Study uncovers previously unconsidered variables correlated with food allergy

Key takeaways:

• Gastroesophageal reflux, antacid drug use, gestational age and birth weight were risk factors for food allergy.
• Blood type A represented increased risk, and blood type O had a protective effect.

WASHINGTON — Findings from an Israeli health care database revealed possible new risk factors for the development of food allergy in children, according to a poster at the American Academy of Allergy, Asthma & Immunology Annual meeting.

“IgE-mediated food allergies are a growing concern in the Western world,” Idit Lachover-Roth, MD, pediatrician, allergy and clinical immunology unit, Meir Medical Center, Kefar Sava, Israel, said during her presentation.

Personal or family histories of other atopic comorbidities, genetic predispositions, male sex, vitamin D deficiencies and hygienic environments all are established risk factors for food allergy, she continued.

“However, those factors do not fully explain most cases of food allergy,” Lachover-Roth said.

Similarly, she continued, early introduction to allergens can have a protective effect against developing food allergies, but this does not account for infants who were introduced to allergens later than recommended and still did not develop any food allergies.

“The current study aimed to search for associations between food allergy and non-specific medical data of infants during fetal life and their first 6 months of life,” Lachover-Roth said.

The researchers focused on the first 6 months because most food allergies develop during the second half of the first year of life or later, she said, adding that focusing on this period could provide clues to factors that might impact the development of food allergy.

The researchers examined data from Clalit Health Service, which they called the largest health service in Israel, including 370,298 infants born between Jan. 1, 2006, and Aug. 31, 2021. This cohort included 6,911 (1.87%) diagnosed with food allergy.

“We recognized 40 variables associated with development of food allergy,” Lachover-Roth said.

The most common variables through age 6 months associated with the development of food allergy included:

1. high socioeconomic status: 80.9%;
2. personal atopic dermatitis history: 24.8%;
3. firstborn status: 52.4%;
4. gastrointestinal disease diagnosis: 42.2%;
5. Maternal asthma: 28.9%;
6. Maternal allergic rhinitis: 26.3%; and
7. Maternal urticaria: 17.5%.

“Infants with socioeconomic score of five had nine times higher odds of developing food allergy compared to those with the lowest economic score,” Lachover-Roth said.

Birth weight and ethnicity also were prominent variables linked to food allergy, as were established risk factors including parental atopic comorbidities.

“However, we also discovered less familiar risk factors including gastroesophageal reflux, antacid drug use, gestational age and birth weight, which had previously been recognized as correlated with food allergy,” Lachover-Roth said.

Neonatal jaundice and blood type were correlated with the development of food allergy as well.

“Infants with blood type A or born to mothers with blood type A are at increased risk of developing food allergy,” Lachover-Roth said. “Conversely, infants with blood type O or born to mothers with blood type O were protected from developing food allergy.”

Prematurity and low birth weight appeared to be protective factors against the development of food allergy, the researchers continued.

But even when these risk factors are considered, the researchers said, many food allergy cases remain unexplained, with less than 1% of the infants with food allergy displaying no more than one of the suggested risk factors.

The timing of allergen introductions into diets also may affect risks for developing food allergy and mask the influence that these risk factors may have, the researchers suggested.

“Our study represents the largest and most comprehensive investigation aimed at identifying new risk factors for food allergy,” Lachover-Roth said. “While it reaffirms the significance of known risk factors, it also sheds light on less familiar and optional risk factors.”

Further investigation should verify the influence that these risk factors may have on the development of food allergy, the researchers said.