What is the metabolism? What happens there and why proteins, carbohydrates and fats are so important? The answer is not simple, as so often...
Metabolism I - an interactive system
- Written by RR
- Published in BlogHealthy
- Date: Monday, 15 February 2021 17:43
- Read: 69 times
About digestion, denaturation and intermediary metabolism
What is metabolism? Is digestion the same thing? What happens in the body? Humans obtain energy, storage substances and building materials from food. Metabolism is the finely regulated system of building and breaking down with numerous functional pathways. Learn more about the main nutrients, why digestion and metabolism are not the same and how the body manages to stay in balance.
It all starts with food intake. What we eat and drink determines what is available to our body. Besides plenty of fluids, it needs protein, carbohydrates and fat.
Digestion and metabolism of proteins
Proteins are the building materials of the body. Each protein consists of many small building blocks, the amino acids. They are put together in long chains and intertwined to form a kind of ball with a three-dimensional structure. Different proteins have different compositions, but the 20 or so different amino acid building blocks are always the same. With their structure, proteins take over many functions in the body. The digestive system, i.e. the stomach and intestines, break down the protein from the food into its amino acids. These are absorbed from the intestine into the body and thus become part of the metabolism. Now they can be built up into the body's own proteins, for example hormones, enzymes or cells.
To ensure that the body has enough building blocks, healthy adults need just under one gram of protein per kilogram of body weight. A person weighing 70 kilograms therefore needs 70 grams of protein. For comparison provide:
- 1 portion of oatmeal (50 g): about six grams of protein
- 1 portion of tofu (approx. 100 g): eight grams of protein
- 1 portion of cooked lentils (150 g): a good 13 grams of protein
In order for the body to build up all the proteins it needs, it is important to have all the amino acids available. However, proteins from different sources provide different amounts of the building blocks. The more similar the composition is to the body's own proteins, the better the person can utilise them. A very important point here is that protein sources can complement each other, because hardly any protein source supplies all the building blocks in exactly the right proportions. Among the vegetable protein sources, cereals and pulses complement each other particularly well.
What does denaturation mean?
Denaturing means that a protein is changed. For example, when heated above about 40 degrees Celsius, the compounds that give proteins their shape dissolve. This process is called denaturing. The amino acids of the proteins remain intact. The body can use them to build its own proteins. Supporters of the raw food diet assume that there is a difference between the protein destruction through cooking and the changes in digestion. This is already described by doctor and nutrition researcher Werner Kollath in his book "The Order of Food". He argues that the less food has been processed before consumption, the better it is for the body. By the way, it is written in an understandable and comprehensible way. A clear recommendation for comprehensive research!
Digestion and metabolism of carbohydrates
Carbohydrates are a large group of substances. They include sugar, but also starch and dietary fibre. Dietary fibres play a role especially in digestion. Sugars are the smallest carbohydrate particles. Glucose (grape sugar) and fructose (fruit sugar) are probably the best known. Starch is composed of many glucose building blocks.
Carbohydrates are absorbed into the body from the intestine. Simple sugars like fructose and glucose can enter the body directly. Starch and other compound carbohydrates must first be broken down. The metabolism of carbohydrates takes place in the cells. Glucose plays the central role here. It is the basic molecule of energy production that powers the entire body. Excess glucose is stored in the muscles, for example. For this purpose, many individual molecules combine to form the storage substance glycogen, an important energy reserve.
Digestion and metabolism of fats
In technical language, fats are also called triglycerides. They consist of a glycerol molecule with up to three fatty acids attached. These can be saturated, unsaturated or polyunsaturated. Saturated fatty acids are found in meat and dairy products, for example. Unsaturated and polyunsaturated fatty acids are found in nuts, seeds and fatty fish. Triglycerides are broken down into glycerol and fatty acids by digestive enzymes in the intestine and only then absorbed into the body. There, fatty acids can follow various metabolic pathways. Some become hormones and messenger substances, others are used for energy production or as storage substances. Recently, nutrition experts have recommended consuming more vegetable oils and unsaturated fatty acids. Their unsaturated fatty acids can have positive effects on the heart, circulation and body.
The previous paragraphs show that digestion does the crucial preliminary work for metabolism. After absorption from the intestine, the molecules needed for metabolism are available to the body. A distinction must be made here between the anabolic and catabolic metabolism. Anabolic processes include the synthesis of the storage substance glycogen from glucose or the build-up of muscle substance with proteins. Catabolic, on the other hand, is the breakdown of glycogen or the production of energy through the breakdown of glucose molecules. The interface between the metabolic pathways that build up and those that break down is called intermediary metabolism. Here, substances are taken from anabolism or catabolism as needed and processed further. The anabolic and catabolic processes are closely interlinked. For example, building up processes use the energy from breaking down. All these metabolic processes are controlled by enzymes and hormones, which are interrelated in complicated control loops on several levels. In a healthy metabolism, all pathways are finely balanced. There are safeguards and possible back reactions everywhere to ensure a smooth process.
Blood sugar level
An illustrative example is the regulation of the blood sugar level. In a healthy person, it is kept stable within a very narrow range. If blood sugar rises above a certain level, the pancreas releases the hormone insulin. Insulin helps to absorb glucose into the cells of the liver and muscles. At the same time, no new glucose is released. The blood glucose level drops and insulin secretion stops.
If, on the other hand, the blood sugar level is low, the pancreas releases the hormone glucagon. It causes an increased breakdown of glycogen from the stores and promotes the formation of new glucose in the liver. The increased blood glucose level is in turn the signal for the body not to release any more glucagon. The body can therefore finely regulate how much glucose the blood contains.
Everything in balance
Basically, if you eat a fresh and colourful diet, you have a good chance of providing your body with all the nutrients it needs. The focus should be on fresh and unprocessed foods. They provide the body with natural nutrients from which it can draw energy.
As part of the metabolism, many mechanisms ensure that all cells and organs receive the right amount of energy and building materials at the right moment. This is the only way we can cope with mental tasks or do sports, go shopping or sit in a café. The body is a balanced machine that we can enable to function smoothly for a long time with a natural and, as far as possible, unprocessed diet.
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