Five questions you should ask about selenium supplements

Selenium is a mineral and an essential micronutrient in our diet. Selenium is highly regulated in the brain as well as in the endocrine system. Selenium is used to make approx. 25 different selenoproteins that function as enzymes in various metabolic pathways. Trace amounts of selenium is quickly taken up by organs including the liver and thyroid. Surplus selenium, however, is toxic to humans.

This article covers five questions that you should ask before taking selenium supplements. 

1)  What is the National Institute of Health’s Recommended Daily Allowance (RDA) of Selenium?

The National Institute of Health publishes the recommended daily allowance of selenium as :   ( *mcg= micrograms) 

2) What foods are rich in selenium? 

The ocean is rich with selenium which is naturally taken up by ocean fish and passed on to humans eating wild caught fish and shell fish. 

Selenium is a mineral and not uniformly deposited on land.  Grains, nuts, and grasses grown in selenium rich zones will take up trace selenium and pass that on to humans directly  or by eating animals grazing on the grasses grown in selenium rich regions.   There are regions in the world far from the ocean and without local selenium where the local population suffers from selenium deficiency. 

3) What happens if my diet is deficient in selenium? 

Selenium deficiencies have been linked to a variety of diseases including skeletal development disorders, cardiovascular disease, cancers, liver diseases and osteoarthritis (1) and even male infertility (2).  Selenium also plays a critical role in hormone regulation and egg formation.

4)  Can I still be at risk of selenium deficiency even if take in my  RDA of selenium by either diet or selenium supplements?

Unfortunately, yes.  Selenium can get depleted by two known pathways,   Reactive Oxygen Species (ROS) and Mercury.

Depletion by ROS

Selenium is often marketed as a valuable antioxidant that can help mitigate the ROS generated by the mitochondria’s energy cycle.  While true,  if you have followed our blogs,  there are numerous micronutrients from the mineral, metal, enzyme and vitamin family that all can act as mild antioxidants. These antioxidants are not powerful enough to regulate ROS.   Early lifeforms had to make a family of more powerful antioxidants called carotenoids.  Astaxanthin is the most powerful carotenoid and if present in our diet,  protects elements like selenium from being oxidized by ROS which prevents selenium from being able to form selenoproteins. 

Depletion by Mercury

Mercury is toxic to humans and like selenium can easily cross the blood brain barrier.  Selenium and mercury have a strong chemical affinity to form a compounds called mercury selenides which are not soluble in blood and the selenium bound up in mercury selenides cannot be used form selenoproteins. 

At the same time,  selenium has been used as an antidote to mercury poisoning as mercury selenide is considered non toxic.

To receive our RDA of selenium from seafood just got much more complicated.  Fish that are high in selenium content can use some of that inventory to mitigate mercury poisoning and be safe to eat while contributing selenium to our diet. However,  dietary intake of species including  sharks and swordfish should be limited given the high mercury to selenium ratios in these fish. 

5) Should I take selenium supplements? 

The answer depends on your dietary intake of bioavailable selenium but also your dietary intake of bioavailable astaxanthin which protects selenium from ROS. 

Consult your physician or nutritionist to examine your diet and determine if you need additional sources of selenium. 

One gelcap of our best immune system booster contains 6 mg nature's most powerful antioxidant,  the  3S, 3'S form of astaxanthin and  approx 35 mcg of of natural selenomethionine to power the formation of selenoproteins. 

1. https://www.nature.com/articles/s12276-020-0408-y
2. https://www.semanticscholar.org/paper/Male-Fertility-Is-Linked-to-the-Selenoprotein-Foresta-Floh%C3%A9/4c1547d6b7d5dc018d0bda65b85cebc498ea34f2