Nine in 10 Australian infants aren't consuming enough iron.

The finding, based on nationwide interviews with 1100 parents who documented their children's diets, has experts worried the pattern of deficiency could affect growth and lead to learning and behavioural problems.

A quarter of all toddlers are also failing to meet the recommended daily iron intake.

Conducted by the South Australian Health and Medical Research Institute, the study focused on children aged six months to two years.

While the majority are getting the right amount of most nutrients, Professor Tim Green and Dr Merryn Netting say 90 per cent of six- to 12-month-olds are consuming "far less iron per day than the recommended amount".

"Not getting enough iron is a concern because we know iron deficiency negatively impacts overall development," Dr Netting said.

"It can also cause tiredness, loss of appetite, as well as poor growth, and lead to anaemia, a condition that reduces oxygen in the body."

Iron is an essential mineral needed to produce red blood cells, which are vital to a healthy immune system, mental function, muscle strength and energy.

Its main role is helping make haemoglobin to carry oxygen from the lungs to all the cells in the body.

Humans can't make iron, so it has to come from food.

National Health and Medical Research Council guidelines recommend infants consume 7mg of iron daily.

To achieve this, they need to eat about 300g of pureed beef or 400g of fortified cereal.

"It's possible the recommended iron intake has been set higher than needed and should be reviewed," Dr Netting said.

"But we won't be able to confirm if this is the case without doing further studies with a larger cohort of infants.

"We have no data on blood iron levels or anaemia in this group and we urgently need it. If iron levels are low, we may need to consider giving infants iron supplements."

The study, which was funded by the Nestle Nutrition Institute, also found about a third of toddlers are consuming too much salt.

Typically, that's down to eating an excess of processed foods, Dr Netting says.

"Children will develop a taste for salty foods that are often unhealthy,'' she said.

"This can contribute to poor eating habits down the road, as well as high blood pressure."

On the positive side, breast-feeding rates surpassed expectations, with 75 per cent of mothers shown to be breast-feeding at six months and 50 per cent at 12 months.

"It's very pleasing to see so many mothers are opting for breast milk with all the added nutrients it provides, rather than reaching for baby formula," Dr Netting said.