Objective: To describe data on effects of LC-PUFAS in neuronal formation in the first thousand days of a child. Methods:A systematic review of 23 articles in the first quarter of 2015 from 2003 to 2015 in Medline, Scielo, Science Direct and Google Scholar. Languages: Portuguese, English and Spanish. Headings (MeSH): fatty acids; arachidonic acid; Omega 3; Omega-6; infant formula; child development; child nutrition; synapses and neurogenesis; child development; child nutrition; synapses and neurogenesis. Inclusion criteria: the LC-PUFAS approach, neuronal training and the first thousand days of children, isolated or associated. Results:The first thousand days of a child involving rapid growth and physical and mental development. There is no evidence that the foetus has docosahexaenoic acid omega 3 family (DHA) sufficient to meet the demand of its neuronal metabolism. Observational studies indicate that DHA intake during pregnancy promotes a variety of positive results in the development of the newborn. The postnatal supplementation with LC-PUFAs for breastfeeding or formula with LC-PUFAs, if not exclusive breastfeeding is associated with better neurological development indices.Conclusion: supplementation with LC-PUFAs is essential to improve the neurological development of children. The intake of DHA promotes better cognitive and visual results compared to no feeding of the substance.