Grape Skin Concentrate
Also known as: Grape Skin Concentrate, Grape skin extract, Grape polyphenols, Resveratrol, Vitis vinifera skin extract
Overview
Grape Skin Concentrate is a dietary supplement derived from the skins of red or purple grapes, known for its high concentration of polyphenolic compounds such as flavonoids, anthocyanins, and stilbenoids, particularly resveratrol. It is primarily utilized for its antioxidant and anti-inflammatory properties, with potential benefits for cardiometabolic health. Research indicates its ability to reduce markers of inflammation and oxidative stress in humans. While studies show promising results, the research maturity is moderate, with existing randomized controlled trials and meta-analyses, though heterogeneity in formulations and dosages across studies limits definitive conclusions. It is generally well-tolerated at typical supplement doses.
Benefits
Grape Skin Concentrate offers several evidence-based benefits, primarily due to its rich polyphenol content. A systematic review and meta-analysis found that grape polyphenol supplementation significantly reduced C-reactive protein (CRP) levels, a key inflammatory biomarker, with a dose and duration-dependent effect (p < 0.001). This suggests a strong anti-inflammatory action. Another meta-analysis of randomized controlled trials (n=633) indicated that grape products improved oxidative stress markers, though these effects were partial and require further confirmation. Preclinical studies suggest that resveratrol, a key component, may have anticancer and anti-aging properties, showing dose-dependent effects on cell growth and apoptosis. These benefits have been observed in both healthy individuals and those with cardiovascular risk factors. The clinical significance of CRP reduction varies by individual baseline inflammation, with longer duration (up to 16 weeks) and higher doses correlating with greater improvements.
How it works
Grape Skin Concentrate exerts its effects primarily through its rich polyphenol content, which acts as potent antioxidants by scavenging reactive oxygen species. It modulates inflammatory pathways, leading to the downregulation of inflammatory markers like C-reactive protein (CRP). Resveratrol, a key stilbenoid, activates endothelial nitric oxide synthase (eNOS), improving endothelial function, and influences MAPK pathways. These compounds interact with the cardiovascular system by improving endothelial function, the immune system by reducing inflammation, and metabolic pathways, potentially improving insulin sensitivity in some models. While polyphenols like resveratrol have low oral bioavailability, they can achieve biologically relevant serum concentrations transiently after ingestion.
Side effects
Grape Skin Concentrate is generally well tolerated in humans at typical supplement doses. The most common side effects, reported at very high doses of resveratrol, are mild gastrointestinal symptoms such as diarrhea. Uncommon side effects (1-5%) have not been consistently reported in randomized controlled trials, and rare side effects (<1%) or serious adverse events have not been reported in reviewed trials. However, caution is advised due to potential interactions with anticoagulants and antiplatelet drugs, as polyphenols can affect platelet aggregation. Contraindications are not well-defined, but pregnant or breastfeeding women should exercise caution due to a lack of sufficient data. While generally safe, some preclinical studies in elderly mice showed adverse vascular effects at very high doses, suggesting potential age-related considerations.
Dosage
The minimum effective dose for Grape Skin Concentrate is not precisely standardized, as meta-analyses included a wide range of grape polyphenol doses (0.1 g to 500 g), with dose-dependent effects observed. Lower doses may have limited efficacy. Optimal dosage ranges for reducing CRP and improving oxidative stress appear to be in the moderate range, though exact milligram amounts of polyphenols are not consistent across studies. Human studies report that trans-resveratrol, a key component, is well-tolerated up to 2000 mg per day without serious adverse effects. Benefits tend to increase with longer duration of use, with studies ranging up to 16 weeks. Various forms, including concentrate, extract, powder, and juice, have been studied, with varying bioavailability and potency. Co-administration with quercetin and food may enhance resveratrol bioavailability. No specific cofactors are established as required for efficacy.
FAQs
Is grape skin concentrate safe for long-term use?
Current evidence supports its safety for up to several months. However, long-term data beyond this period are limited, so caution is advised for extended use.
How quickly can benefits be expected?
Some improvements in biomarkers, such as C-reactive protein, can be observed within 2-4 weeks of consistent use, with more significant effects typically seen over longer periods.
Does grape skin concentrate help with weight loss?
Based on the reviewed studies, there is no consistent evidence to suggest that grape skin concentrate directly contributes to weight loss.
Is it better than grape seed extract?
Both grape skin concentrate and grape seed extract contain polyphenols but differ in their specific compositions. Direct comparative randomized controlled trials are lacking, so a definitive 'better' cannot be stated.
Can it replace medications for inflammation?
No, grape skin concentrate should not replace prescribed anti-inflammatory medications. It may serve as an adjunct therapy but is not a substitute for medical treatment.
Research Sources
- https://www.cambridge.org/core/journals/british-journal-of-nutrition/article/effect-of-grape-products-containing-polyphenols-on-creactive-protein-levels-a-systematic-review-and-metaanalysis-of-randomised-controlled-trials/59C5DC9AEC42490227F9CE5B8C35D87B – This systematic review and meta-analysis of randomized controlled trials investigated the effect of grape polyphenol supplementation on C-reactive protein (CRP) levels. It found a significant reduction in CRP, a key inflammatory biomarker, with the effect size positively correlated with both dose and duration of supplementation. The study was of high quality with no publication bias detected, despite some heterogeneity in grape product types.
- https://pmc.ncbi.nlm.nih.gov/articles/PMC7971097/ – This systematic review and meta-analysis of randomized controlled trials, involving 633 participants, examined the impact of grape polyphenols on oxidative stress biomarkers over durations of 2 to 16 weeks. The findings indicated a partial improvement in oxidative stress markers. The study concluded that further well-designed trials are needed for definitive confirmation, noting moderate quality due to variability in study quality and risk of bias.
- https://pmc.ncbi.nlm.nih.gov/articles/PMC10610408/ – This comprehensive pharmacological review focused on resveratrol, a key polyphenol found in grape skin. It detailed resveratrol's antioxidant, anticancer, and anti-aging effects observed in preclinical models, highlighting dose-dependent biphasic effects. The review also noted that resveratrol is generally well-tolerated in humans at doses up to 2000 mg/day, while acknowledging some adverse effects in animal models at very high doses.
Supplements Containing Grape Skin Concentrate
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