In Search of the Best Cat Food, Part I: Feline Nutrition

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Today I am trying something new on this blog. Almost anyone with a pet has asked the question, “What is the best food to give them?” Even after asking the advice of my veterinarian what to feed my cat, I still felt pretty lost and confused. I am undertaking a series of articles in which I aim to gather as much information as I can about feline nutrition and what difference the many kinds of cat food really make on a cat’s well-being.

The series will have five parts: feline nutrition, wet vs. dry food, diets for different life stages, specialty diets, and indoor diets. I will be interspersing other articles during this series so that it doesn’t get boring. Feel free to comment with your own questions about cat food, and I will look into them.

Of Carnivores and Calories

To begin with, I thought it would be helpful to go over the basic facts of feline nutrition. The fundamental elements of an animal’s diet, humans included, are very simply broken down into protein, fat, carbohydrates, vitamins, and minerals. Cats of all kinds are obligate carnivores. That means that they have evolved to eat only meat, and they are not well-equipped to derive nutrition from plant sources. This has a major impact on their nutritional needs.

The amount of calories a cat needs per day depends upon their age, activity level, health, and whether or not they have been sterilized. Growing kittens and pregnant or nursing queens need significantly more energy. Intact adults need a bit more than neutered adults. An eight-pound adult cat needs about 240 kcal (kilocalories, or what we usually just call calories) each day [1]. The Animal Medical Center of Chicago has a very helpful chart for getting a good idea of how many calories your cat or kitten is likely to need, which you can download a copy of below [2]. Because cats have evolved to eat only meat, their bodies are designed to obtain these calories primarily, if not exclusively, from proteins and fats.

Macronutrients in Feline Nutrition

Carbohydrates and Proteins

Obligate carnivores require a high protein, moderate fat, low carbohydrate diet to be their healthiest. Carbohydrates, which are plentiful in plant matter, can be difficult for cats to digest and are not necessary in the feline diet [3]. Instead of deriving most of their energy from carbohydrates, as humans do, cats use protein as their primary source of energy [4, 5]. A nine-pound cat with a 250 kcal-per-day diet is recommended to receive 12.5 grams of protein each day [3]. It isn’t just the amount of protein that matters, however. Proteins are made of molecules called amino acids. There are 23 amino acids. Cats can manufacture some of these themselves, but there are 11 that they must get from their diet [6, 7]. These are known as essential amino acids. The essential amino acids for cats are:

• Arginine
• Histidine
• Isoleucine
• Leucine
• Lysine
• Methionine
• Phenylalanine
• Taurine
• Threonine
• Tryptophan
• Valine

Taurine is an unusual requirement particular to cats, but it is very important. A taurine deficiency can lead to blindness, deafness, heart problems, and loss of kittens or congenital defects with pregnant queens [3, 7]. Taurine is only present in animal protein, a callback to the nature of cats as obligate carnivores [7].

Fats

Cats also have rather specific needs when it comes to the fats in their diets. We have a tendency to think of fat as a dirty word, but fats serve very important functions in the body, in appropriate quantities. Fats are an important source of energy, they provide insulation to nerve fibers and protection to internal organs, they aid in absorption of the fat soluble vitamins, and they are critical for cell structure and function [3, 6, 7]. Cats can tolerate fairly high amounts of dietary fat since it is such an important energy source for them [3]. The average cat we used as an example before has a recommended daily allowance of 5.5 grams of fat [3].

Fats are composed of fatty acids, and like amino acids, some of these can be made in the body, and some cannot. Science is still learning which fatty acids are essential for cats, but some things are well-known. Cats are unable to manufacture arachidonic acid, an important precursor molecule with end products that have wide range of functions in the body [6]. Arachidonic acid is found only in animal fat [7]. Linoleic acid is an essential fatty acid for all animals [7]. DHA is a fatty acid that has been shown to be important for the neural development of kittens, so it may be necessary for reproducing queens and young, weaned kittens [6, 7].

Micronutrients in Feline Nutrition

Now, let’s talk micronutrients. Vitamins are organic nutrients, manufactured by a lifeform somewhere in the food chain. Minerals are inorganic nutrients that come from the environment. Cats need Vitamins A, D, E, K, and the B complex [3, 6, 7]. They have no need for dietary Vitamin C, as they are able to make that for themselves [6, 7]. Minerals are a bit trickier, since some of them are needed in very small amounts but are still absolutely critical. The US National Research Council considers twelve minerals essential for cats [3], but I included a thirteenth from another source as well [6].

Vitamins

Vitamin A is a big one for cats. Some animals can make Vitamin A from precursors in plants, like beta-carotene, but cats can’t do that [7, 8]. They have to consume Vitamin A in its completed form from animal sources [7, 8]. Vitamin A is important for vision–especially night vision, healthy skin and mucous membranes, and normal bone and tooth growth [6, 7]. Fish oil, liver, eggs, and dairy are natural sources of Vitamin A [6, 7].

Vitamin D is needed for the body to use calcium and phosphorous [6, 7]. Cats can synthesize it in their skin in the presence of UV light, but not very well, so dietary Vitamin D is important [6]. It can be found in marine fish and fish oils, liver, and egg yolks [6, 7]. Vitamin E is an antioxidant synthesized by plants but present in small amounts in animal sources [6]. The amount a cat needs depends upon how much oxidative stress their body is under [6, 7]. Vitamin K is important for blood clotting, but healthy cats are able to synthesize enough of it on their own [6, 7]. If the intestinal bacteria that normally make Vitamin K are decreased, perhaps if the pet is on antibiotics, dietary Vitamin K can become important [6]. In that case, fish meal, egg, and liver can be good sources [6].

There are eight B vitamins, which are necessary for energy metabolism and making healthy tissues [6]. Because they are soluble in water, it is uncommon for a cat to get too much of a B vitamin. The excess just washes out in the urine [7]. Cats usually get enough B vitamins from their food, but while most animals can synthesize niacin, or B3, cats can’t and must get it from their diet [6]. Fortunately, meat is a good source of niacin [6]. The other B vitamins can come from eggs, organ meats, or muscle meat, depending on the B vitamin in question [6].

Minerals

We have a bunch of minerals to get through, and I would feel like I wasn’t providing the most complete information if I left any out. But I don’t think anyone wants this article to go on for twenty pages, so I’m going to summarize the main reasons each mineral is important and where cats get the minerals from in their diet [3, 6, 7].

• Calcium for skeletal and muscular health: poultry/meat meals, bone
• Phosphorous for skeletal health and energy metabolism: meat, poultry, fish
• Magnesium for muscle, nerve, and hormone function: bone meal
• Sodium for homeostasis and nerve function: fish, poultry meal, eggs
• Potassium for nerve and enzyme function: fish, especially salmon [9]
• Chloride for homeostasis: fish, poultry meal, eggs
• Iron for red blood cells and energy metabolism: meat, organ meat
• Copper for tissue synthesis: organ meat
• Zinc for cell growth and wound healing: beef liver, dark poultry meat, egg yolks
• Manganese for bone growth and neurological health: meat, poultry, fish
• Selenium for antioxidant activity and immune health: meat, poultry
• Iodine for thyroid function: meat, poultry
• Sulfur for protein synthesis: meat, poultry, fish

Moving Forward

What do we do with this information? Out of curiosity, I grabbed one of Joon’s cat food cans to see how much of this information is actually available on the label. What I found was a section giving the crude protein, crude fat, crude fiber, moisture, “ash,” calcium, phosphorous, magnesium, and taurine content in either minimum or maximum percentages. Ash is a term sometimes used to refer to mineral content [6]. Below that, the kcal per can and per kilogram (of this food that comes in 170-gram cans) was given. That gives me the ability to calculate the gram values of the nutrients, although it’s frustrating that I have to. And then there’s the brief feeding instructions, with the ingredients on another panel.

It’s less information than I would have hoped for, and it’s presented much less plainly than on human food labels here in the US. So I tried one of the cans of prescription food we give my parents’ elderly cat. I thought maybe it was just the company I buy Joon’s food from. Nope, Rosie’s food had even less information on it. There were no percentages for minerals at all.

As we continue with this series, I’ll delve into different types of food and what it all means. What looking at the back of this can is telling me right now, however, is that as pet parents we need to be as informed as we can. Evidently, no one is going to hand the information we need about feline nutrition to us. At least, not anybody in the pet food aisle. If I look at the ingredients, I can see that this food has a lot of added nutrients and ingredients that provide them naturally, but a few hours ago I wouldn’t have known that including tuna and fish oil in a chicken-flavored food can provide nutrients that the chicken alone might not. The more we know, the better prepared we are to make the best decisions possible for our cats.

Works Cited

1. How many calories should your dog or cat eat daily? (2014, April 25). Dunloggin Veterinary Hospital. https://dunlogginvet.com/how-many-calories-should-your-dog-or-cat-eat-daily/
2. Calorie Requirements for Cats (n.d.). Animal Medical Center of Chicago. https://www.animalmedicalcenterofchicago.com/cat-diet-calorie-requirements-for-cats/
3. Feuer, D. (2006). Your Cat’s Nutritional Needs. National Research Council.
4. Optimum feline nutrition: what should you feed your cat? And feline weight loss and prevention plan. (n.d.). Cat Care Center of Baton Rouge. https://www.catcarecenter.com/services/cats/feline-nutrition-cat-food
5. Llera, R. and Ward, E. (2019). Nutrition: General feeding guidelines for cats. VCA Hospitals. https://vcahospitals.com/know-your-pet/nutrition-feeding-guidelines-for-cats
6. Case, L.P., et al (1995). Canine and feline nutrition. Mosby, Inc.
7. Ackerman, N. (Ed.). (2016) Aspinall’s complete textbook of veterinary nursing, 3rd edition. Elsevier.
8. Schultze, K.R. (2010, February 9). Your cat’s nutritional needs: The basics. Feline Nutrition Foundation. https://feline-nutrition.org/nutrition/your-cats-nutritional-needs-the-basics
9. Millen, B. et al (2015). Appendix 10: Food sources of potassium. Health.gov. https://health.gov/our-work/food-nutrition/2015-2020-dietary-guidelines/guidelines/appendix-10/

Published July 5, 2020

Updated June 20, 2022