With all the nutritional products marketed to cats and dogs, including vitamins, you must wonder if a cat really needs any of this. Lots of people wonder if cats need vitamin C, for instance, since it is so important for humans. Even a basic knowledge of nutrition will tell you that there is no vitamin C in meat!
While cats occasionally eat grass or plants, they do not do this because their bodies need vitamin C. Both cats and dogs are able to synthesize their own vitamin C in their liver. We humans lost this ability long ago, requiring us to obtain vitamin C from plant sources. So, no, a cat does not need vitamin C. It may be, however, that at certain times vitamin C could be conditionally essential for a cat, such as during times of extreme stress or illness. Your vet can determine if and when additional vitamin C is required for your cat.
Liver disease is an example of when cats and dogs may need additional vitamin C, since the levels of vitamin C in the body may decrease due to the liver’s inability to function properly. Other vitamin needs may increase, as well. However, it is important not to take it upon yourself to prescribe vitamin C supplements to your cat, even if he or she is diagnosed with liver disease, as this could actually worsen your cats condition. Only give your cat vitamin C according to your vet’s instructions and under their supervision.
Cats, Ships, and Vitamin C
Your cat’s ancestors arrived here by boat. If there is one thing that, historically, was in short supply during long ocean voyages, it was sources of vitamin C for humans. For many centuries, sailors would suffer from a disease called scurvy. At first, nobody knew what was causing it, but by the mid-eighteenth century, it was discovered that eating citrus fruits could prevent, and reverse, scurvy. It was eventually discovered that the particular nutritional component at work was ascorbic acid or vitamin C. Great news, but this did not mean it was easy to keep oranges during long voyages.
Cats may have been great to have on ships to control rats, natural sailors that they are. But if cats had competed with humans for precious sources of vitamin C, their time on ships probably would have been limited. But, not could they make do on animal protein, they didn’t even need much water.
Cats Do Need Other Nutrients from Their Diet
Although cats have a distinct advantage over humans when it comes to vitamin C, there is always give and take in any evolutionary path. While cats can make vitamin C, for example, they cannot, like humans, make vitamin A.
We can obtain vitamin A from our food, sure, but when needed, we can make our own vitamin A from precursor nutrients like beta-carotene. Cats cannot. They must obtain vitamin A from their diet.
We make vitamin D in our skin, so long as we get enough sunlight. A cat’s skin is not as efficient at making vitamin D, so they need more of it in their diet.
They also need a fatty acid called arachidonic acid, which comes from animal fats, and plays essential roles in the body, and is required for normal reproduction. They also need other EFA’s or “essential fatty acids.”
Cats, like dogs, must also obtain the amino acid arginine from their diet. They also must obtain another amino acid, taurine, from their food. Dogs can meet some of their taurine needs through synthesis in the body, from sulfur-containing amino acids, and we humans can usually make all we need without any dietary sources.