Carbohydrates
Carbohydrates make up the bulk of a common diet in terms of quantity. They serve as primary energy suppliers. In the course of our digestion, carbohydrates are converted into the simple sugar glucose, which is subsequently converted into energy. However, since the body is also able to produce glucose itself (e.g. from proteins / amino acids), carbohydrates are not essential. Theoretically, we could therefore do without carbohydrates altogether. However, we want to take a closer look at why this is not beneficial in the long term in today’s blog.
The most important facts in brief:
- Carbohydrates are found in all animal and plant cells.
- A distinction is made between long-chain and short-chain carbohydrates. Short-chain ones tend to have a negative effect on our health.
- Good sources of carbohydrates lead to a low rise in blood sugar, contain fiber and are rich in nutrients.
- The DGE recommends consuming over 50% of energy in the form of carbohydrates. Even a lower proportion does not have a detrimental effect on the health.
What are carbohydrates?
Carbohydrates are found in all animal and plant cells. They serve us in the form of food not only as energy suppliers, but are also important components of our cells. For example, they serve as building materials, form connections between individual cells, as well as surface features for the recognition of certain cells, are needed for the synthesis of other substances and are part of our genetic material.
What are the different types of carbohydrates?
Carbohydrates can be classified according to the number of their basic building blocks. Thus, we distinguish between monosaccharides (simple sugars), disaccharides (2 monosaccharide units), oligosaccharides (3–9 monosaccharide units) and polysaccharides (>10 monosaccharide units). We are not interested in the chemical details for the time being, but it is important to know that a distinction is made between short-chain and long-chain carbohydrates.
Short-chain carbohydrates (mono- & disaccharides) are generally referred to as sugars. Well-known representatives are glucose, fructose, sucrose (household sugar) or lactose (milk sugar). Our digestive tract has to do little or no enzymatic work (glucose) to break them down into their basic building blocks. If sugar is consumed in isolated form, this results in a rapid rise in blood sugar. Although this provides short-term energy, it then leads to a low blood sugar level due to an excessive insulin response, which quickly makes you feel tired again. Insulin is the hormone that the body secretes to lower blood sugar levels after a sugary meal.
Simple sugars such as glucose and fructose in particular are therefore not recommended. Ordinary household sugar consists of exactly these two simple sugars. The more simple sugars are consumed, e.g. in the form of soft drinks, the higher the cancer risk and the overall mortality risk appear to be.
Fructose appears to be particularly detrimental to health. Excessive consumption is associated with the development of fatty liver, dyslipidemia, obesity and metabolic syndrome. Because it is metabolized independently of insulin, fructose was sold as particularly beneficial for diabetics. However, this is now obsolete due to the risks mentioned above.
Fruit also contains plenty of fructose. Excessive fruit consumption is therefore also not recommended. However, since fruit is consumed with a number of nutrients and in conjunction with fiber, the fructose issue is negligible here. A good habit is to always eat fruit as a whole fruit (with peel) and not in the form of juices.
Dietary fibers are carbohydrates that are not digested in the small intestine and pass undigested into the large intestine. There they serve as “food” for our intestinal bacteria, which use them to produce short-chain fatty acids, which are associated with a number of health effects. They also delay gastric emptying and increase the feeling of satiety. Since about 68% of men and 75% of women in Germany do not reach the daily recommended amount of 30 g of dietary fiber per day, but they are enormously important for a healthy body, we will again devote a separate blog post to dietary fiber.
What are healthy sources of carbohydrates?
As we can see, there are different forms of carbohydrates and their health effects differ. So far, we have been able to determine that isolated simple sugars should be avoided and fiber is good for us.
One way to classify carbohydrate-rich foods is the glycemic index (GI). It indicates how quickly blood sugar rises after eating the food. Generalized, we can say that foods with a low GI are better for us. Even better is the classification according to the glycemic load. Here, the total amount of carbohydrate contained in the product is taken into account and is therefore more meaningful.
Good carbohydrate sources therefore ideally have a low glycemic load, are rich in fiber and also rich in nutrients. First and foremost, vegetables and fruit should be mentioned here. They should not be missing from any diet. Whole grains such as spelt, oats, millet and quinoa are also good sources of energy. Processed carbohydrates such as white flour products, sweets and soft drinks should be avoided as much as possible.
How much carbohydrate do you need?
Carbohydrates are our primary source of energy. Accordingly, we should consume more carbohydrates when our energy consumption is high (a lot of exercise) than when it is low. The DGE recommends to consume more than 50% of the supplied energy in the form of carbohydrates. It should be kept in mind that carbohydrates are actually not essential. Fats can also be used for energy production. Therefore, even a significantly low level of carbohydrates does not seem to have a negative effect on health. However, since good sources of carbohydrates often bring with them a variety of important vitamins and minerals, and since indigestible carbohydrates (dietary fiber) also have a health-promoting effect, a complete elimination of carbohydrates is not recommended.
Text-Sources:
(1) Biesalski, H. (2018) Ernährungsmedizin. (5. Auflage) Georg Thieme Verlag.
(2) Nationale Verzehrsstudie II. Ergebnisbericht, Teil 2. Die bundesweite Befragung zur Ernährung von Jugendlichen und Erwachsenen. 2008. MRI.
(3) J.C. Laguna, M. Alegret, M. Cofan et al., Simple sugar intake and cancer incidence, cancer mortality and all-cause mortality: A cohort study from the PREDIMED trial, Clinical Nutrition, https://doi.org/10.1016/j.clnu.2021.07.031
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