Rehmannia Glutinosa for High Blood Pressure? What the Research Says

Key Findings

This meta-analysis found that Chinese herbal medicine (CHM), including Rehmannia glutinosa, combined with antihypertensive drugs, improved blood pressure, blood pressure variability, postmenopausal symptoms, quality of life, and hormone levels in postmenopausal women compared to antihypertensive drugs alone. Rehmannia glutinosa was the most frequently used single herb. However, the evidence is limited by methodological flaws in the included trials, and the authors caution that further high-quality research is needed to confirm these results.

Study Design

• Type: Systematic review and meta-analysis of randomized controlled trials (RCTs).
• Sample Size: 3,823 participants across 39 RCTs.
• Population: Postmenopausal women in China.
• Duration: Studies included were published up to December 17, 2017; analysis conducted in 2019.
• Methodology: Researchers searched seven databases for trials evaluating CHM (including Rehmannia glutinosa) for postmenopausal hypertension. Outcomes included blood pressure, hormone levels, and symptom scores.

Dosage & Administration

The summary does not specify exact dosages or administration methods of Rehmannia glutinosa used in the individual trials. However, it notes that CHM was typically administered as decoctions (e.g., Er-xian decoction) or single-herb formulations.

Results & Efficacy

• Blood Pressure: CHM + antihypertensive drugs significantly reduced systolic (SBP) and diastolic blood pressure (DBP) compared to drugs alone (p < 0.05).
• Blood Pressure Variability: CHM combination therapy lowered variability (standard deviation of SBP/DBP) with statistical significance (p < 0.05).
• Postmenopausal Symptoms: Kupperman Index scores improved (p < 0.05), indicating reduced symptoms like hot flashes and insomnia.
• Quality of Life: SF-36 scores increased, suggesting better physical and mental health outcomes (p < 0.05).
• Hormone Levels: CHM raised estradiol levels and reduced follicle-stimulating hormone (FSH) (p < 0.05).
• Safety: No severe adverse effects were reported, though safety data was limited.

Limitations

1. Methodological Flaws: Most included RCTs had unclear or high risk of bias due to poor reporting of randomization, blinding, and follow-up.
2. Heterogeneity: Variability in CHM formulations, dosages, and study populations may affect result consistency.
3. Single-Herb Analysis: Rehmannia glutinosa was the most common herb, but its individual efficacy could not be isolated from multi-herb formulas.
4. Short Follow-Up: Duration of trials was not specified, limiting conclusions on long-term safety or efficacy.
5. Geographic Restriction: All studies were conducted in China, raising questions about generalizability to other populations.

Clinical Relevance

This study suggests that Rehmannia glutinosa, as part of CHM, may complement antihypertensive drugs in managing postmenopausal hypertension. However, the lack of detailed dosing data and methodological weaknesses in the original trials mean these results should be interpreted cautiously. Patients should consult healthcare providers before using CHM due to potential herb-drug interactions and the need for personalized treatment. Future research should focus on standardized Rehmannia formulations in rigorously designed RCTs to clarify its role.

Note: The URL provided was not accessible for deeper review, so details on specific dosages, trial durations, or adverse events are limited to the summary provided.