"Severe iron deficiency can delay brain development and may result in impaired cognitive function and behavioural problems. 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 says.

As very little research had been done into toddlers' nutrition and iron levels, Dr Heath and colleagues conducted research to determine whether food-based strategies might be an easy and effective way to improve iron status.

As part of her PhD studies, co-investigator Dr Ewa Szymlek-Gay carried out a five-month intervention trial involving 225 South Island toddlers and their families.

In the randomised double-blind trial, the children were assigned to three groups; one supplied with frozen cooked red meat dishes prepared in 21 varieties, another group with iron-fortified powdered milk and the third, control, group 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 cow's milk replaced with fortified or non-fortified powdered milk.

"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 says.

Blood measurements were taken at the beginning and end of the five month trial. The fortified milk group showed a 44 per cent increase in the concentration of ferritin, a protein that is used to estimate iron stores. Ferritin concentrations remained unchanged in the red meat group and decreased in the non-fortified milk group.

The results show that either giving toddlers iron-fortified milk or increasing their red meat intake is likely to successfully prevent a decline in their iron stores, Dr Szymlek-Gay says.

Dr Heath says that current nutritional recommendations ideally call for increasing iron levels at this age, and that in this regard, replacing toddlers' ordinary cow's milk with fortified milk looks very promising.

"However, in practical terms, both the red meat and fortified milk approaches have their pros and cons," she says.

One major benefit of using iron-fortified milk is that it does not require radical changes to a toddler's diet, which can often be difficult to introduce and maintain, she says.

"On the other hand, fortified milk is a lot more expensive and this may put it beyond the means of some families. 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 says.

"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."

A combined approach might possibly provide improvements in iron status, but further research is required to determine whether this is the case or not, she says.

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.