Get your Brain Health Score (in 4 mins) Take the quiz

Rest of World

Selenium benefits, dosage, and deficiency

What is selenium good for, which foods contain it, and do you need a supplement?

ingredients 18 selenium icon
Sophie Medlin
Sophie Medlin
Head of Nutritional Research
June 29, 2022
5 min read

Present in large quantities in Brazil nuts but little else, selenium is one of the essential minerals that we all need. In this summary, we’ll look at selenium benefits, along with examples of other selenium-rich foods, and the symptoms of a deficiency.

Article breakdown

What is selenium?

While selenium is vital for several key processes in the body, it has recently garnered more attention as an antioxidant, helping to protect cells from damage. This recent attention has led to more research being conducted, so we’re still discovering things about selenium vitamin benefits.

We only need small amounts to reap the benefits of selenium, but as we can’t produce any of it ourselves, we need to get it from external sources—predominantly our food.

Which foods contain selenium?

Brazil nuts are famous as a selenium-rich food, and for good reason. While the exact content can vary based on the quality of the soil it was grown in, on average you can get the full NRV from one Brazil nut. However, there are other examples of selenium-rich foods, including:

  • Tuna

  • Sardines

  • Offal

  • Prawns

  • Cottage cheese

For those following a vegan diet, there are other plant-based sources of selenium but higher quantities will need to be eaten to reach the daily required amount:

  • Sunflower seeds

  • Green or brown lentils

  • Cashew nuts

Should I be taking a selenium supplement?

The nutrient reference value (NRV) is 55mcg per day. Most people can get this from a balanced diet, but the benefits of selenium supplement is that it ensures you get the full amount every day. And to make it simple, every dose of the Heights Smart Supplement contains 55mcg (equal to 1 Brazil nut or a tin of sardines) so 100% of your needs.

Is it safe to take selenium every day?

Yes, you can take selenium every day so long as you don't exceed the recommended upper limit of 350mcg of selenium a day.

What is the best time to take selenium?

When taking a selenium supplement, the time of day doesn't really matter. That said, to help you remember to take it and to avoid any tummy troubles, it may be best to take it with a meal.

Now you know what selenium is, and how to get it in food and supplements, you're probably wondering 'well, what are the health benefits of selenium?' - so let's get into the all-important why you should pay this mineral attention!

Selenium benefits

There is still a lot of ongoing research into the effects of selenium and the full extent of selenium supplement benefits. However, we do know that it contributes to:

  • Healthy function of the immune system

  • DNA synthesis

  • Production of thyroid hormones

  • Normal reproductive function

Selenium’s powerful antioxidant properties can help to prevent cell damage and oxidative stress caused by free radicals. Reducing oxidative stress can protect against cognitive decline, which can lead to Alzheimer’s and mood disorders such as depression.

What are the symptoms of selenium deficiency?

Serious selenium deficiencies are rare, although certain groups are at higher risk than others. Not getting enough can lead to an increased risk of heart disease, male infertility, and arthritis.

A study on young adults also found that low or excessively high blood levels of selenium resulted in higher risk of depressive symptoms than in people with healthy levels.

How we use selenium in the Smart Supplement

We've designed the Heights Smart Supplement with selenium from sodium selenate, so that your brain gets all the benefits. You can be sure that:

  • Each dose contains 100% of the NRV for selenium.

  • Our selenium is pure and quality-tested.

  • Everything is manufactured in small batches.

  • It meets many common dietary and lifestyle practices: It's gluten-free, 100% plant-based, allergen-free and contains absolutely zero GMOs, contaminants, fillers or colourants.

Heights Smart Supplement bottle with blueberries, sugar snap and seeds
Heights Smart Supplement with blueberries and a snap pea
Our formula

The Smart Supplement

4.7/5 on Trustpilot
Find out why the Smart Supplement is the highest rated in the world, and how it helps to keep you feeling better, every day.
Find out more


Here’s a handful of relevant scientific studies on selenium.

We also used these sources when writing this article:

  • Smart Supplement
  • Braincare Journal
Rest of World
© 2022
This product is not designed to replace a varied and balanced diet. Do not exceed stated dose. If you are pregnant, breastfeeding or taking any medication, please consult your doctor before use. Do not use it if the seal has been tampered with. Store in a cool, dry place. Keep out of reach of children.
* These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease