Cysteine Rich Foods in the Diet and Supplement Sources

Consumption of cysteine rich foods may improve human health, promote healthy looking skin, hair and nails, and support the immune system.

Cysteine is also a key ingredient in glutathione – one of the body’s most important anti-oxidants. By increasing levels of this anti-oxidant, L-Cysteine may help to protect the liver from toxins and other forms of environmental damage. It has also been linked to improved stamina for athletes and increased male fertility.

Cysteine is a conditionally essential amino acid, which means that our bodies can synthesize it, but there are some times where we need to consume it from external sources to ensure levels are adequate.

When this is the case, choosing a diet with foods rich in cysteine can help, or you can use supplements that contain a derivative of this amino acid known as N-acetyl cysteine (NAC) What are the best foods that contain high levels of this nutrient and what are the benefits from consuming these foods?

Cysteine

Amino Acid

Skin

Hair

Anti- Aging

How It Works:

• Promotes healthy skin, hair & nails
• Aids in the formation of collagen
• Supports protein structure for anti-aging

Dosage:

Between 200 - 500 mg per day

Safety:

Generally Well Tolerated

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Role of Cysteine in the Body

Cysteine plays several key roles in the body. It is a building block for skin, hair and nails and is often taken as a natural way to combat hair loss. It is believed to protect the body form signs of aging and is often supplemented by the elderly to promote longevity.

It can also improve breathing, work as a decongestant by breaking down mucus, improve the body’s resistance to influenza and other infections. Even athletes and bodybuilders will take it to improve their performance and enhance endurance.

Another important role for cysteine is in the production of glutathione, the body’s master antioxidant substance. L-cysteine from foods that we eat is first converted into N-acetyl cysteine which is the rate limiting factor in the synthesis of the enzyme glutathione peroxidase. Increasing glutathione levels is associated with numerous beneficial effects.

Glutathione molecules cleave to heavy metal, pesticide, free radical and other damaging substances, and escort them out of the body via the urine or bile. It protects the liver from the toxic effects of alcohol and drugs like Tylenol. In fact, NAC is used as a prescription drug to treat the symptoms of acetaminophen toxicity and other types of poisoning.

List of Cysteine Rich Foods

While your body can synthesize small amount of cysteine internally, it has been suggested that increasing your intake can support improved health. Various foods provide adequate amounts of L-cysteine. Of these, the majority also provide appreciable amounts of methionine, the amino acid that is required for the body to synthesize cysteine.

The Recommended Daily Intake (RDI) of cysteine determined by the FDA for general health purposes depends on weight and other case-dependent factors It ranges between 200 mg and 500 mg. The following foods are known to be rich in cysteine.

L-Cysteine in Grains

The following grains, cooked, provide 100 mg of cysteine with each 172 gram serving:

• Couscous: 60%;
• Quinoa: 42%
• Buckwheat: 35%
• Barley (pearled): 29%;
• Rice (wild): 28%;
• Rice (brown): 20%;

Oats and Bran L-Cysteine Content

The following oat and bran foods are listed with their associated RDI percentages per one cup serving:

• Oat bran: 190%;
• Wheat germ: 186%;
• Dry oatmeal (uncooked): 130%;
• Cooked oat bran: 77%;
• Wheat bran: 74%;

Shellfish and Seafood:

The following foods are listed with their associated cysteine RDI percentages per 3 grams cooked servings:

• Clams: 117%;
• Tuna: 96%;
• Salmon: 85%;
• Shrimp: 79%;
• Halibut: 79%;
• Pollock: 76%;

Beef, Lamb, Chicken, Turkey & Pork:

The following meat foods are listed with their associated cysteine RDI percentages per 3 ounce cooked serving:

• Pot roast (beef): 135%;
• Bacon: 130%;
• Lamb (shoulder): 126%;
• Beef ribs: 118%;
• Chicken breast: 116%;
• Pork ribs: 110%
• Chicken thighs and drumsticks: 110%;
• Ground turkey: 99%;
• Turkey wings: 93%;

There are also various dairy and soy foods which are good sources of cysteine. Examples include hard boiled eggs, Swiss cheese, tofu, tempeh, soy bean sprouts, parmesan cheese and soy flour.

Cysteine Rich Beans and Legume Foods:

Per one cup serving, the following beans and legumes provide 100 mg of cysteine. Also listed is the RDI percentage for each, according to the RDI for a 150 pound (roughly 74 kilograms) individual.

• Garbanzo beans (chickpeas): 70%;
• Cranberry beans (Roman beans): 64%;
• Fava beans (broad beans): 56%;
• Lentils: 42%;

Cysteine Rich Nuts and Seeds

The following nuts and seeds are listed with their associated cysteine RDI percentages per one ounce serving:

• Watermelon seeds: 44%;
• Sesame seeds: 42%;
• Pistachios: 36%;
• Pumpkin seeds: 33%;
• Pine nuts: 29%;

Cysteine in Raw Cow Milk

Raw cow’s milk, also known as milk whey, contains three protein chains which are some of the best known sources of naturally absorbable cysteine. They are serum albumin, alpha lactalbumin and lactoferrin.

In these proteins, two molecules of cysteine are bonded by a disulfide bridge. This doubled molecule of cysteine is called cystine and it is easily absorbed by the cells. Once inside the cells, it can be efficiently used to synthesize glutathione.

The fragile disulfide bonds between cysteine molecules are denatured by heating and mechanical manipulations during the refining processes of milk and other mainstream dairy products. The singular cysteine molecules which result are not efficient for generating glutathione.

Other Necessary Cofactors

The production of glutathione requires more than just cysteine. Glutathione synthesis cofactors include selenium, magnesium, zinc, and vitamins B1, B2, B6, B9, B12, C and E.

Without all of these necessary constituents being available in the proper amounts, glutathione production will not occur efficiently. However, because N-Acetyl L-Cysteine is the rate limiting factor in the production of this enzyme, it is the most important to ensure adequate levels.

Safety of Cysteine Foods

All of the above listed cysteine rich foods are known to be healthy for the human body in various ways. They are safe substances which present no ill side effects in healthy individuals without allergies to them. Also, there are very seldom any side effects experienced with L-cysteine tablet or capsule supplements.

However, cysteine toxicity and other conditions are possible for certain individuals. All considering home-based supplementation, or dietary changes to accommodate more cysteine rich foods, should consult with their doctors beforehand.

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