Hay fever sufferers should take a pass on the swiss chard and sunflower seeds. No celery sticks in the shade of a birch tree either. Skip the dill pickles if you react to latex, steer clear of tropical fruit if dust mites make you sneeze, and yes, pork and cat dander can be problematic.
These are all examples of cross-allergies (also known as Pollen-Food or Oral Allergy Syndrome), and like the recent rise of food allergies, they are becoming more common. About a third of seasonal allergy sufferers will cross-react to the wrong foods, but the number is closer to two-thirds if birch or alder pollen are your triggers.
Here’s how it works: the same chemicals that cause hay fever and other airborne allergies can also be found in some foods. There’s a whole grocery list of reactive foods, but the culprit is usually a raw fruit or vegetable that has the same protein as the airborne allergen. Eat the wrong food, and it sends the immune system into overdrive and triggers an allergic reaction. Instead of the sneezing and itchy eyes you get when you inhale the allergen, you’ll end up with a tingly mouth, hives, difficulty swallowing, or even anaphylaxis—all food allergy symptoms.
These are the most commonly occurring cross-allergies and their offending foods:
- Dust/Dust Mites: mangos, shellfish, plums, melons, tomato, avocado, pawpaw, pineapple, peaches, and kiwis.
- Latex: almonds, apples, bananas, kiwis, avocado, dill, oregano, ginger, and sage.
- Birch/Alder Tree Pollen: celery, apples, apricots, cherries and other stone fruits, parsnips, buckwheat, caraway seeds, and coriander.
- Hayfever (Ragweed/Grasses): cantaloupe, watermelon, honeydew, bananas, sunflower seeds, zucchini, cucumber, and chamomile tea.
- Cat Dander: pork.
Some foods contain more of the troublesome proteins than others—peaches more than plums, apples more than pears. And there can be differences between varieties—Gala and Golden Delicious apples cause more allergic reactions than Braeburns, and Crenshaw melons are benign while cantaloupe and watermelon are powerful triggers.
Not every pollen produces cross-allergies; some trees like maple, oak and poplar, don’t share reaction-causing proteins with foods. Nor does having one of these allergies mean you’ll necessarily cross-react with any of the implicated foods. And, if you do react, you may not be allergic to every food on the list.