Pineapple is a nutritious food, providing 131 percent of the daily value for vitamin C and 77 percent of the DV for manganese in each cup of fresh cubed pineapple. The juice isn't quite as nutritious, as it doesn't provide fiber and only has 42 percent of the DV for vitamin C per cup. Some people may want to avoid pineapple, or at least fresh pineapple and pineapple juice, however, due to an unpleasant reaction they experience when eating this fruit.
Pineapple Allergies and Cross-Reactions
Although it isn't common, some people are allergic to pineapple and experience an allergic reaction with symptoms that may include hives, shortness of breath, dizziness, stomach cramps or swelling of the mouth, throat and tongue. If you're allergic to carrot, grass pollen, fennel, celery or wheat, you may be more likely to be allergic to pineapple as well.
When eating pineapple, people with allergies to honeybees, celery, papain, cypress pollen and olive tree pollen may experience a cross-reaction that causes their mouth and lips to itch temporarily. It's best to avoid pineapple entirely if you experience these types of reactions.
Effects of Bromelain
Pineapple contains a substance called bromelain that actually breaks down proteins, which is why it's sometimes used as a meat tenderizer. If your mouth gets sore after eating pineapple or drinking fresh pineapple juice, it may be because the bromelain started breaking down the proteins that make up your mouth. The enzymes in your stomach break down the bromelain, which is why your mouth is usually the only part of your digestive tract affected this way. Your mouth and cheeks may even swell if you eat too much pineapple.
Minimizing the Effects
If it's just the bromelain in the pineapple that's causing your mouth problems, you can minimize the risk of this occurring in the future by only eating cooked or canned pineapple. Heat inactivates the bromelain so it no longer breaks down the proteins in your mouth. This means pasteurized pineapple juice, like most brands sold in the grocery store, shouldn't cause a reaction.
Other Potential Considerations
The bromelain in pineapple can interact with certain medications, including blood thinners, tetracycline antibiotics, sedatives, anti-seizure medications, antidepressants and insomnia medications. Bromelain can also cause diarrhea, nausea and vomiting when consumed in large amounts. Don't drink the juice from pineapples that aren't fully ripe, as this can cause severe vomiting.