Citrus fruits offer a host of health benefits, but is there a downside to oranges, lemons and the like? It's been debated if citrus fruits are foods that cause canker sores. But more research is needed on the exact causes of canker sores, including if these fruits specifically can cause them.
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Here's what to know about citrus fruits, canker sores and how to get relief.
Citrus Fruit Benefits
According to the University of Washington (UW), citrus fruits (think oranges, grapefruits, lemons and limes) are nutritional powerhouses, overflowing with vitamin C, fiber and plant nutrients called flavonoids.
Collectively, UW says, those properties have been linked to the prevention of such conditions as:
- Neurological disorders.
- Gastrointestinal troubles.
According to UW, vitamin C (aka ascorbic acid) content is also known for:
- Boosting the immune system.
- Promoting vascular health.
- Bolstering bone and skin integrity.
But citrus fruits can have downsides. UW cautions that some citrus fruits, including grapefruits and oranges, can interact with the absorption and metabolism of certain prescription medications.
And as to whether citrus fruits actually cause mouth and tongue sores, the picture is a bit more murky.
The Unclear Citrus-Canker Connection
"The cause of canker sores is unclear," St. Louis-based food and nutrition consultant Connie Diekman, RD, LD, former president of the Academy of Nutrition and Dietetics, says. Though she does highlight several possible triggers, "ranging from overbrushing of teeth and gums to diet deficiencies or sensitivities."
The U.S. National Library of Medicine (NLM) also notes that the causes of canker sores aren't clearly defined yet, but that they may also include factors such as:
- A weakened immune system.
- Changes in hormones.
More research is needed on the topic of canker sore causes, including if citrus fruits specifically can be a cause.
Citrus: The Mouth Sore Aggravator
Though the exact causes of canker sores remain unclear at this time, it is thought that citrus fruits may irritate canker sores if you do get them. Diekman says that the citric acid these fruits contain "can aggravate canker sores, triggering more discomfort."
Diekman includes citrus fruits — alongside salty and spicy foods — as items best avoided if you are trying "to manage the discomfort" caused by mouth sores.
Similar advice is offered by the Leukemia & Lymphoma Society, cautioning that people with cancer, who face a high risk for mouth sores due to chemotherapy and radiation treatment, avoid citrus fruits and juices specifically to prevent making existing mouth sores worse.
Read more: The Effects of Eating Too Much Grapefruit
Mouth Sores Be Gone
On the relief front, Mayo Clinic says that most sores resolve by themselves within two weeks. And while larger, more painful sores may take upwards of six weeks to heal, in most cases treatment is really just about addressing the pain and inflammation.
For that purpose, Mayo Clinic says pain relief can come in the form of mouth rinses containing dexamethasone and lidocaine, as well as over-the-counter or prescription liquids, gels, creams or pastes containing pain-relieving ingredients such as benzocaine, fluocinonide and hydrogen peroxide.
"And if you notice a pattern of getting mouth sores when you are stressed," Diekman says, "try to learn stress reduction techniques to help reduce their frequency." Natural remedies for canker sores may also help.
Canker Sore Symptoms
According to the Mayo Clinic, round or oval mouth sores — or canker sores — develop on the soft tissue of the mouth or gums, including the tongue, cheeks or soft palate. Unlike cold (lip) sores, they are not caused by the herpes simplex virus and aren't contagious, the NLM notes.
And if you have them, then you know — canker sores are no fun. The tingling or burning discomfort they incite can interfere with eating and talking, Mayo Clinic says. In fact, any movement related to chewing or speaking can cause pain temporarily, but this should disappear on its own within a week or two.
- Connie Diekman, MEd, RD, LD, FADA, food and nutrition consultant; former president, Academy of Nutrition and Dietetics; coauthor, Everything Mediterranean Diet Book; former director, University Nutrition, Washington University in St. Louis; St. Louis
- University of Washington: “The Powerful Health Benefits of Citrus Fruits”
- U.S. National Library of Medicine: “Mouth Sores”
- Mayo Clinic: “Canker Sore: Symptoms and Causes”
- Mayo Clinic: “Canker Sore: Diagnosis and Treatment”
- U.S. National Library of Medicine: “Canker Sores”
- Leukemia & Lymphoma Society: “Nutrition Tips for Managing Sore Mouth, Throat, and Tongue”
Is this an emergency? If you are experiencing serious medical symptoms, please see the National Library of Medicine’s list of signs you need emergency medical attention or call 911.