If you've been watching some of your favorite wellness experts' Insta-stories, you may have noticed them popping one or two thumb-size nuts daily. The Brazil nut, a tree nut that hails from (you guessed it!) Brazil, is the new food-based supplement du jour. Unlike most nuts, it's not to be casually snacked upon—you wouldn't, for example, want to make a Brazil nut butter or use Brazil nut flour as the base for your gluten-free baked goods. This is because of its superstar component: the incredibly high quantity of selenium. Just one Brazil nut contains 90 micrograms of selenium, or 129 percent of the daily intake recommended by the U.S. government. "As part of my daily supplement regimen, I eat two Brazil nuts every day," says Katie Lemons, the functional medicine expert behind the Twist of Lemons Instagram account and one of the first to popularize the nut as supplement. "They help regulate thyroid function, protect against skin and breast cancer (especially for those with the BRCA1 gene), can prevent mercury toxicity, and are a mood booster. Brazil nuts are safe for all population types without nut allergies. Make sure to buy the nuts in small batches and refrigerate them so they don't go rancid."
Why is it important to consume selenium?
A study found that Brazil nuts were more effective than supplements for raising selenium—and that just one a day was enough to bring bodily levels up to recommended amounts. There are a few key reasons it's important to keep selenium levels up.
Hormone balance (particularly thyroid regulation).
Selenium is the main component of seleno-proteins, which your body needs to make and produce thyroid hormones. If your selenium levels are low, your thyroid has to work harder to make its hormones, which is especially bad given the rising rates of thyroid disorders in the Western world. Taking one or two Brazil nuts daily helps support optimal thyroid health and thyroid balance, whether you have a thyroid disorder or are simply trying to avoid one. Other studies have shown selenium supplementation helping with the symptoms of PCOS, as well as fertility for people suffering from the syndrome.
Studies have shown selenium's protective role in skin cancer and breast cancer, particularly for people genetically predisposed. "One study showed that there were fewer chromosome breaks of the BRCA1 gene," explained Katie, "and basically, if a chromosome breaks it's really bad news and a sign of decay."
Reduced mercury toxicity.
Selenium is an important chelator, meaning that it helps bind with and excrete heavy metals—particularly mercury—from the body. The ideal is to eliminate the mercury before it takes a more permanent place in fatty tissue, meaning keeping selenium levels high enough to do that clean sweep regularly is important, especially if you eat a lot of seafood or have silver dental fillings.
Are there other sources of selenium?
There are—octopus, oysters, sardines, sunflower seeds, bacon, and shrimp, to name a few. But they're by far the highest in Brazil nuts, which is why so many experts choose to use the nut as a daily supplement.
Can you OD on selenium?
Absolutely. Symptoms include rashes, dizziness, a metallic taste in your mouth, and more. Stick to one or two Brazil nuts daily, and skip it if you're eating a diet quite high in other selenium-rich foods.