Huberman’s Cold and Flu podcast hypes unproven wellness ‘hacks’ that he profits from
All while ignoring and dismissing actual evidence-based interventions
(Note: this is part four and final of a multi-piece segment, for the sake of length)
As I’ve come to the end of picking apart this episode, it is apparent that Huberman is a menace to society. He uses his PhD and former lab position (he does not have an active lab at Stanford anymore) to platform pseudoscience and dismiss robust and clinically relevant data.
It is grossly apparent that he did little to no preparation for this “cold and flu prevention” episode. He misrepresents basic immunology, undermines proven public health measures, and exaggerates unproven wellness trends. And here is the crux of the problem:
His podcast is rife with misinformation that harms public health & science literacy.
If you read the other 3 newsletters on this episode, you realize that Huberman does not understand the immune system and you should not trust what he says about it. His pattern of making unsubstantiated claims isn’t limited to this episode.
As I’ve sifted through 2+ hours of misinformation, it’s obvious why people have fallen prey. His episodes are excessively long and filled with almost nothing substantive. The delivery of the content is so circuitous that the topics blur together, and there is so much incorrectly used jargon that it is impossible for the general public to fact-check his claims, so people simply accept what he says.
To recap: part 1 discussed Huberman’s minimization of flu and importance of vaccination (the number one thing that actually does prevent flu). Part 2 discussed his mischaracterization of the immune system and how vaccines generate protection. Part 3 covered his lack of understanding about exercise, cortisol, and immune function.
So let’s get into the last and final section: where we discuss the interventions he recommends to ‘bolster your immune function’.
The only real way to boost your immune system is through vaccination.
If someone purports to have a ‘science-backed’ discussion on cold and flu prevention and doesn’t encourage flu vaccination, they’re doing the opposite. The data are unequivocal regarding the benefits and safety of flu vaccination.
And now, the interventions touted by Huberman (nearly all of which he makes a lot of money off promoting to his listeners).
Sauna or deliberate heat exposure does NOT improve immune function or help stave off full-blown symptoms.
Once again, Huberman is incorrect. As predicted, he cites the 2023 “Finnish sauna” study, the ‘pivotal study’ people use to tout sauna for immune function. He calls it a ‘nice study’ and concludes that it shows improved immune function after sauna. If you only read the abstract (which I’m guessing he did), you might believe that.
But a good scientist, surely someone with a PhD, would know you don’t just skim an abstract. You look at the methods. You look at the results. You see what the data say.
This study included TWENTY people. 20. All college students, all male. That’s it.
That’s not a “nice study” even before looking at data. The abstract claims that they see increased levels of white blood cells (leukocytes) which they EXTRAPOLATE to mean that immune function is improved. You can’t just take blood, count the number of immune cells, and say, voila: immune system boosted! But let’s put that aside for a moment. What do the data show?
Y’all. Come on. The DATA OVERLAP. Those error bars are wild. The authors claim there is a “statistically significant” difference between before and after sauna: statistical and clinical significance are not the same. That’s aside from the fact the study isn’t assessing immune function: they measure numbers of leukocytes and a few subtypes of immune cells which aren’t actually different between groups.
There is no evidence that sauna reduces susceptibility to illness or improves immune function. This study has major limitations and confounding variables, not to mention the fact the data don’t even say what the authors claim they do. If you enjoy sauna, do you. But it isn’t bolstering immune function.
Cold plunges do not improve immune system function and have serious risks associated with them.
He tells listeners to alternate between sauna and cold plunge. There is no robust evidence to support the claim that cold plunges improve immune function. A study of 10 athletes reports a tiny increase in white blood cell counts after repeated cold plunges but another found it didn’t. A study group of 10 (especially 10 male athletes) is not representative of our population. Looking at ‘small increases in white cell counts’ is not a measure of immune function. One randomized controlled trial in the Netherlands found cold plunges led to a reduction of self-reported sickness absence from work by 30% but not actual number of days of illness (placebo effect, anyone?)
Not only is there little evidence to support cold plunge, it can be dangerous. Sudden immersion in water under 60°F can kill a person in <1 minute; cold shock can trigger a sudden, rapid increase in breathing, heart rate, and blood pressure that can cause drowning within seconds if they involuntarily gasp while submerged. It also increases cardiovascular risks, especially for those with underlying health issues. Yes, Huberman has a cold plunge company as a sponsor, so there is an obvious financial motive to promote this.
Nasal breathing is not preventing infection or boosting immune function.
Huberman incorrectly states “consciously focusing on nasal breathing is one of the best things that we can all do to combat any colds or flu”. Mouth taping and nasal breathing is all the rage in the ‘wellness space’, and this isn’t his first time platforming it.
There is no evidence to suggest mouth breathing negatively affects your oral microbiome or susceptibility to infection or that nasal breathing augments your nasal microbiome. Huberman cites a study regarding nitric oxide production by nasal breathing as evidence. While nitric oxide (NO) has a broad range of roles including in immune function, nasal breathing isn’t the only conduit.
We produce nitric oxide through enzymatic reactions of by consuming foods containing nitrates and nitrites. Nitrates in vegetables are reduced to nitrites by oral bacteria, and gastric acid in the stomach converts nitrite to nitric oxide. Enzymatic generation through nitric oxide synthase (NOS) relies on 3 different enzymes, each in different tissues: endothelial (eNOS), neuronal (nNOS), and inducible (iNOS). eNOS is ubiquitous in our blood vessels, nNOS is in the nervous system, and iNOS is in immune cells and is induced to kill pathogens.
All endothelial vessels produce nitric oxide which means other areas in the body produce nitric oxide besides the paranasal sinuses. Nasal breathing does not offer a distinct advantage over mouth breathing it does not directly improves health outcomes, including immune function. It is not “one of the best things that we can all do to combat any colds or flu” - that’s vaccination, which he discouraged.
Nasal breathing can humidify and warm air that you breathe, but inhaling cold air through the mouth does not impair immune function or increase likelihood of respiratory infections. But he wants to promote his buddy’s book, which trumps evidence in a ‘science-backed episode’, right?
The gut microbiome is important, but fermented foods don't uniquely ‘support’ it.
There is a lot of hype around foods or ingredients to boost your immune system or ‘support your microbiome’ like fermented foods and yogurts. While many of these are a good source of nutrition and can be a part of a healthy and diverse diet, consuming them does not confer unique health benefits. If someone makes claims about augmenting specific microbiome populations, they’re misleading you. If you enjoy fermented foods, go for it, but they don’t offer a specific benefit. In fact, most of the live microorganisms will be killed by stomach acid before they get to your intestines.
But this is a perfect segue into his biggest sponsor, AG1, with whom he has a $40 million contract with.
Huberman hypes it up: “now we get to the portion of the discussion that I think probably many people are anticipating which is what can you take to reduce the probability of getting a cold or flu or shorten the duration of a cold or flu.”
The best thing you can take to reduce the probability of getting the flu and shorten the duration of illness: flu vaccines.
If you do get the flu, antiviral medications can inhibit viral replication and reduce illness severity and duration.
Weird that Huberman didn’t mention these, huh?
Antivirals are effective when taken early in the course of infection or illness, before viral replication has started to ramp up. For influenza, antivirals should be started within 1-2 days of symptoms. Prevention (vaccines) is better than treatment, but if you do get the flu, antivirals are a great tool.
One of the common ones, oseltamivir phosphate (Tamiflu) inhibits the influenza virus enzyme neuraminidase, which is required to cleave the attachment of new viral particles (progeny viruses) from the host cell. If it cannot cut the bond, new viruses can’t be released.
Huberman doesn’t encourage either of these things, so let’s talk about what he does encourage: supplements.
Supplements are unregulated pharmaceuticals.
Supplements are made in a laboratory and synthesized. That means that they are pharmaceuticals, but they’re not regulated for safety or efficacy by the FDA. This means even if you buy the same supplement from the same company, there is lot-to-lot variability in the quality, the chemical formulation, and how bioavailable it is. It is better, cheaper, and safer to get the small amounts of micronutrients you need in your diet. There is also the issue that many dietary supplements are multi-ingredient proprietary blends, which means you don’t even know what you’re getting.
A recent study found that the majority of “immune boosting” supplements had inaccurate labels. Of those, 76.4% claimed there were ingredients in them that weren’t detectable. More concerning was that 53% of those with inaccurate labels included ingredients that were not disclosed, meaning people are consuming substances they aren’t aware of, which can pose risks.
Just because something is sold as a “dietary supplement” does not mean that it is safe or benign, and that is a dangerous and widely held misconception.
Many ‘herbal extracts’ can have serious adverse effects on people. They can interfere with medications, inhibit absorption of essential nutrients, and cause acute liver and kidney toxicity. Supplement overdosing accounted for 20% of liver damage and hepatotoxicity in the US in 2017 and that number is likely higher now. Over 50,000 adverse events are reported to the FDA every year, and that is likely lower than those which occur, because people don’t know that you can report supplements.
AG1 has ZERO clinical data to support its use.
The fact that he hypes AG1 in every episode has nothing to do with his $40 million contract with them, or that he is part of their “Scientific Advisory Board”, right?
AG1 (formerly Athletic Greens) markets itself as a cure-all panacea. A visit to their website suggests it can prevent and cure any ailment. And for over $100 for a one-month supply, it better, am I right? According to them, their miracle blend helps you age better, supports your immune system, improves brain health, has prebiotics (a marketing buzzword for fiber), probiotics, “superfoods”, “adaptogens”, and more. Sounds too good to be true, right? Yes.
There are zero specific, large-scale clinical data that link AG1 with improving outcomes to respiratory viruses. With unregulated supplements, it is critical to differentiate between marketing claims and scientific evidence.
AG1 exploits the lax regulations of the supplement industry to label its product as a “proprietary blend” so that it doesn’t actually need to disclose the amount of ingredients to the public. So, you are paying an exorbitant price for unknown ingredients that have no evidence to support their use. Seems sus.
Probiotics do not boost your immune system.
AG1 also claims to include probiotics like Lactobacillus acidophilus, which Huberman manages to insert: “if your goal is to keep your innate immune system fighting off colds and flu sufficiently …support the gut microbiome …maybe a prebiotic probiotic capsule maybe something like athletic greens AG1.” If it wasn’t clear, there is ZERO evidence that AG1 is anything besides expensive urine and a big fat paycheck for Huberman.
Probiotic supplements are unregulated dietary supplements that contain live microorganisms. There is no evidence that people with normal gastrointestinal tracts can benefit from probiotics. Even among those with specific medical issues such as antibiotic-associated diarrhea, constipation, gastroenteritis, and Crohn’s disease, studies have failed to find robust evidence to support use, due to the lack of regulation and standardization of species and dosage in these supplements. Probiotics can pose serious risks for people, especially those who are immunocompromised
Supplements do not prevent viral infection or reduce illness severity or duration.
There is a misconception that if you need a micronutrient (like Vitamin C) in trace levels, then more of it through supplementation is better. The reality is that there is no robust clinical evidence that supplements offer health benefits in those who don’t have clinical indications (like pregnancy), especially with regard to preventing infectious diseases or reducing the severity of infectious illness. Many of these micronutrients can cause harm in excess.
Huberman correctly noted the lack of data to support vitamin C, vitamin D, and echinacea supplementation. However, he still recommended Vitamin D supplements and routine and frequent blood tests, even though this is not recommended by the US Preventive Task Force. I discussed the story behind Vitamin D here.
Zinc is an essential micronutrient, but there is no evidence to support prophylactic zinc supplementation to prevent infection. Only weak observational data exist to support claims that zinc supplementation can reduce illness duration once someone has a respiratory illness. A commonly cited review that claims zinc lozenges improve clearance of cold viruses was withdrawn after an analysis found serious flaws in the paper. Excessive zinc intake can cause zinc toxicity, which can cause adverse effects like nausea, vomiting, loss of appetite, stomach cramps, diarrhea, and headaches. Zinc interferes with copper and iron absorption, so excess can lead to deficiencies in other essential micronutrients, and it can interact with antibiotics and other medications that one may be taking.
Huberman hypes N-acetylcysteine (NAC) which is a precursor to the antioxidant glutathione. Antioxidants are chemicals that scavenge and neutralize byproducts of metabolism, called free radicals. Antioxidants supplements were all the rage for a long time. Just like the current era, tiny grains of truth were exaggerated to suggest that supplements could improve what your body is already very good at doing itself. Most antioxidants (a catchall for hundreds of chemicals) we can make ourselves or get plenty of through our diet. Many taken in excess can cause harm. For example, a large review identified that supplementing with beta-carotene, vitamin A, or vitamin E actually led to increased mortality rates. That’s why the US Preventive Task Services recommends AGAINST taking these supplements. But they’re found in lots of multivitamins and other mixed-ingredient supplements, including AG1.
There is no strong or conclusive evidence that N-acetylcysteine (NAC) is effective to prevent respiratory infections. Currently, data that is cited to support this claim have severe limitations in sample size and study design. Huberman cites a “physician who was responding to his comments on social media” as evidence to support NAC. That is an anecdote, obviously. If you recall the hierarchy of evidence, ‘expert opinion’ is at the bottom, and that’s even assuming this person is actually a physician and a physician in a relevant field. In addition, high doses of NAC can cause gastrointestinal discomfort, rash, or headache, and it may interact with medications.
As I come to the end of this dissection, I am saddened to a degree.
I am saddened by the fact that someone with training in science has used his prominent platform to mislead people and make money off it instead of doing good in the world and trying to improve health outcomes.
I’m saddened that he mischaracterized the complexity and the elegance of the immune system so terribly. The misinformation he shares daily continues to erodes science literacy and public health, which enables people like him to continue promoting falsehoods that cause harm people who don’t know any better.
I hope this long deep dive was useful for people who wondered why Huberman is problematic. Ultimately, social media and prominent voices lead many people to believe things that are not factual, and as a scientist, I feel an obligation to do what I can to try and correct this. As always, this is a free and public article, so please feel free to share it with your friends and family if you also want to stand up for science.