Resveratrol is a natural compound produced by certain plants in response to environmental stress, injury, or fungal attack. This substance is classified as a polyphenol and a phytoalexin, which are molecules that offer protective benefits to the plant. Resveratrol is widely studied for its potential effects on human health, primarily attributed to its antioxidant and anti-inflammatory mechanisms. It is found in various food sources, including the skin of red grapes, peanuts, blueberries, and the roots of Japanese knotweed (Polygonum cuspidatum). Researchers are exploring its biological activities for possible applications in supporting human health.
Understanding the Trans and Cis Forms
Resveratrol exists in two distinct molecular structures, known as isomers: the cis- and trans- forms. While they share the same chemical formula, they have a different spatial arrangement around a central double bond. The trans-resveratrol isomer is the preferred compound for dietary supplements and has garnered the most scientific attention.
The trans configuration is significantly more stable and biologically active within the body compared to its cis counterpart. The cis form is less stable and can be produced when trans-resveratrol is exposed to ultraviolet light, which leads to a loss of potency. Supplements are typically standardized to contain a high concentration of trans-resveratrol because this form is considered the most effective for absorption and utilization by human tissues.
Bioavailability and Metabolism in the Body
The study of trans-resveratrol’s effectiveness is complicated by poor oral bioavailability. While the compound is absorbed efficiently from the gut—often over 70% of an oral dose—very little of the active, unmetabolized form reaches the bloodstream. This is primarily due to rapid and extensive processing that occurs in the intestinal wall and the liver.
This process is called first-pass metabolism, where enzymes attach sulfate and glucuronide molecules to the trans-resveratrol. This conversion transforms the active compound into inactive metabolites that are quickly eliminated from the body. Consequently, the concentration of free, active trans-resveratrol in the blood remains in the nanomolar range, while inactive metabolites are found at much higher micromolar concentrations. Researchers are exploring methods like micronization or encapsulation in liposomes to bypass this rapid metabolism and increase the amount of active compound available to the body’s tissues.
Current Research on Systemic Health Effects
Research into trans-resveratrol focuses on its ability to modulate cellular pathways through its established antioxidant and anti-inflammatory effects. The compound helps neutralize harmful free radicals and influences signaling molecules that regulate the body’s inflammatory response. These properties form the basis for investigations into its systemic benefits across multiple organ systems.
Cardiovascular health is a major area of study, where research suggests trans-resveratrol may improve vascular function. It promotes the production of nitric oxide, a molecule that signals blood vessel walls to relax, potentially supporting healthy blood flow and blood pressure. Metabolic health is another focus, with studies exploring its potential to enhance insulin sensitivity and improve the body’s glucose metabolism.
Trans-resveratrol is also studied for its connection to sirtuins, a family of proteins involved in cellular health, DNA repair, and energy metabolism, particularly Sirtuin 1 (SIRT1). While the exact relationship and clinical outcomes in humans are still being explored, the activation of these pathways is an area of ongoing investigation into the compound’s broader health effects.
Practical Considerations for Supplementation
For individuals considering a supplement, ensuring the product contains a high purity of the trans- form is important to maximize potential activity. Studies have used a wide range of dosages, but typical amounts often fall between 250 milligrams and 1,000 milligrams per day. The effectiveness of these doses is debated due to the compound’s low bioavailability.
Though generally well-tolerated, high doses exceeding 2.5 grams per day have been linked to mild gastrointestinal issues, such as flatulence or abdominal cramping. Potential drug interactions are a concern, as trans-resveratrol may slow down blood clotting. Individuals taking blood-thinning medications or drugs metabolized by the liver should consult a healthcare professional before beginning supplementation to avoid adverse effects.