Background As the prevalence of neurodegenerative diseases increases steadily, the need to develop new treatment approaches intensifies and the possibility of targeting risk and protective factors to delay onset of these diseases is attracting more interest. Dietary habits stand as one of the most promising modifiable risk factors for both Alzheimer's (AD) and Parkinson's (PD) diseases. Scope and approach Over the last 30 years, several groups have generated data indicating that concentrations of specific brain lipids highly depend on dietary intake. Preclinical results show that treatments with omega-3 polyunsaturated fatty acids (n-3 PUFA) improve cognition, provide neuroprotection (and even neurorestoration), reduce neuroinflammation and influence neuronal function, while high-fat diets exert deleterious effects. Preclinical experiments have been conducted in well-recognized animal models of AD, PD, and ischemic stroke. Key findings and conclusions These studies have shown that dietary n-3 PUFA treatments consistently improve cognitive performance in animal models and may also exert disease-modifying actions. N-3 PUFA also provide protection to dopaminergic neurons in animal models of PD and possibly recovery after lesion. Furthermore, some of these effects might depend on specific diet formulations to protect long-chain fatty acids from oxidation or synergies with other nutrients. More generally, this review aims at providing evidence that adjustments in the consumption of dietary lipids alone or combined with other nutrients may be a cost-effective intervention to optimize brain function and prevent AD or PD.