Top 10 Foods Highest in Cystine (Cysteine)

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Dr. Patricia Shelton
Evidence Based. References sourced from PubMed.
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Top 10 Foods Highest in Cystine (Cysteine)

Cysteine is an amino acid, and is used by the human body to make proteins. Cystine is the oxidized dimer form of cysteine, meaning that it’s composed of two cysteine molecules bonded together. It is considered nutritionally equivalent to cysteine, and is the major form in which this amino acid is transported in the bloodstream. (1,2,3)

Among its many functions, cystine helps to create anti-oxidants such as glutathione (4), and is also used in the synthesis of other molecules within the cell.

Cysteine or cystine supplementation is sometimes used for various reasons, including to help with hair health, skin health, liver health, immune system function, and even to delay aging. However, current scientific evidence does not strongly support these claims. Although some studies have found benefits, others have found no effect or harmful effects from cystine supplementation. (5)

High cystine foods include pork, beef, chicken, fish, lentils, oatmeal, eggs, low-fat yogurt, sunflower seeds, and cheese. The reference dietary intake (RDI) for cystine is 4.1mg per kilogram of body weight or 1.9mg per pound. A person weighing 70kg (~154 pounds) should consume 287mg of cystine per day. (6)

Below is a list of the top 10 foods highest in cystine with the %RDI calculated for someone weighing 70kg (154lbs). For more high cystine foods see the extended list of cystine-rich foods.

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A printable list of high cystine foods including pork, beef, chicken, fish, lentils, oatmeal, eggs, low-fat yogurt, sunflower seeds, and cheese.

More Cystine Rich Foods

1. Beef Liver 1 slice 135% RDI
2. Somen Noodles per cup 69% RDI
3. Teff per cup 61% RDI
4. Couscous per cup 59% RDI
5. Firm Tofu per cup 50% RDI
6. Crab Cakes per cake 50% RDI
7. Lima Beans per cup cooked 49% RDI
8. Carrots per cup chopped 21% RDI
9. Shiitake Mushrooms per cup cooked 14% RDI
10. Almond Butter per tblsp 13% RDI

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Data Sources and References

  1. Cunden LS, Nolan EM. Biochemical and Functional Evaluation of the Intramolecular Disulfide Bonds in the Zinc-Chelating Antimicrobial Protein Human S100A7 (Psoriasin) Methods Mol Biol. 2019;1929:379-395. doi: 10.1007/978-1-4939-9030-6_24. 30710286
  2. Kapoor V, Glover R, Malviya MN. Cysteine, cystine or N-acetylcysteine supplementation in parenterally fed neonates Cochrane Database Syst Rev. 2015 Dec 2;2015(12):CD009172. doi: 10.1002/14651858.CD009172.pub2. 26630252
  3. Noda T, Iwakiri R, Fujimoto K, Rhoads CA, Aw TY. The Non-Essential Amino Acid Cysteine Becomes Essential for Tumor Proliferation and Survival Cell Prolif. 2002 Apr;35(2):117-29. doi: 10.1046/j.1365-2184.2002.00229.x. 11952646
  4. Sakanashi M, Sakanashi M, Sugahara K, Sakanashi M. Mechanisms underlying the cardioprotective effect of L-cysteine Clin Exp Pharmacol Physiol. 2007 Jan-Feb;34(1-2):55-60. doi: 10.1111/j.1440-1681.2007.04543.x. 17201736
  5. Mohammadi H, Farzinpour A, Vaziry A. Effects of the Usage of l-Cysteine (l-Cys) on Human Health Reprod Domest Anim. 2017 Apr;52(2):298-304. doi: 10.1111/rda.12902. Epub 2017 Jan 20. 28109029
  6. World Health Organization - Protein and Amino Acid Requirements In Human Nutrition
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