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Fly Me to the Moon: Selenium and Health

By Karen L. Kier
Pharmacist on behalf of the ONU Healthwise Team 

Kaye Ballard sang the 1954 song In Other Words, which was the original version for Frank Sinatra’s 1964 Fly Me to the Moon. Bart Howard–who wrote the song–estimated by the time Sinatra released his, at least 100 versions had been recorded. 

Speaking of the moon!  The chemical element selenium was named for the Greek Goddess of the moon known as Selene.  Selenium is a critical micronutrient for health, but it has some side effects when taken in large quantities.  


The Recommended Daily Allowance for selenium is 55 micrograms per day for ages 14 and older. Although selenium deficiency is rare in the United States, a lack of it can cause Keshan disease (heart), male infertility, and Kashin-Beck disease (a form of arthritis). A deficiency of selenium can result in hair loss and can be seen in bariatric surgery patients. Ironically, too much selenium will also result in hair loss.  

Selenium is found in many foods and most individuals get an adequate supply with their diet.  Interestingly, the amount of selenium in plant foods is based on the amount in the soil where the plants are grown.  The amount of selenium in meat is based on what the animal eats. Foods containing selenium include seafood, meat, poultry, eggs, dairy, breads, cereals, and other grains. 

Most multivitamins contain selenium with 55 micrograms in one tablet. When reading packaging for selenium content, look for other forms such as selenomethionine and sodium selenate. Some products may contain more and it is important to look at the labels.  For best results, stay with a 55 microgram product. Why?

Selenium has an important role in keeping us healthy. Studies have documented an increased risk of certain cancers with a lack of selenium in the diet.  These cancers include colon, prostate, lung, bladder, skin, esophagus, and stomach.  

Unfortunately, the data does not support a reduction of cancers with selenium supplementation.  Studies from the 1980s and 1990s suggested a protective effect of selenium and vitamin E for prostate cancer.  In 2001, a large clinical trial titled the Selenium and Vitamin E Cancer Prevention Trial (SELECT) was started to confirm these results.  The researchers stopped the study early due to negative findings of increased prostate cancer with selenium or vitamin E. The risk was the greatest with those men who supplemented their diet with selenium in vitamins and over the counter products.  

Other diseases evaluated for benefit with selenium supplementation included heart disease, cognitive decline, and thyroid disease. The heart studies are conflicting with a need for additional research to determine a benefit.  Cognitive decline was investigated because our selenium levels decrease with age and researchers were looking for a relationship between the two.  Studies in older adults have not demonstrated a benefit in memory with selenium supplements.  

Selenium is important for proper thyroid gland function. Studies do suggest there is a higher risk of developing thyroid problems in women with low selenium and iodine levels in their blood. What is not clear from the research is if selenium supplements have any benefit in preventing thyroid issues.  

With little evidence of selenium supplement beyond our dietary intake for improving health, what other potential harms can come from excess supplementation besides prostate cancer and hair loss?  Skin rashes, loss of nails, brittle hair or nails, discolored teeth, irritability, and a metallic taste in the mouth can all be cause by too much selenium.

Talk to your pharmacist about selenium products before the Greek Goddess of the Moon creates problems!

Contact ONU HealthWise Pharmacy (419-772-3784) for more information. ONU Healthwise is offering the flu and COVID-19 vaccines. Vaccine clinics occur Monday through Friday from 4:00-6:00 p.m.