Researchers describe rare case of flaxseed allergy in toddler

ANAHEIM, Calif. — After diagnosing an IgE-mediated flaxseed allergy in an 18-month-old child, researchers recommended allergists be aware of this allergy as its incidence may increase with the growing popularity of flaxseed.

This research was presented as a medically challenging case at the American College of Allergy, Asthma & Immunology Annual Scientific Meeting.

“Flaxseed allergy is relatively rare compared to allergies to common allergens, like peanuts, eggs or dairy,” Alana Xavier de Almeida, MD, of the department of pediatrics at University of Miami and the Jackson Health System, told Healio. “Specific prevalence rates for flaxseed allergy in adult and pediatric populations are not yet documented. Further research is needed to demonstrate the prevalence. However, as the use of flaxseed increases, it is expected that the number of allergic reactions associated with this seed will continue to increase.”

Further, most previously described cases of flaxseed hypersensitivity are anaphylactic reactions in adults with associated asthma and/or contact dermatitis, she added.

Xavier de Almeida and colleagues described an 18-month-old male nonatopic toddler who presented with a raised erythematous pruritic rash on his face and chest 20 minutes after consuming a packet of oatmeal, with symptoms resolving within 4 hours.

Clinicians performed skin prick testing for various nuts and seeds and found significantly elevated flaxseed-specific IgE at 15 kU_A/L at 19 months and 47 kU_A/L at 31 months. Testing also revealed a slightly elevated total IgE of 595 kU_A/L at 19 months and 396 kU_A/L at 31 months.

The oatmeal packet contained approximately 1,800 mg to 2,200 mg of flaxseed protein and was the first time the child had consumed flaxseed.

Based on these findings, the researchers diagnosed an IgE-mediated reaction to flaxseed, but the parents preferred to forgo a direct oral flaxseed challenge test.

“Diagnosing a flaxseed allergy in this 18-month-old patient was unexpected given the rarity of such cases in toddlers,” Xavier de Almeida told Healio. “The surprising aspect was not only the young age of the patient but also the immediate IgE-mediated reaction upon the first known oral ingestion of flaxseed. The child exhibited a reaction upon the initial oral ingestion, suggesting prior sensitization, possibly through cutaneous exposure during infancy.”

Specifically, the researchers noted the patient’s mother enjoyed flaxseed smoothies regularly during the child’s infancy, which they hypothesized was the source of the cutaneous exposure and subsequent allergy.

“Furthermore, the patient’s polysensitization to other seeds and nuts, coupled with the unusually high flaxseed-specific IgE levels, raised questions about potential cross-reactivity and the specificity of the allergic response,” Xavier de Almeida added.

As flaxseed becomes more popular, allergists should be aware that this allergy may grow in prevalence, according to the researchers.

“Allergists need to be aware of flaxseed allergy and more research needs to be performed on cross-reactivity among nuts, legumes and other seeds, and positive predictive values of flaxseed specific IgE established,” Xavier de Almeida said, adding that she plans to next identify the specific flaxseed protein subunits that could be causing the IgE-mediated allergy.

Reference:

• ACAAI. Flaxseed allergy appearing more frequently – Present in foods and other substances. https://annualmeeting.acaai.org/2023/flaxseed.cfm. Published Nov. 9, 2023. Accessed Nov. 10, 2023.