You're Shopping
Nature's Select Carolinas
Change Location
toggle menu
You're Shopping
Nature's Select Carolinas
Change Location


Selenium Yeast vs. Sodium Selenite in Dog Food – What’s the big deal?

According to AAFCO (Association of American Feed Control Officials), for a dog food to tout itself as “complete and balanced”, it must meet all of the criteria established by the AAFCO Canine Nutrition Expert Subcomittee.

One of the ingredients deemed necessary in the list of proteins, fats, and nutrients, is selenium.

According to an article on the website for Doctors Foster & Smith,

“Selenium is an antioxidant which functions in conjunction with Vitamin E and certain enzymes to protect cells. Selenium deficiencies are extremely rare in dogs and basically unknown in cats. They are much more common in cattle and sheep who graze plants which grow in soil that is deficient in selenium. If a selenium deficiency would occur, we would see poor reproduction, puppy death, muscle weakness, and abnormalities of the heart muscle.“

Selenium on the periodic table

Sodium selenite is the controversial version of selenium used by many pet food companies, even some rated as 4 and 5 stars on According to the article by Doctors Foster and Smith, selenium acts as an anti-oxidant.So, what’s the big difference between selenium yeast (which is what we use here at Nature’s Select) and the sodium selenite used by many pet food companies?

According to the Federal Occupational Health Department (a division of U.S. Department of Health and Human Services),

“Antioxidants are substances that may protect cells from the damage caused by unstable molecules known as free radicals. Free radical damage may lead to cancer.”

So, antioxidants are good, yes? According to Doctors Foster and Smith, selenium (in it’s natural state) is an antioxidant.

However, when used in the form of sodium selenite, this mineral begins to work like a pro-oxidant, aiding in DNA oxidation and damage. (US National Library of Medicine) In fact, this mineral (which is safe and effective in trace amounts but toxic in large doses) becomes more toxic in it’s chemical form than in it’s natural, organic state. (

Whereas it’s counterpart, natural organic selenium yeast (used by Nature’s Select Pet Foods) is less toxic, serves as an antioxidant, and may help repair/restore brain functionality of pets affected with Dementia or Alzheimer’s disease.

In summary, with so many questions surrounding the use of sodium selenite in dog foods, we decided to go with the safer, more beneficial, alternative.

To see our pet foods and learn more, get a custom pet food recommendation for your pet.


UPDATE: After completing a pet food competitor brand comparison to Nature’s Select for a potential customer, I thought it wise to copy/paste some of the information from the email.


“Sodium Selenite has been linked to cell oxidation, a pro-oxidant, in one study using rats, where the rats showed decreased mortality and increased tumors after being subjected to sodium selenite. (See below for a paragraph from the study, along with the link to the study.)

Organic selenium yeast, used by Nature’s Select, is an antioxidant, helping reduce risk of cancer and tumors, and shows other benefits as well, including studies increasing mental alertness in those experiencing dementia and Alzheimers by lowering MAO-B enzyme activity in the brain. (See link here, page 184)

Unfortunately, the majority of pet foods, even brands touting themselves to be “natural” use sodium selenite in their food as it is more cost-beneficial.”

“Schroeder and Mitchener (1971) studied the toxicity and carcinogenicity of sodium selenate and sodium selenite in weanling male and female Long-Evans rats. Groups of 50 male and 50 female rats were administered 0 or 2 ppm selenium as sodium selenate or selenite in the drinking water. After 1 year, the selenium level in the drinking water of 14 SODIUM SELENATE & SELENITE, NTP TOXICITY REPORT NUMBER 38 the sodium selenate group was increased to 3 ppm. During the first year, mortality reached 50% after 58 days of treatment for male rats and after 348 days for female rats receiving sodium selenite. In rats receiving sodium selenate, 50% mortality was reached in males after 962 days and in females after 1,014 days. Sodium selenite was more toxic than sodium selenate, as the latter did not adversely affect the life span of the animals. The overall tumor incidence was significantly increased in male and female rats receiving sodium selenate (0 ppm, 20/65; 2 to 3 ppm, 30/48). The authors did not tabulate the incidence of tumors by sex.”