Resveratrol
Resveratrol is a substance produced by various plant species which, thanks to its strong antioxidant properties, helps protect our body from cardiovascular and cancer pathologies. It even tells of its - alleged - ability to increase the duration of life, supported by timid scientific evidence demonstrated by some preliminary studies on worms (C. elegans) and fruit flies (D. melanogaster), and never confirmed on man.
Resveratrol in Wine
In the vegetable kingdom, resveratrol, endowed with antifungal functions, is found in particular in the skin of grapes and in wine, to a greater extent in the red one.
The cardioprotective effects of this drink, typical of the Mediterranean food culture, are largely linked to its resveratrol content. However, doctors invite you not to indulge in useless and dangerous enthusiasm, since the beneficial properties ascribable to wine depend on several factors, first of all the dose, which must be moderate (2-3 glasses a day in man, a little less in women).
In addition to the color, the resveratrol content of the wine also depends very much on the cultivation and processing techniques of the grape. This substance, produced by the plant for its precious antifungal activities, is obviously more abundant in grapes not treated with fungicides and pesticides. Furthermore, the resveratrol content of the wine is higher the longer it is fermented together with the skins.
Daily dose of wine equivalent to 50 mg (*) of resveratrol (L)
Other factors affecting the resveratrol content in wine:
COLOR: in the production of white wine the fermentation takes place without the contact of the must with the skins (white fermentation). Since resveratrol is present in the skin of grapes and not in the pulp, it is logical to expect that the content of the substance is lower than in red wines, generally produced with fermentation on the skins.
GEOGRAPHICAL ORIGIN: wines produced at high altitudes seem to have a higher resveratrol content (this substance protects the plant from UV rays). Latitude, on the other hand, does not seem to significantly influence the concentration of the substance.
VINTAGE: climatic conditions that favor a slight fungal attack increase the synthesis of resveratrol in the plant (this substance has an antifungal action).
FERTILIZATION: the concentration of resveratrol in grapes increases as nitrogen fertilization decreases (Bavaresco et al., 2001).
The French paradox
When it comes to resveratrol, one cannot avoid the slightest mention of the French paradox.
At the end of the 1980s, two scientists (Renaud and De Lorgeril) studied the correlation between mortality due to coronary heart disease and the intake of animal fats in the diet. The population samples studied gave a clear result, now known to most: the greater was the average daily consumption of animal fats and the higher was the mortality. Among all the countries examined, only the French sample (collected between the cities of Lille, Strasbourg and Toulouse) gave results contrary to this conclusion. Despite the high consumption of animal fats, the French recorded the lowest mortality rate from coronary heart disease. Since dismissing the fact as the exception that confirms the rule has little scientific evidence, the two French researchers tried to give an answer to this paradox. From the statistical observation of the greater consumption of wine in France, the hypothesis arose that this drink could counterbalance the effects of the high ingestion of animal fats. Since the negative effects of alcohol had already been widely documented and that wine had proved more effective than other alcoholic beverages in reducing the incidence of these diseases, the second step was to hypothesize that the French paradox was not there was alcohol but other substances present in the wine and not yet investigated.
The study of the drink led to the discovery of resveratrol (Siemann and Creasy -Cornell University, Ithaca, NY, Usa- 1992) and other similar substances, such as piceatannol, pterostilbene, epsilon-viniferine, piceid (resveratrol glucoside ).
Does Resveratrol Work?
The biological activities of resveratrol are varied and well documented. First of all, from a clinical point of view, its protective action on cardiovascular diseases has been scientifically demonstrated. The substance is also endowed with a powerful antioxidant activity. The anticancer capabilities of resveratrol, supported by several studies, are still awaiting clinical confirmation.
Although most of the benefits ascribed to this substance have been scientifically confirmed, the high dosages required to obtain these "protective" effects have seriously reduced the enthusiasm for red wine. Even if in this regard there is no "univocal indication, to reach the levels of resveratrol intake proposed by the various studies, certainly harmful quantities of wine would be needed (several liters per day).
Having ascertained that the hope of exploiting the antioxidant properties of resveratrol through the consumption of wine has no scientific value, it is fair to ask whether a moderate consumption of this drink has positive implications on human health or not. In this regard it is not possible to give a certain answer because, starting from the assumption that alcohol is an oncogenic substance, there are some studies (not all) which confirm the health benefits of wine.
Since epidemiological research has established that alcohol is the third leading cause of death in Italy, a dose potentially useful in the prevention of cardiovascular diseases could lead to a higher risk of developing other serious diseases. In addition, too much enthusiasm for wine. and its resveratrol could promote the spread of alcoholism.
For this reason, when it comes to wine, reasonable low-risk intake limits are set, usually identified in about 24-30 g of alcohol per day for men and 12-15 g per day for women, equal to 1 -2 glasses of wine (150-300 ml). Finally, it is worth remembering that wine, regardless of its resveratrol content, has above all a cultural and convivial significance. Its health implications, on the contrary, whatever people say, are still waiting for confirmation.
Doses, methods of use and side effects of resveratrol supplements
In the form of a food supplement, it is advisable to swallow the resveratrol capsules at breakfast or rather on an empty stomach, avoiding concomitant intake with meals rich in fat, which could halve their bioavailability. More difficult to establish and suggest an ideal intake dose of resveratrol (in this regard there is no "clear and unambiguous indication in the literature); if this antioxidant is taken alone, a good compromise between the minimum effective doses and those that would cause adverse effects in the short (mostly diarrhea) and long term (yet to be demonstrated) could be 200/400 mg per day. The case in which resveratrol is inserted in a polyvalent antioxidant mix is different (for example by associating it with other polyphenols, vitamin E, vitamin C, lipoic acid ...); in this case the intake doses may be lower, but in any case in the reasonable minimum order of a few tens of mg.
Below 25 mg per suggested daily dose, the presence of resveratrol in a supplement is considered to be of pure commercial appeal.
