Grapes and their derivatives in modulation of cognitive decline: a critical review of epidemiological and randomized-controlled trials in humans.

With an increase in life expectancy, the incidence of chronic degenerative pathologies such as dementia has progressively risen. Cognitive impairment leads to the gradual loss of skills, which results in substantial personal and financial cost at the individual and societal levels. Grapes and wines are rich in healthy compounds, which may help to maintain homeostasis and reduce the risk of several chronic illnesses, including dementia. This review analyzed papers that were systematically searched in PubMed, MEDLINE, Embase, and CAB-Abstract, using the association between grapes (or their derivatives) and their effects on cognitive functions in humans. Analysis was restricted to epidemiological and randomized-controlled studies. Consumption of grape juice (200-500 mL/day) and/or light-to-moderate wine (one to four glasses/day) was generally associated with improved cognitive performance, while the results for other alcoholic beverages were controversial and inconclusive. Bioactive molecules contained in grapes and wine were also considered, with particular attention paid to resveratrol. Due to the relatively high doses required (150-1000 mg/day) for bioactivity coupled with its low bioavailability, resveratrol is only one of the possible grape-derived compounds that may partly underpin the beneficial effects of grapes on the central nervous system.

Is it scientifically justifiable to exclude wine and/or unfermented grape derivatives from the diet of consumers with or at risk of developing type-2 diabetes?

The abuse of alcoholic beverages has been associated with an increased risk of chronic-degenerative diseases, including diabetes mellitus, so that there is a general diffidence towards the low/moderate consumption of wine by individuals with type-2 diabetes (T2D) or at risk of developing it. This narrative review investigates by critical revision of the scientific literature whether wine/grape derivatives must be excluded or if their low/moderate consumption could be part of the daily diet of T2D individuals. Although further intervention studies on the consumption of alcoholic beverages and the development or control of T2D are needed, the burden of evidence suggests that low/moderate wine consumption could have beneficial effects.

Drinking pattern of wine and effects on human health: why should we drink moderately and with meals?

Conclusions of epidemiological studies examining the effects of alcoholic beverages on human health may be unclear and limited if they do not take into account drinking pattern parameters such as beverage type, regular moderate versus binge drinking and drinking with or without meals. This review considers different aspects of drinking patterns and effects on human health with special attention to wine. We particularly discuss the potential underlying mechanisms for epidemiological evidence that the beneficial effects of wine are more evident if consumed with food. In this context, we address the effects of food on blood alcohol concentration and acetaldehyde production in the gastrointestinal tract, the role of wine components and uric acid in counteracting the detrimental effects of postprandial oxidative stress, as well as wine's antimicrobial properties and its potential to act as a digestive aid. In addition to its biological correlates, drinking patterns with regard to different socio-cultural circumstances in different populations are also considered. In order to avoid confusion and misconceptions in the general population because of the hormetic associations of wine with human health, it is important that all medical and scientific information concerning the effect of wine consumption on human health are evidence-based and communicated in a competent, credible and unbiased manner. In conclusion, we propose several practical recommendations concerning wine consumption and consumer information to minimize the risks of alcohol-related harm and to encourage individual responsibility and a healthy lifestyle.