Is baby’s risk for type I diabetes increased if solids are introduced before 3 months or after 6 months?

Many parents have been concerned about the news reports suggesting that too-early or too-late introduction of solids might increase baby’s risk for type I diabetes. A couple of research studies in 2003 examined timing of introduction of cereals and how this might affect an at-risk baby’s risk for type I diabetes. Following is more information on these studies…

Following is a link to an abstract for one study on type I diabetes and introduction of solids that appeared in the Journal of the American Medical Association:

Norris JM, Barriga K, Klingensmith G, Hoffman M, Eisenbarth GS, Erlich HA, Rewers M. Timing of initial cereal exposure in infancy and risk of islet autoimmunity. JAMA. 2003 Oct 1; 290(13): 1713-20.

A related study also appeared in the same journal issue:

Ziegler AG, Schmid S, Huber D, Hummel M, Bonifacio E. Early infant feeding and risk of developing type 1 diabetes-associated autoantibodies. JAMA. 2003 Oct 1; 290(13): 1721-8.

Some basic information on the studies:

• The babies in these studies were all at increased risk for developing type I diabetes (most because they had a parent with type I diabetes).
• In both studies, introduction of rice or gluten-containing cereals before 3 months of age increased baby’s risk for type I diabetes.
• The first study showed increased risk for babies starting rice or gluten-containing cereals at 7 months or older. The abstract of this study does not give any information on breastfeeding duration or exclusivity, though I understand this data was collected (at least to some extent) in the study. Besides these being babies with increased risk for type I diabetes, there is often a big difference in risk factors between babies not breastfed at all, babies with some breastfeeding, babies exclusively breastfed for 3-4 months, and babies exclusively breastfed for 6 months.
• The second study did not show an increased risk of type I diabetes for babies starting gluten containing foods after 6 months.

One news article from DocGuide.com (aimed at doctors) gives additional information. The article notes:

The adjusted hazard ratios were higher for the 1 to 3 months and the 7 months or older groups whether fed rice or gluten-containing cereals. However if cereals were introduced while the child was still breastfeeding the risk of islet autoimmunity was reduced and this reduction was independent of the child’s age at initial cereal exposure. [emphasis added]

A few quotes from a WebMDHealth article:

Lead researcher Jill Norris, MPH, PhD, tells WebMD that it is not clear why introducing cereals late presents a problem, but it may be that children tend to eat more of a newly introduced food when they are older because they are hungrier. Studies in children with gluten sensitivity suggest that this may play a role in the disorder as the second study suggests.

“It may be that the immune system, even in older babies, requires a gradual introduction of foods, and that introducing too much of a particular food at one time presents a problem,” Norris says.

…

In an editorial accompanying the studies, diabetes researcher’s Mark Atkinson, PhD, and Edwin Gale, MD, urged clinicians and parents to use caution when interpreting the findings.

“It is clear that (these studies) do not present sufficient evidence to suggest that ‘infant cereal causes diabetes,’ and hopefully will not be misinterpreted as such by parents and the public,” they wrote.

Atkinson tells WebMD that even after two decades of research, the environmental trigger or triggers for type 1 diabetes remain unidentified.

“I think these studies do put cereal at or near the top of the list of potential triggers, but we still have to look for other agents,” he says. “I feel for the families of these children because every few years there is a new idea about what causes type 1 diabetes, and, so far, none of them has been proven [to be a cause].”