The importance of selenium for intellectual and cognitive performance

Selenium is incorporated into a number of selenium-containing proteins that are important for, among other things, the nervous system. They also function as antioxidants that protect cells against damage caused by oxidative stress. A Spanish population study published in Frontiers in Nutrition shows that selenium intake and blood selenium levels may be associated with the intellectual and cognitive performance of university students.

Although it is well established that selenium is important for the brain and nervous system, there has been limited knowledge about the importance of selenium for the intellectual and cognitive performance of university students. The researchers behind the new Spanish study therefore set out to investigate this association in greater detail.
The study included 132 university students aged 18-29 years. The participants’ daily selenium intake was assessed using dietary questionnaires. The students also had their blood selenium levels measured, with adequate levels considered to be above 80 µg/L.
The participants’ intelligence and cognitive performance were assessed using the Verbal Comprehension Index (WAIS-IV), which measures verbal skills, vocabulary, and the ability to understand, reason about, and explain concepts in different contexts. The participants’ Full-Scale Intelligence Quotient (FSIQ) was also measured, with the average value in the general population being around 100.
The association between the students’ selenium status, intelligence, cognitive performance, and verbal skills was assessed using a method called Spearman’s rank correlation coefficient.
The study revealed the following:

• 53.5% of the female students and 16.4% of the male students had low blood selenium levels (below 80 µg/L)
• Participants with a Full-Scale Intelligence Quotient (FSIQ) below 90 had lower blood selenium levels than participants with a Full-Scale Intelligence Quotient above 90
• The participants’ blood selenium levels were positively associated with their Full-Scale Intelligence Quotient
• The participants’ blood selenium levels were positively associated with their Verbal Comprehension Index, which, as mentioned, reflects their ability to think and use language in different contexts
• The participants’ blood selenium levels were positively associated with their working memory

The researchers therefore conclude that selenium intake and blood selenium levels may be associated with intellectual and cognitive performance. Because low selenium status is so common, particularly among women, it may be important to assess the selenium status of young students, as it may affect their concentration, memory, verbal skills, and the outcome of their many years of study.

Why is selenium so important for the brain and cognitive functions?

In the introduction to the study, the researchers describe how selenium is incorporated into 25 different selenoproteins, which primarily function as essential enzymes and antioxidants. Among other things, these enzymes are important for energy metabolism, metabolism, and immune function.
The most important antioxidants are GPX (glutathione peroxidases) and TXNRD (thioredoxin reductases). These antioxidants counteract damage to cells and tissues caused by oxidative stress. This is a condition in which potentially harmful free radicals outgun the body’s protective antioxidants.
Because the brain and nervous system have increased metabolic activity, with high blood flow and oxygen supply, correspondingly more free radicals are generated, as they are, among other things, a byproduct of energy metabolism. In addition, the brain and central nervous system are particularly vulnerable, partly because they contain large amounts of polyunsaturated fatty acids such as omega-3 and omega-6, which are easy targets for free radical attacks, triggering potentially harmful chain reactions inside and outside the cells.
During oxidative stress, when free radicals are no longer adequately controlled, there is therefore a risk that they may attack nerve cells and other cells. Oxidative stress in the brain can damage neural integrity and synaptic plasticity, which normally need to remain highly active in young adults. Over time, oxidative stress in the brain may therefore have a negative impact on learning, memory, and cognitive functions.
It is therefore assumed that selenium may protect the brain and nerve cells through selenium-containing antioxidants, which help control oxidative stress and neuroinflammation through various signaling pathways. The researchers also point out that selenium is important for neuronal signaling and homeostasis. Previous studies have shown that a specific selenium-containing protein, selenoprotein P, is important for the formation of new nerve cells, which is essential for brain plasticity and the ability to learn new things.

Low blood selenium levels are a global and complex problem

Foods such as organ meats, meat, fish, shellfish, eggs, and Brazil nuts contain the highest amounts of selenium. Because the soil is low in selenium in Europe as well as in large parts of China, Africa, and other regions, this increases the risk of low selenium status throughout the food chain.
The researchers behind the new study also refer to previous data showing that although many young people in the Madrid region obtain sufficient selenium through their diet (more than 91 µg per day), 14% of young people had blood selenium concentrations below 60 µg/L, which is well below the threshold of 80 µg/L. This discrepancy between adequate selenium intake and low blood selenium concentrations may also be related to widespread overweight and an elevated BMI. This means that several parameters should be taken into consideration when assessing and analyzing the body’s selenium status.
As mentioned, low selenium status is a major health concern in our part of the world, and it also affects young university students. At the same time, we should not consume too much selenium, which is why the upper daily limit has been set at 300 micrograms, including selenium from both food and any supplements.

References:

Martinez-Garcia Rosa Maria et al. Nutritional selenium status in a cohort of university students: impact on intellectual and cognitive performance. Frontiers in Nutrition 2026

Odette Leiter et al. Selenium mediates exercise-induced adult neurogenesis and reverses learning deficits induced by hippocampal injury and aging. Cell Metabolism. 2022