This systematic review with meta-analysis examines the effects of various antioxidant dietary supplements —including , in particular ,curcumin, resveratrol, vitamin C, vitamin E, and N-acetylcysteine (NAC) —on inflammatory bowel diseases (IBD) such as Crohn’s disease and ulcerative colitis.
Of the 316 studies reviewed, 12 randomized controlled trials (RCTs) involving a total of 1,060 participants were included. The results show:
Curcumin significantly improves clinical remission , endoscopic remission, and quality of life .
Resveratrol increases antioxidant markers (SOD, TAC) and lowers inflammation markers (CRP, TNF-α), and also has a positive effect on quality of life.
N-acetylcysteine has been shown to be helpful in maintaining remission in ulcerative colitis during steroid therapy.
A combination of vitamins C and E reduced oxidative stress but did not affect disease activity.
Conclusion: Curcumin and resveratrol, in particular, show promising effects on symptoms and quality of life in IBD. Antioxidant supplementation thus represents a potential complementary treatment option, but should be further validated by larger and longer-term studies.
Background
Inflammatory bowel diseases (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC), are on the rise worldwide and are associated with chronic inflammation, oxidative stress, and a reduced quality of life. Since oxidative processes play a central role in the pathophysiology of these conditions, this review focuses on the effects of antioxidants as dietary supplements in the treatment of IBD.
Methodology
- Design: Systematic review and meta-analysis according to the PRISMA criteria.
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Data source: 12 RCTs involving 1,060 participants from 7 countries (Iran, India, Japan, France, Canada, Hong Kong).
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Interventions: Curcumin (100–3000 mg/day), resveratrol (500 mg/day), NAC (800 mg/day), vitamin C (1000 mg/day) + E (800 IU).
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Endpoints assessed: Clinical and endoscopic remission, disease activity (SCCAI, CDAI), quality of life (IBDQ), markers of inflammation (CRP, TNF-α), markers of oxidative stress (MDA, SOD, TAC).
Results of the meta-analysis
1. Curcumin:
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Clinical remission: significant improvement (SMD: 0.86; p = 0.016)
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Endoscopic remission: improved (SMD: 0.51; p = 0.004)
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Clinical symptoms: significant reduction (SMD: −0.96; p < 0.001)
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Quality of life: significant improvement (SMD: 1.23; p < 0.001)
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The effect was more pronounced among participants aged >40 years.
2. Resveratrol:
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Improved quality of life, reduced disease activity
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Significant reduction in CRP, TNF-α, and NF-κB
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Increase in antioxidant capacity (TAC, SOD) and reduction in MDA
3. NAC (N-acetylcysteine):
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Improved Maintenance of Remission During Prednisolone Therapy
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Reduction in CRP , fecal calprotectin, and ESR
4. Vitamins C and E:
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Improvement in Antioxidant Parameters
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No change in disease activity despite rising plasma levels
Discussion
This meta-analysis shows that curcumin is particularly effective for IBD—both in terms of symptoms and objective markers such as endoscopic findings. Resveratrol was particularly effective for UC, while NAC can help maintain remission.
The wide variation in dosage, duration, and patient groups limited the study’s interpretability. Furthermore, no subgroup analysis was conducted based on disease type (UC vs. CD), even though studies involving CD were in the minority.
Conclusion
Supplementation with antioxidants, particularly curcumin and resveratrol, can promote clinical and endoscopic remission , alleviate symptoms, and improve the quality of life for IBD patients.
However, larger, multinational, long-term RCTs are needed to better understand dosage, duration of action, patient selection, and combination effects.