Sesame (Sesamum indicum) is an oil seed plant of the family of Pedaliaceae, originating in India and cultivated in Africa, Asia, the Balkans, the Middle East, Latin America and USA. It includes four species of which Sesamum indicum is the most important found in commerce. The seeds contain approximately 50% oil, used for cooking, and salad dressings. In recent years the worldwide production and consumption of Sesame seeds has tremendously increased.
Sesame seeds are consumed as whole seeds or are used in food industry for the production of Sesame paste and oil. Common foods containing Sesame are Middle Eastern dishes, dips, salad dressing, vegetarian foods, Turkish halvah, tahini (ground Sesame seed, tehina), fast food confections, and various bakery products. Furthermore, Sesame oil has been used in the pharmaceutical and cosmetic industries due to its presumably low antigenicity.
Sesame seeds are increasingly reported to cause systemic anaphylactic reactions, however, a broad spectrum of clinical symptoms have been reported in several case reports or series of cases. The symptoms of Sesame seed allergy can be grossly classified into:
Systemic reactions: Primarily presenting anaphylaxis characterized by simultaneous involvement of many organs in various combinations of symptoms including hives (urticaria), lip and eyelid swelling (angioedema ) sneezing, nasal itching, congestion, rhinorrhea, wheezing, cough, tightness of throat, hoarse voice, difficulty in breathing, abdominal pain, unconsciousness, shock with drop of blood pressure. In the systemic reactions can also be included severe reactions like dizziness, drowsiness, chills and collapse as has been reported in patients after ingestion of falafel burger.
Symptoms involving skin and mucosa: Facial or generalized redness (“flushing”), hives (urticaria) on smaller or larger parts of the body, swelling of the eyelids, lips or other parts of the face, itching of the eyes or of the skin in general, hayfever symptoms in the eyes and eczema.
Respiratory symptoms: Hayfever, asthma, cough, wheeze, or difficulty in breathing.
Gastrointestinal symptoms: Itching in the mouth and/or tongue soon after chewing and ingesting (Oral allergy syndrome), abdominal pain, swelling of the tongue, throat, and vocal cord, indigestion, nausea, vomiting, diarrhoea.
The onset of the symptoms may occur within a few minutes up to 90 minutes after ingestion of sesame seed flour as it was shown in 7 patients undergoing oral provocation test. In a large series of sesame-allergic infants and young children the most frequent symptoms were from the skin, but about one third had anaphylaxis and less than one tenth had symptoms from the stomach. It was a common finding that most patients had other allergic diseases such as asthma, hayfever, and eczema, and most patients also had a relative with an allergic disease. More than two thirds of the patients also had food allergic reactions to other foods.
How much is too much?
Doses as low as 100 mg of sesame seeds or sesame flour and 3 ml of sesame oil were capable to elicit reactions in sesame allergic individuals during double-blind, placebo-controlled food challenge (DBPCFC). Most patients, however, reacted to 2–10 grams of sesame seeds or sesame seed flour.
Related foods (cross reactivity)
Clinically significant cross reactivities have been shown between sesame seed and poppy seed allergens and between sesame seed food and hazelnut and rye grain. In patients with sesame allergy/sensitivity, associated allergy to Brazil nut, almond, walnut and pistachio has also been reported.
Who, when, how long, and how often?
Current knowledge of the occurrence of Sesame seed allergy is limited but during the last decade sesame is an emerging cause of food anaphylaxis, due to the increasing use of the seeds/flour/oil in food products including food preparations for infants. This can explain the finding of sesame allergy even in extremely young infants. It varies according to the group of individuals studied and the country. In Australia the occurrence of allergy to sesame seed was estimated to be 0.42% among all children, while in the UK it was found to be 0.04% of adults. However the occurrence of allergy to sesame in patients with food allergy was found to be much higher than in the general population varying among the different countries studied, ranging from 0.5% in Switzerland to 8.5% in Australia.
Recently, sesame was found to be a major cause of severe food allergic reactions among infants and young children in Israel. Sesame was found to be second only to cow’s milk as a cause of anaphylaxis. This was attributed to the early exposure in life and the heavy consumption of Sesame-containing foods in Israel. An increase in infantile eczema and anaphylaxis to food in Australia has been associated with sensitization to Sesame seed. The number of children sensitized to sesame seed was higher than the number sensitized to any one tree nut and this sensitization occurred early since 60% were under 24 months. To illustrate the issue an 11 months old infant developed facial swelling, hives, and wheeze when given his first taste of tahini, which his mother had consumed during pregnancy and lactation. A striking increase of cases of allergy to sesame has also been noted in France since 1993.
The natural course of allergy to Sesame is not known but only 15% of children diagnosed at age 10-12 months outgrew their sesame allergy within 1 ½ - 2 years.
Occupational allergy has also been seen in bakers preparing Sesame containing special breads and numerous other bakery products.
It is speculated that since the use of Sesame seed/oil – containing products has spread through Europe and North America, probably due to the introduction of new trends such as vegetarianism, “health food” and exposure to exotic foods, a significant increase of recognized Sesame allergies including many anaphylactic reactions is likely to occur.
A clinical history of allergy to Sesame seeds/flour/oil should be further investigated by skin prick testing (SPT) to commercial extract and/or crude sesame seeds, blood samples and oral provocation to Sesame seeds or oil. In small children “open” challenge can be used but otherwise challenges where the sesame is hidden should be used. Since the quality of the skin tests and blood samples are not sufficiently high it is almost always necessary to confirm the sesame allergy by a challenge.
Patients diagnosed to have an allergy to sesame seeds/flour/oil should avoid all sesame–containing products. Although the stability of allergens is not known, sesame seeds are probably heat stable thus retaining their allergenicity after cooking. In addition sesame seed is a highly significant hidden allergen. Anaphylaxis to Sesame seed oil has been reported at a dose of 3 ml. It should be noted that Sesame oil is supplied in unrefined form and often is a hidden allergen, frequently labelled “vegetable” oil in a wide variety of products like margarine. Labelling of Sesame seeds and their products has been recommended by European Regulations. Patients therefore should try to identify food sources of sesame seed/flour/oil. Sesame sources reported to cause allergic reactions include: Sesame seeds, falafel vegetable burgers, white sauce containing Sesame, seed paste (tahini), salads containing Sesame seed oil, halvah, crackers, candy, hamburger on Sesame seed ban, bakery products, Sesame cake, Chinese food, appetizers, Turkish cake, breads.
Cosmetics containing Sesame seed oil include lipsticks, moisturizing cream, and body oils.
Finally inhalation of sesame seed dust can cause occupational respiratory allergy (asthma, hayfever) to sesame.