Hydrolyzed Infant Formula Doesn't Reduce Islet Autoimmunity

Becky McCall

January 25, 2017

Hydrolyzed cow's milk–based infant formula does not reduce islet-autoimmunity risk and may even increase risk compared with use of nonhydrolyzed formula as the first food used in children with increased genetic risk for type 1 diabetes, new study results show.

The results were published online January 17 in Diabetes Care by Sandra Hummel, PhD, Institute of Diabetes Research, Helmholtz Zentrum Munich, Germany, and colleagues.

The authors say their results provide evidence that "introducing an extensively hydrolyzed formula as the first infant formula does not protect children with a human leukocyte antigen (HLA)–conferred increased risk for type 1 diabetes from the development of islet autoimmunity and, specifically, of [insulin] IAA autoantibodies.

"Rather, our findings indicate that early weaning to an extensively hydrolyzed cow's milk–based formula is associated with an increased risk for islet autoimmunity," they add.

In addition, the authors write that the strengthened association with risk for islet autoimmunity found when extensively hydrolyzed formula was given as first formula during the first 7 days of life suggests "that very early decisions about infant milk feeding may be important in islet-autoimmunity risk."

Risk With Hydrolyzed Cow's Milk–Based Formula in First 7 Days

The analysis — from The Environmental Determinants of Diabetes in the Young (TEDDY) study — shows a significantly increased risk for pancreatic beta-cell islet autoimmunity in infants who received extensively hydrolyzed cow's milk–based formula as first formula, compared with nonhydrolyzed formula, introduced during the first 7 days of life (adjusted hazard ratio [HR], 1.57; P = .03).

But no significant association was seen in infants who received extensively hydrolyzed formula as the first formula during the first 3 months (adjusted HR, 1.38; P = .09).

TEDDY is a prospective cohort study funded by the US National Institutes of Health with the primary goal of identifying environmental causes of type 1 diabetes. It has enrolled children from six centers — three in the United States and one each in Finland, Germany, and Sweden — who are at high genetic risk of developing type 1 diabetes

Of note, the researchers point out that "80.5% of infants receiving extensively hydrolyzed formula as the first formula were from Finland." Compared with other TEDDY countries, the incidence of type 1 diabetes has been reported to be higher in Finnish children.

But they also note that the analyses "suggest that it appears unlikely that country-specific differences are the major factor that would explain these associations."

No significant associations were observed in infants receiving partially hydrolyzed formula, other formula, or no formula during the first 3 months compared with nonhydrolyzed cow's milk formula.

Previous Studies Provide Inconsistent Data, Cause Confusion

The researchers note that TEDDY is unique in the number of children with genetically increased type 1 diabetes risk monitored from birth and its detailed information on infant diet.

Findings from prior work relating to the association between age at first exposure to cow's milk and type 1 diabetes have been inconsistent.

Yet various infant feeding policies suggest that delayed introduction of cow's milk may be protective for type 1 diabetes, and these mixed messages leave mothers and healthcare professionals uncertain about which formula to use.

"This is of particular interest to mothers with type 1 diabetes, who experience difficulties with exclusive breastfeeding and have to introduce infant formula in the early postpartum period," Dr Hummel and colleagues observe.

The aim of the current analysis was to investigate whether the introduction of hydrolyzed cow's milk–based formula as the first formula was associated with reduced islet-autoimmunity risk in the large TEDDY prospective cohort of infants accounting for different degrees of formula hydrolyzation.

Few prior studies have investigated use of protein hydrolysates and the degree of hydrolysis in formula. Furthermore, previous research did not distinguish between whether the infant formula was given as the first or subsequent formula.

But referring to one particular previous study — the Trial to Reduce Insulin-Dependent Diabetes mellitus in the Genetically at Risk (TRIGR) — which comprised a large cohort of over 2000 newborns from 15 countries, the authors of the current study say their results reflect these.

TRIGR found that weaning to extensively hydrolyzed formula did not reduce islet-autoimmunity risk compared with conventional formula.

Over 8000 Infants in Study

In total, data from 8506 infants with HLA genotypes associated with type 1 diabetes were assessed in the current TEDDY analysis.

Autoantibodies to insulin had been measured regularly to define islet autoimmunity, and data had also been collected on infant diet during the first 3 months of life. Other information used in this analysis was age at introduction of formula milk, duration of intake, and formula type; as well as breastfeeding status and duration.

The primary outcome was the development of persistent islet autoimmunity. Median follow-up of infants was 8 years.

Study strengths include the prospective collection of detailed information on the use of different formula types, which minimizes recall bias. In addition, the large sample size from across the United States and Europe enabled investigation of associations between various types of infant formulas and islet-autoimmunity risk, as well as potential country-specific differences.

The authors conclude that although this publication covers early islet autoimmunity, studying whether infant formula feeding is ultimately associated with the progression to clinical type 1 diabetes will require further follow-up of the TEDDY cohort.

The authors report no relevant financial relationships.

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Diabetes Care. Published online January 17, 2017. Abstract

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