Under the category “Sensationalized Medical News for a Slow News Day” comes the story from across the pond warning that certain mouthwashes can raise your blood pressure, and by extension, heart attack and stroke risk. I did a double take reading that one so headed right to the paper for “the rest of the story.” Paul Harvey, God rest his soul, must be smiling. Here I found an interesting little study, published almost a year ago, finding that a particular mouthwash containing chlorhexidine, an oral antiseptic used for the treatment of gingivitis and bad breath, was associated with a small increase in blood pressure in 19 healthy people. But why would scientists look at this?
They hypothesized that the bacteria in our mouths which are implicated in gum disease, plaque and halitosis were reduced enough with the mouthwash to interrupt a recycling function that usually maintains blood relaxation. Older work had suggested that dietary or internally generated nitrates are pumped into saliva from the bloodstream, and oral bacteria convert them to nitrites. Yes, that’s NITRITES. The stuff in processed meats, jerky, bacon (heavenly bacon) that we’ve been telling you to shy away from owing to their proven role in intestinal tract cancers. But I digress. Nitrites are then swallowed, absorbed into the bloodstream through the intestines, and converted in our blood stream to nitric oxide. Nitric Oxide (NO) is the good stuff that our vessel lining makes continuously to keep vessels supple and relaxed, so it’s a good thing to have if you don’t want a heart or brain attack (stroke).
The volunteers had several blood pressure measurements and an ambulatory automated monitor to get baseline readings for a week on a low nitrate diet, then came in after a fast, rinsed with a nitrate solution for 5 minutes, then the was tested for how much nitrite had been converted by oral bacteria. They then rinsed with the mouthwash twice a day for a second week, ending in the same challenge. Blood and urine tests for nitrate and nitrite were checked too on each occasion. The results?
There was a huge reduction in nitrite formation in the mouth and levels of nitrites in blood and urine after the rinse. As predicted, systolic blood pressure went up, an average of 2-3.5 mm Hg to be precise, during the mouthwash week. Moreover, blood levels of nitrites, the raw material for our blood vessel generation of good NO, plummeted after a week of mouthwash. So what’s the so what of all this?
First, the authors admit the study wasn’t placebo controlled nor randomized. That is, a week of placebo mouthwash without antiseptic wasn’t tested, followed by an identical looking and tasting, but inactive, mouthwash. The practical rub here is that chlorhexidine has a flavor that gives it away, so subjects not swishing with it would know the fake from the real McCoy, and the measured responses would not be valid, strictly speaking. All that’s true, and maybe the small blood pressure bump does over the long term connote a small increase in heart disease or stroke. But before you throw out your favorite minty nightcap swisher, hold on a minute!
The authors properly point out the known connections between gingivitis, the inflammatory chaos it provokes, and serious issues like heart disease, premature birth and possibly some cancers. So while your BP may bump a little if you treat or prevent gingivitis, might you be more than overcoming that small downside with protection against serious, life-threatening problems?
Then, there’s the issue that some childhood cancers like leukemia, and yes, pancreatic and stomach cancers in adults have been linked to intake of processed meats with their nitrites in full tow. Funny thing is, it seems the nitrites alone aren’t the cuprit. It might be the nitrosamines formed in the presence of high heat or acid that are the problem. So a steady diet of grilled bacon or cured and processed meats interacting with stomach acid can plausibly raise concern of cancer promotion. All that said, it appears that it takes a steady diet (1 oz/day 5-6 days a week for men, 2-3 days a week for women) is needed over years to be a concern for colon cancer, according to the American Cancer Society. To cloud the issue further, most of our nitrate and nitrite exposure comes from our non-processed diet….vegetables in large part…and from endogenous production.
Bottom line, consider your risks then calibrate behavior! If mom, dad and 2 brothers had heart attacks, might be good to floss twice daily before brushing, and use non-chlorhexidine containing mouthwash, if any. Would I advise bacon to lower BP? HA! Not really, because the salt and fat from this and other processed meats certainly will risk hypertension and obesity, both risk factors for heart disease. On the other hand, a little bacon…ice cream, coffee, candy bar….now and then as a treat? Go for it! Just eat plenty of vegetables, sleep well, and exercise to help your innate immune and repair systems provide a defense agaisnt the occasional delectable assault.