You need to check the ingredients
Social media videos are claiming that mouthwash can raise the risk of if high blood pressure and heart disease by wiping out “good” bacteria that are important for the cardiovascular system, but an expert says the truth is ‘far more complex’.
Our mouths contain a variety of bacteria which help prevent disease, support normal functions and contribute to good health. Joanna L’Heureux, Postdoctoral Researcher in Public Health and Sport Sciences at the University of Exeter, said: “One of the important roles these oral bacteria have is converting the nitrate in our food (typically from sources such as leafy greens) into nitrite. When we swallow nitrite, the body turns it into nitric oxide.” She added: “It’s one example of how bacteria contribute to keeping the body healthy.”
Nitric oxide plays an essential part in regulating blood pressure and supporting brain function and muscle function.
Joanna told The Conversation: “Several small studies have actually found that giving people mouthwash can change the balance of bacteria in the mouth. This may reduce the bacteria’s ability to turn nitrate from vegetables into nitrite, which the body needs to make nitric oxide.”
But, she added: “The key detail that may be missed out of some of these online social media videos is the type of mouthwash used in these studies. Many of the studies which have found a link between mouthwash use and blood pressure gave participants chlorhexidine.
“This is a strong, over-the-counter antiseptic mouthwash only recommended for short-term use in people with gum disease or after dental procedures where its antimicrobial effects are beneficial. Chlorhexidine disrupts oral bacteria to help with infection control – including the bacteria that convert nitrate into nitrite. This makes it an ideal mouthwash to use for researchers wanting to study the nitrate-nitrite-nitric oxide pathway. However, it also means the findings may not reflect what happens with milder, everyday mouthwashes.”
A trial with 12 healthy adults investigated the effect of three different mouthwashes (and gargling water, which acted as a control) on oral bacteria.
After drinking a nitrate-rich juice, researchers measured how much nitrate was converted to nitrite by oral bacteria. Water and the mild mouthwash (which didn’t contain harsh ingredients such as chlorhexidine) caused a typical response, where nitrate was converted into nitrite.
But the cetylpyridinium chloride mouthwash (which also has strong, anti-bacterial effects) partially blocked the conversion of nitrate to nitrite. The strongest chlorhexidine mouthwash almost completely stopped this process. This is consistent with their stronger antibacterial effects. The stronger types of mouthwash were also linked to higher systolic blood pressure.
Alcohol (ethanol) is another common ingredient in many mouthwashes. As an antimicrobial, alcohol may influence the oral microbiome.
Joanna said: “However, there are currently no studies that have specifically examined the effects of ethanol-only mouth rinses on the oral microbiome or cardiovascular health.
“Overall, the body of evidence suggests that a mild, over-the-counter mouthwash, like the kind most people buy at stores, may be less likely to significantly interfere with nitrate-to-nitrite conversion or affect blood pressure.”
More research needed
She added: “Together, these studies suggest that some types of mouthwash (such as chlorhexidine) disrupt beneficial oral bacteria and the nitrate-nitrite-nitric oxide pathway when used long term. But more research needs to be done to truly understand the long-term effects of other types of mouthwash on cardiovascular health – including mild everyday mouthwash brands and those containing alcohol.
“Mouthwash comes in different types for different purposes, so it’s important to check the active ingredient on the back of the packaging. Alcohol-free and milder mouthwashes appear to have less effect on the heart-healthy bacteria than stronger types.
“However, be aware to check the ingredients as even alcohol-free options can contain antibacterial agents such as cetylpyridinium chloride. As such, it’s best to choose one that fits your needs and use it in moderation. Strong mouthwashes containing chlorhexidine are best reserved for helping gum disease or oral infections.
“It’s also worth noting that oral health and untreated infections can also contribute to heart disease more broadly. For example, a systematic review of 82 studies concluded that chronic oral disease and tooth loss was associated with risk of heart problems. This is why maintaining a healthy balance of mouth bacteria matters beyond your teeth.
“Take care of your oral and overall health by keeping up with brushing, flossing, visiting your dentist and choosing a mouthwash that works for you.”
