The 5 Best Selenium-Rich Foods for Better Focus & Thyroid Function

If you constantly feel tired and weak, low energy or experience persistent brain fog, you may actually need to eat more foods high in selenium, such as brazil nuts. Selenium deficiency can lead to severe health problems, including thyroid disorders and nervous system issues, so eating foods high in selenium is essential, especially on a vegan or plant-based diet. The good news is that it's easy to add many healthy sources of selenium (besides brazil nuts) to your diet.

Selenium is a trace element, meaning your body requires it in smaller amounts than other vitamins and minerals such as vitamin A and calcium. “Though a trace element, selenium is an essential nutrient that you must consume through diet or supplements,” states Brittany Lubeck, RD, a registered dietitian, and nutrition writer. “Selenium is a part of DNA production, protein building, reproduction, and immunity.”

Though you don’t need much selenium, this important trace element plays a fundamental role in optimal health. Low selenium levels are associated with the oxidative stress implicated in the development of Alzheimer’s disease (AD), concluded a 2018 meta-analysis of 14 studies published in Biological Trace Element Research. The researchers found that the brains of people with AD had significantly lower amounts of selenium compared to non-AD brains.

Selenium has also been shown to prevent and treat chronic diseases, including cardiovascular disease, diabetes, cancer, and inflammatory diseases.

“The amount of selenium you need each day depends on your age and whether you’re pregnant or lactating,” explains Lubeck. Also, certain groups are more likely to have problems getting enough selenium, according to the National Institute of Health (NIH). This includes people undergoing kidney dialysis, people with HIV, and those living in regions where the soil is low in selenium.

Here are the recommended daily intakes of selenium based on age from the NIH. Males and females require the same amount of selenium.

Most people get enough selenium from their diet as it’s widely available in animal-based foods. Plus, most of us eat plants grown in many different regions of the world, so we’re getting selenium absorbed by plants from the soil. However, those following a vegan or vegetarian diet should pay attention to their food choices to ensure they’re eating plant-based foods with higher amounts of selenium.

“Although a food-first approach to nutrients like selenium is always best, sometimes a supplement may be warranted,” says Lubeck. “This may be the case if you’re deficient in selenium or cannot get enough of the trace mineral through your diet for some reason.”

You can get your daily dose of selenium from oral multivitamin/mineral supplements that typically come in capsule form. There are several forms of selenium, including selenomethionine (organic form) and sodium selenite (synthetic form). According to the NIH, your body absorbs more than 90 percent of selenomethionine but only half of the selenium from selenite.

Fortunately, all forms of selenium are well-absorbed by your body, but selenomethionine — the form present in foods—is optimal. However, there are certain health conditions and bad lifestyle habits to avoid if you want to optimize selenium absorption. According to Mount Sinai, tobacco, alcohol, birth control medication, Crohn’s disease, and ulcerative colitis can inhibit the bioavailability of selenium.

Eating one Brazil nut a day (or a handful of them once per week) is a simple and effective way to meet your selenium requirements. Each brazil nut contains 68 to 91 micrograms of selenium, which exceeds the recommended daily intake, making brazil nuts an easy selenium source.

However, be careful when eating brazil nuts as too many can cause you to exceed the upper limit. Symptoms of too much selenium include garlic breath, nausea, diarrhea, skin rashes, irritability, loss of hair or nails, teeth discoloration, and nervous system issues. Even worse, extremely high selenium intake can cause severe health issues, such as difficulty breathing, tremors, kidney failure, heart attacks, and heart failure.

Here are the daily upper limits of selenium intake from all sources based on age demographics, according to the NIH.

Brazil nuts are by far the best bang for your selenium buck. One ounce (about six to eight nuts) contains 544 micrograms of selenium — that’s 989 percent of your daily value! Be sure not to go nuts snacking on them as you can easily exceed the upper limit intake.

(Give this Kale Caesar Salad with Wakame and Brazil Nut Parmesan a try for your daily dose of selenium.)

Each cup of this healthy whole grain contains 19 micrograms of selenium when cooked, which is 35 percent of your daily value. Brown rice is a versatile food that goes well with almost any meal.

(If you want something new, try this Nutrient-Packed Rice Bowl with Jicama and Brown Beans.)

Who knew your go-to lunchtime sandwich was a good source of selenium? Whole-wheat bread has 13 micrograms per slice, delivering 24 percent of your daily value.

(Sick of avocado toast? Try this Vegan Buffalo Chickpea Salad Sandwich.)

Oatmeal is a breakfast staple for many of us because of its many health benefits. One cup contains 13 micrograms of selenium for 24 percent of your daily value.
A word of caution: Ensure you buy your oatmeal organic and avoid the instant, prepackaged products. These have been found to contain residues of the harmful pesticide glyphosate, according to the Environmental Working Group.

(Like big breakfasts? Then this Vanilla Matcha Oatmeal is a must-try.)

You know lentils are packed with plant-based protein and healthy carbs, but they’re also a good source of selenium. One cup of cooked lentils contains six micrograms, providing 11 percent of your daily value.

(Make these Vegan and Gluten-free Lentil Meatballs that everyone will love.)

Be sure to check the above guide and ensure that you're not surpassing your age group's upper limit for selenium. When taken in too large of quantities, selenium can cause severe health issues.

For more expert advice, visit The Beet's Health & Nutrition articles.