Nutrition et prévention du déclin cognitif et démence

The potential effect of nutrition has become a topic of increasing scientific and public interest. In particular, there are arguments that nutrients (food and/or supplements) such as vitamins, trace minerals, lipids, can affect the risk of cognitive decline and dementia, especially in frail elderly people at risk of deficiencies. We reviewed in this paper data from prospective studies and randomised clinical trials (RCT) relating diet to risk of cognitive decline and dementia. We chose to focus our statements on homocysteine-related vitamins (B-vitamins), antioxidants nutrients (vitamins E and C, carotenoids, flavonoids, enzymatic cofactors) and dietary lipids. Results of the prospective studies are sometimes conflicting and stress the need to develop further prospective studies of adequate duration, including subjects whose diet is monitored at a sufficiently early stage or at least before the onset of disease or cognitive decline. The seemingly contradictory results between the observation studies and the RCT could be explained by the fact that the doses uses in clinical trials are much higher than the highest levels achieved by usual dietary intake which have been found to be associated with the lowest risk of cognitive decline in observational studies. More randomised clinical trials need to be conducted that focus on specific types of subjects (middle-aged and elderly populations; subjects with vitamins deficiencies, normal and high levels). Such research identifying the role of certain nutrients, certain foods or certain dietary behaviours, is an indispensable step before we can propose specific recommendations in the future.