 Why do dogs lick their wounds? In fact, they even lick our wounds. Leading to a question posed nearly a half century ago in the medical literature might there be some kind of healing property of dog saliva? Well, it appears there are a number of immune defense mechanisms in saliva, one of which involves nitric oxide. Licking of human skin results in production of nitric oxide from salivary nitrite, which kills skin pathogens and comes from the nitrates we eat from our diet. How do we know we can get nitric oxide from licked human skin? They had a bunch of volunteers lick their hands all over front and back. Today we have a better way to clean wounds called soap and water, and we should never actually let our pets lick open wounds as there are cases of serious infections reported. The reason I bring it up is because this transformation of nitrates from our diet into nitrites in our mouth has important implications for our health. Insufficient nitric oxide production is recognized as the earliest event in the onset and progression of a number of chronic diseases, including high blood pressure and peripheral artery disease in a number of inflammatory conditions. Do you remember, nitrates come from vegetables in our diets, beets and green leafy vegetables, good bacteria on our tongue. Convert nitrates into nitrites, which can circulate throughout the body to create nitric oxide. And any nitrates our tongue bacteria miss the first time around gets pumped by our body back into our saliva to give our tongue bacteria a second chance. So one way we can become nitric oxide production deficient is to not eat enough vegetables in the first place, so that should be the first step. But if our tongue bacteria die off, the cycle is broken no matter how many vegetables we eat. That's why we should not use antiseptic mouthwash. If you remember me profiling this important study, perhaps the largest public health initiative in the Western world has focused on improvement of diet, particularly in those of high risk of cardiovascular disease, our number one killer, the most protective food for our heart, be green leafy vegetables because, like beets, they have a lot of nitrates. And so if you eat some beet juice, you can get a remarkable drop in blood pressure within just hours, but only if you swallow. The nitric oxide pathway can be interrupted if you use an antibacterial mouthwash or by spitting and not swallowing because of the critical action of our tongue bacteria on the nitrates in our saliva. So we have to eat our vegetables and keep our tongue bacteria happy. So no antibacterial mouthwash. But what about antibacterial toothpaste? There's a toothpaste on the market that contains an antibacterial chemical called triclosan. Concern has been raised about the antibacterial mouthwashes, but what about the toothpaste? We didn't know until this study. Here's the nitric oxide, nitrite, and nitrate levels after brushing with regular toothpaste, and here's after triclosan toothpaste. No difference. See our good bacteria, good tongue bacteria, live in the cracks on the surface of our tongue, and if you just brush your teeth and not your tongue, the chemical doesn't seem to get down there. So is triclosan toothpaste safe? Well, it won't make your heart miss a beat, or beat juice. The use of triclosan toothpaste may not be associated with any increase in serious adverse cardiac events, and though studies on rats suggest the chemical can affect thyroid function, the use of triclosan toothpaste does not seem to affect human thyroid function. A study funded by Colgate—no conflict of interest there— concluded that triclosan was both safe and effective, producing a significant reduction in gingivitis, plaque, and bleeding. Though an independent review by the Cochrane Group suggests that the reduction may be statistically significant, but may not be beneficial enough to yield clinical significance. And with regard to safety, the reason states are starting to ban the stuff is because of data like this. Despite the lack of efficacy, the stuff is so ubiquitous that most of the US population is exposed, because the rapid rise in obesity in the US parallels the introduction of the chemical, because there are two potential mechanisms by which it might alter human weight by mucking with our gut flora or our hormones. Researchers at Stanford decided to assess the association between triclosan levels flowing through people's bodies and how heavy they are, and indeed found an association between triclosan levels and increase in body mass index. They suggest further studies on how this chemical could be altering human growth and well-being.