Selenium deficiency – symptoms, causes and how to rectify it
Selenium is only needed in trace amounts, but a lack can damage the entire organism. How a selenium deficiency manifests itself and how it can be remedied.
The mineral Selenium was discovered in 1818 by Swedish chemist Berzelius and named after the Greek moon goddess Selene for its silvery grey shine. 200 years later, its potential is still not fully researched, but one thing is clear - the essential trace element shines at the body level and plays a role primarily in our thyroid, the immune system, and in the maintenance of healthy hair and nails. Learn more about the trace element and what to look out for.
What is selenium?
Selenium is a mineral found in the earth’s crust, but it is subject to strong regional fluctuations. While the content in volcanic rock is relatively high, there are only low selenium concentrations in the soils of Central and Northern Europe – and thus also in the plants that thrive on it and in the animals that live on it.
For a long time, it was not clear what an important role selenium plays for us humans. It was even wrongly believed by the middle of the last century that selenium was a pure poison for us humans. The turnaround only came in 1957, when scientists discovered that we humans not only need selenium, but that it is actually vital.
Meeting our daily selenium needs isn’t always easy. People living in regions with low selenium soils in particular should keep an eye on their selenium status.
Impact & tasks: What does selenium do in the body?
Selenium is a component of many enzymes and proteins, which contribute to a wealth of important bodily functions. As a radical scavenger, the essential trace element contributes to the protection of cells from oxidative stress. Free radicals are chemical compounds that can lead to cell damage if their number is exceeded.
Selenium is also indispensable for normal thyroid function; after all, it is involved in the formation of active thyroid hormones. The trace element also supports our defences and contributes to the maintenance of normal hair and nails. Selenium is also an important mineral for men. An adequate supply contributes to normal sperm production.
The European Food and Drug Administration EFSA certifies these effects:
- Selenium helps maintain normal hair and nails.
- Selenium contributes to the normal functioning of the immune system.
- Selenium contributes to normal thyroid function.
- Selenium contributes to the protection of cells from oxidative stress
- Selenium contributes to normal sperm formation.
Differences in the effect for women & men
The effects of selenium are generally not different in women and men. Nevertheless, there are a few gender-specific differences. For example, men need more. From the age of 15 onwards their selenium requirement is higher than that of women. In addition to stature (height and weight), gender also plays a role here, because particularly high selenium concentrations are found in the testicles where sperm is formed.
Cell protection against oxidative stress via selenium
Selenium is a radical scavenger. Free radicals stress cells oxidatively. Free radicals are aggressive oxygen particles that are resistant to binding. They are looking for chemical binding partners in the human body and react with cells. This damages the cell. The process is similar to the rust formation of metals. This also leads to oxidation. Free radicals are associated with diseases and with the ageing process.
Selenium can intercept free radicals and, by reacting with them, render them harmless to the cells. Other radical scavengers – often referred to as antioxidants include vitamin C, vitamin E, zinc and vitamin B2.
Processes during which free radicals are formed:
- Stress
- Metabolism
- Lack of sleep
- Smoking
- UV radiation
- Diseases
- Taking medication
- Chemotherapy
- By (environmental) poisoning
Part of enzymes & proteins: The physiological significance of selenium in the human body
Selenium is an essential component of many of the body’s own proteins and enzymes. This also includes the group of so-called "selenoproteins", which is a relatively new discovery. Currently, it is thought that there are up to some 50 of them, with only some of them having been researched so far. All selenoproteins have a complex structure and contain at least one part of the namesake amino acid selenocysteine in their centre. Many of these complex protein constructs act in our bodies as agents of chemical reactions (= enzymes). Arguably the most well-known representative of a so-called selenium-dependent enzyme is glutathione peroxidase, which plays an important role in the protection against free radicals. So-called deiodases are also among the selenium-dependent enzymes and are involved as such in the activation of our thyroid hormones.
In contrast to selenocysteine, selenomethionine does not fulfil any known physiological function in the body. This selenium-containing amino acid is only incorporated into proteins in place of methionine in a non-specific manner, whereby the quantity depends on the amount supplied. Selenmethionine is therefore considered to be the storage form of selenium. Selenmethionine is very well absorbed by the organism as an organic selenium compound.
Selenium for hair, skin & nails
Selenium is an unsung beauty nutrient. Its role as a radical scavenger helps protect all body cells, including skin and scalp cells. Selenium therefore also contributes to the maintenance of healthy hair and nails.
Selenium for the immune system and for colds
Our defences also benefit from a good selenium supply. Not only do the classics zinc, vitamin C and vitamin D support the immune system, but they are also essential in selenium. In addition, the trace element also acts at an oxidative level and thus also contributes, among other things, to the protection of immune cells from oxidative stress.
Selenium and its impact on weight
The thyroid gland is our body’s accelerator pedal and affects the metabolism, body temperature and appetite. Studies have shown a link between weight and thyroid – weight gain that cannot be explained otherwise is a symptom of hypothyroidism. Selenium plays an important role in normal thyroid function. It is involved in the conversion of the thyroid hormone thyroxine into the much more potent triiodothyronine. Selenium also contributes to the protection of the thyroid cells from oxidative stress.
Selenium and its effect on the liver
Selenium is found in all the tissues and organs, but it is unevenly distributed. High concentrations can also be found in the liver, which is a hub of selenium metabolism and an important production site of the above-mentioned selenoproteins. Selenium-containing enzymes play a role in the body’s own detoxification processes and help to protect cells from free radicals, both of which are central functions for the liver.
Selenium and its effect on the eyes
A good selenium supply is also important for our eyes. UV exposure causes free radicals in the eyes every day. To fight off the aggressive particles, selenium-dependent glutathioperoxidase is very active, especially in the eye lens and thus contributes to protecting the cells from radical damage.
Selenium and its effect on sleep
An adequate selenium intake also appears to have a beneficial effect on our sleep. For example, a 2023 study showed that overweight people treated with selenium could sleep longer than those with lower levels. According to the researchers, the sleep-supporting effects of selenium can probably be attributed to its antioxidant effects.
Selenium & blood pressure
As a radical scavenger, selenium helps to protect the cells from oxidative stress, including those of the heart and vessels. Whether the trace element is also good for blood pressure must be researched further. There are currently still contradictory studies on this.
Selenium during pregnancy, lactation and if you wish to have children
The trace element selenium is important if you wish to have a child. Particularly in the male testes, selenium is present in higher concentrations, where it contributes to oxidative cell protection and the production of normal sperm.
If the desire to have children is then fulfilled and the couple are pregnant, selenium is important for the expectant mother and her baby in the womb, but “more” is not necessary during pregnancy (according to DGE - German Nutrition Society). The situation is different during lactation. As with many other nutrients, lactation increases the daily reference value, since the baby is being supplied with breast milk.
Daily requirement: How much selenium do humans need per day?
The amount of selenium humans need per day is still not fully understood. For this reason, the DGE (German Nutrition Society) only provides estimates for an appropriate supply for the trace element. These are 70 μg selenium daily for male adolescents aged 15 years and older and 60 μg selenium daily for female adolescents and adult women.
Occurrence in food
The selenium content of plant-based food is determined by the substrate on which it grows. Whilst volcanic rock has a relatively high selenium content, many European soils have only contained small amounts of selenium since the last Ice Age. Accordingly, Austria and Germany – as well as many other European countries (e.g. Switzerland, Denmark, Finland, Scotland, some parts of the Balkans) – are considered to be low in selenium. Climate change also means that the trace element in soil has become scarce.
Plants integrate selenium into their structures, but do not need it themselves. However, their content is what determines the selenium supply of us humans indirectly as food for animals or directly as plant-based foods.
In the EU, animal food may be enriched with selenium. This makes animal foods such as meat and eggs more reliable sources of selenium than plant-based foods in low-selenium regions. In addition, sea animals, such as sea fish or mussels, naturally offer notable amounts of selenium.
What foods contain selenium?
These foods are particularly rich in selenium (depending on the soil quality, environment and feed):
- Nuts
- Coconuts
- Mushrooms
- Cabbage varieties
- Garlic and onion varieties
- Sea fish such as tuna, mackerel or sardines
- Seafood and shellfish such as prawns, crayfish or mussels
- Eggs
- Meat and offal
Selenium as a dietary supplement
A healthy, varied diet is the best basis for providing the body with sufficient amounts of selenium every day. However, in certain situations in life, it may be useful to turn to the help of a selenium supplement. Regardless of whether selenium capsules, drops or tablets are used for this purpose – the respective selenium preparation should be high-quality and pure (keyword: pure substance principle). In addition to preparations that contain either inorganic or organic selenium, there are also selenium complexes that mix organic and inorganic selenium.
Selenium intake & dosage
When and how to take selenium: Before or after eating?
Selenium can be taken at any time of day or night.
An interval of 1 to 2 hours between meals is recommended when taking inorganic sodium selenite. This prevents the selenium intake in the body from being disrupted by other food components.
Preparations with organic compounds (e.g. selenomethionine, selenium from selenium yeast) should again preferably be taken with a meal.
Daily dose:
Whether you need additional selenium can be determined via a micronutrient analysis. This also helps your doctor to choose the ideal daily dose and duration of use for you.
Which selenium compound is best absorbed?
Selenomethionine is the main selenium compound in food and is particularly easily absorbed and stored by our bodies.
In turn, sodium selenite is considered the gentler way of filling up your selenium stores. Sodium selenite can be used to optimise selenium-dependent enzymes, but surpluses are excreted in the urine, so no selenium deposits are created.
Can you take zinc and selenium together?
Selenium and zinc can easily be taken together in physiological quantities (e.g. in combination preparations such as Erdensalz® Minerals). However, the two trace elements hinder each other in higher concentrations. For this reason, a dosing interval should be observed for higher-dose preparations.
Should selenium and iron be taken together?
Taking iron and selenium together may be beneficial in certain cases. Both minerals pull together when it comes to supporting our immune system.
Vitamin E & selenium
As radical scavengers, vitamin E and selenium keep each other in line, together contributing to the protection of cells from oxidative damage. Based on study data, the German Society for Endocrinology advises men to take a selenium/vitamin E preparation without knowing their own selenium status. Ideally, men should consult with their doctor and, if necessary, define their selenium status before taking such preparations.
Blood values
Various medical measurement procedures are available to determine the selenium status. Since metals such as selenium are largely stored in the blood cells, only a whole blood analysis allows an optimal assessment of the selenium balance. The optimal values in whole blood are 121 to 168 μg selenium per litre of whole blood.
What are the consequences of a selenium deficiency?
An insufficient supply of selenium can manifest itself in different ways. Find out more about selenium deficiency here.
Overdose: What are the consequences of an excessive intake of selenium?
If the daily selenium intake exceeds the need acutely or permanently, physical symptoms such as fatigue or bad breath may occur. A micronutrient analysis is helpful to get an idea of the current supply situation and thus to prevent a potential overdose.
Conclusion
Selenium is a vital trace element that, although we humans only need it in the microgram range, is still used by our body in many ways. The best basis for a good selenium supply is a healthy and balanced diet. In areas of selenium deficiency such as Germany, nutritional supplements can be useful.
Frequently asked questions about selenium
Selenium is a component of many enzymes and proteins in the body. The trace element contributes to the protection of our cells from oxidative stress and ensures healthy hair and nails. Selenium is also important for the normal functioning of our immune system and thyroid gland and contributes to the production of sperm.
How quickly selenium works cannot be answered in a blanket manner. Whether and when the selenium status is optimised depends primarily on the individual starting position (selenium status), the dosage, the duration of administration and the desired purpose of administration.
Selenium capsules and drops can help to provide the body with extra selenium in a targeted way.
A connection between selenium and the brain must be clarified in more detail, but initial findings indicate positive support.
Selenium is not only a mineral for men, but it also extremely important for women. In addition to comprehensive cell protection, selenium helps the body detoxify, strengthens its defences and counteracts cardiovascular diseases. Selenium is also an important protective and functional substance of the thyroid gland.
