Selenium and Antioxidants: A Powerful Pairing

Oct 15, 2020
Erin Howe

Dried lentilsPhoto by Vegan Photo , Flickr Peanut butter and jam. Apples and cinnamon. Pancakes and maple syrup. Some things are just better together.  

Turns out, antioxidants and selenium have a similarly complementary relationship. 

Selenium is a nutrient that’s naturally present in the soil and some foods.  

A systematic review and meta-analysis of earlier research reveals that people who took antioxidant supplements containing the mineral selenium had a lower risk of death from cardiovascular disease (CVD) and all-cause mortality.  

The work was led by David Jenkins and John Sievenpiper, who are both professors of nutritional sciences in the Temerty Faculty of Medicine.  

The paper was published in the American Journal of Clinical Nutrition and examined 43 randomized control trials. 

There is longstanding interest among scientists in the role of antioxidants, like beta carotene and vitamins C and E in reducing the risk of many age-related diseases like CVD, diabetes and cancer.  

But the trials to this point have been mixed.    

In each of the trials the team looked at, participants took oral antioxidant supplements or a placebo for at least 24 weeks. 

Each of the supplements consisted of a combination of two or more antioxidants including retinol, beta carotene, selenium, zinc, copper and vitamins A, C and E. 

Dr. David Jenkins. Photo by Mark BennettDr. David Jenkins. Photo by Mark Bennett “For supplementation, we found that it depends on what’s in the mixture. Without including selenium, antioxidants didn’t have much benefit. On their own, antioxidants may even do more harm than good,” says Jenkins, who is also part of the Department of Medicine and a clinician-scientist at St. Michael’s Hospital. “And selenium by itself does nothing.” 

Though some antioxidant supplements and multivitamins already contain the nutrient, it’s important for people to read the labels.  

Health Canada says people should consume no more than 400 micrograms of selenium per day from food, water and supplements combined. 

The organization regulates selenium levels in food, drugs and natural health products as well as in pesticides, cosmetics and paint. 

Taking too much of the mineral can cause problems like stomach disorders, hair loss, or nail deformation.  

Though it is rare in North America — where the soil is rich in selenium — being deficient in this essential nutrient can leave people vulnerable to other conditions like Keshan’s disease, a form of cardiomyopathy. 

Though the study focused on supplementation, Jenkins says until the long-term effect of selenium on antioxidant supplement use is better understood, eating a balanced diet of antioxidant-rich foods is a good approach.  

“If you eat a variety of plant-based foods, like nuts, seeds, and dried legumes such as peas, lentils or beans, you should get what you need. That’s why we keep seeing these kinds of recommendations coming out,” says Jenkins, pointing to the updated Canada’s Food Guide, which promotes eating more fruits, vegetables, whole-grain cereals and plant-based protein.  

Jenkins says supplementation may be important in some groups, like marginalized or elderly populations which may lack variety in their diets.  

The team plans to further their research by creating a mix of vitamins and nutrients to explore the potential benefits for people with COVID-19. Jenkins says they hope to identify a blend that can help shorten the duration of illness, prevent adverse effects and hospitalization.  

“There is evidence that antioxidants vitamin C and zinc help shorten the duration of a common cold, which is a type of coronavirus”, says Jenkins. “That’s why we’re enthusiastic about pushing into this area.” 

Professors Jenkins and Sievenpiper have received support from government, non-profit and industry funding sources and been on the speakers’ panel, scientific advisory board and/or received travel support and/or honoraria from companies and industry groups that produce or promote nutritional supplements. Please see the Acknowledgements section at the end of the study for a full list of funding sources and industry connections.  


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