How to boost your immune system before it fails

I avoid illness at all costs. No one likes being sick (obviously) but I’m entering a particularly busy season—prepping for my first live course launching October 23, hitting the road to deliver a big keynote speech this fall, running things at Parsley Health, and managing back-to-school craziness with my three kids. I often feel like I can’t afford to get sick. And who can, really? Between our family responsibilities, work schedules, passion projects, health goals, and whatever else keeps you busy, getting benched with a cold or the flu isn’t just annoying, it’s stressful. In this season of life, I want to do everything I can to help you boost your immune system.

With cold and flu season officially underway, I’m amping up my handwashing (which reduces your risk of getting a cold by up to 21%) and doing everything I can to limit my exposure to germs.

Equally important, I’m doing everything I can to support my immune system. If I can’t afford for my immune system to fail me this season, I can’t fail it. And neither can you. Let’s get through this cold and flu season together! 

The research says

First, a quick bio lesson. There are two pillars to the immune system: innate immunity and adaptive immunity. 

Innate immunity:

• What you’re born with 
• Includes physical barriers like your skin and mucous membranes
• Responds the same way to all foreign invaders

Adaptive immunity: 

• Launches a specific response to foreign invaders like viruses and bacteria
• Slower to respond, but more accurate

The immune system is influenced by a delicate ecosystem of factors: 

• Gut health. Trashing your microbiome via a diet rich in ultra-processed foods and refined sugars can lead to dysbiosis, which weakens the lining of the gut and allows toxins to leak into the bloodstream. 
• Diet. While junk food weakens your gut microbiome, eating a diet rich in fermented foods, healthy fats, and antioxidant-rich fruits and veggies can help support immune function by feeding immune cells with micro and macronutrients. 
• Stress. The impact of stress on your immune system is complex. In short bursts, the stress hormone cortisol can trigger a boost in immune function by limiting inflammation. Chronic stress is a different story. Long-term exposure to stress decreases white blood cell count, limiting the body’s ability to fight infection. 
• Sleep. Chronic insomnia increases stress hormones, promotes inflammation, and increases your vulnerability to infections. 
• Exercise. There are several mechanisms by which exercise supports immune function, including by reducing stress and inflammation.
• Alcohol consumption. Chronic alcohol lowers the immune system’s ability to fight off infections from bacteria and viruses. Over time, it also increases the body’s susceptibility to cancer.   

What I’m doing for my own body

As a doctor and a mom of littles, I am extremely conscious of making sure that my immune system is fortified and ready to fight off the onslaught of germs that I encounter daily. 

That starts with prioritizing gut health given 70% of your immune system lies in your gut. 

What you choose to put in your body impacts your gut microbiome, gut barrier function, inflammatory response and white blood cell count. All of these things have a meaningful impact on immune function. 

I avoid ultra-processed foods and snacks at all costs and aim for less than 25g of sugar per day for so many reasons including reducing inflammation. 

During cold and flu season, I also pay special attention to eating foods linked to immune function. 

• Fermented foods like kimchi and yogurt contain probiotic bacteria, which not only support general gut health, but also may help squash viral infections by preventing viruses from attaching to host cells and increasing production of pro-inflammatory cytokines.  
• Antiviral herbs like oregano, peppermint, fennel, and tea have long been used for their medicinal properties. I’ll work oregano and fennel in while I’m cooking and drink a peppermint tea once a day. 
• Vitamin C, vitamin D, and zinc are the micronutrients with the strongest evidence for immune support. I reach for bell peppers (3x the vitamin C of an orange), legumes (high in protein, fiber, and zinc) and fatty fish (for protein and vitamin D).

For most of us getting enough sleep is a struggle. But it’s a pillar of immune function. 

Studies show that if you regularly get less than seven hours of sleep, you may be three times as likely to catch a cold. I make it a priority to make sure I’m winding down by 10 p.m. every night. 

Finally, I prioritize exercising at least three (ideally five) days per week. 

Yoga and pilates classes are a regular stress reliever for me but high-intensity exercise can also be beneficial for immune function as it raises white blood cell count. I work in high-intensity classes like Session Training even though it intimidates me. 

What I recommend for you

To stay healthy this season, start by building a baseline of immune strength with these steps: 

1. Sleep. Get a minimum of 7 hours per night. 
2. Meditate. Meditating for 15 minutes a day (even if I have to take it on the go with a walking meditation after I drop off my kids) is a key part of the way I keep my situational stress from becoming chronic stress. 
3. Exercise. Aim for 3 high-intensity sessions per week. 
4. Avoid ultra-processed foods. They are not only slowly killing you, but also making you more likely to get sick. 
5. Take a daily probiotic. It’s the easiest way to support gut health and gut barrier function. I also avoid unnecessary antibiotics and only drink alcohol occasionally since both are microbiome disruptors. 

Want to learn more about building a resilient gut? Sign up for my first-ever live course Healing Your Gut Through Mind & Body, which begins October 23. Over three intimate sessions, you’ll gain a deeper understanding of how foundational the gut is to your health and start healing your gut in real time.