Health Information

Cysteine

Uses

How It Works

How to Use It

Most people do not need to supplement with cysteine. Almost nothing is known about appropriate supplemental levels, in part because almost all clinical research has been done with Reference N-acetyl cysteine and not cysteine itself.

Where to Find It

The body can synthesize cysteine from Reference methionine and other building blocks. Cysteine, the Reference amino acid from which NAC is derived, is found in most high-protein foods.

Possible Deficiencies

According to several studies, blood levels of cysteine and Reference glutathione are low in people infected with Reference HIV.¹ ^{, 2} ^{, 3} Cysteine has a role in the proper function of the Reference immune system, so a deficiency of this Reference amino acid may either contribute to, or result from, immune suppression associated with HIV.

Interactions

Interactions with Supplements, Foods, & Other Compounds

Adequate amounts of Reference methionine are needed in the diet, as the precursor to cysteine, to prevent cysteine deficiency.

Interactions with Medicines

As of the last update, no reported interactions between this supplement and medicines. It is possible that unknown interactions exist. If you take medication, always discuss the potential risks and benefits of adding a new supplement with your doctor or pharmacist.

The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers’ package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a supplement with your doctor or pharmacist.

Side Effects

No consistent adverse effects of Reference NAC have been reported in humans. One small study found that daily amounts of 1.2 grams or more could lead to oxidative damage.⁴ Extremely large amounts of cysteine, the Reference amino acid NAC is derived from, may be toxic to nerve cells in rats.⁵

Related Information

Reference What Are Depletions & Interactions?

References

1. Eck HP, Gander H, Hartmann M, et al. Low concentrations of acid-soluble thiol (cysteine) in the blood plasma of HIV-1 infected patients. Biol Chem Hoppe Seyler 1989;370:101–8.

2. Droge W, Eck HP, Mihm S. HIV-induced cysteine deficiency and T-cell dysfunction—a rationale for treatment with N-acetylcysteine. Immunol Today 1992;13:211–4.

3. Droge W. Cysteine and glutathione deficiency in AIDS patients: a rationale for the treatment with N-acetyl-cysteine. Pharmacology 1993;46:61–5 [review].

4. Kleinveld HA, Demacker PNM, Stalenhoef AFH. Failure of N-acetylcysteine to reduce low-density lipoprotein oxidizability in healthy subjects. Eur J Clin Pharmacol 1992;639–42.

5. Olney JW, Ho OL. Brain damage in infant mice following oral intake of glutamate, aspartate or cysteine. Nature 1970;227:609–10 [letter].

Last Review: 11-07-2012

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The information presented in Aisle7 is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires June 2013.

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