How to boost your immune system for cold and flu season

Every fall the same question returns: can you actually boost your immune system? In a conversation with a producer of The Doctor's Farmacy show, Dr. Mark Hyman explains that "boost" may be the wrong word, but you can absolutely influence how well your immune system works. Here is the practical plan he follows, from daily foundations to what he does when a scratchy throat appears.

What the immune system is

Hyman describes the immune system as a surveillance network that works like radar. It senses what is happening in your microbiome, in viruses and bacteria and even in cancer cells, and activates when it sees trouble. The adaptive branch makes antibodies through T cells and B cells, while the older innate branch relies on cell mediated defenses, and saunas help activate it. If it becomes overwhelmed, you get sick.

The foundations come first

Almost everything that supports immunity is lifestyle. A poor diet, sugar, nutrient depletion, low zinc, vitamin D, omega 3s or selenium, an unhealthy gut, too little sleep, too little exercise and chronic stress all weaken it. Alcohol and a disrupted circadian rhythm do too. His priorities are:

• Eat whole foods and avoid ultraprocessed food.
• Check your nutrient levels, which you can do through Function Health, the episode sponsor.
• Sleep well and keep regular sleep and wake times.
• Manage stress with meditation, yoga, breathwork or massage.
• Exercise, but do not overdo it.

Metabolic health matters too. Sugar suppresses immune cells and raises inflammation, and insulin resistance creates a vicious cycle. A dessert now and then is fine, but a pint of ice cream every night would not be. Hyman says his insulin is under five and he has about 10% body fat.

Vitamin D is the top supplement

Vitamin D is "probably the most important" immune nutrient, and 60 to 80% of people are insufficient or deficient. He argues the ideal range is about 45 to 60 or 70 instead of the lab's 30. He cites a COVID study in which low vitamin D meant a 75% higher risk of hospitalization or death, while those above 50 had zero deaths. Always measure first, because some people need 1,000 units to reach the target and others need 10,000. He also stresses zinc, vitamin C, selenium and B vitamins, notes that zinc lozenges have data for early colds, and admits vitamin C data are mixed.

What goes in the cart

Hyman treats the grocery store as his pharmacy. He picks ginger and garlic for their anti inflammatory and antimicrobial effects, daikon radish, artichokes for prebiotic fiber, sauerkraut and miso for fermented foods, and colorful plants for phytochemicals. His signature chicken soup uses a whole chicken, ginger, garlic, astragalus, sweet potatoes, carrots and celery.

His travel pack and first symptom protocol

He carries five packets with 50,000 units each of vitamins A and D, Host Defense adaptogenic mushrooms, echinacea and sometimes vitamin C. He also mentions colostrum based Transfer Factor Multi Immune. At the first sign of illness he takes 50,000 units of vitamins A and D for three to five days, and warns that waiting too long makes it ineffective. He admits he also uses thymosin alpha 1 and LL-37, but says that is not ready for prime time and he does not suggest others do it.

He then prioritizes sleep, uses a sauna or steam, rests, gets a massage and eats healthy. He also drinks a strong mix of crushed garlic, boiled ginger, honey, lemon and red pepper, which he calls intense but effective.

Exercise, stress and vaccines

A little exercise helps when you are sick, such as a walk, but overtraining and ultramarathons suppress immunity. Light weight training is fine if you feel only slightly unwell. The stress letdown illness many people feel after a hard stretch is real, he says. On the flu vaccine, Hyman says it works only about 50% of the time. He does not take it, but recommends it for people with lung disease, heart failure, diabetes or other risk. If you get one, ask for a single dose vial to avoid thimerosal, a mercury containing preservative.

The idea behind all of this is resilience. Functional medicine, in his words, is about taking out the bad stuff and putting in the good stuff, so the body can respond appropriately to whatever life throws at it. Hyman says the foundations cover roughly 80% of the work, and a provider can help you sort out the last 20%, such as toxins, gut problems or underlying immune deficiencies.

Quick answers

• Should you starve a fever? No. Hydrate and eat easily digestible food.
• Most underrated tip? Get enough sleep and take your vitamin D.

Conclusion

The best defense is a resilient body: whole foods, sleep, stress control, movement and optimized nutrient levels, with vitamin D first. Supplements and rituals can help, but they work best on top of strong foundations.