By Marta Kasper
I am sure that you have all heard about the importance of taurine in a cat’s diet. Taurine is a naturally occurring amino acid mostly found in muscle meat and organs like heart, kidney and liver and in seafood. In muscles, taurine gets more concentrated the harder the muscle works. Dark meat has more than light meat because it comes from parts of the body that work harder, legs as opposed to breast. Heart is another great example. Although it is termed an organ, it is really the hardest working muscle in the body and it has one of the highest concentrations of taurine. Shellfish such as mussels and clams also have a lot of taurine. They are constantly filtering and they follow the same “hard-working” scenario, concentrating taurine to a high degree in their tissues. Small amounts of taurine are found in dairy products. Plant products contain either low or undetectable amounts taurine. Despite meat being a good source of taurine, there is a significant amount of variability within meat samples according to a published study.¹ Taurine content of meat was not only affected by diet, breed and environment, but also by the freshness of the meat.
Cats, unlike some other carnivores and unlike herbivores or omnivores, are not able to synthesize all the taurine they need from other amino acids like methionine and cysteine. In addition, many animal species can use glycine or taurine to conjugate bile acids into bile salts, but cats can only conjugate bile acids with taurine. This low rate of taurine synthesis combined with the loss of taurine in bile contributes to an increased dietary requirement of taurine for cats. With insufficient amounts of this essential amino acid in their diet, cats can develop central retinal degeneration, reproductive failure and impaired fetal development or heart cardiomyopathy. Clinical signs of taurine deficiency will not be apparent right away, it might take couple of months or years in some cases, but once a cat starts exhibiting clinical signs, usually significant damage has already been done.
One very important property of taurine is its high solubility in water. The final amount of taurine in the food will depend on the food preparation and storage techniques. To minimize the loss, one should always try to retain all of the liquids coming from the meat. For example, if the meat is cooked, it should be done in a small amount of water so that it can all be incorporated back into the food. Cooking meat at temperatures used for normal food preparation by itself does not change the amino acid in any way. It just leeches the taurine out from the meat into the water. I have been asked many times if taurine loses its potency during food storage in the freezer. The answer is yes and no. Freezing does not affect taurine potency, but, during the thawing process a lot of liquid is released. Since taurine is highly water soluble, that liquid will be taking a lot of the meat’s taurine with it. For example, if you buy raw ground meat/bone/organ packages, the liquid that comes out as it thaws – which is not blood despite its red color – is full of dissolved taurine. If this broth is discarded, the meat ends up with a lower taurine content than before freezing.
The Association of American Feed Control Officials, or AAFCO, recommends the minimum allowance of taurine for wet food to be 0.2% on a dry matter basis. The chance is that this amount might be covered by the natural taurine in meat alone, but due to a significant amount of variability of taurine concentrations in meat, high taurine solubility in water, danger of delay in exhibiting clinical signs of taurine deficiency and the fact that taurine supplementation is relatively safe with no reports of any issues associated with taurine overdose, it might be beneficial to always have a small amount of taurine excess in your cat’s diet. So what would be a reasonable amount to add? It is approximately 250 mg of taurine per 1lb of meat. I intentionally use “mg” because all taurine supplements are sold as “mg per capsule.” Since the smallest amount available is 500 mg per capsule, you can either add one of these capsules to two pounds of meat or 1/2 capsule per one pound of meat.
A lot of you might not like the fact that supplemental taurine is always synthetic. While I would also prefer a natural product over synthetic, in this case unfortunately, there is currently no other choice. It is important to keep in mind, however, that chemically there is no difference between synthetic or natural taurine because both structures are exactly the same. Taurine, unlike many other amino acids, does not polarize light so there is no left or right rotation which can differentiate natural or synthetic types. Some companies use this exact reasoning to justify their claim for a natural taurine, but I can assure you that it is only a marketing strategy. Taurine can be extracted from natural sources – there is a company in New Zealand that extracts it from ox bile – but this method is commercially unappealing and significantly more expensive. Nevertheless, I am hopeful that one day, a truly natural taurine will be available to consumers.
1. AR Spitze, DL Wong, QR Rogers and AJ Fascett, “Taurine Concentrations in Animal Feed Ingredients; Cooking Influences Taurine Content,” Journal of Animal Physiology and Animal Nutrition 87, 2003, 251-262.
Marta Kaspar is a Feline Nutrition Foundation Advisory Board member. You can find more of her articles at FelineNutritionFoundation.org.