How Flu Makes You Sick: The Complete Science-Backed Protocol

The flu virus enters through your nose and throat. You can't really prevent exposure—viruses are everywhere, especially during winter when everyone's packed indoors. But you can support your mucosal immunity and respiratory lining.

This is where NAC becomes your secret weapon. N-acetylcysteine is a natural liver antioxidant that does three critical things:

• Thins mucus so you can expel it instead of letting it settle in your lungs
• Reduces inflammation in respiratory tissues
• Boosts glutathione production (more on this in a moment)

I started taking NAC daily years ago after discovering I have an MTHFR gene mutation that limits my body's natural NAC production. Since then? I rarely get sick. When I do catch something, it's mild and brief.

Phase 2: Inflammatory Cytokine Response

Once the virus enters your body, your immune system releases pro-inflammatory cytokines—chemical messengers like tumor necrosis factor (TNF-α) and interleukin-6 (IL-6). ^[8] These compounds are supposed to fight the infection, but they also cause the inflammation that makes you feel like you're dying.

Your lungs become a battlefield. The virus is attacking. Your immune system is counterattacking. And if you don't have enough vitamin D in your system, that inflammation spirals out of control.

Here's what the research shows: vitamin D acts like a fire extinguisher for inflammatory cytokines. ^[1] Studies recommend taking 10,000 IU of vitamin D3 daily for a few weeks during high-risk periods to rapidly raise your blood levels above 40-60 ng/mL. ^[4] After that, maintain with 5,000 IU daily.

Think about it: every winter, you're getting less sunlight. Just 10-15 minutes of morning sun can give you the equivalent of 10,000 IU of vitamin D. But most people aren't getting that, which means they're walking into flu season defenseless.

I've had clients whose vitamin D levels tested as low as 9. That's catastrophic. And then they wonder why every cold knocks them out for weeks.

Here's where NAC becomes even more important: it's the precursor to glutathione, your body's master antioxidant. ^[7]

Glutathione is what actually neutralizes the oxidative stress and inflammation caused by viral infections. But if you have fatty liver disease (which affects 1 in 4 people globally), you're not making enough glutathione. That means your body can't fight back effectively.

When patients come to our clinic with severe flu symptoms, we give them IV bags with NAC and glutathione. The results are dramatic—people who looked half-dead walk out feeling functional within hours.

But you don't need an IV to get these benefits. Oral NAC supplementation increases glutathione production and provides powerful anti-inflammatory effects.^[2] Studies show it reduces TNF-α, IL-6, and other inflammatory markers that cause lung damage during viral infections.^[3]

After years of treating patients and dealing with my own health, here's my personal flu prevention protocol:

Daily (Year-Round):

• The D: 5,000 IU vitamin D3 (10,000 IU during high-risk periods)
• NAC+: For glutathione support, respiratory health, and selenium
• Morning sunlight: 10-15 minutes when possible
• Quality sleep and stress management

When Sick:

• Double NAC+ dosage
• Increase vitamin D to 10,000 IU
• Add zinc supplementation
• High-dose glutamine (our Gut Powder)
• Rest and hydration with electrolytes

Post-Infection Recovery:

• Continue elevated vitamin D and NAC+
• Add adrenal support
• Monitor HRV to track nervous system recovery
• Focus on nutrient-dense foods

This protocol has kept me healthy through countless flu seasons while working directly with sick patients every day.