維生素D能否預防由冠狀病毒SARS-CoV-2引起的Covid-19大流行？ Could Vitamin D prevent a Covid-19 pandemic caused by coronavirus SARS-CoV-2?

Saturday 03/14/2020 (jkzx.com) Vitamin D may help prevent the coronavirus SARS-CoV-2 infection and reduce risk of death from Covid-19 caused by the virus.

We have mentioned in an article posted early that taking vitamin D can boost your innate immunity and help prevent the infection of SARS-CoV-2 which is spreading globally. Now some evidence suggests that vitamin D may help reduce risk of death after a person gets infected with SARS-CoV-2.

Just like its relative SARS-CoV, SARS-CoV-2 viruses enter cells via angiotensin-converting enzyme 2 (ACE2). During the infection, the virus particles bind to ACE2, which lowers the ACE2 level. Also SARS-CoV downregulate the expression of ACE2, which also reduces the ACE2 level.

ACE2 plays an important role in the renin-angiotensin system (RAS), which is a hormone system that regulates blood pressure and fluid and electrolyte balance, as well as systemic vascular resistance, according to wikipedia. ACE2 works to counterbalance the angiotensin-converting enzyme (ACE). When ACE is too high and ACE2 is too low, the RAS is unbalanced, resulting in a series of atherosclerosis, high blood pressure, serious lung injury, heart failure, and chronic kidney disease.

So normally there is a balance between ACE and ACE2. When SARS-CoV-2 viruses infect cells, they sequester a large amount of ACE2, and also suppress the production of ACE2, both leading to a high ratio of ACE to ACE2. This is why patients with Covid-19 can have severe complications like high blood pressure and lung injury. In fact, high blood pressure and lung injury are the two major causes of death from Covid-19, which is caused by SARS-CoV-2 viruses. When ace2 is lowered, the lung is dysfunctional and a condition known as hypoxia occurs. That is why patients often need ventilators for oxygen. But when this condition occurs, it is often times too late.

This ACE to ACE2 ratio is an important indicator for a person’s vulnerability to the infection of SARS-CoV-2. The production of ACE2 has something to do with some genes on the X chromosome. Women have more X chromosome, so they are able to produce more ACE2 than men. Patients with chronic diseases and older people tend to have relatively lower levels of ACE2. That is why men, people with chronic diseases and old people are more vulnerable to the infection of SAR-CoV-2 and more likely to die from Covid-19.

In addition to the lungs, some other organs including the heart, kidney, small intestine, and testes produce ACE2 proteins. So when SARS-CoV-2 strikes, all these organs can be injured. To prevent the injury or death from these injuries, it is important to keep the RAS system running as normally as possible.

One thing to do is keep ACE on check by maintaining certain levels of ACE2. That is, when the ratio of ACE to ACE2 is good, the RAS system acts normally and it will not result in severe clinical consequences. It is known that ACE inhibitors reduce the production of ACE. So taking antihypetensive drugs or ACE inhibitors may help. Because hypertension is the main complication of this SARS-CoV 2 infection that causes death, patients may also take Angiotensin II (Ang II) receptor antagonists to neutralize Ang II which causes high blood pressure.

Another thing to do is taking vitamin D. Studies have shown that vitamin D (calcitriol) can boost ACE2. It has been reported that the 1918 Spanish influenza pandemic resulted in much fewer deaths when hospitals treated patients outdoors where patients got sunshine and were less likely to be vitamin D deficient. To be exact, patients treated outdoors were 3 times less likely to die from the 1918 flu pandemic than those treated indoors.

So definitely, vitamin D can not only boost a person’s innate immunity against SARS-CoV-2,but also participate in the regulation of the RAS system to prevent patients from dying from the complications of this viral infection.

(Dr. Lu)

我們能否預防由冠狀病毒SARS-CoV-2引起的Covid-19大流行？

維生素D可以幫助預防冠狀病毒SARS-CoV-2感染，並減少由該病毒引起的Covid-19致死的風險。

我們在早期發布的一篇文章中提到，服用維生素D可以增強您的先天免疫力，並有助於防止SARS-CoV-2感染全球蔓延。現在，我們要報告的另一個原因是，維生素D有助於預防感染並減少由SARS-CoV-2引起的Covid-19致死的風險。

就像其相對的SARS-CoV一樣，SARS-CoV-2病毒也通過血管緊張素轉換酶2（ACE2）進入細胞。在感染過程中，病毒顆粒與ACE2結合，從而降低了ACE2的水平。還已知SARS-CoV下調ACE2的表達，這也降低了ACE2水平。

維基百科說，ACE2在腎素-血管緊張素系統（RAS）中起著重要作用，RAS是調節血壓，體液和電解質平衡以及系統性血管阻力的激素系統。 ACE2可以平衡血管緊張素轉化酶（ACE）。當ACE太高時，RAS不平衡，從而導致一系列動脈粥樣硬化，高血壓，嚴重的肺損傷，心力衰竭和慢性腎臟疾病。
 
因此，通常在ACE和ACE2之間保持平衡。當SARS-CoV-2病毒感染細胞時，它們螯合了大量的ACE2，並且還抑制了ACE2的產生，兩者都導致ACE與ACE2的比例很高。這就是為什麼Covid-19患者會出現嚴重並發症，例如高血壓和肺損傷。實際上，高血壓或肺部損傷是由SARS-CoV-2病毒引起的Covid-19死亡的兩個主要原因。

ACE與ACE2的比率是一個人感染SARS-CoV-2的脆弱性的重要指標。 ACE2的產生與X染色體上的某些基因有關。女性擁有更多的X染色體，因此她們能夠比男性產生更多的ACE2。患有慢性疾病的患者和老年人往往具有相對較低的ACE2水平。這就是為什麼男人，患有慢性疾病的人和老年人更容易感染SAR-CoV-2，並且更有可能死於Covid-19。 当ace2降低时，肺功能不全，发生称为缺氧的疾病。 这就是为什么患者经常需要呼吸机供氧。 但是，当这种情况发生时，通常为时已晚。

除肺外，其他一些器官，包括心臟，腎臟，小腸和睾丸也產生ACE2蛋白。因此，當SARS-CoV-2襲擊時，所有這些器官都可能受到傷害。為了防止這些傷害或死亡，重要的是要使RAS系統盡可能正常地運行。

要做的一件事是通過維持一定水平的ACE2來檢查ACE。也就是說，當ACE與ACE2的比例良好時，RAS系統將正常運行，並且不會導致嚴重的臨床後果。我們知道ACE抑製劑會減少ACE的產生。因此，服用降壓藥或ACE抑製劑可能會有幫助。另一件事是服用維生素D。研究表明，維生素D（骨化三醇）可以促進ACE2。

據報導，1918年西班牙的流感大流行使醫院在室外接受治療的患者的死亡人數大大減少，因為這些患者有陽光，而且維生素D缺乏的可能性也較小。確切地說，在戶外接受治療的患者死於1918年流感大流行的可能性比在室內治療的患者低3倍。

因此，可以肯定的是，維生素D不僅可以增強人對SARS-CoV-2的先天免疫力，還可以參與RAS系統的調節，以防止患者死於這種病毒感染的並發症。