, however, be paid to the pure carbohydrate content of the sugar, as well as the remaining composition of the food, which influences the glycaemic index. So for example, pure sugar-containing drinks such as “normal” colas or lemonades should only be consumed in emergencies to combat hypoglycaemia, as they lead to a very quick rise in blood sugar levels, which cannot be promptly balanced even by injecting fast-acting insulin. If, apart from the carbohydrates, fats and proteins are also contained in the food, these can be sensibly incorporated into the diet. The nutrient content tables now shown on many foods are useful for calculating carbohydrate content. They provide information not only on the carbohydrates, but also on other ingredients such as fat, protein, dietary fibres, vitamins and minerals. The energy content is always listed there - so they are an ideal aid for people with type 2 diabetes, for example! The carbohydrates are often already converted to BUs. Foodstuffs labelled in this way are of valuable help to diabetics, as well as to overweight and health-conscious people.

There are many internet websites with information on the carbohydrate content of “normal“ foods. We found a very detailed overview here.

Sugar substitutes

Sugar substitutes are carbohydrates with a sugar-like taste but which usually have less sweetness (normally 40 - 70%). Sugar substitutes are processed by the body, but less insulin is needed for this than for sugar. This leads to a slower and clearly lower rise in blood sugar levels, meaning sugar substitutes are often used in so-called diabetic foods to replace normal sugar. Even though the calorific value is only half that of household sugar (approx. 2 calories per gram), it must be included in the daily calorie balance. This is particularly important for weight-reducing foods!

Sugar substitutes are often combined with sweeteners to increase sweetness.

Sugar substitutes are not considered to be harmful to health, but they are not completely absorbed by the small intestine, and so reach the large intestine virtually unchanged. They bond water here and can thus lead to diarrhoea, stomach pain and flatulence if consumed in large quantities. For this reason, products containing more than 10% sugar substitutes must be labelled “can have a laxative effect with excessive consumption”.

Sugar substitutes are often used in food for healthier teeth, as they cannot be processed by cavity-causing bacteria.

Table 2: List of the most common sugar substitutes, their identification code and most important characteristics:

Sugar substitute

ID code

Characteristics

Sorbitol

E420

  • Exists in nature in some fruits (plums, rowan berries).
  • Has half the sweetness of sugar.
  • Is manufactured industrially from glucose using enzymes.
  • Is decomposed in the metabolism like fructose (see Section 3 Sugar).
  • Can lead to diarrhoea, stomach pain and flatulence when consumed in larger quantities.
  • Used in low-energy/sugar-free desserts, ice cream, sugar-free sweets and chewing gums, sauces, mustard.

Mannit, Mannitol

E421

  • Exists in nature in algae, fungi, figs, olives, in the sap of the larch or manna ash (name giver!).
  • Has around half the sweetness of sugar.
  • Is manufactured industrially from fructose using enzymes.
  • Can lead to diarrhoea and flatulence when consumed in larger quantities.
  • Used in low-energy/sugar-free desserts, ice cream, sugar-free sweets and chewing gums, sauces, mustard.
  • Relatively expensive!

Isomalt

E953

  • Exists in nature in sugar beets.
  • Has around the same sweetness as sugar.
  • Is manufactured industrially from the sugar of sugar beets in two processing stages.
  • Can have a laxative effect when consumed in large quantities.
  • Used in sugar free or low-sugar foods (pastries, mustard, sauces, jams, desserts), and in pastries to create sugar decorations because of the supple moldability of the hot isomalt.

Maltitol
Maltitol syrup

E965
E965ii

  • Is manufactured industrially from starch through chemical-enzymatic saccharification. It is possible to use genetically modified organisms.
  • Has around 60 – 90% of the sweetness of sugar.
  • No insulin is needed in the human metabolism to use pure maltitol. The white crystals are thus also suitable for diabetic products. On the other hand, maltitol syrup contains 50 - 77% maltitol, along with glucose and short-chain polysaccharides, for which metabolic degradation is insulin dependent. Maltitol syrup is therefore out of the question for diabetic foods.
  • It can lead to diarrhoea, stomach pain and flatulence when consumed in larger quantities.
  • Used in low-energy/sugar-free desserts, ice cream, low-energy/sugar-free sweets and chewing gums, sauces, mustard. Maltitol is also used as a carrier substance for flavours and vitamins, as well as in cosmetics and tobacco products.

Lactitol

E966

  • Lactitol is extracted from the monosaccharide lactose (milk sugar) through a chemical reaction.
  • It has around 30 – 40% of the sweetness of sugar.
  • It can lead to diarrhoea, stomach pain and flatulence when consumed in larger quantities.
  • Since lactitol is not hygroscopic, it is particularly suitable for food which must remain dry, such as powders or pastries.
  • Used in low-energy/sugar-free desserts, ice cream, low-energy/sugar-free sweets and chewing gums, low-energy/sugar-free cakes and biscuits, sauces, mustard, dietary supplements. Lactitol is also used as a carrier substance for sweetener tablets and in toothpastes.

Xylitol

E967

  • As the intermediate of the carbohydrate metabolism, xylitol is a natural component of living cells.
  • It is created from xylose through a chemical reaction. This so-called wood sugar is extracted from birch wood, among other things. It is also possible to create xylitol from glucose, which is extracted during starch saccharification. Generically modified organisms may be used for this.
  • Xylitol is somewhat less sweet than sugar.
  • It can lead to diarrhoea, stomach pain and flatulence if consumed in larger quantities.
  • Used in low-energy/sugar-free desserts, ice cream, low-energy/sugar-free sweets, chewing gum, low-energy/sugar-free cakes and biscuits, sauces, mustard, dietary supplements.

The sugar substitutes listed here are not subject to any maximum quantity limit. There are no specifications regarding maximum daily intake quantities (ETD or ADI).


Sweeteners

The term Sweetener or Sweetening Agent is a collective term for synthetic and natural compounds with an intense, sweet taste. Their sweetness is 3000 times stronger than sugar (sucrose).

Unlike sugar or sugar substitutes, all sweeteners are food additives which have no or a very low nutrient content (calories!). They are eliminated from the body virtually unchanged and  are available commercially as tablets, powders or liquids.

For people with diabetes, sweeteners are an alternative to sugar in sweet meals and drinks. Aside from this, they are increasingly being used by overweight people or the calorie-conscious as sugar substitutes in weight-reducing food. In the foodstuffs industry, sweeteners are therefore primarily used to sweeten so-called diabetic foods or “light” products. However, in these products, sweeteners are often also mixed with sugar substitutes. Use of these products must be labelled.

Most sweeteners have a specific aftertaste or smack. Some lose their sweetness when heated. Apart from limited taste, the use of sweeteners is also subject to a legal maximum quantity limit. Foods sweetened using sweeteners must have a corresponding entry in the ingredients list.

According to numerous studies, sweeteners do not have any properties harmful to health. Some sweeteners were previously said to cause cancer or increase appetite for sweet foods. The results of the studies showed no indication of this. Unlike sugar, sweeteners do not cause cavities.


Table 1: List of the most common sweeteners, their identification code and most important characteristics:

Sweetener Identification code Characteristics Maximum quantity limit Maximum daily intake = ETD or ADI (WHO)

Acesulfame
Acesulfame-K

E950

  • Manufactured through chemical synthesis.
  • Sweetness approximately 200 times stronger than sugar (household sugar – see Section 3).
  • Metallic smack.
  • Used mainly in drinks, preserves, jams, sweets.

25 - 2500 mg/kg or litre

0 - 9 mg/ kg body weight

Aspartame

E951

  • Manufactured through chemical synthesis, made up of the amino acids aspartic acid and phenylalanine.
  • Sweetness approximately 200 times stronger than sugar.
  • Contains equal amount of calories and protein.
  • Metallic smack in high concentrations.
  • Disintegrates at temperatures over 200 °C.
  • Is often combined with cyclamat.
  • Used mainly in drinks, spreads, desserts, milk products.
  • Must be labelled as a source of phenylalanine.

25 - 6000 mg/kg or litre

0 - 40 mg/ kg body weight

Aspartame-Acesulfame salt

E962

  • Made from 64 % aspartame and 35 % acesulfame.
  • Sweetness approximately 350 times stronger than sugar.
  • May only be used in very small quantities because of its high sweetness, and must therefore be classified as virtually calorie-free.
  • Water-soluble, sugar-like taste.
  • Used in diabetic foods, “light” products, chewing gums, chocolate, instant drinks, instant desserts.

No data

See Aspartame and Acesulfame

Cyclamat, Cyclohexylsulfamic acid, Cyclohexan-sulfamic acid

E952

  • Manufactured through chemical synthesis.
  • Sweetness approximately 35-70 times stronger than sugar (lowest sweetness of approved sweeteners).
  • Is often combined with saccharin to increase sweetness and round off the taste.
  • Suitable for cooking and baking.
  • Used mainly in (reduced-calorie) drinks, pastries or desserts.

0.25 - 25 mg/kg or litre

0 - 7 mg/ kg body weight (Beware! This can quickly be reached in small children through consumption of larger drink quantities.)

Saccharin

E954

  • Is the first industrially manufacturer sweetener (based on chemical synthesis).
  • Sweetness approximately 550 times stronger than sugar.
  • Bitter metallic task particularly in higher concentrations, so it is mainly used in combination with the sweeteners cyclamat or thaumin or the sugar substitute xylitol.
  • Virtually calorie-free.
  • Suitable for cooking and baking.
  • Used mainly in diabetic foods, drinks, preserves, desserts, sweets.

80 - 3000 mg/kg or litre

0 - 5 mg/ kg body weight

Sucralose

E955

  • Extracted from sugar.
  • Sweetness approximately 600 times stronger than sugar.
  • Virtually calorie-free.
  • Sugar-like taste properties with long, sweet aftertaste.
  • Often used in combination with other sweeteners.
  • Used mainly in diabetic foods, “light” products, desserts, sweets.

140 - 2400 mg/kg or litre

0 - 15 mg/ kg body weight

Thaumatin

E957

  • Educed from the seed of the West African Katemfe bush or extracted from plant sources through genetically modified micro-organisms.
  • First approved in the EC in 1996.
  • Sweetness approximately 2000 - 3000 times stronger than sugar.
  • 400 calories per 100 g – but virtually calorie-free due to the low quantities used.
  • Enhances and rounds off taste.
  • Liquorice-like aftertaste particularly in high concentrations.
  • Sweetness not heat-resistant.
  • Mainly used in combination with saccharin.
  • Used mainly in diabetic foods and “light” products.

50 - 400 mg/kg or litre

No ADI determined

Neohesperidin-DC, Neohesperidin

E959

  • Manufactured from flavonoids (water-soluble plant pigments) through chemical synthesis.
  • Sweetness approximately 400 - 600 times stronger than sugar.
  • Negligible calorie content
  • Menthol-like smack limits use.
  • Often used together with other sweeteners and flavours.
  • Mainly used in nibbles and snacks.

30 - 400 mg/kg or litre

0 - 5 mg/ kg body weight

Summary

After describing the various options for labelling food with the taste “sweet”, we want to try and provide a summary and evaluation in this section.

Sweeteners  are primarily suitable for anyone wanting to save on calories. But people whose diabetes is treated with insulin can thus also save on insulin. This particularly applies for drinks.

Sugar substitutes play a large role in diabetic foods, but they are also used in many products aimed at health-conscious people (e.g. sugar-free chewing gums). They are less suitable for overweight people. The energy content (calories!) is often not much less than that of sugar-containing foods. Attention must also be paid to side effects. They can often lead to flatulence, stomach pain and diarrhoea when consumed in larger quantities.

Diabetic foods are expensive and often not necessary. In sensible quantities, and bearing in mind the carbohydrate and energy balance, even sugar-containing foods can often be consumed instead. As long as you don’t want to eat a whole block of chocolate all at once, this doesn’t have to be “diabetic” chocolate. This is discouraged in any case, because of the known side effects of the sugar substitutes it contains!

Light” products play an increasingly greater role in supermarket stock and advertisements to consumers. But beware, “light” is not quite “light”. You have to know which ingredients you want to be “lighter” in each individual case. For example, diabetics should not only pay attention to the “sugar-free” add-on for drinks, but also to the fact that the carbohydrate content is clearly reduced. With these sorts of foods, the sugar is often only replaced by sugar substitutes. This is also an important tip for overweight people. Make sure you are convinced that the calorie content really is less than for “normal” foods by looking at the nutrient content labels on foods. Diabetic puddings with sugar substitutes are not “lighter” than conventional puddings in terms of calories.

Nutrient content tables, which are nowadays placed on many foods, are of valuable help to diabetics, as well as to overweight people, when selecting, calculating and assessing nutrition. These are, in my personal opinion, much more useful that phrases such as “suitable for diabetics”, “sugar-free” or “low-fat”. They not only provide information on the carbohydrate, and therefore the BU content, but also on the energy, fat and protein content. Let us hope that this sort of information will be available on all foods in the future.

Dr. Andreas Müller, Saalfeld Anja Sandeck, Saalfeld
Internal specialist, DDG Diabetologist Graduate engineer in foodstuffs technology and engineering
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