Selenium - what it is, properties, dosage, supplementation

Selenium reduces the risk of cancer, protects against heart disease and is also responsible for thyroid health.

TekstLudwik Jelonek

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Ludwik Jelonek

Natu.Care Editor

Ludwik Jelonek is the author of more than 2,500 texts published on leading portals. His content has found its way into services such as Ostrovit and Kobieta Onet. At Natu.Care, Ludwik educates people in the most important area of life - health.

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RecenzjaJulia Skrajda

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Julia Skrajda

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A clinical nutritionist, she works in the profession and creates personalised menus and recommendations for disease entities.

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RedakcjaMichael Tomaszewski

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Michael Tomaszewski

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Graduate of Journalism and Artes Liberales at the University of Warsaw. Since 2017, he has been working with the biggest portals in Poland and abroad as an editor. Previously worked for 3 years in one of the leading pharmaceutical companies - he knows the health and beauty industry inside out. In his free time, he most enjoys playing tennis or skiing.

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Fact-checkingNina Wawryszuk

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Nina Wawryszuk

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Selenium - what it is, properties, dosage, supplementation

19 August, 2024

17 min

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Selenium is responsible for the formation of DNA, protects cells from infections, and has antioxidant properties. Furthermore, it prevents heart disease and strengthens the immune system. What are the other functions of selenium? Check them out!

Nause of nausea, vomiting or headaches. Nothing pleasant, right? These are selected symptoms of selenium deficiency in the body. This mineral has numerous valuable properties, which is why a lack of it in the body is dangerous. It is no different to an excess, which we must not lead to either. How does selenium work? What are its sources in the diet? What are the manifestations of deficiency and excess? The answers to these questions are just the tip of the iceberg of knowledge you will find below!

From this article you will learn:

What selenium is and how it works
What are the intake standards for selenium and how you should dose it
In which products does this mineral occur naturally
Whether you are at risk of selenium deficiency and how to prevent it

See also:

What is selenium?

Selenium is a trace mineral (our body needs it in small amounts) that is a component of enzymes and proteins. We store most selenium in muscle tissue. However, the highest concentration of this mineral is in the thyroid gland. Sources of selenium are mainly fish, beef, turkey or chicken.

Selenium is a microelement that is extremely important for our body. Without selenium, many metabolic processes would not exist. It is the first step for antioxidant processes, i.e. neutralising free radicals.

Julia SkrajdaDietitian

What are the types of selenium?

There are two types of seleniumand: organic (selenomethionine and selenocysteine) and inorganic (selenate and selenite). Both forms are good dietary sources of selenium. Organic selenium, however, has better bioavailabilityand.

Selenium is an element found in soil and water. This is how it gets into food. Due to its low levels in soils and plant tissues, selenium deficiencies can often be found in the population.

Julia SkrajdaDietitian

Selenium - action

The phrase 'trace' to describe selenium should not confuse us. Despite the fact that our body does not need large deposits of this mineral, it is very important for health. How does selenium work?

Antioxidant activity

Antioxidants are compounds that fight free radicals. Excess free radicals lead to oxidative stressand that has been linked to a number of diseases (Alzheimer's disease, stroke or premature ageing).

Selenium acts as an antioxidant, that is, it reduces oxidative stressand. The mineral protects the body's healthy cells from damage.

Reduces the risk of heart disease

Adequate levels of selenium in the body may support heart health. Research suggests, that 50% more selenium in the body results in a 24% reduction in heart disease riskand. Furthermore, other trials indicate that selenium supplementation reduces inflammatory C-reactive protein concentrationsand.

Reduces cancer risk

Selenium may reduce the risk of certain cancers. A review of 69 studies (on more than 360,00 people) suggested that high levels of selenium were associated with a lower risk of breast, prostate, lung, stomach or oesophageal cancerand. This effect was associated with selenium intake along with diet, not supplements.

It is worth noting that selenium supplementation may reduce the side effects of chemotherapyand. Studies indicate that taking selenium supplements improves overall quality of life and reduces symptoms of diarrhoea in women with cervical cancer.

Prevent neurodegenerative diseases

Selenium may reduce the risk of developing selected neurodegenerative diseases. Studies suggest that Alzheimer's patients have lower levels of selenium in their bloodand. Furthermore, other tests have shown that antioxidants (such as selenium) can positively affect memory in Alzheimer's patientsand.

Selenium has been shown to have positive effects on mood changes like anxiety, confusion and aggression attacks. Therefore, it may be helpful for Alzheimer's or dementia. Furthermore, selenium may slow down the development of neurodegenerative diseases.

Julia SkrajdaDietitian

May reduce asthma symptoms

Asthma has been linked to increased levels of oxidative stress in the body, which selenium can preventand. Research suggests that asthma patients with higher levels of this mineral in their bodies, have better lung functionand. Nevertheless, further tests are needed to confirm the role of selenium in the treatment of asthma.

Selenium is a component of iodothyronine deiodinase, showing active actions on the gland that is the thyroid gland. It is involved in the conversion of the hormones FT3 and FT4. It is a marker for diseases such as hashimoto's or hypothyroidism, as well as Graves' disease.

Julia SkrajdaDietitian

How else does selenium work?

Responsible for thyroid hormone metabolismand.
Prevents progression of HIV to AIDS .
Provides positive effects on the immune system .
Promotes the function of the reproductive system .

Selenium plays a very important role in people with thyroid problems. This mineral is involved in the production and breakdown of thyroid hormones. Selenium also supports the proper functioning of our immune system.

Ula Kawalecdietitian

Selenium - dosage

The dosage of selenium should be adjusted according to our needs. Depending on our age, we need different doses of this mineral. Find out how much selenium you and those close to you need per day.

Recommended daily doses of selenium

Age .	Recommended daily intake of selenium* .
0-6 months	15 mcg
7-11 months	20 mcg
1-3 years	20 mcg
4-9 years	30 mcg
10-12 years	40 mcg
>13 years	55 mcg

The requirement for selenium increases during pregnancy to 60 mcg. Breastfeeding women need even more of this mineral - 70 mcg.

Although selenium is important for the health of the body, moderation is important. What are the healthy dosage limits for this mineral?

Maximum daily dose of selenium

. .

Age .	Maximum daily intake of selenium .
0-6 months*	45 mcg
7-12 months*	60 mcg
1-3 years	90 mcg
4-8 years	150 mcg
9-13 years	280 mcg
>14 years	400 mcg

*For the first few months of life, breast milk should be the only source of selenium for infantsand

Selenium - in which products does it occur?

Selenium can be found in products such as fish, offal and seafood. Would you like to prepare a dish full of selenium? Check out the table with the 10 richest products in seleniumand.

Cooked lamb liver

116 mcg

Product .	Selenium content per 100 grams .
Brazil nuts .	1920 mcg .
Milled mustard seeds	208 mcg .
Cooked oysters	154 mcg .
Cooked lamb's liver
Cooked tuna	108 mcg .
Cooked octopus	89.6 mcg
Cooked lobster .	73.1 mcg
Cooked swordfish	68.5 mcg
Preserved anchovies	68.1 mcg .
Cooked mussels	64 mcg

Selenium is mainly found in products such as meat, cereals, dairy products, some vegetables (white cabbage, broccoli, onions) and Brazil nuts.

Julia SkrajdaDietitian

Selenium deficiency

Selenium deficiency affects between 500 million and up to one billion people worldwideand. This means that one in eight people among your relatives or family may be struggling with this problem. What leads to selenium deficiency?

Causes of selenium deficiency:

improper dietand,
alcoholic disease ,
smoking addiction ,
taking birth control pills ,
inflammatory bowel disease ,

Selenium deficiency can lead to arthritis, cirrhosis, thyroid disease, cardiopathy, macrocytosis, and in extreme cases even cancer (mainly of the intestines, liver or thyroid).

Julia SkrajdaDietitian

Symptoms

Selenium deficiency can lead to a number of symptoms. Which ones are the most common?"

Symptoms of selenium deficiencyand:

fatigue,
muscle aches,
hair loss,
deterioration of mood,
immune system problems,
worse fertility in men and women,

Symptoms of selenium deficiency are mainly muscle pain, impaired concentration and fatigue.

Ula Kawalecdietitian

Are you experiencing these symptoms in yourself? Make an appointment for a consultation with your doctor or blood tests.

Effects

Being negligent of the symptoms mentioned can result in serious health problems. What does untreated selenium deficiency lead to?"

Effects of selenium deficiencyand:

thyroid diseases (undothyroidism or hypothyroidism, Hashimoto's disease, Graves-Basedow disease),
infertility,
cardiovascular disease,
deterioration of cognitive function,
Kashin-Beck disease (osteoarthritis),
Keshan's disease (cardiovascular disease),

Selenium excess

Selenium excess occurs in cases of chronic or acute overdose of this mineral. It is most often led to by unreasonable supplementation.

We can experience selenium overdose both by overdosing on supplements and by consuming too much of this mineral with the diet. An overdose of selenium with food, however, is rare.

Ula Kawalecdietitian

An example of a dietary selenium overdose could be the overconsumption of, for example, Brazil nutsand. About 5-6 pieces consumed at once can result in excess selenium. What will we then experience?

Symptoms of excess selenium :

vomiting,
nausea,
fracture and discoloration of nails,
hair loss,
bad breath,
irritability,
fatigue,

Excess selenium is very dangerous. It can result in chronic poisoning and even death. The dose of the supplement must be well chosen and must be adhered to.

Julia SkrajdaDietitian

Effects

Both chronic and one-off selenium overdoses can lead to serious damage to the body. What conditions result in an excess of selenium?

Effects of excess seleniumand:

myocardial infarction,
kidney failure,
heart failure,
nerve damage,

There are several ways to check the concentration of selenium in the bodyand. One of the more popular ones is to check its serum levels. Selenium concentration can also be tested in the hair or nails.

Selenium - supplementation

Selenium can be purchased in several different formsand. It is found in multimineral supplements and multivitamin supplements. We can also find stand-alone selenium supplements on shop shelves. Selenium supplementation should only apply to those with deficiencies, following consultation with a doctor.

Selenium supplementation prevents the occurrence of cancer, inflammatory and immunological diseases.

Julia SkrajdaDietitian

When to take selenium - morning or evening

Most experts say that selenium can be supplemented at any hour. However, some of them give examples of patients who experienced better results when taking selenium on an empty stomach. Such an action is advised against those with stomach problems.

On the web, there is a lack of reliable research on the best time to take selenium, so ask your doctor's opinion before starting supplementation.

Can zinc and selenium be combined?

Zinc and selenium are essential trace elements that are key to our health. However, taking them at the same time can negatively affect the absorption of these mineralsand. These are preliminary assumptions and further research is needed to confirm this claim.

Many supplements on the market contain both zinc and selenium. This is unacceptable, as these elements act antagonistically and therefore cancel each other out. Therefore, if you want your supplementation to have the desired effect, do not use selenium and zinc in parallel.

Julia SkrajdaDietitian

Can you overdose on selenium?

Selenium can be overdosedand. This condition manifests itself with the same symptoms that occur in excess. Furthermore, in extreme cases, an overdose of selenium can even result in death.

Selenium in pregnancy

Research suggests, that selenium deficiency during pregnancy can negatively affect the growth of the yet-to-be-born childand. Despite this, supplementation with high doses of this mineral during pregnancy is not advisable and can be hazardous to the health of the mother and foetus . It is then necessary to take 60 mcg of selenium daily with the diet.

Selenium is called the element of fertility. It is essential for the health of pregnancy. It also influences spermatogenesis (the process of maturation and sperm formation)and. This micronutrient is an important factor in the treatment of infertility, aiding the process of getting pregnant on the part of both the woman and the man.

Julia SkrajdaDietitian

Selenium and breastfeeding

Selenium is one of the components of human milkand. It is the only source of this mineral for newborn babies, so breastfeeding women should ensure adequate levels. During this period, you should provide your body with 70 mcg per day.

Selenium and alcohol

Selenium deficiency is common among alcohol addictsand. Most often, this deficiency can be made up by stopping alcoholic beverages and supplementing the diet with selenium-rich foods. Supplementation is rarely necessary.

Interactions of selenium with drugs

Selenium may react with selected medications. Take care of your health and check if you need to take special care.

Selen may interactand with:

niacin (vitamin B3),
statins,
corticosteroids,
contraceptive pills,
medications used in chemotherapy,

Note!

Are you taking these or other medications? Under no circumstances supplement selenium on your own. Ask your doctor's opinion before you start taking this mineral.

See also:

Summary

Remember:

Selenium is a trace mineral that is a component of enzymes and proteins.
Selenium is a trace mineral that is a component of enzymes and proteins.
Selenium has an antioxidant effect, prevents heart disease and also reduces the risk of cancer.
Selenium is a trace mineral that is a component of enzymes and proteins.
After the age of 13, you should be taking 55 mcg.
The most selenium will be provided to you by Brazil nuts.
Fatigue, muscle aches or hair loss are selected symptoms of selenium deficiency.
Excess selenium mainly leads to nausea, vomiting or irritability.
Lack of adequate selenium concentrations during pregnancy, can negatively affect fetal growth.
The consumption of large amounts of alcohol leads to selenium deficiency.
Selenium can enter the body during pregnancy.
Selenium may interact with selected medications.

FAQ

Is it worth supplementing with selenium?

Selenium supplementation is necessary for those with known deficiencies and with an increased need. More selenium is useful for the elderly and those with thyroid disease.

Selenium plays a role in many metabolic processes and protection against oxidative stress. Its optimal dose also protects against the development of breast, prostate, liver, colorectal and lung cancers, so if you are a smoker, consider a safe selenium supplement.

Does selenium work for your hair?

Yes, selenium has a positive effect on hair health and condition. It is essential for the production of enzymes that help to counteract cell damage in the hair follicles. Selenium is involved in the production of proteins that are important for strong, healthy hair. Selenium deficiency can lead to hair loss.

Does selenium help the thyroid gland?

Selenium is essential for the proper functioning of the thyroid gland, and selenium deficiencies can lead to the development of thyroid diseases such as Hashimoto's disease. Research suggests that selenium supplementation may benefit people with hypothyroidism, improving thyroid hormone levels and reducing inflammation.

Can selenium be combined with magnesium?

You can take selenium together with magnesium. The combination of these elements lowers lipid concentrations in the body and also has an antioxidant effect. As a result, they will help protect your liver from hyperlipidaemia.

What not to combine selenium with

Do not combine selenium with vitamin B3, or niacin and supplements containing iron, copper or zinc, as they may interfere with selenium absorption. Additionally, selenium can affect the absorption of thyroid hormones, so - without consulting your doctor - do not combine selenium with thyroid medication. Selenium may also interact with contraceptive pills, corticosteroids, statins and drugs used during chemotherapy.

Does selenium affect weight loss?

Selenium is not directly linked to weight loss, but it can help maintain normal levels of thyroid hormones, which control metabolism. Selenium deficiency leads to endocrine disruption, which can make it difficult to shed weight. Additionally, selenium helps protect against oxidative stress, which can cause inflammation and contribute to obesity and metabolic diseases.

How to test your body's selenium levels

The best way to test selenium levels in the body will be to take a diagnostic blood test. Remember - blood needs to be taken on an empty stomach. Refrain from eating for at least 13 hours before the test. Eat a light supper and turn up for the test between 7 and 10 the following day. The price of selenium testing will vary from laboratory to laboratory - be prepared to spend around £120-160.

Selenium quantitative testing should certainly be done by men undergoing treatment for infertility, as well as those suffering from depression, pancreatitis, asthma, cardiovascular disease and RA (rheumatoid arthritis) - all of which can lead to selenium deficiencies.

Sources

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