Salt supplements given to premature babies during the first two weeks of life can improve their mental and physical development up to their teens, according to British doctors this week.
Babies born eight or more weeks early lose more sodium in their urine than full-term infants so premature infants now routinely receive extra sodium.
Doctors at Guy's, King's and St. Thomas's hospitals in London, who followed up two groups of premature babies for up to 13 years, found that those who had received salt supplements scored about 10 per cent higher on IQ tests than children who had not been given extra salt.
They also performed better on memory and language tests.
"Studies have shown that there were short-term benefits for replacing the lost salt but nobody until this paper, to my knowledge, previously looked at the long-term consequences," said Professor George Haycock who conducted the study.
The children who performed better in behavioural, physical and psychological tests had been given very small supplements of sodium for the first two weeks after birth.
After that period, the loss of sodium diminishes in premature babies and supplements are not needed.
"The amount of salt supplement that is needed, according to our calculations, applies to very premature babies who were otherwise well. If they are sick as well they can lose even more (salt)," Professor Haycock explained.
The study is reported in the medical journal Fetal and Neonatal Edition.