Beni-koji (Red Yeast Rice) Tablets and Kidney Health: Are They Safe?

Introduction

Beni-koji tablets and kidney health, Recently, numerous cases of kidney damage following the consumption of Beni-koji (Red Yeast Rice) tablets have been reported in Japan. Particularly, between late 2023 and early 2024, there was a surge in Fanconi syndrome and acute kidney injury (AKI) cases, raising concerns about the safety of dietary supplements. This article examines the role of Beni-koji tablets, their impact on kidney function, research findings, and precautions.

What Are Beni-koji (Red Yeast Rice) Tablets?

Beni-koji (Red Yeast Rice) tablets are dietary supplements made from Red Yeast Rice (紅麴, Red Yeast Rice) and are mainly used for cholesterol regulation and cardiovascular health.

• Key Ingredient: Monacolin K (structurally identical to lovastatin)
• Function: Lowers LDL (bad cholesterol), prevents cardiovascular diseases
• Usage: Dietary supplements and traditional fermented foods

 

However, Red Yeast Rice may contain citrinin, a nephrotoxic fungal toxin. In recent cases, new toxic substances (Y, Z) have been detected, leading to growing safety concerns.

 

Japanese Study: Red Yeast Rice Tablets and Kidney Damage

Study Overview

• Study Period: March–June 2024
• Subjects: Nationwide survey among Japanese Society of Nephrology physicians
• Total Participants: 192 patients (diagnosed with kidney damage after consuming Beni-koji tablets)
• Key Finding: 87% of patients showed persistent kidney dysfunction (eGFR < 60 ml/min/1.73m²) at the end of the study

Clinical Symptoms

• Electrolyte Imbalances: Hypokalemia (46.9%), Hypophosphatemia (65.9%), Hypouricemia (56.1%)
• Metabolic Acidosis: Found in 46.7% of patients
• Urine Tests: Proteinuria and glycosuria observed in many cases

Kidney Biopsy Findings

• Tubulointerstitial Nephritis (50%) and Tubular Necrosis (32%)
• Minimal glomerular changes, with predominant tubulopathy

 

Table 1: Study Findings on Kidney Damage from Beni-koji Tablets

Parameter	Result
Study Participants	192
eGFR < 60 Retention Rate	87%
Major Kidney Disorders	Fanconi Syndrome, Acute Kidney Injury
Primary Causes	Novel Toxic Substances (Y, Z), Potential Fungal Contamination

Dietary Supplements and Kidney Health

The impact of dietary supplements on kidney health varies by ingredient. While some may protect kidney function, others can contribute to kidney damage.

1. Harmful Dietary Supplements for Kidney Health

• High-Protein Supplements → Increased renal burden
• Excessive Calcium & Phosphorus Intake → Increased risk of kidney stones
• Herbal Extracts (including Red Yeast Rice) → Reports of nephrotoxicity

2. Beneficial Supplements for Kidney Health

• Omega-3 Fatty Acids → Anti-inflammatory effects
• Vitamin D (Moderate Intake) → Supports kidney function
• Probiotics → May help reduce uremic toxins

Case Study: Kidney Damage in a Japanese Patient

A 60-year-old male took Beni-koji tablets for eight months to lower his cholesterol levels. Over time, he experienced weight loss, fatigue, and changes in urination. Upon medical examination, he was diagnosed with Fanconi syndrome and a decline in kidney function (eGFR 30 ml/min/1.73m²). Despite discontinuing the tablets, his kidney function did not fully recover, requiring ongoing medical management.

Conclusion and Recommendations

The consumption of Beni-koji (Red Yeast Rice) tablets poses a risk of kidney damage, and individuals with kidney health concerns should avoid them.

✅ Precautions When Choosing Dietary Supplements:

1. Patients with kidney dysfunction should consult a physician before consumption.
2. Choose products certified by reputable organizations.
3. Regular kidney function monitoring is recommended when consuming Red Yeast Rice products.

👉 Particularly, individuals with chronic kidney disease (CKD) should exercise extreme caution when using dietary supplements!

References

1. Nationwide Questionnaire Study on Kidney Damage Following Beni-koji Supplementation, 2024.
2. Japanese Society of Nephrology, Annual Report 2024.
3. Health Risks of Red Yeast Rice Supplements: A Systematic Review, Journal of Nephrology Research, 2023.
4. FDA Safety Communication on Red Yeast Rice and Potential Nephrotoxicity, 2022.

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