A third of New Zealand toddlers were thought to have low iron levels, putting them at a higher risk of developing iron-deficiency anaemia, researcher Dr Anne-Louise Heath, of the university's Department of Human Nutrition, said.
About 3 per cent of toddlers have a severe iron deficiency.
It is believed the decline is a result of the body's high iron requirements during this stage of growth, combined with decreased iron intakes.
But a study by Dr Heath and Dr Ewa Szymlek-Gay, which will be published today in the American Journal of Clinical Nutrition, shows giving toddlers either iron-fortified milk or increasing their intake of red meat can stop a decline in their iron stores.
"Severe iron deficiency can delay brain development and may result in impaired cognitive function and behavioural problems," Dr Heath said.
"To safeguard against sliding into this state, it is important to find sustainable ways to prevent the decline in iron levels that often occur in the second year of life," Dr Heath said.
There has been little research into toddlers' nutrition and iron levels, so Dr Heath and colleagues investigated whether food-based strategies were an easy and effective way to improve iron levels.
Dr Szymlek-Gay carried out a five-month trial involving 225 South Island toddlers and their families.
In the randomised double-blind trial, the children were put in three groups - one was supplied with frozen, cooked, red-meat dishes, one with iron-fortified powdered milk and the third with non-fortified powdered milk.
Toddlers in the red-meat group were encouraged to consume at least two portions of the dishes each day, while those in the other two groups had their regular cows' milk replaced with fortified or non-fortified powdered milk.
Blood measurements were taken at the beginning and end of the trial.
The fortified milk group showed a 44 per cent increase in the concentration of ferritin, a protein that was used to estimate iron stores, Dr Heath said.
Ferritin concentrations remained unchanged in the red-meat group and decreased in the non-fortified milk group.
"Despite the wide variety of textures and flavours in the dishes we developed, the toddlers in the red-meat group upheld their age group's reputation for fussiness by, on average, eating just over two-thirds of a portion daily," Dr Szymlek-Gay said.
Dr Heath said replacing toddlers' ordinary cows' milk with fortified milk looked promising, but both the red-meat and fortified milk approaches had pros and cons.
Iron-fortified milk did not require radical changes to a toddler's diet, but it was more expensive, costing about 40 cents more per day compared with ordinary cows' milk.
"Parents may also inadvertently limit the range of foods they offer to their child due to the sense of nutritional security that using a fortified product may provide."
This could delay the child's move from a predominantly milk-based diet towards a well-balanced, adult-style diet, she said.
"The benefit of taking the red-meat approach is that it is inexpensive, and preventing the decline in iron stores should only require a relatively small increase in the amount toddlers eat daily."
The findings are published online today by the American Journal of Clinical Nutrition, which is the most highly rated peer-reviewed journal in the nutrition and dietetics category.
