Early studies looking at the link between nutrition and development found that breast-fed babies tended to outperform babies fed infant formula without DHA on cognitive evaluations. As researchers began to dig deeper into what could help explain this difference, a spotlight fell on this nutrient: the long-chain polyunsaturated fatty acid (LCPUFA) called docosahexaenoic acid (DHA). So could formula that has DHA help close the gap?
Pinpointing How DHA Helps
Initial research results on the benefit of formula supplemented with DHA to cognitive development were mixed. Several factors could have contributed to the mixed results. Some scientists think the levels of DHA added to formula may have been lower than levels in breast milk and the tests used to evaluate its effects may not have been sensitive enough to pick up subtle differences. Age at testing may have made a difference, too.
The next step: Researchers at the Retina Foundation of the Southwest, Memorial University in Canada, and the University of Texas decided to test 9-month-old infants using a means-end problem-solving test. The formula these babies received provided levels of DHA and ARA that were based on worldwide average breast milk levels.
Putting DHA to the Test
The researchers studied 229 babies, who (through participation in three earlier studies) had been given either formula supplemented with DHA and ARA or conventional formula without DHA and ARA. Some babies were given one of the formulas from one to five days after birth, some after six weeks of breast-feeding, and some after four to six months of exclusive breast-feeding.
Then at 9 months, the babies participated in a problem-solving test. Researchers showed the baby a rattle which was placed in the middle of a large cloth then hidden by another smaller cloth. The babies’ challenge: pull the large cloth closer to themselves in order to pull off the small cloth and grab the rattle. Researchers observed successful retrievals and intention levels at each small step along the way.
While this test sounds simple, it involves thinking skills such as planning and focus. A baby has to identify the goal (find and grab that rattle!) and be able to plan and execute a series of steps to achieve it. Multistep planning, memory, and focus are all involved. In fact, this test (known as a “two-step means-end problem-solving task”) when completed at 8 to 9 months old, is associated with performance on other cognitive tests completed at 3 years of age.
All the babies were rested and alert when tested. Each was allowed to play with the rattle for about 20 seconds. Then a pretest made sure that they could complete each of the steps (lifting the cloth to retrieve the rattle, pulling the cloth). Only those who could do these things within three tries were included in the final testing.
Outcomes After DHA and ARA Supplementation
Which babies were the best rattle detectives in the study?
- Infants who received formula with DHA and ARA after 6 weeks of breastfeeding or shortly after birth were better at figuring out the solution to how to retrieve the toy—compared to infants who received formula without DHA and ARA.
- These two groups had better intention scores than the babies who’d had conventional formula without DHA and ARA and were more successful in reaching the goal (finding and grabbing the hidden rattle).
The researchers credited these outcomes, compared to some earlier studies that used the same test, in part to higher levels of LCPUFA, such as DHA, in the supplemented formula.
The researchers noted two possible explanations for why DHA and ARA consumed early in life offer such benefits:
- LCPUFAs are known to play a key role in cell membranes in the central nervous system. Having more LCPUFAs may help the child process information faster, allowing him to more quickly carry out multistep tasks.
- LCPUFAs may also influence attention, allowing a child to more quickly shift attention from one step of a task to the next.
These thinking skills are signs of brain development.