研究:高鹽飲食會讓你的身體很難抵抗感染

研究:高鹽飲食會讓你的身體很難抵抗感染

There are several risks associated with a high-salt diet, including high blood pressure, heart attack and stroke — but a new study reveals that a compromised immune system should be added to that list.

高鹽飲食會帶來多種風(fēng)險，包括高血壓、心臟病和中風(fēng)，但一項新的研究表明，免疫系統(tǒng)受損也應(yīng)列入其中。

To mitigate the well-documented health risks associated with a high-salt diet, the World Health Organization recommends adults cap their salt intake to about one teaspoon, or 5 grams, per day — an amount equivalent to about two Big Macs.

為了減少高鹽飲食對健康的危害，世界衛(wèi)生組織建議成年人每天的鹽攝入量控制在一茶匙左右，即5克，相當于兩個巨無霸。

Unfortunately, as the Food and Drug Administration points out, Americans consume on average some 8.5g of salt each day — almost double the WHO’s recommendation — which partially explains why the US suffers such high rates of hypertension, a major contributing factor to cardiovascular and metabolic diseases.

不幸的是，正如美國食品和藥物管理局指出的，美國人平均每天攝入8.5克鹽——幾乎是世界衛(wèi)生組織建議的兩倍——這部分解釋了為什么美國高血壓發(fā)病率如此之高，而高血壓是導(dǎo)致心血管和代謝疾病的主要因素。

Now, German researchers at the University of Bonn believe that too much salt could also weaken our immune system — particularly our defenses against bacterial infections.

現(xiàn)在，德國波恩大學(xué)的研究人員認為，過多的鹽也會削弱我們的免疫系統(tǒng)，尤其是我們對細菌感染的防御能力。

“We examined volunteers who consumed 6 grams of salt in addition to their daily intake,” says Prof. Dr. Christian Kurts, whose study was published Wednesday in the journal Science Translational Medicine. “This is roughly the amount contained in two fast food meals, i.e. two burgers and two portions of french fries.”

“我們調(diào)查了那些每天攝入6克鹽的志愿者，”克里斯蒂安·庫爾茨(Christian Kurts)教授說，他的研究周三發(fā)表在《科學(xué)轉(zhuǎn)化醫(yī)學(xué)》(Science Translational Medicine)雜志上。“這大概是兩份快餐所含的量，即兩份漢堡和兩份薯條。

Kurts says their research “prove[s] for the first time that excessive salt intake also significantly weakens an important arm of the immune system.” Yet, these findings contradict prior studies which have shown that a high-salt diet was effective in healing infections caused by certain skin parasites in laboratory animals. Thus, many scientists had previously concluded that sodium chloride could have immune-boosting qualities.

庫爾茨說，他們的研究“首次證明了過量的鹽攝入也會顯著削弱免疫系統(tǒng)的一個重要分支。”然而，這些發(fā)現(xiàn)與先前的研究相矛盾，之前的研究表明，高鹽飲食對治愈實驗動物中某些皮膚寄生蟲引起的感染是有效的。因此，許多科學(xué)家先前已經(jīng)得出結(jié)論，氯化鈉可能具有增強免疫力的性質(zhì)。

“Our results show that this generalization is not accurate,” says Dr. Katarzyna Jobin, lead author of the current study. They explain that the skin functions as a salt reservoir for the body, which lends a hand in the elimination of certain skin diseases. But inside the body, salt concentration is meant to remain constant — save the kidneys, which bear the brunt of high salt intake. This latest study discovered that, as the kidneys filter blood, the presence of salt prompts glucocorticoids, a type of hormone, to build up in the body, which impairs a common type of bacteria-busting immune cell called granulocytes.

“我們的結(jié)果表明，這種概括是不準確的，”卡塔茲納·喬賓博士說，他是目前這項研究的主要作者。他們解釋說，皮膚是身體的鹽庫，有助于消除某些皮膚病。但是在體內(nèi)，鹽的濃度應(yīng)該保持不變——除了腎臟，腎臟承受著高鹽攝入的沖擊。這項最新研究發(fā)現(xiàn)，當腎臟過濾血液時，鹽的存在會促使糖皮質(zhì)激素(一種激素)在體內(nèi)積聚，而糖皮質(zhì)激素會損害一種常見的破壞細菌的免疫細胞，即粒細胞。

“We were able to show this in mice with a listeria infection,” explains Dr. Jobin. “We had previously put some of them on a high-salt diet. In the spleen and liver of these animals we counted 100 to 1,000 times the number of disease-causing pathogens.” Urinary tract infections, the study finds, also healed much more slowly.

“我們能夠在感染李斯特菌的老鼠身上證明這一點，”Jobin博士解釋道。“我們之前曾讓其中一些人吃高鹽食物。在這些動物的脾臟和肝臟中，我們發(fā)現(xiàn)了100到1000倍的致病菌。研究發(fā)現(xiàn)，尿路感染的愈合速度也慢得多。

After just one week on the high-salt regimen, blood samples from test subjects showed that human granulocytes were already failing to cope with bacterial intruders. They also showed increased glucocorticoid levels — which scientists anticipated would have an impact on the immune system, as glucocorticoid cortisones are already used to suppress inflammation (caused by an immune response) in medical settings.

在高鹽飲食僅一周后，來自測試對象的血液樣本顯示，人類粒細胞已經(jīng)無法應(yīng)對細菌入侵。它們還顯示出糖皮質(zhì)激素水平升高——科學(xué)家們預(yù)計這將對免疫系統(tǒng)產(chǎn)生影響，因為在醫(yī)學(xué)領(lǐng)域，糖皮質(zhì)激素已經(jīng)被用來抑制炎癥(由免疫反應(yīng)引起)。