Sesame is a seed, not a nut, but it represents one of the most serious and rapidly increasing food allergies worldwide. The allergy is an adverse immune response mediated by Immunoglobulin E (IgE) antibodies reacting to proteins in the seeds of the Sesamum indicum plant. Due to the severity of reactions and the widespread use of sesame in food preparation, the rising prevalence of this allergy has prompted governments to recognize it as an allergen requiring mandatory labeling.
Seed Status and Regulatory Recognition
Botanically, sesame is classified as a seed from the flowering plant Sesamum indicum, belonging to the Pedaliaceae family. This classification clearly distinguishes it from tree nuts and peanuts (a legume). Despite these differences, sesame contains highly allergenic proteins that can trigger reactions as severe as those caused by peanuts or tree nuts.
Due to the potency of its allergens and its increasing use in global cuisine, sesame has received significant regulatory attention in the United States. The Food Allergy Safety, Treatment, Education, and Research (FASTER) Act of 2021 officially designated sesame as the ninth major food allergen. This legislation mandates that all packaged foods regulated by the Food and Drug Administration must clearly declare the presence of sesame on the label. This regulatory step provides individuals with a sesame allergy the same level of consumer protection afforded to those with allergies to the other eight major allergens.
Clinical Manifestations
A reaction to sesame can manifest a wide range of symptoms, generally occurring rapidly, often within minutes to an hour of consumption. Mild to moderate symptoms may involve the skin, presenting as hives, redness, or generalized itching, or the gastrointestinal tract, causing abdominal pain, vomiting, or diarrhea.
More severe systemic reactions, known as anaphylaxis, can affect multiple organ systems and are life-threatening. Anaphylaxis may involve respiratory distress, such as wheezing, difficulty breathing, or a tight feeling in the throat due to airway swelling. Circulatory symptoms like a rapid, weak pulse, dizziness, or a sudden drop in blood pressure are also signs of a severe reaction.
Diagnosis Testing and Avoidance Strategies
Diagnosis of a sesame allergy typically begins with a detailed medical history followed by specific testing overseen by an allergist. Skin prick tests involve placing a small amount of sesame extract on the skin and monitoring for a localized reaction, such as a raised bump or wheal. Blood tests measure the level of specific IgE antibodies the immune system produces in response to sesame proteins.
The gold standard for definitively confirming a sesame allergy remains the oral food challenge, which is conducted in a medical setting where the patient consumes controlled, increasing amounts of sesame under close supervision. Following a confirmed diagnosis, the primary management strategy is strict avoidance of sesame and all sesame-containing products. This requires meticulous label reading, especially since the FASTER Act is relatively new and some older products may still be on shelves without the required allergen declaration.
Sesame can be a hidden ingredient, sometimes listed under alternative names:
- Tahini
- Benne
- Gingelly oil
- “Spice” or “natural flavoring” on older labels
Individuals must also be vigilant for cross-contact in restaurants and during food preparation, particularly with baked goods and certain ethnic foods where sesame is common. Carrying an emergency action plan and two epinephrine auto-injectors at all times is necessary for those diagnosed with a sesame allergy to treat accidental exposure.
Cross-Reactivity with Nuts and Peanuts
While sesame is not a nut, having a sesame allergy does not automatically mean a person will also be allergic to tree nuts or peanuts, as these are botanically distinct food groups. However, there is a common phenomenon known as co-sensitization, where a person is independently allergic to multiple foods.
Studies have shown that individuals with a confirmed allergy to both peanuts and tree nuts are significantly more likely to also be sensitized or allergic to sesame. This overlap may be partly explained by structural similarities between the storage proteins found in sesame, peanuts, and tree nuts. Although co-sensitization is frequent, true immunologic cross-reactivity, where the immune system mistakes a protein from one food for a protein in another, is less common. Therefore, a clinical diagnosis for each specific food is necessary to confirm the full range of allergies.