Rehmannia Extract
Also known as: Rehmannia glutinosa, Chinese Foxglove, Di Huang, Rehmannia root, Rehmanniae Radix Praeparata
Overview
Rehmannia glutinosa, also known as Chinese Foxglove or Di Huang, is a plant widely used in Traditional Chinese Medicine (TCM). Native to China, it has been employed for over a millennium to address various health conditions, including diabetes, kidney diseases, and ovarian hypofunction. The root of the plant is the primary part used, containing bioactive compounds such as catalpol, an iridoid glycoside considered its main active component. Rehmannia is often processed before use, resulting in Rehmanniae Radix Praeparata, which is believed to enhance its therapeutic effects. Research on Rehmannia glutinosa is ongoing, with a mix of preclinical and clinical studies. While existing evidence supports its potential benefits, more high-quality clinical trials are needed to fully establish its efficacy and safety.
Benefits
Rehmannia glutinosa offers several potential health benefits, primarily related to diabetic nephropathy and ovarian hypofunction. Catalpol, its main active compound, has shown promise in improving renal function in animal models by reducing serum creatinine, blood urea nitrogen, proteinuria, and fasting blood glucose levels, as well as alleviating renal pathological changes and reducing inflammation and oxidative stress. Processed Rehmannia glutinosa (Rehmanniae Radix Praeparata) has been found to improve ovarian function by enhancing granulosa cell proliferation, exhibiting antioxidative and anti-aging properties, and modulating the immune and inflammatory microenvironment. Preclinical evidence suggests potential protective effects against cardiovascular and cerebrovascular diseases, and neuroprotective effects from catalpol may benefit cognitive function. These benefits are supported by preclinical systematic reviews, meta-analyses, and some clinical trials, but further rigorous clinical trials are needed to confirm these findings.
How it works
Rehmannia glutinosa and its active compound, catalpol, exert their effects through multiple biological pathways. These include reducing inflammation and oxidative stress, improving podocyte apoptosis, regulating lipid metabolism, delaying renal fibrosis, and enhancing autophagy. In the context of ovarian hypofunction, Rehmannia enhances granulosa cell proliferation, exhibits antioxidative and anti-aging properties, and modulates the immune and inflammatory microenvironment. The herb interacts with the renal system by improving kidney function and reducing proteinuria and serum creatinine levels, and with the reproductive system by improving ovarian function and modulating hormonal balance. Catalpol can cross the blood-brain barrier and has good oral bioavailability.
Side effects
While Rehmannia glutinosa is generally considered safe in Traditional Chinese Medicine, its safety profile requires more rigorous clinical assessment. Human studies are limited, but preclinical studies have not shown significant adverse effects in animal models. Common, uncommon, and rare side effects are not well-documented in the reviewed studies. Drug interactions are not well-defined, so caution is advised when using it with other medications, and consultation with a healthcare provider is recommended. There are no well-documented contraindications, but caution should be exercised in patients with known allergies to plants in the same family or those with severe kidney or liver disease. Pregnant or breastfeeding women should use Rehmannia glutinosa under medical supervision due to the lack of comprehensive safety data.
Dosage
The minimum effective dose of Rehmannia glutinosa or catalpol is not well-established in human studies. Traditional Chinese medicine formulations often use processed Rehmannia glutinosa (Rehmanniae Radix Praeparata), but exact dosage ranges are not standardized and vary based on the specific condition being treated. There is no established maximum safe dose for Rehmannia glutinosa or catalpol in human studies. The timing of administration is not well-defined and may depend on the specific condition being treated. The herb can be administered in various forms, including raw root, processed root, and extracts. Oral administration is common, and catalpol has shown good bioavailability and absorption when taken orally. There is no specific information on required cofactors for its absorption or efficacy.
FAQs
Is Rehmannia glutinosa safe?
While generally considered safe, more clinical trials are needed to fully assess the safety profile of Rehmannia glutinosa. Consult with a healthcare provider before use.
How should I take Rehmannia glutinosa?
The timing and administration should be guided by traditional Chinese medicine practices or under the supervision of a healthcare provider for best results.
What results can I expect from taking Rehmannia?
Expected results include improvements in renal function for diabetic nephropathy and improvements in ovarian function for ovarian hypofunction, based on available research.
Is Rehmannia a cure-all?
No, Rehmannia glutinosa is not a cure-all. It should be used as part of a comprehensive treatment plan under medical guidance, not as a standalone treatment.
Research Sources
- https://pubmed.ncbi.nlm.nih.gov/32664082/ – This meta-analysis of 1222 patients (2382 eyes) found that Lycium-rehmannia pills combined with western medicine showed superior therapeutic efficiency compared to the control group in treating dry eye symptoms. The study acknowledges limitations due to the quality and quantity of the literature, and some controversial results regarding specific tests.
- https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2023.1192694/full – This preclinical systematic review using animal models found that catalpol significantly improved renal function in diabetic nephropathy models by reducing serum creatinine, blood urea nitrogen, proteinuria, and fasting blood glucose levels. The review identified methodological shortcomings and calls for more high-quality studies to confirm these findings.
- https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2024.1426972/full – This review of clinical applications and preclinical studies indicates that processed Rehmannia glutinosa showed significant clinical effectiveness in improving ovarian function and mitigating health risks associated with ovarian hypofunction diseases. The review highlights the need for further studies on toxicology and standardized clinical trials to fully establish efficacy and safety.
