Can Eating Many Brazil Nuts Really Kill You?

A dietician-turned-influencer/ YouTuber set the internet ablaze when she claims that eating too many Brazil nuts daily can be deadly. With the web now flush with fear and confusion, it’s time to separate scare tactics from science. Can a simple snack really take you out for good—or is this another health hysteria?

The Double-Edged Star Mineral: Selenium

Brazil nuts are most famous for one thing: selenium. As a trace mineral, selenium is essential—vital for DNA production, thyroid function, and defending the body against cell damage—but the line between “enough” and “too much” is alarmingly narrow.

• Selenium content: 1 Brazil nut = 68–91 micrograms (mcg) of selenium.
• Recommended dietary allowance (RDA): 55 mcg per day for adults.
• Upper limit (UL): 400 mcg per day for adults.

That means one Brazil nut delivers more than your daily requirement, and just four or five might push you over the safety threshold.

Can the selenium toxicity in Brazilian nuts poses danger to humans?
Regularly eating too many Brazil nuts can put you at serious risk of “selenosis,” the clinical term for selenium overdose. 

Symptoms of selenium toxicity include: Garlic-scented or metallic breath; Nausea, diarrhea, and abdominal pain; Hair loss and brittle nails; Skin rashes or lesions; Neurological symptoms such as tremors or irritation; Fatigue and dizziness. 

Severe selenium toxicity escalates the danger: Difficulty breathing, Abnormal heart rhythms, Kidney failure, Heart failure.  In extremely rare, but documented, cases—death.

What Does the Research Say?

Multiple major health sources and clinical studies confirm the potential toxicity of overconsuming Brazil nuts. Here’s what the evidence reveals:

Acute Toxicity: Eating a huge amount of Brazil nuts (dozens or more) in a single sitting could, in theory, result in fatal selenium poisoning, but this is exceedingly unlikely for most people due to the large quantity required and an immediate onset of nausea and vomiting, prompting individuals to stop eating.

Chronic Toxicity: Regularly eating more than five nuts a day over months can result in selenium building to toxic levels in the body, with cumulative, potentially life-threatening effects over time189.

Documented Cases: While actual deaths from Brazil nut ingestion are not commonly reported, medical literature and toxicology reports confirm that chronic selenium overdose can be fatal. However, it’s far more often that patients experience serious symptoms that lead to medical intervention before fatality occurs.

How many Brazil Nuts are "Too Many?

Nutrition experts offer a short, surprising answer: Just two to three Brazil nuts daily is more than enough—and eating more, especially over long periods, raises real health risks.

Brazil Nut Eaten	Selenium Consumed (Estimate)	Safety Level	Health Impact
1 nut	~70–90 mcg	Safe—above RDA, below UL	Meets daily selenium needs, unlikely to overdose
3–4 nuts	~210–360 mcg	At/just below upper limit	Risk rises for sensitive people or with supplements
5+ nuts	Over 400 mcg	Dangerous regularly	Selenosis possible, potential for serious symptoms
20+ nuts	Over 1,400 mcg	Likely toxic	Acute selenosis possible, severe medical risk

For children, the limits are even lower.

What if you "one-off" overeating?

Accidentally eating a handful of Brazil nuts once is unlikely to be fatal for a healthy adult. The real risk comes from habitual excess. If you gorge on Brazil nuts daily for weeks to months, you’re running a real risk of severe toxicity.

Nuts have other risks besides selenium.  For example, Aflatoxins can happen when nuts are improperly stored and the fungi creates toxins, which can be carcinogenic.

And Brazil nuts naturally contain barium and even small, harmless amounts of radium or cadmium, but not at acutely dangerous levels with moderate intake.

Expert Quotes

“Eating too many Brazil nuts can lead to toxic levels of selenium... In rare cases, very high levels can cause kidney failure, cardiac arrest, and even death.” — University Hospitals

 “An intake of 5,000 mcg of selenium, which is the amount in approximately 50 average-sized Brazil nuts, may result in toxicity.” — Healthline

“Doctors advise eating no more than five Brazil nuts a day to avoid potential health risks like selenium toxicity. This condition is linked to breathing problems, heart issues, and kidney failure.” — WebMD

Without exception, nutritionists and medical centers agree: You should not treat Brazil nuts as a bottomless snack. They’re potent, healthy in tiny doses, but dangerous in excess.

So if you just want to know the bottom line, based on the science:

True: Routinely eating large numbers of Brazil nuts can cause selenium poisoning and in rare, severe cases, lead to death.

Casual consumption (a few nuts now and then) is safe for most people.

Key nuance: The lethal threat isn’t immediate or likely from eating a handful one time, but chronic, excessive consumption poses a genuine danger.

Enjoy up to two Brazil nuts a day—that’s healthy and enough selenium for almost everyone.

Avoid eating more than four or five a day, especially over consecutive days or weeks.
If you’re taking selenium supplements, cut back even further—or skip Brazil nuts entirely.

So, think before you snack. With Brazil nuts, all I can think of is: "What doesn't kill you make you stronger".