The 2 most abundant long-chain polyunsaturated fatty acids (LCPUFAs) in the brain are docosahexaenoic acid (DHA) and arachidonic acid (ARA), where they have a functional and structural role in infant development. DHA is concentrated in the prefrontal cortex, which is important for association and short-term memory, and in some retinal cells. Concentrations of PUFAs in human breast milk are relatively consistent during the first year of life, and studies have shown that breast-fed infants have a greater mean weight percentage of DHA and a greater proportion of DHA in their red blood cells and brain cortex than formula-fed infants. Furthermore, cortex DHA in breast-fed infants increases with age, probably due to the length of feeding.

Maternal supplementation with cod liver oil, which is rich in DHA and eicosapentaenoic acid, improved children's intelligence quotient compared with corn-oil supplementation by 4 years of age.

The LCPUFA content of human breast milk is affected by a number of factors, including diet, gestational age, parity, and smoking. Supplementation of formula feed with DHA and ARA results in infant development that is similar to breast-feeding, and may have benefits on blood pressure in later childhood.

The beneficial effects of LCPUFA supplementation on visual acuity continue after weaning irrespective of the type of diet. The long-term effects and duration of supplementation of breast- and formula-fed infants requires further investigation.