Understand nutritional information
In Europe and many other countries around the world, it is mandatory that all pre-packaged foods have nutritional information. Consumer information is a great thing and when we go shopping we often look at the small list with the information on calorific value, fat, saturated fat, carbohydrates, sugar, fiber and salt.
These values are also listed on all products from the l-carb shop, both on the packaging and in the online offer. Nevertheless, there are always questions.
In fact, these values, which appear to be the result of scientific research, need to be explained, especially if you are trying to eat low carb.
The reason is that the composition of food is not that easy to determine!
Every food consists of thousands of different substances. There are an infinite number of different fats, proteins, fibers and carbohydrates. Even the assignment of substances to one of these categories is not always clear. To date, it has hardly been possible to determine the concentration of all the chemical compounds that make it up for any food.
Depending on the effort that is put into determining the composition, the results would vary considerably in many cases.
For this reason, not only the labeling but also the procedure for determination is specified in an EU directive.
However, the guiding principle was not the greatest possible scientific accuracy, but rather the establishment of practicable procedures and good comparability.
This approach, which is very good in itself, has its pitfalls, especially for low-carb users. Unfortunately, you have to understand how these values come about in order to really interpret them correctly.
1. How are the ingredients determined?
The amount of ingredients contained in a food may be measured, calculated or taken from relevant literature. One might think that the measurement would then be the most accurate method. However, if you consider that food is mostly a natural product and that one fruit is not like the other, it makes sense to compare your own measurement results with values from scientific publications.
Ingredients of processed foods are usually calculated from the composition of raw materials.
1.1. Determination of water, minerals and salt
The simple chemical substances such as water, table salt and other mineral salts can be determined very easily and precisely. By heating to 160°C, all the water evaporates and the water content in the original sample can be measured from the weight loss. If you heat it even higher to over 500 °C, all organic substances burn and the mineral part of the sample remains. The common salt content can easily be determined chemically by titration.
It is incomprehensible to us why cooking salt is still specified in the consumer information. Similar to the unsaturated fatty acids, the long-assumed danger of salt is now more than controversial.
The water content, which we often state in our products, would be much more interesting from my point of view.
1.2.Indication of the percentage of fat
The most accurate information in a nutritional table is the fat content. With the right methods, the fatty acids can be almost completely extracted from a food and you can then weigh it.
The proportion of saturated fatty acids can also be determined easily and precisely.
After it turned out that the demonization of saturated fatty acids was a scientific error, one could ask the question why the dangerous trans fatty acids are not given here instead of unsaturated fatty acids. The lobbying power of the margarine industry in Brussels is probably still too great for that!
1.3. Angabe des Eiweißanteils
Wesentlich ungenauer ist dann schon die Angabe des Eiweißanteils. Eiweißmoleküle besitzen ein Stickstoffatom. Durch Bestimmung des Stickstoffanteils in der Probe lassen sich dadurch Anhaltspunkte für den Proteinanteil ziehen. Für die Nährwertkennzeichnung ist vorgeschrieben, den gemessenen Stickstoffgehalt mit dem Faktor 6,25 zu multipizieren und den gefundenen Wert als Eiweißgehalt anzugeben. Der Faktor 6,25 ist aber nur ein Mittelwert über viele in Lebensmitteln vorkommende Eiweißsorten . So kommen bei Milchprodukten durch dieses Verfahren regelmäßig zu hohe Werte heraus, bei pflanzlichen Eiweißen wie zum Beispiel Weizenkleber zu wenig. Diese durch ein Gesetz festgeschriebene Ungenauigkeit führt zu Fehlern bis zu 10%. Weitere Ungenauigkeiten kommen durch andere auch aus Stickstoff bestehenden Substanzen zustande.
1.4. Angabe von Ballaststoffen und Kohlenhydraten
Die Anzahl der Stoffe, die sich unter den Begriffen Ballaststoff und Kohlenhydate zusammenfassen lassen ist unglaublich groß. Rein chemisch gesehen sind auch alle Ballaststoffe Kohlenhydrate. In der Amerikanischen Nomenklatur der Nährwertangaben sind unter "Carbohydrates" auch immer die Ballaststoffe mitgezählt, was bei Produkten die international vermarktet werden immer für Verwirrung sorgt.
Regelung in USA und vielen Teilen der Welt:
"Carbohydrates" umfassen alles, was nicht Fett, Eiweiß, Mineralien (Asche) oder Wasser ist. Von dem so ermittelten Wert können dann noch mal "Dietrary Fiber" und "Sugars" getrennt ausgewiesen werden. Des weiteren ist es nicht ungewöhnlich, dass die für Low Carbler eigentlich entscheidenden verwertbaren Kohlenhydrate (also Zucker und Stärke, die mit Insulin verstoffwechselt werden ) auch noch extra als "Net Carbs" dargestellt werden.
Regelung in der EU
In der EU umfasst der Wert der Kohlenhydate nicht die Ballaststoffe. Die Ballaststoffe werden extra bestimmt . Ähnlich wie in den USA wird dann der Rest als Kohlenhydrat deklariert und Zucker extra ausgewiesen.
Probleme bei der Ballastoffbestimmung
Nach EU Verordnung wird der Ballastoff Anteil nach der Prosky Methode bestimmt. Diese baut nach der Entfernung von Fett, Eiweiß und Mineralstoffen die enthaltene Stärke ab. Der Verbleibende Rest wird als Ballastoff deklariert. Leider ist der enzymatische Abbauprozess nicht so trennscharf wie erwartet. Nicht als Stärke verstoffewechselte (und damit für Low carbler attraktive) Stoffklassen wie resistente Stärke und nicht lösliche Oligosacharide werden mit abgebaut. Das Ergebnis ist, dass der angegeben Ballastsoffanteil des Lebensmittels zu gering, der Anteil and Kohlenhydraten zu hoch angegeben wird. Für viele Lebensmittel spielt das keine Rolle. Leider gibt es Lebensmittel, bei denen es recht viel ausmacht. 20% der Stärke in Haferflocken sind resistente Stärke . Oligosacharide bilden die Hälfte der Kohlenhydrate in Frühlingszwiebeln, die dadurch für Low Carbler wesentlich attraktiver werden. Auch wir haben uns durch diese Falschmessung davon abhalten lassen Lupinenmehl zu nutzen, da uns der angegebene Kohlemhydratanteil zu hoch war. Tatsächlich sind fast alle Carbs in Lupínen Oligosacharide und für Low Carb prima geeignet.
Auch grüne Bohnen und Erbsen sind durch den Messfehler viel besser für Low carb geeignet, als die Nährwerttabellen vermuten lassen
2. Problem der Kohlenhydratdeklaration für Low Carbler
Die Bestimmung des Kohlenhydratanteils als "Rest" ist für Low Carbler sehr problematisch.
Zum einen potenzieren sich alle Fehler der anderen Bestimmungsmethoden.
1.3. Specification of the protein content
The specification of the protein content is then much more inaccurate. Protein molecules have one nitrogen atom. By determining the nitrogen content in the sample, reference points can be drawn for the protein content. For the labeling of nutritional values, it is mandatory to multiply the measured nitrogen content by a factor of 6.25 and to state the value found as the protein content. However, the factor 6.25 is only an average of many types of protein found in foods. With dairy products, this method regularly results in values that are too high, with vegetable proteins such as wheat gluten, too little. This inaccuracy, stipulated by law, leads to errors of up to 10%. Further inaccuracies are caused by other substances that also consist of nitrogen.
1.4. Indication of dietary fiber and carbohydrates
The number of substances that can be summarized under the terms dietary fiber and carbohydrates is incredibly large. From a purely chemical point of view, all dietary fiber is also carbohydrate. In the American nomenclature of nutritional information, dietary fiber is always included under "carbohydrates", which always causes confusion with products that are marketed internationally.
Regulation in USA and many parts of the world:
"Carbohydrates" include anything that is not fat, protein, minerals (ash) or water. "Dietary Fiber" and "Sugars" can then be shown separately from the value determined in this way. Furthermore, it is not uncommon for the usable carbohydrates (i.e. sugar and starch, which are metabolized with insulin) that are actually decisive for low-carb people to be shown separately as "net carbs".
regulation in the EU
In the EU, the value of carbohydrates does not include fiber. The dietary fibers are determined separately. Similar to the USA, the rest is then declared as carbohydrate and sugar is shown separately.
Difficulty determining dietary fiber
According to the EU regulation, the fiber content is determined using the Prosky method. After removing fat, protein and minerals, this breaks down the starch contained in it. The remainder is declared as dietary fiber. Unfortunately, the enzymatic degradation process is not as selective as expected. Substance classes that are not metabolized as starch (and therefore attractive for low-carb people) such as resistant starch and insoluble oligosaccharides are also broken down. The result is that the specified fiber content of the food is too low and the carbohydrate content is too high. For many foods, this is irrelevant. Unfortunately, there are foods where it makes quite a difference. 20% of the starch in oatmeal is resistant starch. Oligosaccharides make up half of the carbohydrates in spring onions, making them much more attractive to low-carb fans. We were also prevented from using lupine flour by this incorrect measurement, as the specified carbohydrate content was too high for us. In fact, almost all of the carbs in lupines are oligosaccharides and are great for low carb.
Green beans and peas are also much more suitable for low carb than the nutritional tables suggest due to the measurement error
2. Problem of carbohydrate declaration for low carblers
Determining the carbohydrate content as "rest" is very problematic for low carblers.
On the one hand, all the errors of the other determination methods increase exponentially.
Example: Due to the inaccuracy in the prescribed determination method for protein, the proportion of gluten in wheat gluten is always given 5% too low. For example 80% instead of 85% in reality. As a result, the remaining carbohydrates have to be declared up to 3 times too high.
For many foods, the prescribed determination method for dietary fiber gives totally wrong values. For example, the dietary fiber inulin is not recorded as such, but counted among the carbohydrates. For the very inulin-containing lupins, this results in a totally wrong carbohydrate value. Unfortunately, this also applies to many vegetables.
The assignment of sugar alcohols (polyols) is particularly problematic. These substances, which are actually metabolized like roughage or not at all (i.e. they are not processed in the small intestine like sugar or starches with the release of insulin, but - if at all - converted into protein and fat in the rectum by intestinal bacteria) are not included in the roughage substances according to EU regulations .
The rule: "the rest are carbohydrates" then ensures that these are assigned to the carbohydrates, although they do not belong there at all.
For foods that contain sugar alcohols that are particularly important for low-carb enthusiasts, such as chocolate, gummy bears or candies, the problem arises that the specified carbohydrate values remain exactly the same despite the sugar being replaced by sugar alcohols. This even applies to the natural sugar substitute erythritol, which is known to not be metabolized at all.
Therefore, in all cases where polyols are listed separately in the nutritional value table, low-carbers should deduct them from the carbohydrate value. Then the gummy bears will taste much better! ;-)
At this point, a specific feature of the EU approach regarding dietary fiber should be pointed out. While the US standard distinguishes between digestible and indigestible dietary fibers and when calculating the calorific value, the former are rated at 14 kJ/g and the latter at 0kJ/g, the EU has opted for an averaging and 8kJ/g for all dietary fibers. In the case of pure fiber products such as psyllium or guar gum, this results in calorific values that deviate from reality by up to 1000%.
4. Specification of the calorific value
It gets completely absurd now when we come to the specification of the calorific value (calories). This information in the nutritional value table, which is probably the most observed, is also the most imprecise.
While natural science understands something very defined by the calorific value, namely the energy that is produced when a substance is actually burned, the physiological calorific value of nutritional science is a very theoretical, vague construct. It is intended to indicate how much energy a person extracts from a food. This not only differs from person to person and day to day, but also from the eating habits, the composition and quantity of the food. By definition, it is not the net calorific value (i.e. the energy available to the body for activities) that is given here, but the gross calorific value, which does not take into account the energy the body needs to develop the energy. Since this is by far the lowest for sugar and starch, the calories from fats and proteins are potentially far too high.
Curiously, the basis of these values were actually determined by combustion tests in the 1920s. People were given a certain amount of food to eat. For this amount, the calorific value was then determined by burning. After that, what "came out from below" was burned. The difference then had to be what the body could use.
How do the calorific values come about?
Based on such measurements and other empirical values, nutritionists then agreed on the following average values after decades of heated discussions:
| Protein | 17 kJ/g |
| Carbohydrates | 17 kJ/g |
| Fat | 37 kJ/g |
| Fiber | 8 kJ/g |
| Alcohol | 29 kJ/g |
| Polyole | 10 kJ/g |
| Erythritol | 0 kJ/g |
So in order to determine calories, the ingredients (as mentioned above very imprecisely) are determined, multiplied by the values in the table and then added up.
Here again there are differences. Depending on the fat, carbohydrate or protein, the "real" value can deviate by up to 20%.
3. CONCLUSION
If one were to apply criteria for serious science, such as those that apply in physics, chemistry or biology, nutritional labeling would probably be classified in the area of shamanism and quackery. However, since the process of agreeing on this approach in nutritional science was very difficult and lengthy, today they insist on it more vehemently than the Pope on his infallibility.
Unfortunately, the press and literature also deal with the topic very uncritically and sell calorie information with x digits after the decimal point as the last word of wisdom.
If you take the EU goal of enabling consumers to make comparisons, you might be able to see some sense in it. The absolute values are at best a guide and sometimes just plain wrong!
I find it alarming that the legislature has probably not checked in more detail either. Despite the extremely thin scientific basis, this approach has become the basis for laws and EU standards. It's like admitting a fortune teller to a criminal trial.
Nevertheless, we are also bound to comply with the labeling regulation. If the results there are too wrong, we also indicate the "usable carbohydrates", similar to what is usual in the USA.