Sesame

Sesame as a Food Allergen in the Human Body

Sesame (Sesamum indicum) allergy is a serious IgE-mediated food allergy that is increasing in prevalence worldwide. Due to its high oil and protein content, sesame is a potent allergen, capable of triggering mild to severe allergic reactions, including anaphylaxis. It is one of the top 9 major food allergens recognized by the FDA.

How Sesame Allergy Develops in the Immune System

Initial Sensitization (Immune Priming)

• Sesame proteins (allergens) are ingested, and some remain undigested due to their resistance to gastric enzymes.
• Dendritic cells in the gut-associated lymphoid tissue (GALT) present sesame allergens to naive T-helper (Th2) cells.
• Th2 cells stimulate B-cells to produce IgE antibodies specific to sesame proteins.
• IgE binds to mast cells and basophils, making them “sensitized” to sesame allergens.

Subsequent Exposure (Allergic Reaction)

• When sesame proteins re-enter the body, they bind to IgE on mast cells.
• This triggers mast cell degranulation, releasing histamine, prostaglandins, and leukotrienes.
• These inflammatory mediators cause allergic symptoms:
  1. Skin: Hives, eczema, swelling (angioedema)
  2. Gastrointestinal tract: Nausea, vomiting, diarrhea, abdominal pain
  3. Respiratory tract: Wheezing, coughing, shortness of breath
  4. Systemic reaction: Anaphylaxis (severe cases)

Major Sesame Allergens and Their Role in Reactions

Sesame contains multiple allergenic proteins, but Ses i 1, Ses i 2, and Ses i 3 are the most significant.

Sesame Allergen	Protein Family	Molecular Weight	Immune Reaction	Heat Stability
Ses i 1	2S Albumin	~9 kDa	Major allergen, responsible for severe reactions	Highly stable
Ses i 2	7S Vicilin	~50 kDa	Cross-reactive with legumes (peanuts, soy)	Heat-resistant
Ses i 3	11S Legumin	~60 kDa	Cross-reactive with tree nuts, peanuts	Stable
Ses i 4, Ses i 5	Oleosins	~15-20 kDa	Lipid-binding proteins, may contribute to allergenicity	Highly stable in sesame oil

• Ses i 1 (2S Albumin) is the most potent sesame allergen, triggering anaphylaxis in highly sensitive individuals.
• Ses i 2 (7S Vicilin) and Ses i 3 (11S Legumin) cross-react with other legumes and nuts, increasing the risk of multiple food allergies.
• Sesame allergens are highly stable, meaning roasted, toasted, or processed sesame (tahini, sesame oil) still retains allergenicity.

Symptoms of Sesame Allergy

Mild to Moderate Reactions

• Skin: Hives, swelling, eczema
• Gastrointestinal (GI): Nausea, vomiting, diarrhea, bloating
• Respiratory: Sneezing, coughing, nasal congestion
• Oral Allergy Syndrome (OAS): Itchy mouth/throat after consuming sesame

Severe Reactions (Anaphylaxis)  Requires immediate administration of epinephrine (EpiPen®).

• Airway restriction: Difficulty breathing, throat swelling
• Drop in blood pressure (anaphylactic shock)
• Dizziness, fainting, confusion
• Swelling of lips, tongue, or face
• Tachycardia (rapid heartbeat)

Diagnosis of Sesame Allergy

Skin Prick Test (SPT)

• Detects IgE-mediated allergic response to sesame proteins.

Serum IgE Testing

• Measures specific IgE antibodies to sesame allergens.

Oral Food Challenge

• Gold standard for confirming sesame allergy, performed under medical supervision.

Component-Resolved Diagnostics (CRD)

• Detects specific sesame allergens (Ses i 1, Ses i 2, etc.) to assess reaction severity and cross-reactivity risk.

Managing Sesame Allergy

Strict Sesame Avoidance

• Avoid all sesame-based foods:
  • Sesame seeds, tahini, sesame oil, sesame flour
  • Processed foods with sesame extract, sesame paste
  • Middle Eastern, Asian, and Mediterranean foods (hummus, sushi, falafel, halva)

Alternative Seed Options

Sesame-Free Substitute	Safe Alternative
Sesame Oil	Olive oil, avocado oil, coconut oil
Tahini (Sesame Paste)	Sunflower seed butter, almond butter (if no nut allergy)
Sesame Seeds in Recipes	Chia seeds, flaxseeds (if tolerated)

Emergency Treatment

• Epinephrine injection (EpiPen®) for anaphylaxis.
• Antihistamines for mild allergic reactions.
• Corticosteroids for prolonged symptoms.

Conclusion

• Sesame allergy is caused by multiple proteins (Ses i 1, Ses i 2, Ses i 3, Oleosins).
• Ses i 1 (2S Albumin) is the most potent sesame allergen, triggering severe reactions.
• Sesame allergens are heat-stable, meaning roasted or processed sesame retains allergenicity.
• Sesame cross-reacts with peanuts, tree nuts, legumes, and sunflower seeds.
• Severe sesame allergy can lead to anaphylaxis, requiring strict avoidance and emergency preparedness (EpiPen®).