N-acetylcysteine (NAC): useful against mood disorders?

N-acetylcysteine: a stable cysteine derivative

N-acetylcysteine, or NAC, is a stable, synthetic form of cysteine, a non-essential sulphur-containing amino acid that the body can produce from food.

Cysteine plays a crucial role in the synthesis of glutathione, one of the most powerful natural antioxidants produced by the human body, essential for cellular detoxification and protection against oxidative stress.

The 'N-acetylated' form has been developed to improve the chemical stability, solubility and oral bioavailability of cysteine, making it easier to assimilate.

Once in the body, NAC is easily converted into cysteine. This supports the endogenous production of glutathione and enables the body to benefit from its protective effects.

Current research is exploring the various potential effects of NAC in the body, particularly its impact on mood.

NAC and glutathione: their effects on the body

As a precursor of glutathione, N-acetylcysteine is being studied for its role in antioxidant defence, the reduction of oxidative stress and cellular detoxification (1).

A powerful endogenous antioxidant, glutathione is involved in neutralising free radicals, helping the liver to function properly and protecting cells.

More widely, NAC is also known for its mucolytic properties (liquefying bronchial secretions), which explains its traditional use in respiratory medicine (2).

It is also being studied in various other medical fields, notably for its potential protective effect on brain cells and inflammatory pathways (3-4).

As a result, it is now found in the form of dietary supplements, often aimed at supporting vitality, the immune system or oxidative balance.

Discover N-Acetyl Cysteine, a supplement with a high dose of NAC to support glutathione production and protect against oxidative stress.

NAC and mood disorders: what recent research reveals

While N-acetylcysteine is best known for its role in glutathione synthesis, several recent studies suggest that it may help regulate certain biological mechanisms involved in mood disorders.

Studies looking at low mood, mental fatigue and emotional instability

In recent years, N-acetylcysteine (NAC) has attracted growing interest in mental health research, particularly for its potential role in supporting emotional balance.

Several clinical studies have explored its effects in a variety of contexts, including mild to moderate depression, persistent anxiety and certain states of chronic discouragement, mental fatigue or emotional instability.

A study published in 2023 in Clinical Psychopharmacology and Neuroscience (5) assessed the effects of 2000 mg/day N-acetylcysteine supplementation for 12 weeks in adults suffering from major depression.

Although no significant improvement was observed at 12 weeks, notable benefits were seen at 16 weeks, including improvements in mood, optimism, social relationships and the ability to function daily.

These results suggest that NAC could offer useful progressive support that complements traditional approaches, particularly in a medium-term strategy for emotional rebalancing.

Potential action on several mechanisms linked to emotional balance

Another study published in 2024 in General Hospital Psychiatry (6) looked at the effects of NAC supplementation on mood disorders.

This meta-analysis compiled data from 12 randomised controlled trials, involving a total of 904 participants suffering from mood disorders (particularly depressive episodes). The doses of N-acetylcysteine (NAC) ranged from 1,000 to 3,000 mg/day, over a period of 8 to 24 weeks.

Result: compared with placebo, NAC was significantly associated with a reduction in depressive symptoms, with a standardised mean difference of -0.24 (indicating a modest but real effect).

The authors conclude that NAC could be an interesting complementary option for improving emotional state, particularly as a support to conventional treatment.

Although this work remains exploratory, several plausible biological mechanisms have been put forward to explain these results:

• support for glutathione production, which reduces oxidative stress, a factor often associated with mood disorders (7);
• modulation of neurotransmission systems, particularly glutamate, imbalances of which are frequently observed in depressive states (8);
• an indirect anti-inflammatory effect, through the regulation of certain pro-inflammatory cytokines that could affect brain function (9);
• a regulating effect, which could support emotional well-being.

Unlike certain supplements or substances that act directly on brain chemistry, N-acetylcysteine produces neither a stimulating nor a euphoric effect.

Instead, it may have a more subtle, underlying effect, helping to restore a certain overall balance.

Recent research suggests that NAC supports emotional resilience, particularly in people experiencing mental fatigue, withdrawal, reduced motivation or chronic fatigue.

The scientists point out that NAC is not a substitute for medical treatment in the case of a proven disorder.

However, it could be an interesting complementary support when integrated into a more holistic approach to well-being. It may be particularly relevant for adults aged 40 and over, who are more exposed to oxidative stress and age-related neurochemical imbalances.

In this context, NAC is a gentle but potentially valuable form of support, best used alongside a balanced diet, good sleep, regular physical activity and effective stress management tools.

Discover N-Acetyl Cysteine, a stable, well-tolerated supplement which supports glutathione synthesis, studied in the context of oxidative stress and emotional balance.