Wednesday, 13 December 2017 15:19

Resveratrol – scientists and wine makers seek to increase the level to be biologically relevant

In an aging population, the risk of chronic diseases such as cardiovascular disease, diabetes, etc. needs to be prevented. The damages associated with such diseases occur in the body’s cells due to oxidative stress. Plant-derived polyphenols, in particular resveratrol, have received increased scientific attention as antioxidants and potential health benefits have been attributed to moderate wine consumption. However, the low amounts of resveratrol when drinking wine moderately may not be sufficient to prevent biological damage.

Aging and the associated chronic non-communicable or lifestyle diseases such as cardiovascular diseases, diabetes, oncological and neurodegenerative diseases, start as functional problems many years before their clinical manifestations. During aging, an accumulation of damages in molecular structures occur over time, which have a common denominator: the oxidative stress. This is the result of an increased free radical production and/or a decrease in the production of antioxidant molecules. Considering that the world’s population is growing at an unprecedented rate, where the number of individuals worldwide aged 65 and over is projected to double to approximately 17% by 2050, research into simple dietary and lifestyle interventions to reduce the risk of these chronic diseases is becoming increasingly important.

Although a system of “antioxidant defense” inside the human cells exists to protect themselves from damages caused by oxidative stress, such a defense system depends almost exclusively on the food supply of antioxidants. This makes the cells vulnerable to oxidative stress, if there is an insufficient supply. In other words – without an appropriate dietary antioxidant balance, the cellular structures of the body may be damaged.

A variety of foods and beverages of vegetable origin contain several polyphenolic compounds synthesized by plants and exert antioxidant effects. Among those resveratrol - which is naturally occurring in the fruits and leaves of edible plants, peanuts, mulberries, grapes and red wine - it is currently considered to be one of the most beneficial polyphenols for human health. Wine is the main sources of dietary resveratrol. The concentration in wine increases during fermentation with skins and seeds, but may subsequently decrease as some of the phenolic compounds combine with proteins and yeast hulls and precipitate. In addition, the concentration of total phenolic compounds continues to decrease with fining and filtration, and during maturation. As a result, the average concentration of total resveratrol in red wine is 7 mg/L, 2 mg/L in rose and 0.5 mg/L in white wine, but it ranges widely according to grape variety, geographical indication and vintage.

Potential benefits of moderately drinking red wine with meals have been partly ascribed to wine’s relatively large content of polyphenols such as resveratrol. However, the average intake of resveratrol with moderate wine consumption is only in the order of a few milligrams per day, which is not enough to support healthy biological actions. Consequently, nutraceutical research seeks to thoroughly explore means to increase its concentration to be biologically relevant in wines. Ultrasonication techniques for example, have been successfully tested to enhance resveratrol levels in wine. In addition, must could be enriched with resveratrol-rich grape skins pre and post fermentation. Alternatively, grape-derived resveratrol could simply be added during winemaking; however, this practice is not allowed in all countries.

Further research is necessary to thoroughly investigate the effects of resveratrol on human health and its bioavailability.

 

Pastor RF, Restani P, Di Lorenzo C, et al. Resveratrol, human health and winemaking perspectives. Crit Rev Food Sci Nutr. 2017 Dec 5:1-19. [Epub ahead of print]

For more information about this article, read the scientific abstract here.

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