One of your most frequently asked questions on my Instagram is on the supplements that complement my cats’ diets. As I explained in the article about the Prey Model raw diet, an 80/10/10 ratio may be deficient in nutrients. That’s why I add some additional whole food or supplements in order to fill this nutritional gap and to better follow the NRC guidelines. This prey model diet with additional supplements is sometimes referred to as a PMR+ diet (Prey Model Raw plus).

This article has not been made to tell you which supplements you should give to your cat. I wrote it to encourage you to check whether the diet you are feeding is lacking in some nutrients and to make your research on which whole food could fill the possible nutritional gaps. Moreover, don’t fall in the pit of giving to your cat every supplement you heard about: it is important to give supplements for a precise reason and in appropriate quantities.

Fish

I personally don’t consider fish as a supplement, as it’s often considered as an essential component of a raw diet, at the same level as meat, organs, and bones.
Small oily fish are generally added to a raw diet because they provide omega 3 and vitamin D. However, some precautions need to be taken, such as freezing it for at least one week before feeding it raw to your cat. Keep in mind that some fish contain thiaminase, an enzyme that destroys thiamine, the vitamin B1. This might be harmful to your cat if you feed your cat with large quantities of fish, as they may get a vitamin B1 deficiency. If you want to know more about this, you can check out my article about fish in a raw diet.

Nutritional yeast

I regularly sprinkle some nutritional yeast on top of my cats’ food. Nutritional yeast is rich in B vitamins, particularly vitamin B1 and B9. Nutritional yeast can also be used as an appetent, as many cats love its taste. The B vitamins are water-soluble and, therefore, there’s no risk of overdose, as the excess will be eliminated in the urines. However, too much nutritional yeast can cause diarrhea in some cats.

Vitamine E

Vitamin E is an antioxidant that is often lacking in a raw diet, especially if you feed oily fish. In fact, when you increase the quantity of omega 3 in the diet, you also increase the need for vitamin E. There is no known toxic level of vitamin E. You can find more information on how to supplement it in my article about vitamin E.

Kelp

I add some kelp to my cats’ diets to provide iodine but also for the beneficial effect on their teeth tartar. In fact, Ascophyllum Nodosum, a type of kelp, can help to reduce the quantity of tartar on their teeth.
If you feed kelp, be sure to buy a brand that indicates the quantity of iodine. Feeding too much kelp can cause thyroid issues as it’s extremely rich in iodine. You can learn more in my article dedicated to iodine and kelp.

Psyllium husk

I often add some psyllium husk rehydrated in water, as a source of fibers in the diet. I use it when I don’t feed whole prey, as the feathers or fur of a whole prey are already rich in fibers. Fibers help your cat to have healthy guts. You can find more information about fibers in this article.

Mussel

I feed blue-lipped mussels to provide manganese to the cats. Mussels also contain zinc, iodine, omega 3 and they are rich in taurine.
I feed them cooked, as raw mussels are more expensive and difficult to open. I buy them frozen and already steamed, without any added ingredient.

Eggs

Eggs provide good quality proteins and fats, but also vitamins such as vitamins A, D, choline, biotin. I usually give one or two quail eggs a week to each cat. I prefer giving quail egg as they are better sized for a cat than a chicken egg. Eggs are quite nutritious and if you give an entire chicken egg for the first time to your cat it may have diarrhea.
When giving eggs you shouldn’t give the white alone: give either entire eggs or yolks only, as the whites contain avidin, an inhibitor of biotin (vitamin B8). Feeding raw egg white on a long period could cause a deficiency in vitamin B8.

There are many other supplements that you can add to your cat diet such as fish oil, oyster, kefir, bone broth, green-lipped mussel, taurine... Though the most important thing to remember is to always add a supplement for a reason: don’t add it just because you have seen another person doing it. Add a supplement to fill a nutrient gap that you identified in the diet of your cat. Moreover, before feeding your cat anything new, do some research about it to be sure it’s not dangerous.
Finally, always be careful about the quantities: some supplements such as kelp can be harmful if given in large quantities. That’s also why you shouldn’t give the same quantity of supplements that other people give to their cats, as their pets may have different needs from yours.

You can find the content of this article in video (with English subtitles):

Which supplements do I add to my cats diets?