New Scientific Discovery: The 5:2 Intermittent Fasting Regimen Improves Non-Alcoholic Steatohepatitis and Reduces Hepatocellular Carcinoma Occurrence

Research Background and Problem Statement

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide, with its prevalence increasing alongside rising obesity rates. NAFLD is a manifestation of metabolic syndrome in the liver and can progress to non-alcoholic steatohepatitis (NASH) and even hepatocellular carcinoma (HCC). Currently, there is no specific medication for NAFLD, NASH, or their progression to HCC, making the search for new therapeutic approaches highly significant. Intermittent fasting (IF) regimens, as a non-invasive dietary intervention, have shown potential benefits for obesity and metabolic diseases, but their specific mechanisms in NASH and its progression to HCC remain unclear.

Source of the Paper and Author Information

This research paper, titled “A 5:2 intermittent fasting regimen ameliorates NASH and fibrosis and blunts HCC development via hepatic PPARα and PCK1,” was written by Suchira Gallage and others and published in the journal Cell Metabolism. The primary institutions involved include the German Cancer Research Center (DKFZ), University of Tübingen, King’s College London, and Heidelberg University. The paper was published on June 4, 2024, by Elsevier Inc. The article is open-access, allowing anyone to view it.

Research Methods and Process

This study investigated the preventive and therapeutic effects of the 5:2 intermittent fasting regimen on NASH and NASH-HCC models induced by different diets. The specific experimental procedures are as follows:

1. Experimental Design: Male C57BL/6J mice, 8 weeks old, were used to induce NASH with a Western diet (WD) for 32 weeks. The control group mice ate ad libitum, while the experimental group mice underwent two non-consecutive fasting days per week, with each fasting cycle lasting 24 hours.
2. Sample Processing and Experimental Procedure:
   • Fasting Regimen: The experimental group mice began fasting during their active phase (7 PM) and were only allowed to drink water during fasting.
   • Dissection and Measurement: All mice were dissected 48 hours after fasting ended, with serological, histological, and physiological measurements conducted to ensure consistent nutritional status.
   • Multi-Omics Analysis: Key molecules were identified through proteomics, transcriptomics, and metabolomics analysis, with a particular focus on the expression and signaling of PPARα and PCK1 in the liver.

Research Results

Experiment 1: Preventive and Therapeutic Effects of the IF Regimen on NASH

1. Body Weight and Fat Content: Mice in the IF regimen group had significantly lower body weight and fat content compared to the ad libitum group, with no significant loss in muscle mass. The fasting group also showed decreased serum cholesterol and glucose levels, indicating improved lipid and glucose homeostasis.
2. Liver Pathology: The IF group exhibited reduced levels of liver injury markers (ALT/ALP), decreased liver weight, and significantly less hepatic steatosis, inflammation, and fibrosis.

Experiment 2: Impact of Fasting Duration and Timing on the IF Regimen

The study found that the duration and start time of the fasting cycle had a significant impact on the efficacy of fasting: 1. Fasting Duration: A regimen with 24-hour daily fasting (6:1) showed better results in terms of body weight, fat content, cholesterol, and glucose levels than a regimen with 12-hour fasting per cycle (5:2-12h). 2. Fasting Start Time: Beginning fasting during the active phase (7 PM to 7 AM) was more effective in significantly reducing liver inflammation and fibrosis than starting during the inactive phase (7 AM to 7 PM).

Experiment 3: IF’s Impact on Whole-Body Metabolism

The IF regimen did not affect total caloric intake but significantly altered whole-body metabolism, enhancing fatty acid oxidation and ketone body production while reducing oxygen consumption and activity levels.

Experiment 4: Key Molecular Mechanisms

1. Proteomics Analysis: PPARα and PCK1 were significantly upregulated under the IF regimen, promoting fatty acid oxidation. Both were downregulated in NASH models and human NASH samples.
2. Metabolomics Analysis: The fasting state showed a significant increase in hepatic ketone body 3-hydroxybutyrate and a decrease in glucose and lactate levels, indicating increased ketone body production.
3. Dynamic [18F]FDG-PET Scanning: Revealed fasting-induced changes in hepatic glucose metabolism, with increased glucose uptake in the brain and muscle after refeeding in the fasting group.

Experiment 5: Importance of PPARα and PCK1 in Fasting

Experiments using adeno-associated virus vectors (AAV8) in mice demonstrated that knocking down PPARα and PCK1, either individually or jointly, significantly weakened the metabolic improvements brought by fasting, especially the genes involved in fatty acid oxidation and ketone body production. Mice lacking PPARα and PCK1 exhibited more severe liver inflammation and fibrosis under fasting conditions.

Research Significance

This study proposes the 5:2 intermittent fasting regimen as a promising intervention for NASH. The discovery of PPARα and PCK1 highlights their critical roles in the liver’s response to fasting, potentially providing new avenues for the treatment of NASH and related diseases in the future. The study also emphasizes the importance of fasting cycle length and timing in the efficacy of fasting, laying the foundation for more scientifically based dietary interventions.

Research Highlights

1. Key Findings: The 5:2 intermittent fasting regimen significantly improves NASH and related liver diseases and reduces the occurrence of hepatocellular carcinoma.
2. Mechanism Elucidation: Multi-omics analysis revealed the key roles of PPARα and PCK1 as core executors in fasting.
3. Clinical Significance: Provides a non-invasive, easy-to-implement intervention regimen with significant guidance for managing obesity and NASH.

Conclusion

This study comprehensively explored the mechanisms by which the 5:2 intermittent fasting regimen affects NASH and its progression to HCC. Through multi-omics analysis and animal model experiments, the study revealed the core molecular mechanisms involved, emphasizing the importance of fasting start time and cycle length. The research results not only offer a new approach for treating NASH but also provide an important theoretical basis for future clinical applications.