Elderberry, primarily sourced from the Sambucus nigra plant, is a widely used natural remedy, often found in syrups, extracts, and lozenges. The dark berries and flowers are prized for their high concentration of antioxidants and immune-supportive properties. As consumption of elderberry products increases, understanding the nature and likelihood of an allergic response is necessary for safe use.
Overall Likelihood of Elderberry Allergy
A true allergy to elderberry is uncommon compared to reactions from major food allergens like peanuts or shellfish. The prevalence of sensitization to elderberry proteins is low; one study showed a positive skin prick test or specific IgE antibodies in approximately 0.6% of tested patients. This low incidence contributes to limited large-scale data regarding elderberry allergies.
A genuine allergic reaction involves an immune system response to specific proteins within the plant. The existence of a defined elderberry allergen, known as Sam n 1, confirms the potential for a Type I hypersensitivity reaction, even though the overall risk remains low.
Allergy Symptoms Versus Toxicity Symptoms
Adverse reactions to elderberry are often misunderstood, confusing an immune-mediated allergy with non-allergic gastrointestinal distress. A true elderberry allergy is an immediate, IgE-mediated response that manifests with classic food allergy symptoms. These include dermal reactions such as hives, itching, and swelling of the lips, tongue, or throat. More severe reactions involve respiratory symptoms like wheezing, difficulty breathing, and, rarely, anaphylaxis.
Toxicity Symptoms
The most common adverse effects reported from elderberry consumption are symptoms of toxicity, which are dose-dependent and related to improper preparation. Raw elderberries, leaves, stems, and roots contain cyanogenic glycosides, such as sambunigrin. When ingested, these compounds metabolize into cyanide, leading to acute gastrointestinal upset. Symptoms of this toxicity include nausea, vomiting, severe diarrhea, and abdominal cramping.
Toxic reactions are not an immune response but a direct result of ingesting a harmful compound. Consuming large quantities of raw or insufficiently cooked elderberry products has, in rare instances, necessitated hospitalization due to severe vomiting and diarrhea. The key differentiator is that toxicity symptoms are almost exclusively gastrointestinal and linked to these glycosides, while allergy involves skin, respiratory, and circulatory systems.
Specific Factors That Increase Allergy Risk
While elderberry allergy is uncommon, certain pre-existing conditions can increase an individual’s risk. The most recognized risk factor is the presence of other plant-based allergies, which can lead to cross-reactivity. Individuals who experience Oral Allergy Syndrome (OAS), also known as Pollen Food Allergy Syndrome (PFAS), may have a higher likelihood of reacting to elderberry.
OAS occurs when the immune system confuses proteins in certain fruits or vegetables with those found in common pollens, such as birch or grass pollen. Although the major elderberry allergen, Sam n 1, is distinct from primary birch pollen allergens, individuals with a generalized plant protein sensitivity are still more susceptible. The elderberry plant belongs to the Adoxaceae family, and sensitivity to this family or similar plant proteins, such as thaumatins, could increase the risk of an allergic response.
The specific allergen, Sam n 1, is a protein with homology to ribosomal inactivating proteins (RIPs). People with a history of allergic rhinoconjunctivitis, or hay fever, may experience sneezing and nasal congestion upon contact with elderberry flowers or pollen. A general history of reacting to fruits and berries should prompt caution before introducing elderberry products.
Preparing Elderberry Safely
The most effective way to prevent common adverse reactions is through proper processing of the plant material. The cyanogenic glycosides responsible for toxicity are heat-sensitive, so cooking the berries is necessary to neutralize these toxic compounds before consumption.
It is recommended to avoid consuming raw elderberries, as well as any part of the plant other than the properly cooked berries or flowers. This includes the leaves, stems, and roots. Homemade preparations, such as syrups or jams, must be brought to a sufficient boil and simmered for an extended period (often 25 to 45 minutes) to ensure toxic components are fully deactivated.
Commercially prepared elderberry products, such as standardized extracts and supplements, are manufactured to eliminate the toxicity risk. Consumers should verify that the product is made from properly processed fruit. When preparing elderberry at home, the focus should be on thorough heat treatment to mitigate the risk of gastrointestinal distress, which remains the most common negative reaction.