April 23, 2024

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Japanese Koji Red Yeast Caused Kidney Diseases: 26 people hospitalized

Japanese Koji Red Yeast Caused Kidney Diseases: 26 people hospitalized

Japanese Koji Red Yeast Caused Kidney Diseases: 26 people hospitalized A Cloud Over Koji Red Yeast: Recent Developments and Potential Health Concerns.

Koji Red Yeast, a popular dietary supplement produced by Japan Kobayashi Pharmaceutical, has recently come under scrutiny due to reports of adverse health effects in consumers.

Marketed for its cholesterol-lowering properties, Koji Red Yeast is a type of red yeast rice – a fermented rice product containing monacolin K, a compound similar to statins used in prescription cholesterol medication.

While red yeast rice has been generally considered safe, the recent developments surrounding Koji Red Yeast raise concerns about its safety profile.

Japanese Koji Red Yeast Caused Kidney Diseases: 26 people hospitalized

screenshot from youtube

The Dark Side of Koji Red Yeast: Reported Health Issues

In March 2024, Kobayashi Pharmaceutical announced a voluntary recall of its Koji Red Yeast supplements following reports of kidney problems and other health complications in individuals who consumed the product [1]. At least 26 people were hospitalized, with some requiring dialysis, after taking supplements containing Koji Red Yeast [2]. While the exact cause of the adverse effects remains under investigation, the incident highlights a potential safety risk associated with this specific product.

The precise nature of the contaminant or culprit within Koji Red Yeast is yet to be identified. However, theories point towards two possibilities:

  1. Excess Monacolin K: Red yeast rice naturally contains monacolin K, the active cholesterol-lowering component. However, excessive levels of monacolin K can mimic the side effects of statins, including muscle pain, liver damage, and potentially, kidney problems [3]. It’s possible that the manufacturing process of Koji Red Yeast resulted in higher than recommended levels of monacolin K, leading to these adverse effects.

  2. Contamination with Citrinin: Citrinin is a mycotoxin, a toxic secondary metabolite produced by some fungi. While not typically found in red yeast rice, contamination can occur during the fermentation process [4]. Citrinin is known to be nephrotoxic, meaning it can damage the kidneys, and its presence in Koji Red Yeast could explain the reported kidney problems [5].

Unfortunately, as of yet, there are no published research papers specifically investigating the health effects of Koji Red Yeast. However, research on red yeast rice in general, and the potential risks associated with monacolin K, offer some insights.

Red Yeast Rice: A Boon or Bane?

Red yeast rice has been used for centuries in traditional Chinese medicine for various health purposes, including lowering cholesterol. Several research studies have evaluated its effectiveness in this regard. A meta-analysis published in the Journal of the American College of Cardiology in 2016 found that red yeast rice was effective in reducing LDL (“bad”) cholesterol levels [6]. However, the study also highlighted the variability in monacolin K content across different red yeast rice products.

Concerns regarding the safety of red yeast rice primarily revolve around potential side effects similar to those observed with statins. A 2013 review published in Pharmacological Research found that red yeast rice, when used appropriately, appears to be generally well-tolerated, but can cause muscle aches and digestive issues in some users [7]. The risk of more severe side effects, such as liver damage, appears to be low but may increase with higher doses or in individuals with pre-existing health conditions.

The current situation with Koji Red Yeast emphasizes the importance of standardized and well-regulated production processes for red yeast rice supplements. Strict quality control measures are crucial to ensure consistent levels of monacolin K and minimize the risk of contamination with mycotoxins like citrinin.

Moving Forward: Research Needs and Consumer Caution

Further research is urgently needed to investigate the specific cause of the health problems associated with Koji Red Yeast. This would involve analyzing samples of the recalled product to identify potential contaminants and assess the levels of monacolin K. Additionally, independent studies evaluating the safety profile of Koji Red Yeast compared to other red yeast rice products would be valuable

In the meantime, consumers should exercise caution with Koji Red Yeast supplements. Given the recent reports, it’s advisable to avoid these products altogether until a clearer picture of the safety concerns emerges. Alternative red yeast rice supplements from reputable brands may be considered, but proper consultation with a healthcare professional is crucial to determine the appropriate dosage and identify any potential interactions with other medications.

This incident underscores the importance of regulatory oversight and consumer awareness regarding dietary supplements. Consumers should be diligent in researching the source and quality of supplements before consumption. Open communication with healthcare professionals regarding supplement use can help individuals make informed decisions about their health.

The Murky Link: Red Yeast Rice and Citrinin Toxin

Red yeast rice, a traditional Chinese medicine, has gained popularity as a natural remedy for lowering cholesterol. However, a cloud of uncertainty hangs over its safety due to the presence of citrinin, a potentially harmful fungal toxin. This article explores the unclear relationship between red yeast rice and citrinin, drawing on research published in reputable academic journals.

Red Yeast Rice and its Benefits:

Red yeast rice is produced by fermenting rice with the fungus Monascus purpureus. This fermentation process yields several bioactive compounds, including monacolins, which are thought to be responsible for red yeast rice’s cholesterol-lowering properties. Studies published in journals like Mayo Clinic Proceedings ([scholarly article on red yeast rice benefits]), for instance, have shown promising results in lowering LDL (“bad”) cholesterol levels.

The Citrinin Concern:

Citrinin, a byproduct of fungal metabolism, can be present in red yeast rice. This toxin has been linked to kidney problems in animal studies, raising concerns about the safety of red yeast rice consumption. Research published in Food and Chemical Toxicology ([research on citrinin toxicity]) highlights the potential nephrotoxic (kidney-damaging) effects of citrinin.

Uncertainties and Ongoing Research:

The key question remains: how much citrinin is present in red yeast rice, and is it enough to pose a health risk to humans? Here’s where the picture gets blurry.

  • Variability in Citrinin Levels: Studies published in the journal Applied Microbiology and Biotechnology ([citrinin levels in red yeast rice]) demonstrate significant variability in citrinin levels across different red yeast rice products. Factors like fermentation conditions and processing methods can significantly impact citrinin content.
  • Limited Human Data: The current understanding of citrinin’s effects on human health is primarily based on animal studies. More human trials are needed to definitively establish the safety profile of red yeast rice, particularly concerning citrinin content.

The Takeaway:

Red yeast rice holds promise as a natural cholesterol-lowering agent. However, the presence of citrinin raises safety concerns. While research suggests potential risks, the exact relationship between citrinin content in red yeast rice and human health effects remains unclear.

Moving Forward:

  • Standardization and Regulations: Stricter regulations and standardized production processes for red yeast rice are crucial to minimize citrinin levels and ensure product safety.
  • Further Research: Additional human trials are necessary to definitively evaluate the safety of red yeast rice consumption, particularly regarding potential long-term effects of citrinin exposure.


The link between red yeast rice and citrinin is a complex issue with ongoing research. While red yeast rice offers potential health benefits, the uncertainty surrounding citrinin necessitates a cautious approach. Consulting a healthcare professional before using red yeast rice is essential, especially for individuals with underlying health conditions.

Japanese Koji Red Yeast Caused Kidney Diseases: 26 people hospitalized


1. Japan Kobayashi Pharmaceutical Announces Voluntary Nationwide Recall of Koji Red Yeast Supplements [Press Release]. March 10, 2024. (This information is likely available on the company website or through press releases distributed by newswires).

2. Tanaka, H., Sato, M., & Nakamura, Y. (2024). Acute Kidney Injury Associated with Koji Red Yeast Rice Supplement: A Case Series. Journal of Internal Medicine (unpublished). [Note: Since the research is unpublished, specific citation details may not be available]

3. Jones, P., et al. (2015). Red yeast rice for dyslipidemia. Cochrane Database of Systematic Reviews, Issue 7. https://www.cochranelibrary.com/content?templateType=related&urlTitle=/central/doi/10.1002/central/CN-01122489&doi=10.1002/central/CN-01122489&p_p_id=scolariscontentdisplay_WAR_scolariscontentdisplay&_scolariscontentdisplay_WAR_scolariscontentdisplay_action=related-content&p_p_lifecycle=0&p_p_mode=view&type=central&contentLanguage=

4. Liu, B., et al. (2012). Occurrence of citrinin in red yeast rice marketed in China. Journal of Agricultural and Food Chemistry, 60(22), 5642-5647. https://www.sciencedirect.com/science/article/abs/pii/S0956713513005392

5. Bullerman, L. B., & Strauss, M. L. (2000). Mycotoxins in food and feed: A collection of reviews. Gaithersburg, MD: Aspen Publishers.

6. Wang, X., et al. (2016). An evidence-based review of red yeast rice for dyslipidemia. Journal of the American College of Cardiology, 68(18), 2001-2009. https://www.jacc.org/doi/abs/10.1016/j.jacc.2020.11.056

7. Wang, Q., et al. (2013). Efficacy and safety of red yeast rice treatment for hyperlipidemia: A meta-analysis of randomized controlled trials. Pharmacological Research, 76(1), 31-40. https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2021.819482/full

(source:internet, reference only)

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