Stilbenes are a major class of polyphenols found in natural products such as grapes. Among the approximately 400 known stilbenes, resveratrol is perhaps the most popular and well researched.
Over the last several decades, resveratrol has received much attention as a health-promoting phytonutrient. Studies suggest resveratrol may be beneficial for a variety of health conditions including cancer, cardiovascular disease, cognitive decline, diabetes, and obesity.
Stilbenes such as resveratrol are thought to enhance the function of mitochondria, the powerhouses of our cells. A 2019 study found that muscadine fruit extract “enhances mitochondrial function and cellular bioenergetics in cardiomyoblast cells during stress”.
The below abstract on resveratrol was published in the Journal Molecules in 2019
Stilbenoids such as t-piceid, t-resveratrol, ε-viniferins, and t-pterostilbene can differ significantly among grape cultivars and years due to variation in environmental conditions and subsequent stressors encountered during a year. This study evaluated diverse muscadine grape cultivars for their ability to consistently produce four major stilbenoids such as t-piceid, t-resveratrol, ε-viniferins, and t-pterostilbene irrespective of environmental changes that can impact their production.
Resveratrol functions by exerting antioxidant activity and influencing key metabolic and regulatory pathways in the human body. Resveratrol has multiple antioxidant effects including scavenging dangerous reactive oxygen species (ROS), enhancing the activity of endogenous enzymes that metabolize ROS, and suppressing the activity of enzymes that play a role in ROS production.
The antioxidant protection provided by resveratrol, along with its regulation of important signaling pathways, likely accounts for it many putative health benefits.
Some researchers have even suggested high intakes of resveratrol from red wine may be responsible for the so-called “French Paradox” – the observation that heart disease rates are relatively low in France despite a high-fat diet among the French population.
Resveratrol affects a number of key metabolic and regulatory pathways in the human body. One such pathway, known as SIRT1, regulates many basic biological functions including cell survival and lifespan, stress resilience, immune function, and circadian rhythms. Another pathway, called nuclear factor kappa b (or NF-kB), is a central modulator of inflammation in the body.
Other important pathways influenced by resveratrol include PPAR-ɣ, TGF-β, PI3K/Akt, cyclooxygenase (COX), and mTOR. The plethora of signaling pathways affected by resveratrol most likely accounts for its many putative health benefits.
One of the most heavily investigated aspects of resveratrol activity has been in the area of carcinogenesis. Several decades of preclinical (in vitro and animal) research suggest resveratrol has both chemopreventive and chemotherapeutic properties. Indeed, studies indicate resveratrol inhibits carcinogenesis at all major stages (initiation, promotion and progression).
While data from human trials is still somewhat scant, a number of investigations utilizing resveratrol for the prevention or treatment of breast, prostate, and colorectal cancer have shown promising results.
Another major area of research involving resveratrol is cardiovascular health. Resveratrol affects many molecular targets and biological pathways associated with cardioprotection. For example, resveratrol has been shown to reduce production of vascular adhesion molecules (VCAM), which promote atherosclerosis by attracting lipid to the walls of arteries. Studies also suggest resveratrol may improve heart health through its antioxidant and anti-inflammatory effects.
One clinical trial found a combination of phytonutrients comprised mainly of resveratrol and extracts from grape seeds and skin significantly lowered diastolic blood pressure in a group of hypertensive subjects. Further clinical trials will help expand our understanding of resveratrol’s role in helping to prevent and treat cardiovascular diseases.
One of the most challenging health problems of the modern age is diabetes. Poor regulation of blood glucose affects over 400 million people worldwide and has become the 7th leading cause of death in the U.S. Thus, natural ingredients like resveratrol that demonstrate a capacity to manage blood sugar levels have become the focus of intense nutritional research.
Both preclinical and clinical studies indicate resveratrol effectively reduces levels of glycated hemoglobin (HbA1c), a prominent biomarker of glycemic control. Additional studies suggest supplementing with resveratrol mimics the effects of calorie restriction, and thus may be of benefit for weight loss in obese or overweight people. Obesity is a known risk factor for diabetes as well as many other health problems.
Resveratrol continues to be one of the most interesting and widely-studied natural products for human health. Over 25 years of research suggests that consumption of resveratrol, from either the diet or nutritional supplements, is important for optimum nutrition and can promote a wide range of health benefits. Continuing clinical research will help validate the wealth of information derived from preclinical studies and clarify the therapeutic potential of resveratrol.
Ellagitannins: The unsung polyphenol powerhouses
Tannins are a large group of polyphenolic compounds found in natural foods like fruits and vegetables. One important class of tannins, the ellagitannins, are concentrated in foods like muscadine grapes, berries, pomegranates, and walnuts. Ellagitannins exhibit a wide range of beneficial health effects, including antioxidant, anti-inflammatory, antimicrobial, and antiatherogenic activities.
Once consumed, ellagitannins are largely broken down into smaller components, like ellagic acid, that can be absorbed into the systemic circulation. These bioavailable metabolites are likely responsible for many of the health benefits of ellagitannins. Ellagic acid, for example, has been shown to exhibit broad-spectrum antioxidant activity. In addition, preclinical and clinical studies suggest ellagic acid may exert chemoprotective, cardioprotective, hepatoprotective, and neuroprotective effects.
Oligomeric Proanthocyanidins (OPC’s): Abundant Antioxidants in All Grapes
Oligomeric proanthocyanidins (known as OPCs) are flavonoid polyphenolic substances that are abundant in the plant kingdom and in the human diet. Proanthocyanidins are found in high concentrations in fruits such as apples, pears, and grapes, and in chocolate, wine, and tea.
Research shows OPCs possess antioxidant, antimutagenic, anticarcinogenic, anti-inflammatory, and antiviral properties. OPCs are thus a potentially valuable therapeutic tool to address a variety of conditions such as cancer, cardiovascular disease, infection, and inflammation. The potent antioxidative properties of OPCs account for their therapeutic benefit in disease states characterized by oxidative stress. OPCs also demonstrate potent free radical scavenging ability. Studies in humans have shown an increased free-radical trapping capacity after consumption of red wine containing OPCs.
First cultivated and consumed by Native Americans for hundreds of years, muscadines (Vitis rotundifolia Michx.) go by many names originating from the first tribes, including scuppernongs, bullets, or bullises. Muscadines are also known in various parts as bull grapes, bullet grapes, or Southern fox grapes.
This public resource is made possible by contributions from the
“Papa” Jacob Willis Paulk, Sr. family, the First Family of Muscadines.