如果你在运动后用漱口水，会发生一件奇怪的事情

In ads on TV, it all looks so simple. People use mouthwash, it instantly neutralises all the nasty bacteria hiding in their mouths, and – just like that – their dental hygiene is assured.

在电视广告中，一切看起来都很简单。人们使用漱口水，它能立即中和隐藏在嘴里的所有讨厌的细菌，而且——就像那样——他们的牙齿卫生得到了保证。

But what's really going on when you rinse a cap-load of antibacterial chemicalsaround your mouth? What does that to your body, and to other kinds of microorganisms that may actually be beneficial to health?

但是，当你漱口时，口腔周围的抗菌化学物质会发生什么呢?这对你的身体和其他可能对健康有益的微生物有什么好处?

As a new study shows, the downstream effects can be surprising, and far-reaching too, affecting much more than just your dental wellbeing.

一项新的研究表明，这种副作用不仅会影响你的牙齿健康，还会带来意想不到的深远影响。

In an experiment led by scientists from the UK and Spain, researchers found that the simple act of using mouthwash after exercising can reduce one of the benefits of exercise: lowering blood pressure.

在一项由英国和西班牙科学家领导的实验中，研究人员发现，运动后使用漱口水会降低运动的一个好处:降低血压。

When you exercise, your blood vessels open in response to the production of nitric oxide, which increases the diameter of blood vessels. This process is called vasodilation, and it increases blood flow circulation to active muscles.

当你锻炼时，血管会随着一氧化氮的产生而打开，一氧化氮会增加血管的直径。这一过程被称为血管舒张，它增加了活跃肌肉的血液循环。

For a long time, researchers thought this only happened during exercise, but in more recent years, evidence has shown that circulation stays high (meaning blood pressure is lowered) even after exercise – thanks to how bacteria interact with a compound called nitrate, which forms when nitric oxide degrades.

很长一段时间以来，研究人员一直认为这只发生在运动期间，但近年来，有证据表明，即使在运动之后，血液循环仍然保持高水平(意味着血压降低)——这要归功于细菌与一种名为硝酸盐的化合物的相互作用，这种化合物是在一氧化氮降解时形成的。

"Research over the last decade has shown that nitrate can be absorbed in the salivary glands and excreted with saliva in the mouth," explains physiology specialist Raul Bescos from Plymouth University.

普利茅斯大学的生理学专家劳尔·贝斯科斯解释说：“过去十年的研究表明，硝酸盐可以在唾液腺中被吸收，并随唾液一起在口腔中排出。”

"Some species of bacteria in the mouth can use nitrate and convert into nitrite – a very important molecule that can enhance the production of nitric oxide in the body."

“口腔中的一些细菌可以利用硝酸盐并转化为亚硝酸盐——这是一种非常重要的分子，可以增强体内一氧化氮的生成。”

Once nitrite is produced and swallowed with saliva, it becomes absorbed into blood circulation and reduces back to nitric oxide, which keeps blood vessels wide and lowers blood pressure.

一旦亚硝酸盐产生并与唾液一起吞咽，它就会被血液循环吸收，并还原为一氧化氮，从而保持血管扩张，降低血压。

But according to this small study, it looks like this biological mechanism can be significantly interrupted if anti-bacterial mouthwash gets added into the post-exercise mix.

但根据这项小型研究，如果在运动后的混合液中加入抗菌漱口水，这一生物机制似乎会被明显打断。

In an experiment, 23 healthy adults ran on a treadmill for 30 minutes. After the workout, the participants were asked to rinse their mouth with either an antibacterial mouthwash or a mint-flavoured placebo.

在一项实验中，23名健康成年人在跑步机上跑了30分钟。训练结束后，参与者被要求用抗菌漱口水或薄荷味安慰剂漱口。

These mouth rinses occurred immediately after the exercise, and also at 30, 60, and 90 minutes after.

运动后马上漱口，和在30、60和90分钟后漱口分别进行了实验。

The participants also had their blood pressure taken during the experiment, immediately after the exercise, and during their rest period.

在实验期间、运动后和休息期间，参与者还测量了血压。

The results showed that at one hour after the treadmill session, average reduction in systolic blood pressure in the placebo group was –5.2 mmHg (millimetres of mercury).

结果显示，在跑步机训练后1小时，安慰剂组的收缩压平均降低-5.2 mmHg(毫米汞柱)。

The reduction in the mouthwash-using group was much lower, showing an average of –2.0 mmHg at the same point in time, suggesting the use of the antibacterial mouthwash (0.2 percent chlorhexidine) had lowered the systolic blood pressure reduction by over 60 percent.

使用漱口水组的血压下降幅度要低得多，在同一时间点的平均值为-2.0 mmHg，这表明使用抗菌漱口水(0.2%氯己定)降低了60%以上的收缩压。

At the end of the monitoring window, two hours after the treadmill session, the mouthwash group showed no sign of blood pressure reduction stemming from the exercise, whereas the placebo group still showed a significant reduction compared to their pre-exercise values.

在监测窗口结束时，跑步机训练两小时后，漱口水组没有因运动而出现血压下降的迹象，而安慰剂组与运动前相比仍有显著下降。

"This is the first evidence showing that the nitrate-reducing activity of oral bacteria is a key mechanism to induce the acute cardiovascular response to exercise during the recovery period in healthy individuals," the authors explain in their paper.

作者在他们的论文中解释说：“这是第一个证据表明，口腔细菌降低硝酸盐的活性是导致健康个体在康复期间对运动产生急性心血管反应的关键机制。”

While it's only a small study, it serves as an important reminder of how not all bacteria are necessarily bad for us – and that ingesting antibacterial chemicals that indiscriminately terminate mouth-dwelling microbes could hamper important biological processes necessary for good health.

虽然这只是一项小规模的研究，但它却提醒我们，并非所有的细菌都对我们有害，而且摄入不加选择地终止口腔微生物的抗菌化学物质，可能会妨碍健康所必需的重要生物过程。

"These findings show that nitrite synthesis by oral bacteria is hugely important in kick-starting how our bodies react to exercise over the first period of recovery, promoting lower blood pressure and greater muscle oxygenation," says one of the team, nutritionist Craig Cutler.

研究小组的一位营养学家克雷格·卡特勒说：“这些发现表明，口腔细菌合成亚硝酸盐对于启动我们身体在第一个恢复期对运动的反应、促进低血压和肌肉氧合非常重要。”

"In effect, it's like oral bacteria are the 'key' to opening up the blood vessels. If they are removed, nitrite can't be produced and the vessels remain in their current state."

“实际上，口腔细菌是打开血管的‘钥匙’。如果去除了亚硝酸盐，就不能产生亚硝酸盐，容器仍保持当前状态。”

The findings are reported in Free Radical Biology and Medicine.

这一发现发表在《自由基生物学和医学》杂志上。