Essential Amino Acids


Taurine is probably the single most important essential amino acid (I mean, they are all important, but this one is cat specific). Unlike dogs or other animals, cats cannot create taurine from other amino acids. They need taurine in the diet. Taurine is found in meat meals, not plant sources. In fact, there is no significant vegetable source for taurine. This is another reason they are obligate carnivores. A cat that eats a mouse consumes about ten times the amount of taurine then any of the pet food brands out there. Taurine is essential for eye health, skin health, and a healthy heart.

At one point, pet food companies didn’t put any taurine in their prepared foods. This caused thousands of cats to die due to heart failure related to taurine deficiency. This is because pet food companies would add the taurine before the cooking process. During the cooking process, the taurine’s bioavailability is destroyed, meaning that cats do not get any of the taurine. Taurine is lost during the meat grinding process as well.

Taurine deficiency, aside from the heart failure, can cause other significant problems. This includes eye degeneration (leading to blindness), reproductive failure, and abnormal growth in kittens.


Mammals use arginine as a source for eliminating ammonia from the body. Ammonia is a toxic waste resulting from the breakdown of protein. Ornithine is actually the amino acid that binds to the ammonia and makes it non-toxic. Other animals can create this ornithine through a variety of ways, but cats can only produce it through arginine. Meaning, if there is no arginine, there is no ornithine. This can cause the ammonia to build up and become toxic and poison the cat on its own wastes. Excessive drooling, stumbling, seizures, and possibly death can result from the high ammonia levels. This usually occurs several hours after the cat has a meal.

The cat’s natural source of arginine is meat. Peas are a good source of arginine as far as vegetable sources go.

In terms of essential amino acids and cats, taurine and arginine are the big two.


Lysine is similar in structure to arginine. Lysine is known to fight the herpes virus in cats. This is because while lysine is similar to arginine, it is different enough where the herpes virus attaches more readily to lysine, than with arginine.
This virus is responsible for diseases of the respiratory tract. This is known to be very common in cats. Signs include eye discharge, sneezing, squinting, fever, mouth or throat sores and sinus congestion. The lysine helps by limiting the virus’ capabilities as well as limits the signs and symptoms in infected cats.

Lysine is also involved in the production of collagen and particular chemicals. These chemicals help the cat produce a healthy looking coat and skin.


Histidine is important in absorbing zinc and transporting it to tissues. Without a proper level of histidine, the radiation from the metal can cause serious damage to the body. Histidine is also important in the creation and maintenance of myelin sheath. This is basically fat that covers and insulates the nerves. It protects the nerves as well as allows impulses to be sent at a rapid rate (basically as soon as you touch something, you feel it). Without this myelin, the impulse will travel at a much slower rate (you won’t feel the touch right away)

Histidine is needed to create histamine. Histamine is well known in its role in allergic reactions. Histamine is released when the body is allergic to something, and it creates the sneezing, etc to protect the body and ward off any potential hazards.

Histamine is also important in the digestion of foods. Histamine helps produce the gastric juices in the stomach that assists in the breakdown of foods. It is also needed for the creation of red and white blood cells.


Leucine increases protein synthesis in skeletal muscle. As a regular part of the diet, leucine slows the breakdown of muscle tissue by increasing the protein synthesis. This helps protect the muscle and act as fuel for the body. Leucine also promotes the healing of muscle tissue, skin tissue, and bones. A decrease in leucine can be characterized as weight loss/less muscle mass.


Along with leucine and valine, isoleucine is found mostly in skeletal muscle. This is why it is required for optimum growth. Because it is found in the skeletal muscles, it helps promote growth and helps repair the tissues. It also plays a role in protein synthesis.

Isoleucine can be metabolized during exercise or fasting to form glucose. This helps regulate the blood sugar levels. This is where isoleucine is mostly used in animals.


As previously mentioned valine, leucine, and isoleucine are extremely similar in both structure and purpose. It is found mostly in the skeletal muscle. It helps promote growth of the muscle and prevent breakdown from occurring.

Valine also helps remove excess nitrogen from the liver, and is able to transport this nitrogen to other parts of the body as needed.


Methionine plays a role in the prevention of urinary crystals. The metabolism of this particular amino acid creates a product called sulfate. This sulfate is then excreted by the urine as sulfuric acid. Well, as it turns out sulfuric acid is exactly what is sounds like: an acid. This makes the urine a slightly more acidic environment. Crystals thrive in an alkaline environment. Therefore, this discourages crystal formation.

Methionine also helps the liver process fats and protects the liver and the kidneys. It regulates the formation of ammonia. Ammonia is a toxic waste in cats. It also helps create ammonia free urine.


Threonine is essential in maintaining a healthy heart, liver, and immune system.

Threonine is needed to create glycine and serine. These two amino acids are important in the production of collagen and elastin. This keeps muscle tissue throughout the body strong and helps maintain elasticity. This includes the heart, where strength and elasticity is vital.

Threonine teams up with methionine to help the liver process fats and fatty acids. Without threonine, the fats could build up in the liver. This can cause liver failure.


Tryptophan plays an important role in serotonin creation. Tryptophan is the only essential amino acid that can be converted into serotonin. Serotonin is then turned into melatonin in the brain. Melatonin is a natural way to help prevent anxiety or stress. It has a calming effect on the body. In fact, in cats with severe stress or aggression, melatonin supplements are prescribed by the vet to help relieve the symptoms.

Serotonin is also used by a variety of systems including the digestive system, the reproductive system, and the cardiovascular system. Serotonin causes the gut to contract and move the food. Serotonin has a role in the growth of a cat, finding a mate to reproduce with, and regulate memory and learning.


Phenylalanine is converted in tyrosine. Tyrosine in turn gets converted into dopamine and norepinephrine. Through the conversions, phenylalanine can aid in the memory and learning of a cat. This allows the cat to remain sharp and alert. This is because dopamine, norepinephrine and epinephrine are responsible for creating either a calm relaxed state, or an uptight, alert state.

One of the big signs of a black cat not getting enough tyrosine is that its fur will start to turn a reddish-brown color. This can be reversed by feeding it phenylalanine or, in other words, meat or foods rich in protein.

There is a common theme among these amino acids: MEAT source

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