Selenium is the 34th element on the periodic table. Classified as a metalloid, meaning its characteristics and properties fall between those of metallic and nonmetallic minerals, selenium has a number of industrial uses.
For humans, however, selenium is an essential trace mineral, meaning we need it to survive and thrive but only in small, trace amounts. This does not mean that selenium is unimportant. On the contrary, it attests to the potency of selenium.
Although our bodies need this mineral to carry our many important physiological processes, too much selenium can be toxic and cause damage.
Let’s review what selenium is, how it enhances your health, and how much selenium is recommended for optimal health.
How Do You Consume Selenium?
Because the human body is unable to produce selenium naturally, the only way to get it is from external sources. Fortunately, many foods provide adequate amounts of selenium.
Soil is selenium’s bridge from the earth’s crust to living organisms. You get selenium when you consume plants that have absorbed selenium from the soil or meat from animals that were raised on selenium-rich plants or in selenium-rich water.
What Foods Contain Selenium?
Whether or not there is much selenium in plants depends entirely on the mineral makeup of the soil and water in the area where they were grown. Therefore, the selenium content of any type of plant may vary dramatically from one place to the next.
For example, grains grown in North America are generally a good source of selenium. Yet, studies have shown that the soils in many areas of Russia, China, and other countries are low in selenium, so plants grown there have a lower content.
Despite these variations, certain vegetables, grains, and nuts are known to contain this element. Rice, oats, lentils, and whole-wheat bread are reasonably good sources.
Brazil nuts are the richest natural source of selenium. A single nut contains 68–91 micrograms! Eating lots of Brazil nuts could be a benefit for someone with a selenium deficiency but a risk for someone with normal or high levels of selenium in their system.
The main sources of selenium in the average diet are foods from animal sources. Cattle, chickens, and other livestock obtain selenium in the plants and feed they eat. So, red meat, poultry, milk, and eggs contain healthy amounts of selenium.
Other sources include fish and shellfish due to trace amounts of selenium that have filtered into the ocean.
What Are the Benefits of Selenium?
Selenium helps support many different bodily processes by serving as a component of essential enzymes and proteins. Proteins that contain selenium are known as selenoproteins, and they play important roles in the body
Selenium-dependent proteins have many critical functions. Some are required for the metabolism of thyroid hormones. Others are necessary for reproduction or for the synthesis of DNA. Several are components of glutathione or other antioxidants, so they help protect against oxidative stress.
All told, selenium serves as a vital nutrient for the heart, immune and reproductive systems, and other organs. Many studies suggest that selenium may play a role in disease prevention as well.
Although human bodies cannot naturally produce selenium, they can store it. Most of the time, selenium is diverted into muscle tissue for storage. However, the thyroid gland contains the highest concentration of selenoproteins, which help regulate the production of thyroid hormones.
How Much Selenium Do You Need?
For adults, the recommended daily amount selenium is 55 micrograms. For pregnant or lactating women, the suggested dosage is 60 and 70 micrograms, respectively. The safe upper limit for adults in 400 micrograms per day.
Numerous studies have shown that deficiencies in selenium increase the risk of cardiovascular disease, immune dysfunction, thyroid disorders, and cognitive decline. Supplemental selenium may be protective against these and other diseases.
As with any nutrient, the amount required will vary depending on sex, age, body type, and overall state of health. While an individual can suffer from a lack of selenium, it can also be detrimental to consume too much selenium. Advice from a doctor or dietitian will help determine the proper, safe amount for you.
What Risks Arise From Too Much Selenium?
Despite selenium’s protective properties, excessively high selenium intake can cause toxicity.
Symptoms of selenium toxicity may include fatigue, hair loss, nausea, and vomiting. In severe cases, toxicity can lead to respiratory problems, heart attacks, and kidney malfunction.
Selenium toxicity is blessedly rare, although a handful of cases of acute toxicity have been reported by individuals who took 200 times the recommended level.
It would be hard to get too much selenium from the usual amount in supplements or from food, unless you ate handfuls of Brazil nuts every day.
In Conclusion
Selenium is an essential trace mineral that is involved in many critical physiological functions.
Nature usually provides all the selenium that humans require, and although the amount of selenium in food and supplements is generally safe, be mindful that getting too much is problematic.
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