L-Cysteine
A powerful antioxidant amino acid that supports detoxification and respiratory health.
Also known as: Cysteine • N-Acetyl-L-Cysteine • NAC
Overview
L-Cysteine is a semi-essential amino acid found naturally in the human body and in certain foods. It plays a crucial role in protein synthesis, detoxification, and the production of the master antioxidant, glutathione. Its supplement form, N-Acetyl-L-Cysteine (NAC), is widely used for its health-promoting benefits.
Key Benefits
Boosts Glutathione Production
L-Cysteine is a precursor to glutathione, a powerful antioxidant that protects cells from oxidative damage.
Supports Respiratory Health
As NAC, it helps break down mucus in the airways, making it beneficial for chronic respiratory conditions.
Aids in Detoxification
It plays a vital role in the body's detoxification pathways, helping to neutralize toxins and heavy metals.
Enhances Brain Health
By regulating glutamate levels and replenishing glutathione, NAC may help with various psychiatric conditions and improve brain function.
Dosage & How to Take
L-Cysteine dosage varies depending on the form and reason for use. N-Acetyl-L-Cysteine (NAC) is the most common supplemental form.
| Purpose | Dose | Notes |
|---|---|---|
| General Antioxidant Support | 600-1,200 mg/day of NAC | Often split into two daily doses. |
| Respiratory Conditions | 600 mg of NAC, twice daily | Can be effective in reducing exacerbations of COPD. |
| Mood Support | 1,200-2,400 mg/day of NAC | Higher doses may be used under medical supervision. |
Best Time to Take
Can be taken with or without food, though taking it with meals may reduce potential stomach upset.
With or Without Food
Optional, can be taken with food to minimize gastrointestinal side effects.
Forms & Bioavailability
| Form | Absorption | Best For | Notes |
|---|---|---|---|
| N-Acetyl-L-Cysteine (NAC) | High | Overall health, antioxidant and respiratory support. | The most stable and well-absorbed form of cysteine. |
| L-Cysteine | Medium | General supplementation. | Less common than NAC and may be less stable. |
| Food Sources | Varies | Dietary intake. | Found in high-protein foods like chicken, turkey, yogurt, cheese, eggs, and legumes. |
Side Effects & Safety
Common
- Nausea
- Vomiting
- Diarrhea
- Stomach cramps
Rare
- Rash
- Fever
- Headache
- Drowsiness
Contraindications
- Should be used with caution in people with asthma or bleeding disorders.
Interactions
May increase the effect of nitroglycerin and the risk of side effects like severe headaches.
Can reduce the absorption of NAC.
NAC may have blood-thinning properties and could increase the risk of bleeding when taken with anticoagulant or antiplatelet drugs.
Scientific Research
N-acetylcysteine for treatment of psychiatric disorders: a systematic review
NAC shows promise in the treatment of several psychiatric disorders, including depression, bipolar disorder, and schizophrenia.
A Review on Various Uses of N-Acetyl Cysteine
NAC has a wide range of clinical applications, from treating acetaminophen overdose to improving respiratory and cardiovascular health.
Food Sources
Products With L-Cysteine
1 product in our database contains this ingredient
Frequently Asked Questions
Medical Disclaimer
This content is for educational and informational purposes only and is not intended as medical advice. Always consult with a qualified healthcare professional before starting any supplement regimen, especially if you have pre-existing health conditions or are taking medications. The statements on this page have not been evaluated by the Food and Drug Administration.