Pumpkin seeds are high in zinc, good for the immune system.
NutriVals is a free database of Nutrition Facts.


What is Cysteine?

Cysteine is a non-essential amino acid that contains a thiol or sulfhydryl group (-SH) in its side chain. It is one of the 20 amino acids that are the building blocks of proteins. Cysteine is also a precursor for other important molecules, such as glutathione and taurine, that have various functions in the body.

Why we need Cysteine?

Cysteine plays several essential roles in the body, such as:

Protein synthesis: Cysteine is necessary for the formation of many proteins in the body, including enzymes, hormones, and structural proteins.

Antioxidant defense: Cysteine is a precursor for glutathione, which is a powerful antioxidant that protects cells from oxidative stress and damage.

Detoxification: Cysteine also helps in the detoxification of harmful substances, such as heavy metals, drugs, and alcohol.

Immune function: Cysteine is involved in the function of immune cells, such as T-cells and B-cells, which protect the body from infections and diseases.

Skin and hair health: Cysteine is an important component of keratin, which is the protein that makes up hair, skin, and nails.

Where is Cysteine found?

Cysteine is present in many dietary sources, such as animal products (meat, fish, poultry, and dairy), legumes (beans, lentils, and peas), soy products, and nuts (walnuts, cashews, and almonds). It can also be synthesized by the body from other amino acids, such as methionine.

Daily requirements

The daily requirements for cysteine vary depending on age, gender, and overall health status. However, the average recommended daily intake for adults is about 500 mg to 2 grams per day. Vegetarians and vegans may require higher intakes of cysteine as plant sources of protein may have lower levels of cysteine compared to animal sources.

Cysteine deficiency

Cysteine deficiency is rare, as the body can synthesize it from other amino acids. However, people with certain genetic disorders that affect cysteine metabolism, such as homocystinuria and cystinosis, may have a higher risk of deficiency. Symptoms of cysteine deficiency may include skin problems, slow growth, and impaired immune function.

Can you get too much Cysteine?

Excessive intake of cysteine supplements can lead to adverse effects, such as gastrointestinal problems, nausea, vomiting, and diarrhea. In high doses, cysteine can also cause oxidative stress and damage to cells. Therefore, it is important to follow the recommended dosage and consult a healthcare professional before taking any supplements.

Should I get Cysteine supplements?

Most people can meet their cysteine needs through a balanced diet that includes protein-rich foods. However, some individuals, such as athletes, bodybuilders, and people with certain medical conditions, may benefit from cysteine supplements to support their immune function, muscle growth, and recovery. It is always recommended to consult a healthcare professional before taking any supplements.

Fun facts

Cysteine was first isolated from wool in 1810.

Cysteine has a distinctive odor, which is why it is used as a flavor enhancer in many foods, such as meat, savory snacks, and soups.

Cysteine is also used in the manufacturing of various products, such as cosmetics, drugs, and industrial chemicals.

Food high in Cysteine

This list shows food that are top sources of Cysteine and the quantity of Cysteine in 100g of food

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Fruit Vegetables Meat Dairy Eggs Bread Superfood Legumes Cereals Nuts and Seeds Seafood Other Spices and Herbs
Macronutrients Carbohydrate Fat Protein Water Fiber
Vitamins Thiamin (B1) Riboflavin (B2) Niacin (B3) Pantothenic Acid (B5) Pyridoxine (B6) Folate (B9) Cobalamine (B12) Ascorbic Acid (C) Vitamin A Vitamin K Vitamin E Vitamin D
Minerals Calcium (Ca) Iron (Fe) Magnesium (Mg) Phosphorus (P) Potassium (K) Sodium (Na) Zinc (Zn) Copper (Cu) Manganese (Mn) Iodine (I) Selenium (Se) Fluoride (F)
Amino acids Arginine Histidine Lysine Aspartic Acid Glutamic Acid Serine Threonine Asparagine Glutamine Cysteine Selenocysteine Glycine Proline Alanine Isoleucine Leucine Methionine Phenylalanine Tryptophan Tyrosine Valine