Abstract: Background: omega3 polyunsaturated fatty acids and anti-oxidants could have a protective effect against brain aging. Objective: to analyze the potential protective effect of nutritional factors against cognitive decline and dementia. Methods: the data como from de PAQUID (Personnes Agées QUID) and EVA(Etude du Vieillissement Artériel) epidemiological studies. A representative sample of 3777 community dwellers aged 65 and over was included at baseline in the PAQUID study and followed for 10 years with repeated neuropsychological testing and identification of incident cases of dementia. Nutritional data included a brief food sequency questionnaire, a dietary survey in a sub-sample (N=169), and biological data (Cholesterol, vitamin E and A, and MDA plasma levels, biological, Apolipoprotein E genotype). In EVA 1389 voluntary participants aged 60-70 were included at baseline and followed for nine years with repeated neurpsychological assessments. Markers of oxidative stress and fatty acids were measured in plasma (selenium, carotenoids, TBARS) or erithrocytes (vitamin E, fatty acids). Results: moderate wine consumption, a higher intake of flavonoids and higher vitamin E plsma level were associated with a decreased risk of incident dementia in the PAQUID study. MDA was increased, but not significantly, in future dementia cases. In EVA, there was a significant association between a low level of plasma selenium, a high level of lipoperoxidation and cognitive decline. Regardind fatty acids, al least weekly fish consumers included in the PAQUID study had a decreased risk of incident dementia (rr=0.66). In a subsample of 246 EVA participants, there was an increased risk of cognitive decline with increased w6 erythrocyte level (OR=1.26), and a decreased risk with w3 (OR=0,74). Conclusion: these results are in agreement with other studies showing a protective effect of nutritional anti-oxidants and w3 fatty acids against cognitive decline or dementia.