The recommended age at which parents should introduce their infants to solid foods has varied dramatically over the past century. Currently, solid food is not recommended before four months of age because earlier introduction may increase the risk of allergies. Despite these recommendations, there has been no systematic review of the evidence. In addition, parents tend to feed their children solid foods at an even younger age. One study found that 52 percent of nonbreastfed infants and 29 percent of breastfed infants were given cereal at two to three months of age. Tarini and colleagues evaluated whether early introduction to solid foods increased the risk of allergic disease in infants.

Allergic diseases were defined as asthma, eczema, food allergies, pollen allergies, allergic rhinitis, and animal dander allergies. A study was included if it explicitly mentioned early introduction of solid foods, was missing additional and simultaneous allergy reduction interventions, had a comparison group, measured one of the allergy diseases, and was published in English.

The authors found 2,719 articles, but only 13 met the inclusion criteria and only one was a controlled trial. Five studies discovered that early solid food introduction was associated with eczema, and the association was persistent for up to 10 years. However, four studies did not find a correlation between early solid food introduction and eczema, and only one found an association between the timing of solid food introduction and pollen allergies. No sufficient evidence was found indicating an association between early solid food introduction and persistent asthma, persistent food allergies, allergic rhinitis, or animal dander allergies.

The authors conclude that the introduction of solid foods in infants before four months of age may increase the risk of eczema, but there is little evidence to support the association of early solid food introduction with other allergy diseases. They also state that more trials of this type are needed to help physicians instruct parents on when it is appropriate to introduce cereals to their children.