South Australian researchers have thrown into doubt reported benefits of giving preterm babies omega-3 supplements, after studies found no noticeable difference in the health of premature infants after being given the fatty acids.

The project was undertaken by the South Australian Health and Medical Research Institute (SAHMRI), and was designed to shed light on whether supplementing premature babies with high-dose omega-3 docosahexaenoic acid (DHA), which has anti-inflammatory activity, would reduce the risk of developing chronic lung disease.

According to researchers, most babies born preterm need extra oxygen and help with their breathing, otherwise there is heightened risk of developing chronic lung disease.

In order to determine the tangible benefits of omega-3 DHA, researchers gave preterm infants either a supplement providing extra omega-3, or a control supplement without DHA, from birth until the time they were allowed to leave the hospital.

The results of the study surprised researchers. Dr Carmel Collins from SAHMRI said supplementing omega-3 fats for premature babies was widely "unnecessary."

"Our results suggest that additional supplementation of DHA is unnecessary and reinforces the need to thoroughly test all nutritional interventions designed for babies," Collins said in a statement on Thursday.

Meanwhile Dr Andrew McPhee from Neonatal Services South Australia said the results could help pediatricians better inform new parents about how to care for their premature children.

"We have learned a lot and now have definitive information to help guide health professionals in their nutritional management of very premature infants," McPhee said.

"The results reinforce that we need to be careful about the amounts of all nutrients, including DHA. More is not necessarily better."