Background

Non-alcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases worldwide and is closely associated with:

• Obesity
• Insulin resistance
• Type 2 diabetes
• Dyslipidemia
• Metabolic syndrome

Oxidative stress plays a major role in the progression of NAFLD to inflammation (NASH) and fibrosis. Since N-acetylcysteine (NAC) replenishes intracellular glutathione, a major antioxidant, researchers investigated whether it could improve liver function.

Objective

To determine whether oral NAC improves liver function in patients with NAFLD.

Study Design

• Type: Prospective randomized clinical trial
• Duration: 3 months
• Participants: 30 patients with confirmed NAFLD
• Diagnosis: Elevated liver enzymes and ultrasound evidence of fatty liver
• Patients were randomly divided into two groups.

Intervention Group

• NAC: 600 mg twice daily
• Total daily dose: 1,200 mg/day

Control Group

• Vitamin C: 1,000 mg/day

Both groups received:

• Advice on weight reduction
• Low-fat diet
• Regular exercise

Parameters Measured

Researchers evaluated before and after treatment:

• Alanine aminotransferase (ALT)
• Aspartate aminotransferase (AST)
• Alkaline phosphatase (ALP)
• Total bilirubin
• Lipid profile
• Fasting blood sugar
• Body weight
• Spleen size (ultrasound)
• Liver ultrasound findings

Results

1. ALT (Primary Liver Enzyme)

NAC produced a significant reduction in ALT.

• Improvement was significantly greater than Vitamin C.
• Indicates reduced liver cell injury.

2. AST

AST also decreased significantly in the NAC group.

Again, improvement exceeded that seen with Vitamin C.

3. ALP

ALP decreased significantly with NAC treatment.

4. Spleen Size

One interesting finding was:

Patients receiving NAC experienced a significant reduction in spleen size, suggesting possible improvement in portal congestion or liver inflammation.

5. Bilirubin

No significant changes.

6. Blood Sugar

No significant improvement.

7. Lipid Profile

No significant changes in:

• Total cholesterol
• LDL
• HDL
• Triglycerides

8. Body Weight

Weight loss occurred in both groups because all patients received dietary and exercise advice.

The difference between groups was not significant, indicating that NAC’s liver benefits were unlikely to be explained simply by greater weight loss.

9. Ultrasound Fatty Liver Grade

Ultrasound appearance showed only minimal improvement during the 3-month study.

Researchers note that structural liver changes usually require longer treatment than biochemical improvements.

Why NAC May Work

The paper discusses several mechanisms:

Restores Glutathione

NAC is the direct precursor of glutathione, the liver’s principal intracellular antioxidant.

Reduces Oxidative Stress

Oxidative stress contributes to:

• Lipid peroxidation
• Hepatocyte injury
• Inflammation

NAC reduces reactive oxygen species by restoring antioxidant defenses.

Improves Mitochondrial Function

By preserving glutathione stores, NAC may improve mitochondrial function and reduce oxidative injury.

Reduces Inflammatory Damage

Lower oxidative stress may reduce inflammatory signaling involved in progression from fatty liver to steatohepatitis.

Safety

• NAC was generally well tolerated.
• No serious adverse effects were reported.
• Compliance was good.

Authors’ Conclusions

The authors concluded that:

• Oral NAC 600 mg twice daily for 3 months significantly improved liver function tests in patients with NAFLD.
• ALT, AST, ALP, and spleen size improved more than with Vitamin C.
• Improvements in liver enzymes occurred without significant changes in blood sugar, lipid profile, or body weight.
• NAC may help protect the liver by replenishing glutathione and reducing oxidative stress.
• Longer treatment durations may produce greater improvements in liver structure and ultrasound findings.

Key Takeaways

Overall conclusion

This randomized clinical trial provides evidence that 1,200 mg/day of NAC for 3 months improves biochemical markers of liver injury in patients with NAFLD, likely through its antioxidant effects and restoration of glutathione. The authors suggest that longer treatment may be needed to produce meaningful improvements in liver fat and structural changes visible on ultrasound.