Foods High in Selenium: Brazil Nuts and More

Selenium is a trace element the body only needs in tiny amounts — and yet getting the right amount determines a whole range of functions. In Central Europe, the soil is comparatively low in selenium, which is why plant-based foods here often supply less than in other regions. The interesting question, then, is: which foods reliably cover selenium needs — and why is the Brazil nut a double-edged sword?

What is selenium, and why does it matter?

Selenium is an essential trace element that humans must obtain through food. It's a component of what are known as selenoproteins — proteins that contain the element as a fixed building block. Through these proteins, selenium is involved in several metabolic pathways. Several health claims are approved for selenium in the EU. Specifically: selenium contributes to normal function of the immune system and selenium contributes to normal thyroid function. It is also approved that selenium contributes to the protection of cells from oxidative stress.

The body cannot produce selenium on its own and can only store limited amounts. A regular supply through diet is therefore sensible. The German Nutrition Society (DGE) gives an estimated value for an adequate selenium intake in adults of 70 micrograms per day for men and 60 micrograms per day for women. That sounds like very little — and indeed, small portions of the right foods already go a long way.

Which foods contain a lot of selenium?

Selenium is found in both animal and plant foods. With plant foods, however, there's a decisive catch: how much selenium a grain, nut or legume contains depends largely on how selenium-rich the soil was that the plant grew in. Animal foods, through feeding, usually provide more consistent levels.

Brazil nuts — the selenium champion

No other common food source supplies as much selenium as the Brazil nut. Its content varies greatly by origin, but often falls in the range of around 100 micrograms or more per single nut. That means just one to two Brazil nuts can, in theory, cover the daily requirement. But that's exactly where the risk lies too — more on that below.

Fish and seafood

Saltwater fish such as tuna, herring, sardines and plaice, as well as seafood, are among the most reliable animal-based selenium sources. A single portion of saltwater fish can already supply a substantial part of the daily requirement, and it additionally brings along iodine and omega-3 fatty acids.

Meat, organ meats and eggs

Meat — especially organ meats like liver and kidney — counts among the richer selenium sources. Ordinary muscle meat from beef, pork and poultry also contributes noticeably. Eggs are an uncomplicated everyday source: one egg provides a small but consistent contribution.

Grains, legumes and nuts

Whole grains, oats, lentils and other legumes contain selenium — but here the soil dependency kicks in. In growing regions with more selenium-rich soil, they supply considerably more than they do here. For people who eat a plant-based diet, they are nevertheless important building blocks, ideally supplemented with targeted sources.

Selenium and a plant-based diet: the soil factor

In Germany and large parts of Europe, farmland soils are naturally low in selenium. As a result, grain and vegetables grown here tend to contain less selenium than, say, produce from North America, where feed grain and, in some cases, food-grade grain are additionally fortified with selenium. Anyone eating a purely plant-based diet should therefore deliberately plan in selenium-rich plant sources. The same attention to origin and variety is worthwhile in general, by the way — for example with foods high in antioxidants or foods high in magnesium, whose levels likewise vary depending on variety and cultivation.

Who is selenium intake especially relevant for?

Most people in Germany reach the recommended amount of selenium with a varied mixed diet, even though the soil is poor — animal foods make up for a lot. People who eat a strictly vegan diet, as well as those with a very one-sided diet, should take a closer look. Needs can also differ with certain medical conditions or in particular life stages. Whether an individual is actually undersupplied can only be reliably determined through a medical blood test — guessing based on symptoms rarely gets you anywhere.

As a general rule: selenium is part of a bigger picture. Anyone aiming for a good supply of trace elements and vitamins is best off combining several building blocks. How nutrients work together to support metabolism is described in our guide on nutrients for more energy. And anyone wanting to improve iron absorption from plant foods will find useful connections in foods high in vitamin C.

Caution with Brazil nuts: keeping the upper limit in mind

As practical as the Brazil nut is as a selenium source, restraint is warranted here. For one thing, the selenium content of individual nuts varies greatly and can be very high, so that even a few nuts a day can lead to a selenium intake that exceeds requirements. Too much selenium over a longer period isn't harmless. Germany's Federal Institute for Risk Assessment (BfR) therefore advises against regularly eating large amounts of Brazil nuts. For another, Brazil nuts can naturally accumulate small amounts of radioactive substances such as radium from the soil — another reason to treat them as a delicacy rather than a daily selenium pill.

A practical rule of thumb: enjoy Brazil nuts in moderation — one or two nuts occasionally are unproblematic for healthy adults, but don't make large portions a daily habit. If you want to cover your selenium needs in a targeted, measured way, a combination of fish, eggs, meat and whole-grain products is usually the more balanced approach.

Selenium from food or as a dietary supplement?

For most people, targeted supplementation isn't necessary if the diet is varied. Selenium supplements can make sense where needs are hard to cover through normal diet alone — for example, with a strictly plant-based diet lacking selenium-rich building blocks, or with a medically confirmed deficiency. But because selenium has a comparatively narrow range between an adequate intake and one that's too high, supplementing shouldn't happen on a hunch. It makes sense to have your individual situation medically assessed and to base any product on the approved daily maximum amount, rather than combining sources without control.

Honestly assessed: what's established and what isn't

What's established is that selenium is an essential trace element and, via the approved EU claims, contributes to the immune system, thyroid function, and the protection of cells from oxidative stress. It's also established that soils in Central Europe are low in selenium, which is why animal foods represent a particularly reliable source. The evidence is less clear-cut for many further-reaching health promises: higher amounts of selenium don't automatically mean more benefit, and overdosing can cause harm. If you're unsure whether you're adequately supplied, don't guess — get it checked by a doctor. Selenium is a good example of a trace element where the right amount is what counts, not as much as possible.

Frequently asked questions (FAQ)

Which food contains the most selenium?

The Brazil nut is by far the selenium champion. Depending on origin, a single nut can already contain around 100 micrograms of selenium or more, enough to cover the daily requirement. Precisely because of this high and variable content, though, Brazil nuts should only be eaten in small amounts.

How much selenium does a person need per day?

The German Nutrition Society gives an estimated value for an adequate intake in adults of 70 micrograms per day for men and 60 micrograms per day for women. This amount can usually be reached well with a varied mixed diet of fish, meat, eggs and whole-grain products.

Do vegans get enough selenium?

It's possible, but it requires attention. Since Central European soils are low in selenium and the most reliable sources are animal-based, people on a purely plant-based diet should deliberately plan in selenium-rich building blocks. Whether the supply is sufficient is most reliably determined through a medical blood test.

Can you take in too much selenium?

Yes. Selenium has a comparatively narrow range between an adequate intake and one that's too high, and consistently too much selenium isn't harmless. That's why the Federal Institute for Risk Assessment advises against regularly eating large amounts of very selenium-rich foods like Brazil nuts, or combining supplements without control.

How many Brazil nuts a day are safe?

For healthy adults, one to two Brazil nuts occasionally are considered unproblematic. Because of the high, variable selenium content and the possible natural accumulation of small amounts of radioactive substances, larger portions shouldn't become a daily habit.