Selenium is a crucial mineral that can be acquired from a variety of foods. This trace element is instrumental in promoting the healthy functioning of your body, playing a significant role in your metabolism, immune system, and thyroid health. While it may not be a common term in your daily conversations, this remarkable nutrient is essential for your overall well-being.

As an essential mineral, selenium must be ingested through your diet, as our bodies cannot produce it independently. Although it is required in only trace amounts, its impact on vital bodily processes is profound, particularly regarding metabolism and thyroid function.

This article will delve into seven scientifically-supported health benefits of selenium, showcasing its remarkable contributions to your health.

1. Acts as a Potent Antioxidant

Antioxidants are vital compounds found in various foods that play a crucial role in preventing cellular damage caused by free radicals. These free radicals are naturally occurring byproducts of metabolic processes generated within your body on a daily basis. While they often carry a negative reputation, free radicals are actually essential for maintaining health, as they perform significant functions, including safeguarding your body against diseases.

Nevertheless, factors such as smoking, excessive alcohol consumption, and chronic stress can lead to an overproduction of free radicals. This imbalance results in oxidative stress, which can harm healthy cells. Oxidative stress has been associated with several chronic conditions, including heart disease, Alzheimer’s disease, and cancer, in addition to contributing to premature aging and elevating stroke risk. Antioxidants, such as selenium, are effective in mitigating oxidative stress by regulating the levels of free radicals in the body.

2. Potentially Lowers Your Risk of Specific Cancers

Beyond its role in mitigating oxidative stress, selenium may play a significant part in reducing the likelihood of developing specific cancers. This property is linked to selenium's capacity to minimize DNA damage and oxidative stress, enhance the immune response, and eliminate cancerous cells.

A comprehensive review encompassing 69 studies with over 350,000 participants revealed that elevated blood levels of selenium were correlated with a decreased risk of various cancer types such as breast, lung, colon, and prostate cancers. Notably, the protective effect was solely linked to selenium obtained from food sources, rather than from supplements.

Nevertheless, some studies indicate that selenium supplementation may alleviate side effects for individuals undergoing radiation therapy. For instance, research demonstrated that oral selenium supplements could enhance overall quality of life and lessen radiation-induced diarrhea in women diagnosed with cervical and uterine cancer.

3. Potential Heart Disease Protection

A diet abundant in selenium could be beneficial for maintaining heart health, as insufficient selenium levels have been correlated with a heightened risk of heart disease. A comprehensive analysis encompassing 25 observational studies revealed that a 50% increase in blood selenium concentrations was linked with a significant 24% decrease in heart disease risk. Furthermore, selenium has the potential to diminish markers of inflammation within the body, which is one of the primary contributors to heart disease.

For instance, a review of 16 controlled studies involving over 433,000 individuals diagnosed with heart disease indicated that the administration of selenium supplements led to a reduction in levels of the inflammatory marker C-reactive protein (CRP). Additionally, selenium supplementation was found to elevate levels of glutathione peroxidase, a robust antioxidant. This suggests that selenium may aid in mitigating heart disease risk through the reduction of inflammation and oxidative stress in the body. These two factors, oxidative stress and inflammation, have been closely associated with atherosclerosis, which is the accumulation of plaque within the arteries.

Atherosclerosis can precipitate severe health complications such as strokes, heart attacks, and other cardiovascular diseases. Therefore, incorporating foods rich in selenium into your diet serves as an excellent strategy to minimize oxidative stress and inflammation levels.

4. Aids in the Prevention of Cognitive Decline

Alzheimer’s disease is a profoundly challenging condition characterized by memory loss and detrimental effects on thinking and behavior, ranking as the sixth-leading cause of mortality in various countries, including the United States. As the prevalence of Alzheimer’s continues to rise, it is crucial to explore effective strategies for preventing this debilitating degenerative disorder.

Research indicates that oxidative stress plays a significant role in the initiation and progression of neurological disorders such as Parkinson’s, multiple sclerosis, and Alzheimer’s. Notably, several studies have revealed that individuals diagnosed with Alzheimer’s exhibit lower serum levels of selenium.

Moreover, various investigations have suggested that antioxidants found in both dietary sources and supplements may enhance memory functions in those suffering from Alzheimer’s. For instance, a small-scale study demonstrated that daily supplementation with a single selenium-rich Brazil nut could lead to improvements in verbal fluency and cognitive abilities among patients experiencing mild cognitive impairment.

Furthermore, the Mediterranean diet, which is abundant in high-selenium foods such as seafood and nuts, has been linked to a reduced risk of developing Alzheimer’s disease. Incorporating such nutrient-dense foods into one’s diet may offer protective benefits.

5. Importance of Selenium for Thyroid Health

Selenium plays a crucial role in ensuring the optimal function of the thyroid gland, as this vital organ contains the highest concentration of selenium compared to any other organ in the human body. This remarkable mineral acts as a protective shield against oxidative damage, contributing significantly to the synthesis of thyroid hormones.

A well-functioning thyroid is essential since it regulates metabolism and oversees growth and development. Insufficient selenium levels can lead to thyroid-related issues, such as Hashimoto’s thyroiditis (Hashimoto ki thyroiditis), a form of hypothyroidism where the immune system mistakenly attacks the thyroid gland.

In a notable observational study involving more than 6,000 participants, researchers discovered that low serum selenium levels correlated with a heightened risk of autoimmune thyroiditis and hypothyroidism. Furthermore, various studies suggest that selenium supplementation could offer advantages for individuals suffering from Hashimoto’s disease.

One comprehensive review indicated that daily selenium supplementation over a span of three months resulted in reduced thyroid antibodies and enhanced mood and overall well-being among those affected by Hashimoto’s disease. However, it is important to note that further research is necessary before making definitive recommendations regarding selenium supplements for individuals with this condition.

6. Strengthens Your Immune System

The immune system is vital for maintaining your health as it works to identify and combat various potential threats, such as bacteria, viruses, and parasites. A critical player in this protective mechanism is selenium, an essential mineral known for its antioxidant properties.

Selenium significantly contributes to the health of your immune system by reducing oxidative stress in the body, which in turn decreases inflammation and bolsters immune function. Research indicates a positive correlation between elevated blood selenium levels and a more robust immune response.

Conversely, a lack of selenium can hinder the function of immune cells, resulting in a sluggish immune reaction. This deficiency has been linked to heightened risks of illness and mortality, particularly in individuals living with HIV; studies suggest that selenium supplementation may reduce hospitalizations and improve symptoms in these patients.

Moreover, selenium supplements have shown potential in fortifying the immune systems of individuals suffering from conditions such as influenza, tuberculosis, and hepatitis C. Countries like India, Australia, Japan, and Canada recognize the importance of selenium in dietary strategies aimed at improving immune health.

7. Potentially Alleviates Asthma Symptoms

Asthma is a persistent condition that impacts the airways responsible for transporting air to and from the lungs. These airways can become swollen and constricted, leading to symptoms such as wheezing, shortness of breath, chest tightness, and coughing. It has been observed that asthma is linked with elevated levels of oxidative stress and inflammation within the body.

Given selenium’s capacity to mitigate inflammation, numerous studies indicate that this essential mineral might assist in alleviating asthma-related symptoms. Research indicates that individuals suffering from asthma tend to exhibit lower concentrations of selenium in their bloodstream.

For instance, a particular study revealed that asthmatic patients who had higher blood selenium levels experienced improved lung function compared to those with reduced levels. Furthermore, selenium supplements may also contribute to easing asthma symptoms. In one study, participants with asthma who received 200 mcg of selenium daily demonstrated a decrease in their reliance on corticosteroid medications typically prescribed to manage their symptoms. Nevertheless, it is important to note that findings in this field have been inconsistent, and more comprehensive studies are necessary to fully comprehend selenium’s influence on asthma development and management.

Top Dietary Sources of Selenium

Fortunately, numerous nutritious foods are rich in selenium, an essential trace mineral that plays a vital role in various bodily functions.

The following foods are exceptional sources of selenium:

  • Oysters: providing a remarkable 238% of the Daily Value (DV) in just 85 grams (3 ounces)
  • Brazil nuts (Brazilian nuts): delivering 174% of the DV in a mere single nut (5 grams)
  • Halibut: offering 171% of the DV in approximately 159 grams (6 ounces)
  • Yellowfin tuna: containing 167% of the DV in 85 grams (3 ounces)
  • Eggs: contributing 56% of the DV in 100 grams (2 large eggs)
  • Sardines: providing 46% of the DV in about 48 grams (4 sardines)
  • Sunflower seeds: containing 27% of the DV in approximately 28 grams (1 ounce)
  • Chicken breast: offering 12% of the DV in 84 grams (4 slices)
  • Shiitake mushrooms: providing 10% of the DV in roughly 97 grams (1 cup)

The selenium content in plant-based foods can fluctuate significantly based on the selenium levels present in the soil where they are cultivated.

This means that the concentration of selenium in crops largely depends on their geographical farming location. For instance, research has demonstrated that the selenium concentration in Brazil nuts can vary dramatically by region; one nut from a particular area may contain up to 288% of the recommended intake, while another might only yield 11%.

Risks Associated with Excessive Selenium Intake

Selenium is an essential trace element crucial for maintaining optimal health, yet excessive consumption can pose significant risks. In fact, ingesting elevated doses of selenium can lead to toxicity, which may have severe and potentially fatal consequences.

Although cases of selenium toxicity are uncommon, it is vital to adhere to the recommended daily intake of 55 mcg and to avoid surpassing the tolerable upper limit of 400 mcg per day. This is particularly important for individuals in regions like India and Australia, where dietary habits may vary.

Notably, Brazil nuts (Bertholletia excelsa) are known for their exceptionally high selenium content. Overindulgence in these nuts could raise the risk of selenium toxicity significantly. It is essential to understand that toxicity is more frequently associated with supplements rather than from natural food sources rich in selenium.

Common signs of selenium toxicity can include:

  • hair loss
  • dizziness
  • nausea
  • vomiting
  • facial flushing
  • tremors
  • muscle soreness

In severe instances, acute selenium toxicity can result in alarming intestinal and neurological issues, heart attacks, kidney failure, and in extreme cases, death.

The Bottom Line

Selenium is an essential trace mineral that plays a vital role in ensuring the optimal functionality of your body. This remarkable mineral is integral to various processes, including metabolism and thyroid function, while also providing protection against oxidative stress-related damage. In addition to these benefits, selenium may enhance your immune response, mitigate age-related cognitive decline, and potentially lower your risk of developing heart diseases. This valuable micronutrient is abundant in an array of foods, including oysters, mushrooms, and Brazil nuts (castanha-do-pará). Incorporating more selenium-rich options into your diet is a fantastic strategy for promoting overall health and wellness.