“Synthetic vitamins may be identical with naturally occurring substances or closely related. The close relations, although useful in many ways, pose some problems in that they may have only a fraction, whether large or small, of the biological activity of the natural products. Synthetic vitamins may perform some of the functions of their natural counterparts while being useless for others. But what may be more important is the fact that synthetic vitamins, prepared from chemicals instead of nature, are frequently less active biologically than their natural counterparts, thereby reducing any beneficial effect they may have.”

- Isobel Jennings, Member of the Royal College of Veterinary Surgeons, Cambridge University

The value and effectiveness of nutrition can be debated on whether synthetic vitamins are just as effective as vitamins sourced from whole foods. This debate trickles down from the same argument humans have about their own nutrition and now we want to highlight the same points for our pet's nutrition.

What are synthetic vitamins?

Synthetic vitamins are essentially "replicas" of the nutrients we can find in whole food sources. But most synthetic vitamins are made in the lab by substances with acids, bases, or other reducing compounds. The use of synthetic vitamins has gained popularity due to the modernization of agriculture and the depletion of nutrient rich soil. Sadly, as the demand for food in today's modern world grows, so does the lack of nutrients that used to be present in our soil and food. The use of synthetic and concentrated vitamins was originally used to supplement inadequate and "lacking" diets but is now used to fortify almost every diet, especially animal diets.

Why are synthetic vitamins used in my pet's food?

Most pet food brands (especially dry food) follow AAFCO's nutritional requirements for cats and dogs. AAFCO stands for Association of American Feed Control Officials. In order to advertise "complete and balanced” labeling based on AAFCO's standards, pet food companies must meet certain levels of nutrients.

So a lot of pet food companies formulate their recipes by using just a handful of "real" food ingredients and then filling in the gaps of missing nutrients by adding in synthetic vitamins, minerals, and amino acids. This is the easiest and cheapest way that most companies use to create recipe so it can be considered "complete and balanced". The screenshot below shows a typical pet food label that uses synthetic supplementation.

So what's the problem?

The heavy reliance and use of synthetic vitamins in our pet's food is not the same as using whole food sources. There are issues regarding overdosing, lack of nutrients (bio-availability) and quality that can affect our pet's health when using synthetic vitamins.

Firstly, the overdosing of synthetic vitamins can be extremely dangerous for our pets. Especially fat soluble vitamins like vitamins A, D, E and K which cannot be expelled from the body as easily as water soluble vitamins which are excreted in the urine. 

This chart from Truth About Pet Food: from 2019-2022 showcases how the second highest cause of pet food recalls was caused by "Excess vitamins/minerals (mainly excess vitamin D)" accounting for nearly 12,277,322 pounds of pet food.

Even though fat soluble vitamins are a big concern, sometimes water soluble vitamins can also pose a risk. For example, an early study done at UC Berkeley by Alice Faye Morgan PhD (from the letters of Dr. Royal Lee) that demonstrated the use of administration of synthetic B vitamins to dogs actually caused a worse state of health than pure starvation. This study showcased how the use of synthetic vitamins may be more dangerous because there are a lot of factors that need to be involved and present in the dog's body in order to utilize a certain type of synthetic vitamin efficiently (and safely!). We will discuss how synthetic vitamins are metabolized in another post!

In simpler words, it is not as easy as most people may think when adding synthetic supplements to a diet. It is not a simple math equation. There are levels to synergy and metabolism that cannot be replicated in a lab.

What are the side effects of synthetic vitamin toxicity?

Early signs of vitamin toxicity can include not eating, lethargy and/or weakness. Other clinical signs include vomiting, diarrhea, drooling, increased thirst, increased urination, and weight loss. Vitamin toxicity can even lead to kidney failure and, in some cases, death.

Back in 2018, Hill's Nutrition had a recall that affected their prescription diets which contained toxic levels of synthetic Vitamin D. Many pet owners began submitting complaints and reports to the FDA after their pets became ill and died.

Even though some synthetic vitamins can be excreted from the body, some vitamins can affect pets differently and have deadly consequences like the 2018 Hill's recall. Synthetic vitamins in our pet's food should be looked at as seriously as prescription pharmaceuticals because the risk of side effects can be deadly.

So what should I do?

- Avoid pet food brands that say "EXCEEDS" nutritional requirements. Some companies like to think that they are doing our pets a favor by stating this, but it can be harmful in the long run especially if the dosage is on the high end.

- Look for clean, whole food ingredients only! Unfortunately, most of the pet food on the market uses synthetic vitamins in their recipes.

That's why Bibim Paws chose to only use high-quality, whole food ingredients in all of our recipes. Obtaining nutrients from organic, whole food sources is less risky because the body is equipped to work in harmony with every molecule that is present in a whole food ingredient. There are "co-factors" (think of them as assistants) present in whole food ingredients that know how and when to balance and eliminate themselves from the body if consumed in excess more efficiently than synthetic vitamins. They work in harmony with each other and have their own back-up and automated emergency plan in place so you don't have to worry about extreme side effects.

Sources (and a couple other articles below that are interesting reads regarding synthetic vitamins in dogs):

Science, "The Effect of Imbalance in the Filtrate Fraction of the Vitamin B Complex in Dogs," Agnes Fay Morgan, March 14, 1941, Pg. 261.

Truth About Pet Food, "2019 through 2022 Pet Food Sales And Recalls", Susan Thixton, February 23, 2023.

More reads:

Frost, D. V., & Dann, F. P. (1944). Unidentified Factor(s) in Yeast and Liver Essential to Cure of Achromotrichia in Dogs on Synthetic Diets. The Journal of Nutrition, 27(5), 355–362.

Krehl, W. A., Teply, L. J., & Elvehjem, C. A. (1945). Effect of Corn Grits on Nicotinic Acid Requirements of the Dog. Experimental Biology and Medicine, 58(4), 334–337.