When trying to lose weight, it can be tempting to look for supplements that can speed up the process.
Selenium is a mineral with many important roles in your body, one of which is the production of thyroid hormones that help regulate your metabolism. For this reason, it is often touted as beneficial for weight loss. (1)
Although it is essential, you only need a small amount in your diet, and deficiency is rare.
This article discusses whether taking selenium supplements can be beneficial and whether they can help with weight loss.
Your thyroid gland contains high levels of selenium, which is used to produce and metabolize thyroid hormones. These hormones regulate many metabolic functions in the body, including how many calories you burn. ( 2 )
Selenium deficiency is associated with a higher risk of thyroid disease. Studies show that taking selenium supplements improves thyroid function in people with mild hypothyroidism and autoimmune thyroid disease. ( 3 )
Supplements may also benefit those with normal thyroid function.
In a small 12-week study in 37 overweight adults, those who took a daily supplement of 240 mcg of selenium in combination with a calorie-restricted diet lost more weight than a group that tried calorie restriction alone. ( 4 )
Those who took the daily supplement also lost more fat and had lower levels of leptin, a hormone that helps regulate fat storage.
The Recommended Dietary Allowance (RDA) – which is the average daily amount of a nutrient that meets most people’s daily needs – for selenium is 55 mcg per day.
Foods that contain selenium
Selenium is a mineral that occurs naturally in soil and water. It is transferred to plants and then through the food system. As such, it is available in a wide variety of whole foods.
Good selenium-rich foods include: ( 5 )
|food||The amount of selenium||% PDP*|
|1 Brazil nut||98 mcg||140|
|85 grams of yellowfin tuna||92 mcg||167|
|85 grams of seaweed||47 mcg||85|
|85 grams of chicken breast||22 mcg||40|
|210 grams of low-fat cottage cheese||20 mcg||36|
|1 cup (195 grams) of brown rice||19 mcg||35|
|1 cup (198 grams) lentils||6 mcg||11|
|1 large egg||15 mcg||27|
|1 slice of whole wheat bread||13 mcg||24|
|1 cup cooked rolled oats||13 mcg||24|
Tab. 1 (selenium for weight loss) *recommended daily intake
Brazil nuts are an excellent source of this nutrient.
Eating just two a day can raise your blood selenium levels more than taking a selenium supplement. ( 6 )
On the other hand, highly processed foods—those that are packaged, ready-to-eat, and have a long list of ingredients—tend to be lower in selenium. ( 7 )
In a study of more than 3,200 people, those who consumed less selenium in their diet had a higher body mass index (BMI). The scientists also found that each 1 mcg/kg/day increase in selenium corresponded to a 3-6% reduction in body fat. ( 8 )
Since selenium is found in many foods, it is possible to plan a weight loss diet that is high in this nutrient. This can provide you with similar weight loss benefits as taking a supplement.
In order for selenium to benefit your body, you should not consume too much or too little of it. The safe upper limit for the mineral is set at 400 mcg per day.
If you frequently take a high-dose selenium supplement in addition to a selenium-rich diet, you may be at risk of poisoning. In severe cases, it can cause kidney or heart failure.
Symptoms of too much selenium include hair and nail loss, brittle nails, a metallic taste in the mouth, and a garlicky breath. It can also cause nausea, vomiting and diarrhea.
There have been reports of selenium poisoning from taking a mislabeled supplement. In 2008, a product labeled as containing 200 mcg of selenium was found to contain 200 times that amount. (9)
If you want to try a selenium supplement, look for one that has been analyzed or verified by an independent laboratory.
The most common symptoms reported after using the product for less than a month are diarrhea, fatigue, hair loss, and joint pain. Of the people who reported hair loss, 18% lost all of their head hair.
Before taking a selenium supplement, you can first try to optimize your diet to include more of the nutrient.
If you decide to supplement with selenium, make sure the nutrient has not been added to other supplements you are taking. For example, it is often added to multivitamins and mineral supplements.
Based on older and more recent research, selenium supplements are considered safe to take in regular doses, usually around 100-200 mcg per day (10).
If you prefer to stick to a diet, eating two Brazil nuts each day provides the same amount. Because these nuts are also rich in other minerals and healthy fats, they may offer other health benefits as well. ( 11 )
Just keep in mind that due to their high selenium content, don’t eat more than five Brazil nuts, which contain about 400 mcg, per day.
That said, one study found no signs of selenium poisoning in people who regularly consumed Brazil nuts. ( 12 )
The mineral selenium has many health benefits and is essential for thyroid function. Among other things, the thyroid gland helps regulate your weight.
Studies show that taking a selenium supplement or getting more of the mineral from your diet can speed up fat loss.
However, an overdose can have side effects such as hair loss, brittle nails, or garlic-like breath.
To increase your selenium intake to promote weight loss, try adding foods high in selenium to your diet, such as Brazil nuts and yellowfin tuna. If you choose a supplement, stick to one that provides no more than 200 mcg of selenium.