Selenium (also known as Se) is a trace mineral which is important for the human health, immune system and for reproduction. It is found in soil and occurs naturally in certain foods such as whole grains, Brazil nuts, sunflower seeds, seafood, etc. It has antioxidant and anti-inflammatory properties. Though Selenium is not produced in the body, it’s essential for proper thyroid, immune system function, fertility and reproduction, DNA synthesis, antioxidant enzymes and energy metabolism.
Selenium has nootropic quality. Studies suggest that deficient Selenium concentrations may be associated with cognitive decline. Marginal or deficient selenium concentrations might be associated with age-related declines in brain function, possibly due to decreases in selenium’s antioxidant activity.
A picture of selenium rich foods.
Selenium is an important element that has immense health benefits. It has antioxidant and anti-inflammatory properties and nootropic quality and can help improve cognitive decline. Its antioxidant properties protect cells from damage. It is said that selenium supplements may reduce the odds of prostate cancer. The health benefits of Selenium are still being studied widely, but certain very important health benefits are already well known which are mentioned below.
- Acts as an antioxidant 
- Improves cognitive performance 
- Defends against oxidative stress 
- May help people who are fighting cancer 
- Enhances immunity 
- Relieves inflammation 
- Improves blood flow and lowers chance of heart disease 
- Regulates thyroid health 
- Improves longevity 
- Helps reduce asthma symptoms 
- Can help boost fertility 
- Improves mental health 
- Improves mood 
Selenium has been reported to enhance both the humoral and cellular immune responses and to possess anticarcinogenic activity.
How it works
Selenium is an essential mineral heralded for its anti-oxidant capabilities; it forms a part of some anti-oxidant enzymes such as glutathione to confer protective effects. It is important for making many body processes work correctly. It has the ability to increase the action of antioxidants The main mechanism of action of selenium is that it works as a cofactor for various antioxidant enzymes, together with glutathione peroxidase. Also Selenium has shown other immune system effects and positive circulatory effects.
Studies on selenium and cognitive function or Alzheimer’s disease have yielded inconsistent results. The results in the study support the hypothesis that a lifelong low selenium level is associated with lower cognitive function.
When taken at normal doses, Selenium is usually safe. But an overdose of Selenium may cause bad breath, fever, nausea, and liver, kidney and heart problems. Even at very high levels, selenium could cause death. It also may cause skin cancer.
Selenium may interact with other medications and supplements, like antacids, chemotherapy drugs, corticosteroids, niacin, cholesterol-lowering statin drugs and oral contraceptives. So you are recommended to consult your healthcare provider before starting this supplement.
You have to be careful about consuming Selenium. Not always is taking more selenium beneficial, and high doses reaching 400 micrograms can even be harmful. The recommended daily allowance for selenium depends on your age and is as follows, according to the USDA: 
- Children 1–3: 20 micrograms/day
- Children 4–8: 30 micrograms/day
- Children 9–13: 40 micrograms/day
- Adults and children 14 and up: 55 micrograms/day
- Pregnant women: 60 micrograms/day
- Breastfeeding women: 70 micrograms/day