Macronutrients – basic knowledge

Macronutrients are needed by our body every day in order to function. But what are the so-called macronutrients, what significance do they have for our metabolism and how much should we consume every day?

Macronutrients (Greek makros = large) include carbohydrates, fats, proteins and alcohol. They form the main component of our diet and are particularly important as a source of energy. Furthermore, their building blocks - such as amino acids and fatty acids - are used to build up the body's own compounds. A sufficient supply of macronutrients is therefore essential for maintaining the metabolism.

Liquids

Since alcohol (or ethanol) is also burnt by the body and converted into energy, the literature sometimes lists it as a macronutrient. Although water and fibre are not considered macronutrients in the strict sense, they also play an important role in the organism.

Makronährstoffe, Wasser und Ballaststoffe

Water

More than 60% of the human body consists of water, which is why a deficiency quickly leads to health problems. After just 2 – 4 days without water, the blood thickens and the circulatory system fails. Water not only serves as a means of ventilation and transport. The body also needs it for numerous enzymatic reactions and to regulate the body's heat balance.

In order to compensate for water loss through sweat, urine and breathing, around 1.5 litres of fluid should be consumed daily in the form of drinks. In the event of high losses, for example as a result of high physical exertion, heat, fever or diarrhoea, the fluid intake should be adjusted accordingly. In the case of high water losses, it is also particularly important to replace the excreted minerals - e.g. potassium and chloride - in addition to the lost fluid.

Protein

Protein - macronutrients for muscles

Protein, or protein, is a macronutrient alongside fats and carbohydrates and is primarily used to build and maintain muscle mass. They are important for building enzymes, hormones, cells and tissues. They also play a central role in the immunoglobulins immune system.

About 8 - 10% of your daily energy intake should consist of protein. This corresponds to approximately 0.8 g of protein per kg of body weight. A 75 kg man therefore has a daily requirement of around 60 g of protein. About 15 % protein should make up the daily diet. Athletes in particular are an exception here, as they have a much higher protein requirement depending on the type of sport.

The calorific value of protein is around 4 kcal/g.

In addition to the quantity of protein consumed, the quality - i.e. the amino acid composition or biological value - is also very important. There are 22 amino acids that can be used as building blocks for proteins (so-called proteinogenic amino acids), nine of which cannot be produced by the body itself. They must therefore be ingested with food and are therefore considered essential. The amino acids ingested are used to build the body's own proteins, which fulfil numerous functions in the organism. However, they are not only needed to build muscle mass, but also play an important role in the immune system (so-called immunoglobulins), in the transport of substances (e.g. the transport of oxygen by haemoglobin), in blood clotting and as structural proteins (collagen). However, the majority of proteins are active in the form of enzymes. They are therefore responsible for the course of biochemical reactions in the body. Furthermore, amino acids are precursors of important hormones and neurotransmitters. These include serotonin, adrenaline and choline.

The body's proteins are subject to constant synthesis and degradation processes. To ensure that all functions can be guaranteed, it is essential to supply the body with the required amino acids (both essential and non-essential) in sufficient quantities. If just one amino acid is missing, important proteins can no longer be formed. Good plant-based sources of protein are cereal products, nuts, pulses, sprouts and soya products.

Carbohydrates

Carbohydrates are the most important source of energy for the body. They provide the body with around 4 kcal per gram. About 55% of the diet should consist of carbohydrates . The brain and red blood cells in particular are dependent on glucose (dextrose) as a source of energy.

Food contains carbohydrates in the form of monosaccharides (monosaccharides), disaccharides (disaccharides) and polysaccharides (polysaccharides). Monosaccharides, such as glucose or fructose, are absorbed directly by the body and thus lead to a rapid rise in blood sugar levels. Disaccharides consist of two monosaccharide building blocks. Well-known examples are lactose (milk sugar) or ordinary household sugar (sucrose). Polysaccharides consist of several simple sugar building blocks. These include starch and some dietary fibres. They are often referred to as complex carbohydrates, as the compounds must first be broken down into simple sugars during digestion. This leads to a slower rise in blood sugar levels and therefore longer satiety. For this reason, it is advisable to consume more carbohydrates from foods rich in starch and fibre. In addition, these foods usually also contain many essential nutrients and phytochemicals. This further increases their positive benefits.

Note: The fewer compounds the individual sugar has, the faster it is metabolised in the body and converted into energy.

Good sources of this are potatoes, vegetables, fruit and cereal products.

Fats

Fats also form a group of macronutrients. Dietary fats mainly consist of so-called triglycerides. These consist of glycerol and three fatty acids. The most important components are the fatty acids, which can be saturated, monounsaturated or polyunsaturated. They are an important component of membranes and precursors of the body's own substances. With the exception of linoleic (ω6) and &alpha-linolenic (ω3) acids, they can also be produced by the body itself.

Fats provide the highest amount of energy per gram, i.e. a total of 9 kcal. They are therefore important sources of energy. Their energy content is more than twice as high as that of carbohydrates and proteins. In addition, dietary fats are flavour enhancers and contain other important compounds such as fatty vitamins and phospholipids. They are of particular importance for the building of cell membranes and are also required for hormone synthesis.

As fats are efficient forms of energy, the body stores the excess energy it absorbs in the form of fat. The body can also deposit excess fat in the blood vessels or organs, which can impede blood flow and favour cardiovascular diseases. As a high-fat diet is also associated with diseases such as arteriosclerosis, colon cancer and increased blood fat and cholesterol levels, care should be taken to ensure that daily fat intake does not exceed 30% of energy intake. In particular, the intake of saturated and trans fats should be minimised.

Dietary fibre

Fibre - macronutrients for better digestion

The term dietary fibre refers to plant-based food components that cannot be broken down by human digestive enzymes. Most dietary fibres are classified as carbohydrates. They include, for example cellulose, pectin, resistant starch or inulin. Dietary fibres can be divided into soluble and insoluble fibres. The former are mainly found in fruit and vegetables. The latter are mainly found in wholemeal cereals. The nutritional value of dietary fibre is on average 2 kcal/g. Dietary fibre has a positive effect on health and is said to prevent the development of diseases such as diabetes, lipometabolic disorders and colon cancer. For this reason, the DGE recommends integrating 30 g of fibre into your daily diet.

Effects on metabolism and digestion

The positive effects on the human metabolism are based on various mechanisms of action and can be observed throughout the entire digestive process. It starts with chewing: High-fibre food is chewed for longer and is therefore also better mixed with saliva. This has a positive effect on digestion and the feeling of satiety. Thanks to their ability to bind water, soluble fibres in particular increase the volume of food in the stomach. As a result, the emptying of the stomach is delayed, leading to a longer feeling of fullness. In the small intestine, the increased volume stimulates intestinal motor activity, which speeds up the passage of the chyme and promotes digestion. Fibre is also able to bind other substances such as cholesterol or bile acids. This is particularly important when cholesterol levels are high. Furthermore, minerals and trace elements are also bound and thus excreted. However, as a high-fibre diet contains many essential nutrients, this aspect is negligible.

In the large intestine, bacteria can break down the soluble fibre into short-chain fatty acids. These have a favourable effect on the pH value and thus promote healthy intestinal flora. They are also absorbed by the body and utilised for energy production. In addition to short-chain fatty acids, CO2 and methane are also produced, which lead to undesirable side effects. Insoluble fibre also swells up in the large intestine, but - unlike soluble fibre - cannot be broken down by intestinal bacteria. They therefore cause a further increase in volume, which has a positive effect on intestinal motility and stool consistency.