Minerals Part II: Sodium, Chloride and Potassium
As already shown in the last article on calcium and magnesium, minerals are divided into so-called trace and bulk elements. This subdivision is based on the amount of substance to be supplied daily. In contrast to trace elements, bulk elements exceed the daily dose of 50 mg per kilogram of body weight.
Three other important representatives of the minerals are sodium, chloride and potassium. Since these substances occur in the body as charged ions, they, like calcium and magnesium, are counted among the electrolytes. Sodium, chloride and potassium are found in the upper ranges of the intake reference values and consequently fall under the bulk elements. It should be said in advance that all three quantity element representatives have extremely important functions, which is why their substance concentrations are subject to the strictest regulatory mechanisms.
Sodium, chloride and potassium in a nutshell:
- Salt is the main source of sodium and chloride. According to the recommendation, 1,500 mg of sodium and 2,300 mg of chloride should be consumed daily. However, one should pay attention to a moderate salt intake in order not to damage one’s cardiovascular system.
- Sodium and chloride are found mainly outside the cells. The two ions help transport substances through the cell membrane, play an important role in the water balance and are a central ion in cell excitation.
- A sodium and chloride deficiency often leads to cramps, headaches, nausea and impaired consciousness due to disturbances of the water balance.
- For potassium, a daily amount of 4,000 mg is recommended. Fruits and vegetables are particularly good sources. Bananas and dried fruits are particularly good sources of potassium.
- Potassium is found mainly inside the cells. It contributes a large part to the water balance within the cell and plays a central role in cell excitation.
- A potassium deficiency mainly affects excitable cells. Symptoms include gastrointestinal, heart and muscle problems
Salt is the source of sodium and chloride
The German Society for Nutrition recommends a daily intake of 1,500 mg and 2,300 mg respectively for an adequate supply of sodium and chloride. As a rule, these ions, which are immensely important for the organism, are absorbed via the usual table salt (= sodium chloride). Consequently, foods with sufficient salt content are considered good sources of sodium and chloride. However, caution is advised here. Although an adequate intake of sodium and chloride is necessary, care should be taken to moderate salt intake. The WHO recommends consuming no more than five grams of salt daily. The reason for this is that salt increases blood pressure. Thus, a high salt intake increases cardiovascular diseases, such as the risk of a heart attack or cerebral infarction.
Sodium and chloride are the most important ions outside the cells
Our body can be better visualised by dividing it into compartments. First and foremost, we distinguish between the space inside and outside the cells. In technical terms, we speak of intracellular and extracellular space. Sodium and chloride are typical representatives of the extracellular space and are found there in large quantities. At this location, the substances can optimally perform their functions, such as acting as co-transporters within the framework of substance transport across the cell membrane. The two elements thus help selected substances to pass through the membrane into the cells or out of the cells. Furthermore, as osmotically active components, these ions determine the total volume of the space outside the cells. According to physiological laws, they play a significant role in the movement of water between the compartment inside and outside the cell. Sodium also plays a central role in cell excitation (especially nerve and heart cells).
A deficiency of sodium and chloride can have unpleasant consequences
In the case of a deficiency of these valuable ions, which can be caused by vomiting or diarrhoea, for example, there is a risk of water shifting into the tissues, resulting in cramps. Especially if the water shift occurs in the brain, there is a risk of headaches, nausea and impaired consciousness. In the worst case, excessive diarrhoea can lead to severe dehydration with acute danger to life.
Bananas are a good source of potassium
As a typical representative of the intracellular space, potassium also plays a central role. The daily recommended amount by the German Nutrition Society is 4,000 milligrams. Various fruits and vegetables are suitable sources of potassium. Bananas in particular stand out with a content of approx. 550 milligrams per piece (approx. 150 grams). Dried fruits in particular are considered extremely potent sources of potassium, although these foods should only be consumed in moderation due to their high sugar content.
Potassium is the determining intracellular ion
Potassium as a component is an essential factor for the milieu within the cell. Together with phosphate and proteins, potassium provides the osmotic gradient within the cell and thus contributes a fair share to the cell’s water balance. With regard to excitable cells such as nerve cells and heart cells, potassium is jointly responsible for maintaining the resting membrane potential and consequently plays a prominent role in cell excitation.
A potassium deficiency primarily affects excitable areas
Since potassium is important for cell excitation, a deficiency of this ion primarily manifests itself in those areas of the body where excitation of individual cells is central. This includes, in particular, nerve and heart cells. Symptoms of a deficiency can consequently be muscle weakness or even paralysis, gastrointestinal problems such as constipation up to intestinal obstruction and cardiac arrhythmia. It should be mentioned that excessive consumption of liquorice can indicate symptoms of potassium deficiency. This is because liquorice resembles a hormone produced by the body that is responsible for increased potassium excretion via the kidneys.
Text sources:
(2) https://www.dge.de/presse/pm/dge-aktualisiert-die-referenzwerte-fuer-natrium-chlorid-und-kalium/
(3) Biesalski et al., Pocket Atlas of Nutrition, 8th edition, 2020
(4) Behrends et al., Physiology, 3rd edition, 2016
(5) Neumann, Nutrition in Sport, 8th edition, 2016.
Image sources:
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