"Can regular use of antiseptic mouthwash be responsible for global increase in blood pressure?”
This clever title comes from a recent review article by researchers (Hill et-al) from the University of Alabama. Recent studies have shown that just seven days of antiseptic mouthwash use, particularly chlorhexidine, wipes out the local oral bacteria. This results in nitrates not being converted in the mouth into nitrites. This reduction is quickly seen as lower blood levels of nitrites by as much as 25%, and the effect seems to last for a week. Additional studies have shown that the use of mouthwash and its subsequent reduction of Nitrates cause blood pressure to increase by about 3.5mmHg in healthy individuals. While the increase may not seem significant, it is estimated that a 2mmHg increase in blood pressure is associated with a 7% and 10% increase in death from heart disease and stroke respectively. Thus, a 3.5mmHg would result in 11% and 15% increase in death from heart and stroke incidents respectively! Such an effect may be even more pronounced in people with high blood pressure though this remains to be seen.
It is estimated that in the UK and the US around 35-40% of the adult population regularly use mouthwash. The implication of such a wide-spread use may have national and even global consequences with respects to increasing the incidence of heart disease and stroke. Of course, this is speculative but nonetheless an intriguing question to ponder.
The seminal research from the 1980’s on NO as a signaling molecule led to the honoured Nobel Peace Prize in 1998, and has propelled continued research on the subject since. Over the last two decades, various researchers, notably Jon Lundberg and Eddie Weitzberg, (Karolinska Institute in Stockholm, Sweden), Nigel Benjamin (University of Exeter in the UK) and many others have rapidly progressed the research on Nitric Oxide. This research includes how Nitric Oxide is generated, as well as its myriad of biological effects in the body.
Prior to their work, most people thought that Nitric Oxide was generated from the amino acid L-arginine and was dependent on various enzymes requiring plenty of oxygen. However, the above researchers quickly showed that Nitric Oxide could be made from an alternate pathway not requiring arginine or oxygen. In fact, it was repeatedly pointed out that this pathway is an evolutionary mechanism. It acts as a backup in times of oxygen deficiency, which can occur in various disease conditions like angina, asthma, emphysema, kidney disease, chronic obstructive pulmonary disease and others. It was discovered that nitrates, which are abundant in our diet especially in leafy green vegetables like kale, spinach, lettuce, celery, and even beetroot could be converted rapidly and efficiently by the body into Nitric Oxide. Furthermore, once Nitric Oxide is formed and performs its biological duties, it can be converted back into nitrate and nitrite, which are then called upon whenever the need for Nitric Oxide arises. This pathway offers distinct advantages, namely that the nitrates are more stable and stay in the body for over 6 hours, compared to a fraction of a second for Nitric Oxide.
The conversion process of Nitric Oxide requires oral bacteria to convert nitrates into nitrites, which in turn renders the conversion of Nitric Oxide either in the stomach or in the tissues when required.
It is estimated that the saliva is concentrated 1000-fold in nitrates compared to the amount present in the blood; which is why animals lick their wounds or themselves during injury!
A multitude of studies have shown that high nitrate and nitrite levels in the blood correlate with a reduction of blood pressure as well as other health benefits (see blog entries on this issue here and here).
What do you think of this headline? Let us know in the comments below!
Kapil, V et-al “Physiological role for nitrate-reducing oral bacteria in blood pressure control” Free Radical Biology and Medicine, 2013; 55: 93-100
Lundberg, JO et-al “The nitrate-nitrite-nitric oxide pathway in physiology and therapeutics” Nat Rev. Drug Discovery 2008; 7: 156-167
Duncan C et-al “Chemical generation of nitric oxide in the mouth from the enterosalivary circulation of dietary nitrate” Nat. Med. 1995; 1: 546-551
Giovani M et-al “The increase in plasma nitrite after dietary load is markedly attenuated by an antibacterial mouthwash” Nitric Oxide 2008; 19: 333-337
Hill B G et-al “What part of NO don’t you understand?” J Biol. Chem. 2010; 285: 19699-19704