Resveratrol is a natural compound found in various plants, recognized as an antioxidant-rich polyphenol. It is particularly present in the skin of red grapes. This article explores the quantity of resveratrol in wine, the factors influencing its concentration, and its implications as a source.
Typical Resveratrol Levels
The amount of resveratrol in wine can vary significantly, but red wines generally contain more than white or rosé wines. A typical 5-ounce glass of red wine may contain between 0.03 and 1.07 milligrams (mg) of resveratrol. Some estimates suggest a broader range, from 0.25 to 1.5 mg per typical glass, with an average around 1.9 mg per liter. The concentration can range from undetectable levels to more than 10 mg per liter.
White wines, by contrast, contain considerably less resveratrol, typically ranging from 0.01 to 0.27 mg per 5-ounce glass. This is roughly ten times lower than the levels found in red wines. Rosé wines also have very low amounts, averaging around 0.20 mg per bottle, similar to white wines. These figures represent averages, and the actual content can differ widely depending on many variables.
Factors Influencing Resveratrol Content
Several factors contribute to the varying levels of resveratrol in wines. The grape variety plays a significant role, as resveratrol is concentrated primarily in the grape skins. Dark red and purple grapes naturally possess higher concentrations. Varieties such as Malbec, Petite Sirah, St. Laurent, and Pinot Noir are known for having some of the highest resveratrol content, with Malbec grapes noted for their thick skins. Pinot Noir can contain up to 1.5 mg per liter, while Cabernet Sauvignon and Merlot typically have lower amounts.
Climate and geographical conditions also impact resveratrol production in grapes. Grapes grown in cooler climates or at higher altitudes tend to accumulate more resveratrol, partly as a response to environmental stress. Sunlight exposure and ultraviolet (UV) light can also stimulate the grapes to produce higher concentrations of the compound. The vine’s natural defense mechanisms against fungal infections further influence resveratrol levels. Grapes produce resveratrol as a phytoalexin, a substance protecting the plant from pathogens like fungi. Stress conditions, including fungal pressure, therefore trigger its synthesis.
The winemaking process significantly affects the final resveratrol content. Since resveratrol resides mainly in grape skins, the duration of skin contact during fermentation is a primary determinant. Red wines undergo longer fermentation periods with the grape skins, allowing more resveratrol to be extracted into the wine. Conversely, white wines have minimal to no skin contact during their production. The specific yeast strains used and the aging methods can also play a part in the compound’s final concentration.
Understanding Wine as a Resveratrol Source
Given the variability and generally modest concentrations of resveratrol in wine, it is not typically considered a reliable or primary source for obtaining significant amounts of the compound. The levels present are often low and can fluctuate unpredictably. To achieve the higher therapeutic doses of resveratrol, often ranging from hundreds of milligrams to several grams, one would need to consume an impractical and unhealthy quantity of wine.
For those seeking targeted resveratrol intake, supplements offer a more concentrated and safer alternative without the associated alcohol consumption. While red wine does contain resveratrol, its contribution to overall resveratrol intake is limited compared to dedicated supplements. While wine can be part of a balanced diet, it is not an efficient means to achieve high levels of resveratrol.