 The human mouth is an important habitat for microbes, harboring up to 10 billion bacteria, and no wonder it's a warm and moist providing a suitable environment for bacterial growth, some of which are actually beneficial. For example, it's widely recognized that dietary nitrate affords cardiovascular protection by turning into nitric oxide. And guess what contributes to the generation of nitric oxide? Our oral microbiome. First we eat nitrate-rich vegetables like dark green leafies and beets. The nitrate is then absorbed into our bloodstream, and our body then pulls it out of circulation to be concentrated in our salivary glands and secreted back into the oral cavity. Why? Because our body knows there are good bacteria on our tongue to tweak it, eventually resulting in the synthesis of the artery-protecting nitric oxide. We've got more than a billion people with high blood pressure. Most of which is uncontrolled. As such, it's critical to optimize daily behaviors to support blood pressure regulation and incorporate nitrate-rich foods, maybe an optimal strategy as it supports opening of arteries via the enterosalivary pathway, the gut saliva pathway, thanks to the friendly flora in our mouth. Dietary nitrate can provide sustained blood pressure lowering, and that starts with eating our greens. Leafy green vegetables contribute 80% of nitrate intake, but it doesn't matter how many greens we eat if we have oral dysbiosis, if we don't have the right tongue bugs to take advantage of them. How can you screw up your oral-friendly flora by using an antiseptic mouthwash? Yeah, it can kill the bad bugs that cause plaque, but it can indiscriminately kill the good bugs, too, and that can have systemic consequences. For example, studies show an increase in blood pressure following the use of antibacterial mouth rinses, because they reduce the protective bacteria in your mouth necessary for the nitric oxide pathway, a pathway that's vital to blood pressure regulation and overall cardiovascular health. Just a single week of antibacterial mouthwash use can cause a significant increase in blood pressure. It's not just one study all human studies done to date have revealed deleterious effects of antibacterial mouthwash, okay, so what about tongue cleaning? Brushing your tongue or using a tongue scraper? Regular tongue cleaning is recommended by the American Dental Association as a way to cut down on the bacteria on your tongue that cause bad breath, but if it wipes out those bacteria, it might wipe out the good ones, too. It turns out tongue cleaning may give you the best of both worlds. Those who clean their tongue twice or more per day as part of their normal oral hygiene were more likely to have an increase in systolic blood pressure during use of the antibacterial mouthwash, suggesting they had more of the good bugs to kill. Here's the graph. The mouthwash was worse for those with better tongue hygiene, so regular tongue cleaning may result in a baseline tongue microbiome that has a greater ability to tweak nitrate and, conversely, failure to clean the tongue daily may result in a microbiome composition that is unfavorable to nitrate conversion. Now, but wait a second. Maybe tongue cleaning just disrupts the surface bacteria, making them easier for the mouthwash to pick off. To see if tongue cleaning was actually associated with a better oral microbiome, they did DNA analyses to elucidate the dynamics of the tongue microbiome to compare differences between time points and tongue hygiene cohorts, and it turns out tongue cleaning does appear to have a significant impact on the composition of the tongue microbiome, specifically increasing the proportion of the good bacteria. So, based on this study, tongue cleaning assumes a new importance from the perspective of blood pressure regulation, as daily tongue cleaning appears to favor the increased abundance and metabolic activity of the nitrate metabolizing species like Nigeria, whereas failure to clean the tongue daily may result in a microbiome composition that is less favorable to nitric oxide production. Now, you still have to eat your vegetables, regular tongue cleaning, together with adequate dietary intake of nitrate, since that has a two-fold benefit. First, dietary nitrate improves artery function. Eat some nitrate-rich vegetables within three hours in improvement of artery function. And the nitrate can also act as a prebiotic for the oral microbiome. The most abundant best nitrate converter is Nigeria flavocins, and you can boost its abundance after feeding it with vegetables. After six weeks of beet juice that's had its nitrate removed, not much change, but after six weeks of regular beet juice in Nigeria, jumps right up making your mouth a nitric oxide-making machine. And if you look at the association between nitrate-reducing oral bacteria and cardiometabolic outcomes, having more of this good bacteria in your mouth has linked all sorts of cardiometabolic benefits, letting you take full advantage of the veggies you eat. What if all you ate was plants? The impact of a vegan diet on the human salivary microbiome and a fully plant-based diet was associated significantly with more of the good, nice, serious bugs that help you churn out nitric oxide. So not only does eating plant-based boost the beneficial bacteria at the end of your digestive tract, but at the beginning, too. And eating nitrate-rich vegetables like greens doesn't just boost the good bacteria, but beats down the bad guys, the bacteria that cause cavities, bad breath, and gum disease. And indeed, if you feed people lettuce or lettuce juice so you can do a randomized double-blind placebo-controlled trial with a lettuce juice control that's had the nitrate removed, you can significantly improve the health of your gums with greens. The researchers conclude that dietary nitrate consumption may be a useful adjunct to the control of chronic gingivitis. So when reviews suggest there's no reason to clean your tongue unless you have bad breath and in the absence of a coating on your tongue there's no reason to clean it, that was all before this new data which suggests additional benefits. The only caveat would be those with heart valve problems or a pacemaker or anything else that puts you at risk for endocarditis, an infection within the heart. You may want to stay away from tongue scraping, given this case report tentatively tying the two together. Just like you can get a heart infection after tongue piercing, tongue scraping may introduce a few bacteria in your bloodstream that could be hazardous for someone at risk.