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NCCIH Clinical Digest

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Hepatitis C and Dietary Supplements:
What the Science Says

May 2016
Milk Thistle

© Thinkstock

Clinical Guidelines, Scientific Literature, Info for Patients: 

Dietary Supplements

Milk Thistle

Milk thistle is known as silymarin, a chemical extracted from the seeds. Silymarin is a group of flavonoids (i.e., silibinin, silidianin, and silicristin). Current evidence suggests that milk thistle is no better than placebo as a treatment for hepatitis C.

The Evidence Base

  • The evidence base on efficacy of milk thistle for hepatitis C consists of several randomized controlled trials and systematic reviews and meta-analyses.


  • A 2014 meta-analysis of five randomized controlled trials found that the effects of silymarin on ALT levels of patients with hepatitis C were similar to those of placebo; however, no beneficial effects were found for silymarin. Improvements in the quality of life of silymarin and placebo recipients were relatively identical.
  • A 2012 controlled trial showed that two higher-than-usual doses of silymarin were no better than placebo in reducing alanine aminotransferase (ALT) levels in patients with chronic hepatitis C. Decreases in serum ALT levels are correlated with improvement in hepatic necroinflammatory activity after interferon therapy for hepatitis C.
  • Findings from the 2008 HALT-C study suggest that silymarin use by hepatitis C patients was associated with fewer and milder symptoms of liver disease and somewhat better quality of life, but there was no beneficial effect found on serum ALT or hepatitis C virus RNA levels. It is important to note that the finding of improved quality of life in patients taking silymarin was not confirmed in the more rigorous 2012 study described above.
  • A 2009 Cochrane systematic review assessed the beneficial and harmful effects of milk thistle in patients with alcoholic liver disease and/or hepatitis B or C liver diseases and found that there is not enough high-quality evidence to support the use of this intervention.


  • Available evidence from clinical trials in people with liver diseases suggests that milk thistle is generally well-tolerated.
  • Side effects can include a laxative effect, nausea, diarrhea, abdominal bloating and pain, and occasional allergic reactions.


Only a few studies have examined the effects of probiotics on hepatitis C, and of those studies, there isn’t any clear evidence that probiotics are helpful in people with hepatitis C.

The Evidence Base

  • The evidence base on efficacy of probiotics for hepatitis C consists of only a few randomized controlled trials.


  • A 2014 randomized controlled trial involving 53 patients with chronic liver disease found that short-term probiotic administration is effective in alleviating small intestinal bacterial overgrowth and clinical symptoms, but ineffective in improving intestinal permeability and liver function.


  • Most people can use probiotics without experiencing any side effects—or with only mild gastrointestinal side effects—but there have been some case reports of serious adverse effects in people with underlying serious health conditions.


There isn’t sufficient evidence to draw clear conclusions about the benefit or safety of zinc supplementation on hepatitis C disease activity.

The Evidence Base

  • The evidence base on efficacy of zinc supplementation for hepatitis C consists of only a few preliminary trials, most of which were conducted outside the United States.


  • A 2015 multicenter randomized controlled trial in 53 patients with hepatitis C found that branched-chain amino acids (BCAA) and zinc-enriched supplements reduced the serum α‑fetoprot (AFP) levels in patients who had elevated serum AFP levels at baseline. The authors of the study concluded that BCAA and zinc-enriched supplementation may prolong the survival of patients with hepatitis C by improving amino acid imbalance and zinc deficiency, and by partly down regulating AFP.
  • A 2012 study evaluating the effects of vitamins E, C, and zinc on oxidative stress in patients with hepatitis C found that the antioxidant supplementation had a protective effect on participants, attenuating oxidative stress related to the disease.


  • Zinc is generally considered to be safe when used appropriately, but it can be toxic if taken in excessive amounts.


There is currently insufficient evidence to determine if glycyrrhizin is helpful for hepatitis C. Glycyrrhizin is the major sweet-tasting constituent of Glycyrrhiza glabra (liquorice) root.

The Evidence Base

  • The evidence base on efficacy of glycyrrhizin for hepatitis C consists of only a few clinical trials.


  • A 2012 randomized controlled trial in 379 patients with chronic hepatitis C who failed to respond to previous interferon-based therapies found that glycyrrhizin exhibited a significantly higher ALT reduction compared to placebo after 12 weeks of therapy and an improvement of necro-inflammation and fibrosis after 52 weeks of treatment.


  • In large amounts, glycyrrhizin or licorice can be dangerous in people with a history of hypertension, renal failure, or cardiovascular diseases.


Chlorella is a genus of single-cell green algae from the Chlorophyta phylum. There is currently insufficient evidence to determine if Chlorella supplementation is efficacious for hepatitis C.

The Evidence Base

  • The evidence base on efficacy of Chlorella supplementation on hepatitis C disease activity consists of one small study.


  • A 2013 study in 18 adults with chronic hepatitis C genotype 1 found that Chlorella supplementation was well tolerated in these patients and was associated with a significant decrease in ALT liver enzyme levels.


  • There is insufficient evidence to draw conclusions about the safety of Chlorella for patients with hepatitis C.


NCCIH Clinical Digest is a service of the National Center for Complementary and Integrative Health, NIH, DHHS. NCCIH Clinical Digest, a monthly e-newsletter, offers evidence-based information on complementary health approaches, including scientific literature searches, summaries of NCCIH-funded research, fact sheets for patients, and more.

The National Center for Complementary and Integrative Health is dedicated to exploring complementary health products and practices in the context of rigorous science, training complementary health researchers, and disseminating authoritative information to the public and professionals. For additional information, call NCCIH's Clearinghouse toll-free at 1-888-644-6226, or visit the NCCIH Web site at NCCIH is 1 of 27 institutes and centers at the National Institutes of Health, the Federal focal point for medical research in the United States.


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This page last modified July 18, 2016