( CNN ) '' Breast is best '' -- you could call it a mantra of sorts that sums up much of today 's research on breastfeeding . Not only does breastfeeding have clear short-term benefits , such as protection from infectious diseases and a reduction in mortality , it 's also been shown to be associated with an increase in intelligence . Prior studies have shown an increase of up to 7.5 IQ points in elementary age children who were breastfed , as well as an increase in verbal , performance and comprehensive IQ in adults . The latest addition to this perspective is a long-term study of infants born in Pelotas , Brazil , in 1982 . Published in Lancet , the study interviewed 5,914 new mothers about their plans for breastfeeding and then followed up to see how they did . `` Information on breastfeeding duration was collected very close to the time when weaning happened , so we had a very precise information on the duration of breastfeeding , '' said study author , Dr. Bernardo Lessa Horta , in a podcast on Lancet . What makes this study unique is that it followed the subjects all the way to age 30 . `` We were able to follow about 68 % of the participants , which is a very good follow-up rate , '' said Lessa Horta . `` We observed that breastfeeding was positively associated with performance and intelligence at 30 years old , as well as with education , school achievement and higher monthly incomes . '' In fact , Lessa Horta said the subjects who had been breastfed for 12 months or longer had a higher IQ ( about 3.7 points ) , more years of education and earned roughly 20 % more than the average income level . `` It 's suggesting that the positive effect of breastfeeding on IQ leads to a higher income , '' he said . `` This is our main finding at this moment . '' One possible reason for the advantage of breast milk , Lessa Horta added , is that it is `` rich in long-chain polyunsaturated fatty acids which are important to brain growth and development . '' Called LCPUFA for short , these essential fatty acids are found in salmon and shellfish and have been added to infant formulas since the 1990s . However , the benefit to mental or psychomotor development from adding LCPUFA to infant formula is unclear . Because the study did not measure home life , intellectual stimulation or bonding between mother and child , it was not able to tease out whether these factors may have also contributed to the increase in IQ . That leaves it open to critics , such as Texas A & M Professor Joan Wolf , author of `` Is Breast Best ? `` This study does not address the very real possibility that mothers who choose to breastfeed , regardless of income or education , distinguish themselves from those who bottle-feed in all kinds of ways that are likely to promote intelligence , '' Wolf wrote CNN . For Lessa Horta , the implications of his study are clear : `` The finding supports the promotion of breastfeeding . It 's more evidence that besides the clear short term benefits , breastfeeding also has long term consequences in terms of human potential . ''
Long-term study finds that IQ at age 30 was nearly 4 points higher for babies breastfed for a year or more . Study conducted in Brazil also associates longer breastfeeding with higher income and education levels . Critic points out that the study does n't account for other possible contributing factors .