Guidelines for Using Dihydromyricetin and L-cysteine Together for Medical Treatment
There are currently no established clinical guidelines specifically addressing the combined use of dihydromyricetin and L-cysteine for medical treatment, and their combined use lacks sufficient evidence for safety and efficacy.
L-cysteine: Evidence-Based Recommendations
Parenteral Nutrition Applications
- Bioavailable cysteine (50-75 mg/kg/day) is recommended for preterm neonates receiving parenteral nutrition, with higher doses showing no additional benefits 1
- L-cysteine is considered important for glutathione synthesis, which has antioxidant properties and maintains redox potential and calcium homeostasis 1
- The stability of cysteine is low in solution, making it challenging to administer, though it can be added to amino acid solutions just before administration 1
Clinical Considerations for L-cysteine
- Cysteine supplementation significantly increases plasma cysteine levels, while N-acetylcysteine (NAC) supplementation does not 1
- NAC supplementation has not shown significant benefits for clinical outcomes such as:
- Death by 36 postmenstrual weeks
- Broncho-pulmonary dysplasia
- Retinopathy of prematurity
- Necrotizing enterocolitis requiring surgery
- Periventricular leukomalacia
- Intraventricular hemorrhage 1
N-acetylcysteine (NAC) Limitations
- NAC has poor bioavailability (approximately 50%) compared to L-cysteine 1
- High-quality evidence demonstrates that NAC does not prevent contrast-induced acute kidney injury (AKI) in patients undergoing angiographic procedures 1
- The American College of Cardiology Foundation/American Heart Association explicitly states: "Administration of N-acetyl-L-cysteine is not useful for the prevention of contrast-induced AKI" (Level of Evidence: A) 1
Dihydromyricetin: Limited Clinical Evidence
- Dihydromyricetin (DHM) is a flavonoid component found in herbal medicines with potential hepatoprotective properties 2
- Animal studies suggest DHM may:
Safety Concerns for Combined Use
- A 2021 review of hangover treatments found that many products containing DHM and NAC do not report dosages (59% and 73% respectively) 4
- No peer-reviewed human data demonstrates either safety or efficacy of products containing these ingredients 4
- Many hangover products exceed daily recommended intake levels for various ingredients, with 62.2% of products containing excessive vitamin doses 4
- DHM has poor bioavailability, which limits its clinical utility despite promising mechanisms 5
Clinical Implications and Recommendations
For parenteral nutrition in preterm neonates:
- L-cysteine supplementation at 50-75 mg/kg/day is appropriate 1
- Higher doses do not provide additional benefits
For contrast-induced nephropathy prevention:
- NAC is not recommended based on high-quality evidence 1
- Hydration with isotonic saline and minimizing contrast volume remain the only proven strategies
For combined DHM and L-cysteine use:
- No established guidelines exist for combined therapy
- Lack of human clinical trials demonstrating safety or efficacy
- Potential drug interactions remain unstudied
Practical Considerations
- If considering these supplements:
- Be aware that many commercial products containing these ingredients make unsubstantiated disease modification claims (64.6% of products) 4
- NAC is registered as a drug by the FDA and is prohibited as an ingredient in dietary supplements or foods in the US 4
- DHM's poor bioavailability and rapid clearance limit its effectiveness when administered orally 5
Research Gaps
- Human clinical trials are needed to establish:
- Appropriate dosing regimens
- Safety profiles for combined use
- Efficacy for specific medical conditions
- Potential drug interactions
Until high-quality clinical evidence becomes available, the combined use of dihydromyricetin and L-cysteine cannot be recommended for any specific medical treatment.