'Step-Down' Approach to Baby Formula Shows Benefit for Milk Allergy

Switching infants with IgE-mediated cow's milk allergy (CMA) from an amino acid-based baby formula to an extensively hydrolyzed casein (EHCF) product supplemented with a probiotic was feasible and led to higher rates of immune tolerance acquisition, a small randomized trial from Italy showed.

In the single-center, double-blind study of 59 infants without CMA symptoms after at least 4 weeks on an amino acid-based formula, the 1-year rate of immune tolerance acquisition to cow's milk proteins was 48% (95% CI 29-67) for kids switched to EHCF plus Lactobacillus rhamnosus GG (LGG), as compared with 3% (95% CI 0.1-17) for those kept on their original formula, reported Roberto Berni Canani, MD, PhD, of the University of Naples in Italy, and colleagues.

Body growth patterns during the 1-year study were similar regardless of the baby formula used, the researchers detailed in Allergy.

While amino acid-based formula can be the first-line strategy in severe CMA cases, "when a full resolution of symptoms is achieved, the step-down approach with EHCF+LGG could promote faster acquisition of immune tolerance," Berni Canani's group concluded.

Amino acid-based formula "is considered the safest dietary strategy for severe CMA children, but it is also the most expensive," they noted. Furthermore, "preclinical and clinical data suggest that this formula is unable to promote tolerogenic effects, substantially due to the absence of peptides," while prior evidence has suggested that EHCF+LGG "could promote the acquisition of immune tolerance."

The results of the SDACMA (Step-Down Approach for Cow's Milk Allergy) study confirm that "EHCF+LGG has a greater potential in reducing disease duration" compared with an amino acid-based formula, Berni Canani and coauthors wrote. "These data are relevant considering the most recent evidence suggesting that the natural history of CMA has changed over time, with slower rates of resolution and a higher proportion of children with disease persisting into school age and older."

CMA is one of the most common forms of food allergy, with one recent study estimating that nearly 5% of the U.S. population have the allergy. Babies unable to receive breast milk must receive specialize formulas -- often EHCF as a first-line approach, or an amino acid-based formula for severe forms of CMA or in those with multiple food allergies -- leading to high costs for families if the disease persists.

Strict exclusion criteria were used in the SDACMA trial, and infants with multiple food allergies, eosinophilic gastrointestinal disorders, and CMA-induced anaphylaxis could not enroll. During a double-blind placebo-controlled food challenge, 98% (95% CI 91-99) showed tolerance to the hydrolyzed formula on their first exposure, a far higher rate than in past series, the researchers noted, perhaps due to the trial design among other factors.

Fifteen adverse events, none serious, were recorded during the study (acute gastroenteritis, respiratory infections, and febrile illness/viral infections), though none were classified as related to the formulas.

A total of 60 infants under 6 months old with CMA were included in the study, which was conducted at a single center in Italy from 2018 to 2020. All kids (about 5 months old on average, 56% boys, two-thirds with a familial risk for allergies) were on a cow's milk protein elimination diet and had been on an amino acid-based formula for at least 4 weeks prior to the start of the trial.

Following skin-prick tests, they were randomized 1:1 to either stay on the amino acid-based formula (n=30) or switch to EHCF+LGG (Nutramigen LGG; n=29). Nursing staff, the researchers, and families of the patient were blinded to which formula was provided.

While all the infants had positive skin-prick test results for raw milk, 58% were positive for casein, 71% for beta-lactoglobulin, and 81% were positive for alpha-lactalbumin. At the time of allergy onset, 71% of infants were experiencing gastrointestinal symptoms, 73% had cutaneous symptoms, and 12% had respiratory symptoms.

For the double-blind placebo-controlled food challenge, patients were given seven doses of formula -- either EHCF+LGG or the amino acid-based formula they were already on as placebo. Doses started at 3 mg and increased up to 3,000 mg at intervals of 20 minutes, and patients were observed for 2 hours after the last dose for reactions.

If infants showed no symptoms in the first full day, parents were advised to administer a single dose of formula every day at home for 7 days and instructed to introduce no new foods. "In addition, an emergency treatment plan and prescriptions for emergency medications were provided to the parents," the researchers noted.

If infants were able to tolerate the 7-day initial testing, they were then randomly assigned to either continue the amino acid-based formula or switch to EHCF+LGG for the full study duration, with follow-up visits conducted at 6 and 12 months.

Limitations to the study include that the findings cannot be generalized to children with non-IgE-mediated CMA or those tolerating baked milk, along with other CMA patients excluded from enrollment.

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