
Immunity
Boost Your Immune System
Discover why some people get sick while others don't — and how vitamin D, nitric oxide, and UV light strengthen your immune system. A scientific overview of the key factors for robust immunity.

Immunity
Discover why some people get sick while others don't — and how vitamin D, nitric oxide, and UV light strengthen your immune system. A scientific overview of the key factors for robust immunity.
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Have you ever wondered why some people are constantly sick while others seemingly never are?
By the same logic, one could have asked as early as last February why COVID mortality seemed so peculiar: young people don't die from it, and for them it's even milder than the flu — yet it kills some people rapidly. Is it magic?
In any case, when you look at the research on immune system function, there are apparently significant differences. Some of it's genetic, certainly. But: if you review a few studies — search for "Vitamin D + COVID" and you'll find plenty — it becomes clear that something as simple as a vitamin might cut your chance of getting sick in half.
Something similar happened in a recent study, quote:
Can vitamin D protect Black women from COVID-19? According to a study from the Slone Epidemiology Center at Boston University, the answer might be yes. In a recent study of Black American women, low vitamin D levels appeared to be associated with higher rates of COVID-19 infection. The study estimates that Black American women with vitamin D deficiency have a 69 percent higher risk of COVID-19 infection than women with adequate vitamin D levels.
Now, you don't need to be naive about this: vitamin D deficiency is more common in people who live unhealthily. That's also proven fact. Regardless, we want to remind you of the largest meta-analysis on vitamin D's protective effect against infections, which showed that correcting vitamin D deficiency works about as well as a flu vaccine or protection against flu-like infectious diseases.
Now, here's what many people don't know: one of the strongest weapons against (viral and bacterial) infections is the gas nitric oxide, or NO for short. The body doesn't just use it as natural Viagra, widening arteries and protecting them (Nobel Prize 1998, Ignarro & Furchgott), but — deliberately and in high doses from immune cells — as a superweapon against pathogens.
Here's what many people don't know II: vitamin D sharpens your immune system partly because it helps immune cells produce this NO. A deficiency in vitamin D will weaken this and hamper your immune system's effectiveness. In other words: NO — and thus vitamin D — protects in two ways: by protecting your cardiovascular system and by arming your immune system.
This isn't new, especially regarding COVID: researchers found some time ago a connection between mortality rates and UVA light exposure. Those who get more sun are better protected. A suspected reason: UV light generates NO in the skin. The researchers write:
In other words: vitamin D is nice. But UV light — sunlight — increases NO production not just through vitamin D formation but induces NO production directly. Probably a key reason why SARS-CoV-2 always disappears for us in summer.
Now: there's more to report. Recently one reads in Focus:
Now EBV is also coming into doctors' sights with COVID-19. Because there's mounting evidence that SARS-CoV-2 infection can reactivate the Epstein-Barr virus. Research teams in China, France, Italy, and Austria have documented EBV reactivation in 78 to 95 percent of patients with acute COVID-19. This reactivation could be involved in the severity of COVID-19's course.
The researchers believe: «Long COVID» isn't Long COVID at all, but rather EBV reactivation. Mind you: virtually everyone has EBV in them. And here too: some people get hit hard, while others notice nothing at all.
To complete the circle, we should mention at this point that many studies show that NO — nitric oxide — protects against EBV (re)activation. It inhibits both replication and reactivation, as long as cells — yours and mine right now — are infected.
So now let's close the second circle: who has plenty of healthy NO in their body? Right. Healthy people. Who has little of it? Right, sick people. You can also prove this: first, NO levels drop with an unhealthy lifestyle. Second, low NO levels themselves make you metabolically sick. And third, low NO levels are a prerequisite for your cardiovascular system to become sick at all.
If that was too much at once, here it is briefly:
Why did we write an entire chapter on NO in our book? Exactly for this reason. Because it's at the center of what fundamentally controls your health. How to get healthy NO levels without having to do much is in the book too. Here's the excerpt:
If you live like this... you're very likely fundamentally healthy from a structural perspective. And you'll very likely have significantly more NO in your body and thus a significantly better immune system.
Everyone should understand that NO is just one — albeit essential — lever. We want to remind you that a healthy lifestyle doesn't just bring NO levels to an adequate level, but also creates real robustness. Then you actually do «adventurous» things, like not holing yourself up at home but deliberately seeking out viruses. If you then catch a cold virus (intentionally!), that can protect you from COVID-19 infection. Exactly: a trained immune system protects. A normal lifestyle protects.