What I Actually Do When I Feel a Cold Coming On (It's Not Vitamin C)

Episode Overview

• In this "Office Hours" episode of The Dr. Hyman Show, Dr. Mark Hyman and co-host Emma explore whether you can truly "boost" your immune system and outline the foundational dietary, lifestyle, and supplement protocols needed to build resilience against cold and flu season.
• Dr. Hyman explains the biological mechanisms of the innate and adaptive immune systems, detailing how everyday factors like sugar, sleep, circadian rhythms, gut health, and micronutrient status directly suppress or optimize immune surveillance.
• The conversation progresses from foundational daily habits (handling 80% of immune health) to targeted testing—specifically emphasizing Vitamin D—and concludes with acute onset protocols, medicinal foods, and Dr. Hyman's perspective on flu vaccines.
• Listeners receive practical, step-by-step remedies for the first 24 hours of illness, alongside transparent disclosures regarding Dr. Hyman's business ties to Function Health (an episode sponsor he helped build that offers over 160 lab tests for $365/year) and his upcoming book out next March.

Key Concepts

• Optimizing vs. "Boosting" Immunity: Dr. Hyman notes that "boost" may not be the right word; rather, you influence and optimize immune function by removing negative modulators. Poor diet, sugar, nutrient depletion (low zinc, vitamin D, omega-3 fats, and selenium), an unhealthy gut microbiome, lack of sleep, lack of exercise, stress, alcohol, and disrupted circadian rhythms all actively suppress immunity.
• The Two Branches of Immune Surveillance: The immune system acts as a radar split into the adaptive immune system (more evolved, producing antibodies against viruses, bacteria, proteins, or foods) and the innate or cell-mediated immune system (our ancient system, which can be activated and made more resilient by taking saunas). Together, they activate T-cells and B-cells to produce substances like hydrogen peroxide and ozone to kill pathogens, or create antibodies so macrophages can eat invaders like "Pac-Man."
• The 80/20 Rule of Immune Resilience: Fixing foundational lifestyle habits—nutrition, sleep, exercise, and stress—handles 80% of immune health. The remaining 20% involves working with a provider to resolve deeper underlying gut issues or heavy toxin loads.
• Sugar and Metabolic Health as Immune Regulators: Sugar acts as a direct immune suppressant that impairs immune cell function, increases inflammation, heightens vulnerability to infection, and drives insulin resistance in a vicious cycle. Maintaining strong metabolic health (for example, Dr. Hyman at age 66 maintains 10% body fat and a fasting insulin under 5, indulging in ice cream only once every month or two) allows the body to stay resilient rather than fragile.
• The Critical Role of Vitamin D Over Other Foundations: According to Dr. Hyman, 60% to 80% of people are insufficient or deficient in Vitamin D. While standard lab reference ranges mark 30 as sufficient, optimal levels should be 45 to 60 or 70. Citing a big Israeli study on COVID-19 outcomes, he notes that people low in Vitamin D had a 75% higher risk of hospitalization or death, whereas those with levels over 50 had zero deaths. He considers correcting severe deficiency (under 30) even more important than sleep, because sleep alone cannot overcome a low Vitamin D level.
• Hormetic Stress, Exercise, and the "Let-Down Effect": Moderate exercise improves immunity, and Dr. Hyman even engages in light movement (like walking or reduced biking/running) when mildly sick, though he notes there isn't a lot of data on weight training and immune function. Conversely, over-exercising (such as running ultramarathons) causes inflammation and suppresses immunity. Similarly, while there may not be a randomized controlled trial on getting sick right after a stressful period ends, Hyman views this "let-down" phenomenon as real, driven by prolonged stress and sleep deprivation dysregulating hormones and immunity.
• Evidence Nuances in Supplementation and Vaccines: Dr. Hyman distinguishes between well-supported interventions and areas with mixed or emerging data. He notes there is some data on zinc lozenges for early colds, B vitamins are important for methylation and immunity, and colostrum-based products (like Transfer Factor Multi-Immune) support the gut, whereas the data on Vitamin C is mixed despite its general importance. He also shares his personal use of immune and antimicrobial peptides (Thymosin Alpha-1 and LL-37) during the first 24 hours of symptoms, heavily caveating that this is not ready for prime time and he is not recommending it to others due to the higher risk. Regarding the flu vaccine, he states it is his personal opinion that the literature is "kind of iffy," noting it works only about 50% of the time (though it can reduce severity) and that he only recommends it for high-risk patients (those over 65 or with asthma, lung disease, diabetes, or heart failure) rather than universal administration from 6 months to 106 years old.

Quotes

• At 1:33 - "So absolutely, your immune system can be optimized by modulating the things that we know affect your immune function. So there's no doubt about that. The science on this is really clear." - Dr. Hyman reframing the concept of "boosting" immunity into the actionable science of removing immune suppressors and optimizing foundational inputs.
• At 3:39 - "I mean, there was a great study in COVID where they looked at people who were low in vitamin D, they had a 75% higher risk of ending up in the hospital or dying. That's big, okay? And those who had a vitamin D level over 50—this was a big Israeli study—there were zero deaths. Zero. Not one." - Highlighting why standard lab cutoffs of 30 are inadequate and why maintaining a Vitamin D level above 50 is critical for severe illness protection.
• At 8:20 - "So the whole, the whole purpose of functional medicine and of the work that I do is not to create a restrictive life. It's actually the opposite. It's to make you more resilient and less fragile. And the, we, when we look at health, health is about resilience." - Explaining the core philosophy of building a baseline of metabolic and immune health so the body can handle occasional stressors or indulgences without breaking down.
• At 14:46 - "The most important is vitamin D. And I think you make sure, make sure you not just take vitamin D, but that you measure your vitamin D level because some people need 1,000 units to get their levels up, some people need 10,000 units. So you can't know unless you test before and after." - Emphasizing the necessity of personalized blood testing due to a tenfold variation in individual Vitamin D dosing requirements.

Takeaways

• Test and Optimize Your Vitamin D Levels: Measure your baseline Vitamin D (Dr. Hyman mentions using Function Health, which he helped build) and test again after supplementing to find your personal maintenance dose—which can range from 1,000 IU to 10,000 IU daily—aiming for an optimal target range of 45 to 70 rather than the standard lab cutoff of 30.
• Execute an Acute First-24-Hours Protocol: At the very first sign of feeling off (waiting too long makes it ineffective), take 50,000 IU of Vitamin A and 50,000 IU of Vitamin D per day for 3 to 5 days, alongside adaptogenic mushrooms (such as Host Defense or Chinese mushroom herbal formulas), echinacea, zinc lozenges, and optionally Vitamin C. If you choose to get a seasonal flu shot, ask your provider for a single-dose vial to avoid the mercury (ethylmercury/thimerosal) preservative used in multi-dose vials.
• Use Kitchen "Farmacy" Remedies Daily and Acutely: Support daily gut and immune health with fermented foods (sauerkraut, miso soup), prebiotic fiber (artichokes), detoxifying daikon radish, anti-inflammatory curcumin, and medicinal chicken soup made with a whole chicken, lots of garlic and ginger, root vegetables (sweet potatoes, carrots, celery), and astragalus. For acute symptom relief, make a 16-ounce garlic-ginger tea by crushing 1 to 2 cloves of raw garlic into a mug, pouring water boiled with sliced ginger over it, adding honey, lemon, and red pepper flakes, and steeping for a couple of minutes before drinking.