https://pubmed.ncbi.nlm.nih.gov/37375715/

Diet is a determining factor for health, populations that consume a diet rich in fruits and vegetables have a lower incidence of inflammatory, neurodegenerative, and cardiovascular diseases compared to populations with lower intakes of these foods. A Mediterranean-style diet, with a high content of phytochemicals, including polyphenols, is associated with a lower degree of inflammation biomarkers and a protective role in cerebrovascular and cardiovascular events. 

Among the foods rich in polyphenols is the grape, whose moderate consumption is believed to have benefits at a cognitive level. However, the effect of raisins, in which polyphenolic compounds are well represented on cognitive performance has not been previously studied.

The objective of this study, recently published in Nutrients, was to analyze the effects of adding 50 g of Málaga muscatel raisins to the usual diet on cognitive performance, quality of life, and functional activities in healthy older adults. It was a parallel randomized controlled clinical trial, enrolling 80 subjects over 70 years of age. For 6 months, the intervention group (IG; n = 40) consumed 50 g of raisins per day added to their usual diet, whereas the control group (CG; n = 40) received no supplement. All variables were measured at baseline and at 6 months.

The results of this study show an improvement in “orientation”, assessed both in the MOCA test and in the MMSE test (temporal orientation), after daily consumption of 50 g of Málaga muscatel raisins. In addition, in the “visuospatial/executive” and “language” categories, also assessed with the MOCA test, a higher score was observed in the IG after 6 months. In the final score of the MOCA test, we also observed a significant improvement in the IG. With the Rey Verbal Auditory Learning test, we observed an improvement in the “immediate recall” and in the “retention memory” of a list of 15 words, in the IG subjects after a non-amnestic interference task. “Immediate recall” is understood as the number of words recalled on the first attempt after the researcher has read 15 words. The “retention memory” is the number of words correctly remembered 30 min after a non-amnestic interference task.

No relevant differences were found in the other items evaluated and in verbal fluency either.

The results of this study suggest that the supplement of 50 g of Málaga muscatel raisins slightly improves cognitive performance, specifically orientation, visuospatial/executive capacity, language, the overall MOCA test score, and immediate and delayed recall. In addition to showing a slight improvement in quality of life and functional activities. These are positive data, but more research is needed to know exactly the mechanism of action of polyphenols on cognitive performance.