There is increasing evidence that oxidative stress is involved in cerebral aging and dementia. The objective of this review is to give a progress report on the more recent results of the various epidemiologic cohorts studied for the association between nutrition of older people, the evolution of cognitive performances and the risk of later occurrence of dementia or stroke. The oxidative theory of pathological brain ageing is supported by animal laboratory experiments. Furthermore, experimental research has consistently suggested that diet-related factors play an important role in cognitive functions in ageing. In humans, a number of epidemiological case-control and prospective studies analyzed the association between nutrition, particularly fatty acids and antioxidant molecules (vitamins A, E, C, beta-carotene and polyphenols) and cognition. In the context of evidence already available, further studies are needed to identify the specific role of various nutrients, their interactions and the influence of genetic factors and living habits on cerebral aging and dementia. Vascular dementia and Alzheimer's disease, that share several risk factors, might be targets for primary prevention through nutritional recommendations and/or supplementation.