Osmanthus food allergy

Osmanthus fragrans does cause food allergies and belongs to the category of niche food-borne plant allergens. According to the 2023 National Food-borne Allergen Monitoring Sampling Data from the China Centers for Disease Control and Prevention, this type of allergy accounts for about 0.12% of the domestic food allergy population. Most symptoms are mild and only manifest as perioral redness and swelling and gastrointestinal discomfort. Only a few people with severe allergies may induce airway edema or anaphylactic shock. As long as allergens are avoided in time and standardized intervention is performed, there is almost no fatal risk.

I came across a typical case when I was an intern in the allergy department. In autumn, a 22-year-old girl bought the sweet-scented osmanthus wine dumplings from an online celebrity store. After eating half a bowl, her mouth became swollen and shiny, and she vomited twice in a row. At first, she thought she was intolerant to alcohol, so she went to a community hospital to prescribe anti-allergic medicine and took it for two days before it went away. Later, a specific IgE test was performed and it was discovered that her allergy index to sweet-scented osmanthus was four times higher than the upper limit of normal, but both alcohol and glutinous rice were negative.

Regarding the sensitization mechanism of osmanthus food allergy, there are actually two different voices in the academic circles. Not everyone thinks that osmanthus itself is the "culprit". Most traditional allergology researchers believe that the lipid transfer proteins and pan-allergen profilins contained in osmanthus are core allergens. These proteins are very stable and difficult to be completely inactivated even after high-temperature cooking. In particular, the protein activity of fresh osmanthus is higher. After ingestion, it can easily trigger the immune system to misjudge and attack it as a harmful invader, resulting in allergic symptoms.

However, many scholars in the field of food toxicology have different views. They have counted the cases of "osmanthus food allergy" reported in the past three years and found that nearly 60% of patients will not be allergic to pure osmanthus extract alone. Instead, they are allergic to pollen, dust mites, or mixed with dried osmanthus products. The sweet-scented osmanthus flavors and preservatives added by merchants have shown positive reactions, and many of them are blamed on the ingredients that are paired with sweet-scented osmanthus - such as eggs and milk in sweet-scented osmanthus cakes, and pollen in sweet-scented osmanthus nectar, which are common strong allergens. Many people blame sweet-scented osmanthus without knowing it clearly.

Many people may have questions. I just sneezed and had a runny nose when I breathed in osmanthus pollen. How come I feel uncomfortable after eating something made from osmanthus? In fact, this is the cause of pollen-food allergy syndrome. Many people who are allergic to artemisia and ragweed pollen have antibodies in their bodies that cross-react with allergenic proteins with similar structures in sweet-scented osmanthus. This is equivalent to the immune system “confusing the enemy.” Originally, they were only allergic to inhaled pollen, but they eventually became infected by eating related foods.

How do you usually distinguish whether you are really allergic to osmanthus, or whether you are allergic to impurities or ingredients? If you just feel uncomfortable after eating commercially available osmanthus products and have no history of severe allergies, you can try making very light warm tea with unadded dried osmanthus. Hold a sip in your mouth for about 10 seconds and spit it out. After that, observe for 24 hours whether there is numbness, redness and swelling around the mouth or itchy throat. If you have a basic knowledge, you can be sure that you are allergic to the osmanthus itself. However, people with a history of systemic allergic reactions must not try it on their own. It is safer to go directly to the hospital for allergen testing.

Now that autumn has arrived, every store is offering osmanthus-only rolls, such as osmanthus latte, osmanthus basque, and osmanthus sauce braised ribs. Many businesses will secretly add osmanthus to enhance the flavor, and it is not listed on the menu at all. The girl who was diagnosed before later told me that she ordered a sweet and sour short ribs last time when she went out to eat, and her mouth felt numb after taking a bite. When I asked, I found out that the chef added osmanthus sauce to enhance the flavor, but it was not written in the name of the dish. It was hard to guard against it. By the way, as a digression, osmanthus has not yet been included in the list of allergens that are mandatory for food labeling in my country, so merchants have no obligation to proactively label it. People who are really allergic can only ask more questions themselves.

There is also an interesting little discovery. When we were sorting out cases, we found that people who are allergic to sugared osmanthus and osmanthus preserves made from fresh osmanthus are nearly three times more allergic than people who are allergic to hot foods processed from dried osmanthus. This is mainly because the process of high-temperature drying and long-term heating will denature some allergenic proteins. After the activity decreases, the allergenicity will be much lower. However, this rule only applies to people with mild symptoms. People with severe allergies should stay away from osmanthus in any form.

In fact, there is really no need to avoid osmanthus because of the possibility of allergies. After all, the allergy rate is only about one in a thousand. Most people will be fine if they eat some osmanthus cake and drink an osmanthus latte. It is not a big deal if they are found to be allergic. Pay more attention to it at ordinary times. If it is serious, keep an epinephrine pen with you. It is comfortable enough to smell the cinnamon all over the street. There is no need to join in the excitement of eating, right?