Brazil nuts are very nutritious and can introduce a lot of essential nutrients into your body, including selenium, which helps you maintain a healthy thyroid gland and improves your immune system. However, when consumed without moderation, Brazil nuts can actually jeopardize your health.

Though selenium is beneficial in small amounts, eating too much of it can be toxic. A little goes a long way when it comes to Brazil nuts, and consuming too many can cause gastrointestinal problems, brittle hair and nails, joint pain, tiredness, and in rare cases, kidney failure or heart attacks.

A recommended two Brazil nuts a day is a healthy number for most adults to help keep a happy thyroid and boost immune functions. However, in terms of the maximum, adults should eat no more than 5 Brazil nuts at a time, which will bring them to the maximum amount of selenium they should consume.