What Is Cysteine & What Foods Can I Find It In?

3D-model of Cysteine (src)

Cysteine is mostly a non-essential amino acid.

Non-essential means that the body can synthesize the acid itself.

But in some cases, cysteine can be essential for infants, the elderly, and some people with certain metabolic diseases, making it a conditionally essential amino acid.

For the body to be able to synthesize cysteine, it is crucial that there is a sufficient quantity of the amino acid methionine.

Cysteine has the same structure as the amino acid serine.

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Benefits Of Cysteine

Cysteine is a conditionally essential sulfur-containing amino acid. (source )

Cysteine is found in beta-keratin, an important component of skin, hair, and nails. (source )

You can find other benefits of cysteine in Cysteine: 5 Research-Backed Benefits .

Celiac Disease And Cysteine

Celiac disease is a condition that damages the small intestine when the gluten-sensitive person eats gluten. Gluten is found in wheat, barley, and rye.

The damage that occurs to the small intestine, due to the presence of gluten in the diet.

The damage can include inflammation, and a decreased ability to absorb iron and calcium.

Cysteine is needed for proper digestion of gluten and for the body to absorb the iron and calcium that gluten takes in.

Cysteine In The Body

Cysteine in the body is a conditionally essential amino acid, meaning that it can be made from other amino acids.

It is an important structural component of proteins, forming a peptide bond with other amino acids.

Cysteine is found mainly in our muscles, connective tissues and hair.

Cysteine is not a building block of proteins, but is instead used in the body for a variety of purposes.

The human body uses cysteine to produce the antioxidant glutathione, as well as the amino acid taurine.

The body can also convert cysteine into glucose for a source of energy. (source )

Cysteine In Food

Cysteine is found in most high-protein foods.

By eating enough protein in your diet, you get all of the cysteine and all other important amino acids you need. (source )

Adding cysteine to foods is not that common, since cysteine has strong odor and flavor characteristics.

It is hard to remove the odor and flavor characteristics of cysteine from the raw material, to be able to add it to foods without affecting the original flavor or odor of the food.

Uses Of Cysteine

Cysteine is often used in the production of various cosmetic products.

Cysteine is also used as an additive in the production of toothpaste.

Cysteine is widely used as a stabilizer in pharmaceuticals, such as tablets and capsules, because it can reduce the recrystallization of poorly soluble drugs.

Benefits Of Cysteine

Cysteine is an important component of the antioxidant glutathione.

Cysteine plays a role in a number of essential metabolic processes, such as the biosynthesis of hormones and vitamins, iron homeostasis, and regulation of the innate immune system.

Foods You Can Find Cysteine In

You find Cysteine mostly in legume, dairy and egg, and sausage and luncheon meat products.

Examples of food sources include

Foods in our nutrition tool

You can find regularly updated top-ranked lists of foods for over 200+ nutrients in our nutrition tool.

If you are interested in what foods contain the most Cysteine, we recommend you visit our tool.

Here's our top-ranked list of foods that contain Cysteine.

Sara Niemelä

co-founder Care Omnia, Head Content Creator

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Nutrition is my passion. I've spent thousands upon thousands of hours reading, analyzing, categorizing and comparing research studies.

I’m a wife and a mother of three. I enjoy the outdoors, cooking, and spending time with my family.