Vegan Cats 101: nutrients, not ingredients is what really matters


The word vegan for many is associated with tomatoes, cucumbers and other veggies. When thinking of cats we think carnivores, hunters and sharp instincts. No wonder then that putting the two words - vegan and cats - in the same sentence has been the subject of many heated debates.

In this post we'll reconcile the two words in 3 ways:

  1. by comparing two formulas - a meat-based formula and a vegan formula
  2. by looking at several studies
  3. by looking at other considerations

    Comparison of two formulas

    The meat-based formula in our comparison is a typical cat food formula - Purina Friskies Savoury SelectionsThe vegan cat food formula is Evolution Diet Gourmet Fondue. To help with the comparison we'll group the ingredients in three categories:

    1. animal-based sources - provide proteins and fats
    2. plant-based sources - provide proteins, fats, carbs and fibre
    3. produced in a lab - vitamins and minerals and certain amino-acids

    As carnivores, cats require specific nutrients: protein, fat, fibre, fatty acids (such as arachidonic acid), vitamins (A, B2, B3, B12, E etc), amino acids (taurine, arginine etc) and many others. Regulators (for example, AAFCO in North America) do not say which ingredients to put in – all they say is the amounts of nutrients that have to be present for a cat to be healthy. Whether the nutrients come from meat or from plant-based sources is irrelevant from the regulatory perspective.

    Andrew Knight, a prominent veterinarian and scientist explains it well:

    Cats—and indeed all species—require specific nutrients, rather than specific ingredients. There is no reason why diets comprised entirely of plants, minerals, and synthetically-based ingredients (i.e., vegan diets) cannot meet the necessary palatability, bioavailability, and nutritional requirements of cats (1).

    The table below helps us understand where these nutrients come from in each formula.

    Meat-based formula

    [ingredients in Purina Friskies Savoury Selections cat food]

    Plant-based formula

    [ingredients in Evolution Diet Gourmet Fondue for cats]

    Animal sources (A)
    • Meat and Bone Meal (protein and fat)
    • Beef Tallow Preserved with Mixed-Tocopherols (Form of Vitamin E) (fat)
    • Turkey By-Product Meal (protein and fat)
    • Fish Meal (protein and fat)
    • Animal Liver Flavour
    Plant sources (P)
    • Ground Yellow Corn
    • Soybean Meal (protein)
    • Corn Gluten Meal (protein)
    • Whole Grain Oatmeal
    • High Protein Maize Gluten Meal
    • High Protein Soybean Meal
    • Pea Protein
    • Potato Flakes
    • Molasses
    • Yeast
    • Rosemary Extract
    • Yucca Schindigera Extract
    • Kelp Meal
    Made in lab (L)
    • Phosphoric Acid
    • Salt
    • Choline Chloride
    • Added Colour
    • Taurine
    • Potassium Chloride
    • DL-Methionine
    • Zinc Sulphate
    • Red 40
    • Ferrous Sulphate
    • Manganese Sulphate
    • Niacin
    • Vitamin E Supplement
    • Yellow 5
    • Blue 2
    • Vitamin A Supplement
    • Calcium Pantothenate
    • Copper Sulphate
    • Thiamine Mononitrate
    • Vitamin B-12 Supplement
    • Riboflavin Supplement
    • Pyridoxine Hydrochloride
    • Vitamin D-3 Supplement
    • Folic Acid
    • Calcium Iodate
    • Menadione Sodium Bisulfite Complex (Source of Vitamin K Activity)
    • Sodium Selenite
    • Biotin
    • V-4520-C
    • Dicalcium Phosphate
    • DL Methionine
    • Phosphoric Acid
    • Taurine
    • L-Lysine
    • Potassium Chloride
    • Choline Chloride
    • L-Carnitine
    • Micro-encapsulated Vitamin C
    • Iron Proteinate
    • Zinc Proteinate
    • Copper Proteinate
    • Magnese Proteinate
    • Cobalt Proteinate
    • Magnesium Proteinate
    • Furrous Sulfate
    • Zinc Sulfate
    • Zinc Oxide
    • Copper Sulfate
    • Manganous Oxide
    • Sodium Selnite
    • Mineral Oil
    • Calcium iodate
    • Cobalt Carbonate
    • Salt
    • Vitamin A Acetate
    • Vitamin D Supplement
    • Vitamin E Supplement
    • Niacin
    • D-Calcium Pantothenic
    • Thiamine Mononitrate
    • Riboflavin Supplement
    • Pyrrolidone Hydrochloride
    • Folic Acid
    • Source of Vitamin K Activity
    • Biotin
    • Vitamin B12 Supplement
    • Inositol
    • L-Trytophan

    The first glance at the table immediately tells us that vegan cat food is not simply a salad mix, it is an advanced formula composed of numerous ingredients. Furthermore, note that in both formulas the majority of ingredients are actually made in the lab (third section in the table). Notably, taurine, an amino-acid critically important for cat's eye-sight and cardiovascular function, is produced in the lab and added to both diets. The heavy supplementation in both diets is the result of compliance with AAFCO cat food standards. AAFCO prescribes that cats have to have certain amounts of vitamins and minerals and hence the heavy supplementation.

    Furthermore, both formulas obtain protein (wholly or partially) from plant-based sources. For example, soybean meal and corn gluten meal in Purina are rich sources of plant-based protein, and that contributes to the overall protein content in that meat-based formula. So using plant-based proteins is not a new practice - the meat-based kibbles have been using them for a long time. Of course Purina also contains meat-, bone-, fish- and turkey-meals, while Gourmet Fondue does not. The question then is if we are to source proteins from plant-based sources alone - will the cat be ok?

    To answer that question we'll need to look at protein structure. Proteins are composed of amino-acids

     

    AAFCO prescribes the "ideal" amino-acid profile for obligate carnivores. 

    Amino-acids Kittens and pregnant cats (%) Adult cats (%)
    Arginine 1.24 1.04
    Histidine 0.33 0.31
    Isoleucine 0.56 0.52
    Leucine 1.28 1.24
    Lysine 1.2 0.83
    Methionine 0.62 0.2
    Methionine-cystine 1.1 0.4
    Phenylalanine 0.52 0.42
    Phenylalanine-tyrosine 1.92 1.53
    Threonine 0.73 0.73
    Tryptophan 0.25 0.16
    Valine 0.64 0.62
    Taurine (extruded) 0.1 0.1
    Taurine (canned) 0.2 0.2 

    The only essential amino-acid for cats that is hard to find in plant-based sources is taurine. All other amino-acids can be found in plants in abundance. And so the only way to meet the taurine requirement for vegan cat food is to add synthetic taurine. Adding synthetic substances doesn't sound very natural, however, Purina and all other producers also add synthetic taurine in meat-based foods, because during the manufacturing process the natural taurine is baked off from animal ingredients due to high temperature and pressure. As a result, both formulas use synthetic (vegan) taurine. And with this addition the amino-acid profile of plant-based proteins becomes complete and 100% sufficient for cats. 

    By comparing the two formulas we have established that

    • properly balanced vegan cat food is not a salad mix, but rather an advanced formulation
    • the majority of the ingredients in both formulas are actually made in the lab (to meet AAFCO standards)
    • both meat- and plant-based kibbles utilize plant-based proteins, which are very much digestible and palatable
    • the amino-acid profile of plant-based proteins becomes complete with the addition of the synthetic taurine, which is used in both meat- and plant-based diets

    Overall, looking at the fundamental nutritional blocks - proteins, fats, minerals and vitamins - the two formulas are not that much different and meet the requirements of AAFCO.

    Studies

    The above comparison provides a good theoretical foundation, however, to make the definitive argument it would require the support of practical experimentation, which is why we wanted to see if studies have been done with cats and vegan cat food. A recent (2016) paper reviewed other studies for appropriatness of vegan diets for cats and dogs (1). The paper concluded that

    "Both cats and dogs may thrive on vegetarian diets, but these must be nutritionally complete and reasonably balanced."

    Study by Semp (2014) (2)

    Examination included assessments of general appearance, body condition, skin and coat, lymph nodes, vital signs; cardiovascular, respiratory and digestive systems; and defecation. Haematological (complete blood count) and biochemical (liver, kidney, and pancreatic) parameters were assessed, as well as levels of magnesium, calcium, iron, total protein, folic acid, vitamin B12, and carnitine. No abnormalities were detected that were associated with diet. Most examined cats appeared happy and bright. When considering blood test results, serum total protein of cats studied were within normal ranges. No significant deviations (with exception of folic acid) from normal values were observed.

    Study by Wakefield et al. (2006) (3)

    Thirty four cats were maintained on vegetarian diets and 52 on conventional diets, for at least one year. Most of the caregivers in both groups described their cats as healthy or generally healthy. Wakefield and colleagues also measured blood taurine and cobalamin (Vitamin B12) levels of 17 of these cats that had exclusively been fed either a commercial or homemade vegetarian diet. Cobalamin levels were within the normal range in all cases, and taurine levels were similarly normal in 82.4% (14/17) of cases. The remaining three cases were cats who were partly maintained on dinner table scraps. Because such scraps are not nutritionally complete, these should comprise a minority of diets.

    One word of caution from (1) was

    "Owners should also regularly monitor urinary acidity, and should correct urinary alkalinisation through appropriate dietary additives, if necessary."

    This is a great segue to our next section.

    Other considerations

    Urinary health

    plant-based diet contributes to making a cat's urine more alkaline. In itself it's not a problem, however, in male cats urine with more alkaline pH can lead to the formation of struvite crystals in the urinary tract (a mixture of magnesium, ammonium, and phosphate), which in turn can lead to urethra obstruction.

    To bring urine pH back to normal, cats (especially male cats) need to be supplemented with acidifiers, which dissolve the struvite crystals. Most popular vegan dry kibbles (Evolution Diet and Ami) and meat-based diets (see the table above) are supplied with ingredients like DL Methionine and other ingredients to help keep acidity in the 6.0 - 6.5 range. So again, in that regard the two formulas are not different as both rely on an additive - DL Methionine - for pH balance. See more information about urinary health in this article.

    Recalls

    One fact that definitely sets the two formulas apart is the risk that comes with meat-based diets. Regular meat-based cat and dog food is notorious for poisonings and recalls. This page shows that there were over 200 reported recalls since 2008. 73 out of 200 cases are the Salmonella contamination cases. Salmonella is a bacteria found in raw meats, eggs and poultry. In most meat-based formulas the quality of meat is very low (discover why the quality of meat is low here) and keeping the meat safe is a big challenge. Vegan formulas, on the other hand, have no meat-based ingredients, and therefore present a much lower risk of poisoning.

    Externalities

    The above comparison of two formulas and the study show nutritional adequacy (and in the case of recall safety - superiority) of vegan diets. Many cats have gone through the transition and they are doing really well. In addition, vegan diets are also better than the meat-based diets from the ethical and the environmental perspectives. 

    In the making of meat-based cat foods there are 2 often-ignored factors (which I call externalities) -

    1. an animal (a cow, a pig or a chicken etc.) had to be slaughtered in order to make cat food
    2. a large dose of greenhouse gases was emitted in the process of growing the animals, and the gases ended up in the atmosphere thus contributing to global warming

    With vegan diets no animals were killed and a small fraction of greenhouse gases was emitted. So if people were to consider the impact of these externalities for meat-based foods, then the vegan diet is the winner.

    Cost and Availability

    Currently the cost of vegan cat food is about twice the cost of regular meat-based cat food. This is counter-intuitive because generally meat-based ingredients are more expensive than plant-based ingredients. How can pet food be so cheap? This is almost entirely due to low quality of meat-based ingredients and due to the economies of scale. Availability of vegan cat food is currently limited. However, the cost of vegan food and availability will change as more people become aware of the alternatives with no externalities and lower risk of recalls. The more we can spread the word and raise awareness, the more cost effective and easily available plant-based cat food alternatives become. 

    Conclusion

    To conclude, commercial vegan formulas are carefully formulated to meet the nutritional requirements of cats and are not simply a salad mix. The apparent contradiction of the words cat and vegan is not a contradiction if you compare meat- and plant-based formulas side-by-side, consider safety and the externalities of modern cat foods:

    • From nutritional perspective
      • when properly balanced, vegan diet is healthy for cats and a recent study supports this
      • cat guardians, however, should be cautious to monitor the pH of cat's urine to avoid urinary health issue - this applies to both vegan and non-vegan diets
    • From the recalls and safety perspective
      • vegan diet is safer than meat-based diets
    • From ethical and environmental perspectives
      • vegan cat food is superior
    • From cost and availability perspectives
      • meat-based cat food is cheaper and readily available in stores

    Final Note

    Many cat guardians have done the transition to vegan cat food. There are online forums where people share their experiences. So if you still have questions - don't take our word for it - ask other people, who probably at one point had the exact same questions as you have now. 

    Facebook group - Vegan Cats

    References

    (1) Vegetarian versus Meat-Based Diets for Companion Animals Andrew Knight and Madelaine Leitsberger, Centre for Animal Welfare, University of Winchester, Winchester SO22 4NR, UK; Published: 21 September 2016

    (2) Semp, P.-G. Vegan Nutrition of Dogs and Cats. Master’s Thesis, Veterinary University of Vienna, Vienna, Austria, 2014. [Google Scholar]

    (3) Wakefield, L.A.; Shofer, F.S.; Michel, K.E. Evaluation of cats fed vegetarian diets and attitudes of their caregivers. J. Am. Vet. Med. Assoc. 2006, 229, 70–73. [Google Scholar] [CrossRef] [PubMed]