Is Selenium Helpful or Harmful in MS?

This Antioxidant Has an Ambiguous Role in MS

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Selenium is an essential mineral that is found in trace amounts in the body. It's an antioxidant, and some experts think that oxidative stress caused by free radicals plays a role in MS.


What is Selenium and How Does It Work?

What Is an Antioxidant?

When the cells in our bodies use oxygen, they naturally produce free radicals. Free radicals are unstable molecules that can cause damage to cells in our bodies as they seek to “steal” electrons from other molecules because they are missing one of their own. Antioxidants are substances that can prevent or slow the oxidative damage to our body. They “donate” one of their electrons to make the free radical stable and less harmful to our bodies.

What Is the Link Between Selenium and MS?

In one Finnish study, the selenium levels in the blood of people with MS were lower than in that of people without MS. In another study, low selenium levels were found in the red blood cells of people with MS. However, other studies have found normal, or even higher, levels of selenium in the blood of people with MS, so there is no clear consensus about the link between the two. 

Is There a Concern With Taking Selenium?

If there is a link and those with MS actually do have lower selenium levels, would supplementing selenium hurt?

While it's true that selenium plays an important role in immune system processes and inflammation, there is a worry that since selenium is an antioxidant, it may stimulate the immune system. In other words, selenium has a dual role, both an immunostimulating effect and an anti-inflammatory effect within the body (sort of a conundrum).

MS is an autoimmune disease, meaning that parts of the immune system are already too active. Therefore, it is theoretically possible that increasing immune activity by using antioxidants may stimulate MS disease activity. While this has not been seen directly, it is something to remember when considering antioxidant therapy.

In one study of animals with an MS-like condition, selenium supplementation actually worsened their disease and increased their rate of death. In addition, a small (18 people), short (5 weeks) study examined the effects of selenium supplementation on people with MS. It improved the levels of selenium in the red blood cells but failed to show any clinical benefit. 

In the end, it may be just the right amount (moderation, so to speak) of selenium that does the trick. The National MS Society suggests obtaining selenium from food sources until more research is known.

Sources of Selenium

The good news is that most people in the United States consume enough selenium, as it's found in a number of food sources. The Recommended Dietary Allowance is 55 mcg for adults.

Dietary sources of selenium include:

  • Seafood (tuna, halibut, shrimp, sardines)
  • Meat products
  • Legumes
  • Eggs and dairy products
  • Some nuts (cashews, Brazil nuts) 
  • Cereals and whole grains

Interestingly, sugary foods like baked goods and sweetened beverages can actually leach minerals like selenium from the body, so avoiding foods in addition to eating the right foods is key to optimizing your MS and overall health.

High doses of selenium (more than 400 micrograms) can be toxic, causing a variety of symptoms including nausea, diarrhea, rash, irritability, nervous system problems, hair and nail loss, and tooth decay. Doses that are even higher can cause significant neurological, stomach, and intestinal problems, as well as heart and kidney failure.

So if you're eating a healthy, balanced diet, supplementing is likely not necessary or beneficial based on the available research.

A Word From Verywell

The safety and benefit of supplements and diets rich in selenium in multiple sclerosis are simply not known, and there is some concern that it may increase a person's immune system activity. While it's a good idea to consider the importance of nutrition in your MS and overall health, please do not take any minerals, vitamins, or supplements without the guidance of your doctor.

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