Long Yam Rhizome Extract
Also known as: Long Yam Rhizome Extract, Dioscorea alata, Chinese yam extract, Shanyao, yam extract, Dioscorea opposita
Overview
Long Yam Rhizome Extract is derived from the tuberous root (rhizome) of *Dioscorea* species, primarily *Dioscorea opposita* or *Dioscorea alata*. It is a botanical dietary supplement traditionally used in East Asian medicine, particularly in Traditional Chinese Medicine (TCM) where it is known as Shanyao. Key bioactive compounds include steroidal saponins like diosgenin, proteins such as dioscorin, and various polysaccharides. The extract is primarily investigated for its potential to improve glycemic control in type 2 diabetes mellitus (T2DM), modulate lipid profiles, and support cognitive function. Preclinical research indicates it possesses hypoglycemic, anti-inflammatory, and lipid-lowering properties, along with antioxidant effects. While animal studies show promising results, human clinical trials specifically on isolated Long Yam Rhizome Extract are limited, with most human data coming from studies on multi-herb formulations containing *Dioscorea*.
Benefits
Long Yam Rhizome Extract shows significant promise, particularly in metabolic health. A systematic review of 10 rodent studies consistently demonstrated improvements in glycemic parameters, including statistically significant reductions in fasting blood glucose, enhanced glucose tolerance, and improved insulin levels. These studies also reported improvements in lipid profiles, such as reductions in total cholesterol, triglycerides, and LDL, alongside increases in HDL. Additionally, reductions in inflammatory markers like IL-1β and NF-κB were observed. While animal studies show robust benefits, human evidence is primarily derived from meta-analyses of multi-herb formulations containing *Dioscorea*. For instance, a meta-analysis of Chinese medicinal herbs, including *Dioscorea*, showed improved HDL levels (mean difference 0.15 mmol/L, 95% CI 0.08 to 0.22) when combined with hypoglycemic agents in T2DM patients. The evidence is strongest in rodent models of T2DM, suggesting potential for human application, though direct human RCTs on isolated extract are needed to confirm these effects and establish clinical significance.
How it works
Long Yam Rhizome Extract exerts its effects primarily by modulating glucose and lipid metabolism. It is believed to enhance insulin sensitivity and secretion, thereby improving glycemic control. The extract influences glucose metabolism enzymes and reduces oxidative stress and inflammation, which are key factors in metabolic dysfunction. Its active compounds, such as diosgenin and related saponins, are thought to modulate insulin receptor signaling pathways, inhibit the NF-κB inflammatory signaling pathway, and regulate genes involved in lipid metabolism. These actions collectively impact pancreatic β-cells, liver glucose metabolism, adipose tissue lipid metabolism, and systemic inflammatory pathways. The oral bioavailability of diosgenin and polysaccharides can be variable, and specific pharmacokinetic data for the extract are still limited.
Side effects
Long Yam Rhizome Extract is generally considered safe based on animal studies and its long history of traditional use. Human safety data from studies involving herbal formulations containing *Dioscorea* indicate a favorable safety profile with fewer adverse effects compared to some Western medicines. No significant common, uncommon, or rare side effects have been consistently reported in the reviewed literature. Mild gastrointestinal discomfort is a possible, though not well-documented, side effect. There is a potential for interaction with hypoglycemic agents due to its additive effects on blood glucose levels, so caution is advised, and medical supervision is recommended if taken concurrently with such medications. No specific contraindications have been identified, but due to a lack of sufficient data, caution is advised for pregnant and lactating individuals. Most human studies have been conducted in adults with T2DM, so data for other special populations are limited.
Dosage
The optimal dosage for isolated Long Yam Rhizome Extract is not well established, as most research involves animal models or multi-herb formulations. Animal studies have utilized variable doses standardized to active compounds like diosgenin or polysaccharides, making direct translation to human dosing challenging. Clinical studies on herbal formulae containing *Dioscorea* also show a wide range of dosages, preventing a consensus on isolated extract dosing. A minimum effective dose and maximum safe dose for the isolated extract have not been defined. Typically, it is administered orally on a daily basis. For consistency and efficacy, extracts standardized to specific active compounds like diosgenin or polysaccharides are preferred. Bioavailability may be enhanced when consumed with fat-containing meals. No specific cofactors are identified as required for its efficacy.
FAQs
Is Long Yam Rhizome Extract effective for diabetes?
Animal studies strongly support its benefits for glycemic control. Human evidence is indirect, primarily from studies on multi-herb formulations containing *Dioscorea*, showing promising but modest effects.
Is it safe to take with diabetes medications?
It is likely safe, but it may potentiate the hypoglycemic effects of diabetes medications. Medical supervision is recommended to monitor blood glucose levels and adjust medication if necessary.
How long before effects are seen?
Animal studies show effects within weeks to months. Human data are limited, but effects from herbal formulations typically manifest over several weeks to months of consistent use.
Does it help with weight loss?
Some animal studies suggest a reduction in adiposity. However, there is currently a lack of human evidence to support its use specifically for weight loss.
Research Sources
- https://pmc.ncbi.nlm.nih.gov/articles/PMC9346617/ – This systematic review of 10 rodent RCTs investigated the benefits of yam (Dioscorea) or its extract for glycemic control. It consistently found significant improvements in fasting blood glucose, glucose tolerance, and insulin levels, along with improved lipid and inflammatory markers in animal models of T2DM. The study highlights strong preclinical evidence for its metabolic benefits but notes the absence of human RCTs on isolated extract.
- https://onlinelibrary.wiley.com/doi/10.1155/2016/2146204 – This systematic review and meta-analysis of 11 RCTs evaluated the efficacy and safety of Chinese medicinal herbs, including *Dioscorea*, for hyperuricemia. It concluded that Chinese herbs showed similar uric acid-lowering effects but better overall efficacy and fewer adverse effects compared to Western medicines. The study provides insights into the safety profile of *Dioscorea* within multi-herb formulations.
- https://pubmed.ncbi.nlm.nih.gov/34521490/ – This article, also referenced as part of the systematic review on yam consumption for glycemic control, reinforces the findings from rodent studies. It emphasizes the consistent and significant improvements in various glycemic parameters, lipid profiles, and inflammatory markers observed in animal models, underscoring the potential therapeutic value of *Dioscorea* extracts.
- https://www.frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2020.553288/full – This meta-analysis of 53 RCTs investigated the additional benefits of Chinese Medicine Formulae including Shanyao (*Dioscorea*) in T2DM patients. It found that CHM formulae combined with hypoglycemic agents improved HDL levels and glycemic control more effectively than hypoglycemic agents alone. The study suggests that *Dioscorea* contributes to the overall efficacy of multi-herb formulations in managing T2DM.