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Probiotics and xylitol gum found ineffective at relieving sore throats

A substantial number of sore throats are bacterial infections, such as strep throat, which is caused by streptococcal bacteria. Those infections do respond to antibiotic drugs.

Probiotics and xylitol chewing gum are not effective at relieving sore throat symptoms, according to a study conducted by researchers at the University of Southampton in Great Britain and published this week in the Canadian Medical Association Journal (CMAJ).

The findings are disappointing, for it had been hoped that these two over-the-counter products might reduce the amount of antibiotics that doctors prescribe — often unnecessarily — for sore throats.

The overprescribing of antibiotics is a major factor in the development of drug-resistant bacteria — what’s being called “the health crisis of our generation.

Most sore throats are caused by viruses, for which antibiotics are useless. But a substantial number of sore throats are bacterial infections, such as strep throat, which is caused by streptococcal bacteria. Those infections do respond to antibiotic drugs.

Too often, however, doctors will prescribe antibiotics before confirming whether the infection is viral or bacterial. They do this, in part, because patients pressure them to “do something” for their sore throat pain.

That’s where xylitol and probiotics come into the picture. It’s been hoped that they could be recommended in lieu of antibiotics to some patients who show up at the doctor’s office with a painful, but not medically complicated, sore throat.

Xylitol, a sugar originally derived from the bark of birch trees, has been found in laboratory studies to interfere with bacterial growth. It has also been shown to adhere to the walls of the pharynx, the cavity behind the nose and mouth. Probiotics, which are benign bacteria, have also been shown to interfere with the growth of disease-causing bacteria. Some studies have even suggested (but haven’t proved) that probiotics might reduce the risk of upper respiratory tract infections.

“It is plausible that both probiotics and xylitol could limit the severity of pharyngeal infections and help with symptom control, but there is no direct evidence to support this supposition,” write the authors of the CMAJ study.

So they decided to set out to see if they could find that evidence.

Study details

For the study, the researchers recruited almost 1,000 children and adults who had shown up at their doctor’s office complaining of a sore throat. About two-thirds of the patients had an inflamed throat, and more than half also had a cough.

Most had experienced at least one other sore throat within the previous three months.

The researchers randomly assigned the patients to a specific treatment regimen. About two-thirds of them were asked to chew a stick of gum five times a day for three months, while the other third were instructed not to chew any type of gum. Half of the gum-chewers were given gum with xylitol; the other half were given similarly tasting gum, but without the xylitol. People in each of those three groups were also randomly assigned to take a daily capsule containing either a probiotic or a placebo.

The study’s participants were also asked to complete a diary at the end of each day that documented their sore throat symptoms, including the severity of the pain and any swallowing difficulties. Data was also collected on whether they took time off from work or other daily activities. (Parents filled in this information for their children.)

An analysis of all that data revealed a clear finding. “There was no significant differences between groups for both the xylitol and the probiotic groups, which suggests that neither intervention helped in controlling acute symptoms,” the authors write.

Limitations and implications

The study comes with several caveats. Most notably, about 300 patients either dropped out of the study or failed to provide complete data. Also, the study may not have gone on long enough to see if taking probiotics and/or xylitol can help reduce sore throat symptoms.

Yet, as the study’s authors conclude, “there is no reason for clinicians to advise patients to use either of these treatments for the symptomatic management of pharyngitis.”

What can you do to ease the pain and discomfort of a sore throat? The Mayo Clinic recommends these home remedies:

  • Rest. And rest your voice.
  • Drink fluids. Fluids keep the throat moist and prevent dehydration. Avoid caffeine and alcohol, which can dehydrate you.
  • Try comforting foods and beverage. Warm liquids — broth, caffeine-free tea or warm water with honey — and cold treats such as ice pops can soothe a sore throat.
  • Gargle with saltwater. A saltwater gargle of 1/4 to 1/2 teaspoon of table salt to 4 to 8 ounces of warm water can help soothe a sore throat. Gargle the solution and then spit it out. 
  • Humidify the air. Use a cool-air humidifier to eliminate dry air that may further irritate a sore throat or sit for several minutes in a steamy bathroom.
  • Consider lozenges or hard candy. Either can soothe a sore throat, but don’t give them to children age 4 and younger because of choking risk.
  • Avoid irritants. Keep your home free from cigarette smoke and cleaning products that can irritate the throat.

FMI: You can read the study in full on the CMAJ website.

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