Gold Star Microbiome Reporting: Mouthwash, the Microbiome, and Diabetes

Photo by Mike Mozart [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

 As a graduate student, I worked on nitrate-reducing oral bacteria and their ability to contribute to blood pressure control. So, when I recently found this article in the Globe and Mail, written by Alex Hutchinson, I was intrigued — and sincerely hope that it wouldn't be too hypy. The article is entitled "Is chronic mouthwash use endangering your beneficial bacteria?" — as question that I had had since my PhD studies. The title is not too hypy; it summarizes nicely the point of the article, as well as the conclusions drawn by the study authors, without going too far out into left field. Good start so far.

The beginning paragraph is perfect:

"It sounds like one of those spurious correlations that show up whenever you sift through large piles of data, such as the supposed link between cheese consumption and death from bedsheet strangulation."

Rather, it's the follow-up to the first paragraph that is perfect. Although Hutchinson has set this up to flow nicely into "But it's not actually one of those spurious correlations," he says instead, "But the results of a new epidemiology study linking mouthwash use and diabetes risk are — to all appearances at least — a real effect." (emphasis mine) The real effect? Increased risk for diabetes — at least in a cohort of Puerto Ricans.

Hutchinson does a great job of explaining all of the background science on oral nitrate reducing bacteria and health, as well as the studies showing how use of mouthwash can disrupt the pathway and negate some of the beneficial effects. Another point!

Alex then does what good journalists do and speaks to several different scientists, gathering golden quotes such as:

"It's tempting then, to wonder how we can nurture the 'good' nitrate-convertin bacteria while suppressing the 'bad' oral bacteria that contribute to gum disease, bad breath, and tooth decay. But it's not that easy, says Dr. Anni Vanhatalo ... [who] wasn't involved in the study. 'It's about a balance,' she says. 'We have around 700 species of bacteria in our mouths, most or all of which have the potential to be pathogenic ... in that sense there are no 'good' or 'bad' bacteria.'" Hutchinson goes on to compare this concept to what we know about the gut microbiome: "That's similar to the emerging understanding of the complexity of gut bacteria, where greater diversity, rather than any particular superbug, is associated with better health." (emphasis mine)

"Joshipura notes that the people in her study who reported using mouthwash just once a day didn't have any elevated risk of prediabetes or diabetes, but adds that further evidence is needed to make recommendations." (emphasis mine)

"'People with specific oral conditions may need to use mouthwash as prescribed,' Joshipura says. 'However, we are concerned that mouthwash is often used routinely long-term in the absence of specific oral needs, without awareness of potential long-term effects.'" I really love that Hutchinson included this quote, because it cautions people not to do something potentially dangerous by ceasing the use of something that they actually need for their health (i.e., oral surgery requiring strong mouthwash in follow-up care), and then qualifies the real concern: chronic, unwarranted use.

Then, Hutchinson offers what in my mind is a perfect mixture of acknowledging the reader's potential frustration at reading yet another article stating that there is promise but we "aren't there yet" while also offering something tangible that the reader can do today: 

"Finally, if all this sounds a little gloomy, it's worth concluding on a more positive note. The negative effects of blocking nitrate conversion are, in a way, a reminder of all the benefits you can get from nitrate-rich foods – in addition to beets, leafy greens like arugula and spinach are very high in nitrates, as are rhubarb and celery – if you don't block them."

I thoroughly enjoyed reading this article, not only because it was well-written, but because it covered a topic near and dear to my heart. Great job Alex Hutchinson — I'm happy to give your article a Gold Star Microbiome Reporting Award!