Sue Hefle, Ph.D.
When discussing food allergies, we often hear about the eight common foods that cause approximately 90% of all allergic reactions to foods. These include peanuts, tree nuts, eggs, milk, soy, fish, shellfish (e.g., shrimp, crab, lobster, crawfish), and wheat. There are at least 160 other foods that cause the other 10% of allergic reactions to food. While reactions to many of these latter foods are very rare, there is a “second tier” of foods that seem to cause allergic reactions more frequently than the rest.
This second tier includes some of the seeds, namely sesame, sunflower, and poppy. These foods can cause reactions equally as severe as the foods that commonly cause reactions; they just affect fewer people in the population. Sesame, sunflower, and poppy seeds have been associated with cases of anaphylactic shock. We enjoy the use of seeds in many food products. For the purposes of this article, “seeds” include sesame, poppy, sunflower, and cottonseed. Sesame, poppy, and sunflower seeds are used in many bakery items, such as cookies, breads, muffins, and cakes. Sesame seeds are used in many types of crackers, and sunflower seeds are often used in trail mixes. Cottonseed is not usually used in food products.
In recent years, consumers have developed a particular liking to bakery items, such as bread containing many different kinds of seeds. Extracts of some seeds are even showing up as ingredients in certain hair care products. Therefore, individuals with seed allergies should check the ingredient listing of new shampoos, conditioners, lotions, and styling agents much as they would check an ingredient listing on a food product, because the seed extracts in the products could cause hives or perhaps more serious reactions through contact with the skin. A question often asked is if seed oils are safe to consume by those who are allergic to seeds. Seed oils are used in some types of ethnic cooking and occasionally can be found as ingredients in packaged food products. Some seed oils are highly refined, using a process that removes the proteins from the oil. Seed oils that are usually highly refined include cottonseed and sunflower oils. Proteins in food are what cause allergic reactions, and individuals are not likely to be allergic to these highly refined oils.
However, some seed oils, such as sesame seed oil, are not highly refined, and consequently they can contain potentially hazardous amounts of protein. Therefore, persons allergic to seeds should be cautious about ingestion of these seed oils.
On packaged food products, seeds are usually labeled as a separate ingredient, although sesame and poppy are considered spice seeds, and might simply be listed on labels collectively as “spices.” It is important to remember that seeds come in different shapes, colors, and sizes; for example, there are both black and white sesame seeds.
Some researchers suggest that sesame seeds should be included in the list of foods that commonly cause reactions, as anecdotal reports give the impression that sesame seeds are becoming an increasing cause of food allergy. While there are numerous reports of anaphylaxis to sesame seeds in the literature, the general prevalence of sesame seed allergy is still unknown, and to date, there is not enough data to warrant inclusion of sesame seeds in the list of the major allergens.
An interesting observation about the prevalence of sesame seed allergy is that many of our most popular fast-food restaurants use sesame seeds extensively on their hamburger buns. Given our love of fast food, this means that the population is being exposed to regular doses of sesame seeds.
Seeds are particularly challenging to clean up for the food industry, due to their small size. You may have experienced this yourself if you have ever accidentally spilled poppy seeds while making muffins; you probably saw poppy seeds seemingly appear out of nowhere in your kitchen for some time afterward.
The baking industry, where most seeds are used, has extensive cleaning and scheduling procedures in place to try to prevent the accidental presence of seeds in products where they don’t belong. However, in the smaller retail baking establishments, consumers allergic to seeds should ask questions of the staff about how various breads and other products are handled and should examine their purchases closely before eating them.
One should also be careful when purchasing bakery items from the grocery store, where they may be offered in a self-serve format. Errant seeds on the bottom of a bin used previously for holding sesame seed or poppy seed bagels may stick to freshly made plain bagels that are then dumped into the bin, and they might not be readily noticeable. Again, a thorough examination of your bakery products should be made before consumption.
Sue Hefle, Ph.D., is assistant professor and co-director of the Food Allergy Research and Resource Program, University of Nebraska-Lincoln, Lincoln, Neb.
Reprinted from Food Allergy News, Vol. 12, No. 1.
The Food Allergy & Anaphylaxis Network (800) 929-4040 www.foodallergy.org
