It’s commonly known that physical activity boosts the brain’s ability to form new brain cells – or neurons. Still, the underlying mechanisms have been a mystery to science. A team of Australian scientists, however, has recently discovered that, during exercise, mice produce a selenium-containing protein that helps the brain synthesize new brain cells. The scientists consider this to be a rather fantastic study, and it is assumed that selenium therapy may be used in the future to prevent and treat cognitive decline in people who are unable to carry out physical exercise or in those likely to be selenium-deficient. This is particularly relevant for Alzheimer’s patients and people who have suffered a stroke. It should be added that it can be quite a challenge to get enough selenium from an otherwise balanced diet in our part of the world.
The human brain’s enormous neuronal network and ability to handle information is a precondition of good mental and physical health. It has long been thought that the formation of new nerve cells in the central nervous system ceases at birth or shortly after. Nonetheless, it turns out that the brain continues to produce new nerve cells in several sites and that brain plasticity continues throughout life. Earlier studies have already demonstrated that running stimulates the production of neurons in the hippocampus, which is the brain center that is important for learning, memory, and orientation. Still, scientists have not understood which molecules initiate the process.
Exercise increases the brain’s content of a particular selenium compound
Tara Walker, a neurologist at the University of Queensland’s Brain Institute in Australia, headed the new study. About seven years ago, she studied blood plasma from mice that had been running in treadmills for a period of four years. The blood samples were compared with blood samples from inactive mice. Walker and her team of scientists identified elevated levels of 38 proteins in the physically active mice. One specific protein called selenoprotein P was particularly noticeable, as levels of this protein had doubled. This discovery is highly relevant because selenoprotein P transports selenium into the brain. Here, selenium supports things such as energy turnover and gene regulation. Selenium also has powerful antioxidant properties and protects brain cells against oxidative damage caused by free radicals. Because the human brain contains a large amount of polyunsaturated fatty acids and has a tremendous amount of blood flowing through it, it is especially vulnerable to oxidative damage that can destroy neurons and supporting cells. Selenium therefore plays a particularly vital role in the brain’s function and antioxidant defense.
- Selenium supports around 25 different selenoproteins
- Selenoprotein P transports selenium in the blood, bringing it to the brain and other tissues
- The different selenoproteins have multiple functions and support things such as energy turnover, gene regulation, and cellular construction
- Selenium also supports powerful antioxidant complexes that help to protect cells against damage from oxidative stress
Selenium plays a key role in the formation of new neurons
In their new study, Doctor Walker and her research colleagues observed that when a selenium compound was injected directly into the brains of mice, it tripled the levels of certain neurons in the hippocampus. The scientists also discovered that mice who lack selenoprotein P or its receptor fail to form new neurons in connection with physical activity. The scientists therefore theorize that selenoprotein P is the key to neuron formation.
Next, the scientists set out to study if selenium can prevent ageing processes in the brain. They added a selenium compound called selenomethionine to the drinking water of mice aged 18 months (the equivalent of 60 human years).
One month later, the number of neurons in their hippocampus had doubled. The selenium-treated mice also showed signs of improved memory when subjected to various tasks. They were compared with a control group to show the difference.
Lastly, the scientists looked at whether selenium is able to prevent cognitive impairment caused by brain damage. The mice were exposed to hippocampal injury that damages the neurons and the memory in a way similar to what happens to someone who has suffered a stroke. It turned out that the mice who were subsequently treated with selenium regained their memory, in contrast to the mice that did not receive selenium. Selenium appears to have a unique ability to help the brain form new neurons.
The new study is published in Cell Metabolism.
Selenium as a new way to treat and prevent cognitive decline
Bárbara Cardaso, a neurologist from Monash University´s Victorian Heart Institute in Australia, calls it a “fantastic study”. In earlier research, she has demonstrated that selenium supplementation of old people can help improve their language skills, memory, and ability to copy drawings. According to Bárbara Cardaso, selenium supplements may be used to treat or prevent cognitive decline in people who are unable to carry out physical activity or are likely to get too little selenium. This includes older patients who have suffered a stroke or have been diagnosed with Alzheimer’s disease.
Selenium deficiency is rather widespread in Europe, China, and others parts of the world due to low selenium levels in the agricultural soil. This appears to increase the risk of cognitive decline unless supplements are used to compensate for the deficiency.
- Selenoprotein P has a key role in the formation and protection of neurons
- Selenium helps preserve or improve cognitive skills – even in people who are not physically active
- This is only the case if you get enough selenium, however
Odette Leiter et al. Selenium mediates exercise-induced adult neurogenesis and reverses learning deficits induced by hippocampal injury and aging. Cell Metabolism. February 3, 2022
Rodrigo Pérez Ortega. Widely available supplement may explain brain boost from exercise. Science.org 3, Feb 2022
Aparna Shreenath. Selenium Deficiency. StatPearls. May 6, 2019
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