Huberman Lab

How to Prevent & Treat Colds & Flu

Mon Jan 08 2024

coldsflusimmune systemtransmissionpreventionexercisesupplements

Description

The podcast episode discusses colds and flus, including what they are and how they impact the brain and body. It provides science-supported techniques to avoid getting colds and flus, although it acknowledges that it is impossible to completely avoid them. The immune system is explained in a way that is accessible to everyone, regardless of their background in biology. Behavioral tools for bolstering the immune system are discussed, along with various compounds that can enhance its function. Common myths about treatments for colds and flus are debunked, with an emphasis on science-supported protocols and compounds.

Insights

Colds and flus are caused by viruses

Over 160 different types of viruses known as rhinoviruses cause the common cold. The flu is caused by different types of flu viruses categorized into A-type, B-type, and C-type based on proteins expressed on their surface.

Transmission of colds and flus

Colds and flus are primarily transmitted through respiratory droplets from coughing, sneezing, or blowing the nose into tissues. Touching contaminated surfaces and then touching the eyes, nose, or mouth can also lead to infection.

Preventing colds and flus

Practicing good hygiene, such as washing hands frequently and avoiding touching the face, can help prevent the spread of cold and flu viruses. Having a strong immune system through adequate sleep, exercise, and nutrition can also reduce the risk of getting sick.

The role of the immune system

The immune system has physical barriers, innate immune responses, and adaptive immune responses to defend against cold and flu viruses. Skin acts as a physical barrier, while neurochemicals and antibodies are deployed by the innate and adaptive immune systems, respectively.

Exercise and the immune system

Regular exercise of moderate intensity can enhance the function of the innate immune system, but excessive exercise or intense activity when feeling rundown can compromise immune function. Sauna sessions and heat exposure can also boost the activity of the innate immune system.

Supplements for colds and flus

Zinc supplementation at a dosage of 90 to 100 milligrams per day can help reduce the duration of a cold. N-acetylcysteine (NAC) is a mucolytic substance that can relieve sinus congestion. Vitamin C supplementation may not be effective in preventing or treating colds and flus.

Chapters

Colds and Flus
Causes and Transmission of Colds
Transmission and Contagion of Colds
Influenza and Flu Shots
Immune System and Defense Mechanisms
Mucosal Lining and Portals of Entry
Preventing Cold and Flu Infections
Innate and Adaptive Immune System
Adaptive Immune System and Exercise
Sleep, Exercise, and Immune System
Gut Microbiome and Immune System
Fermented Foods and Immune System
Exercise and Immune System
Exercise and Immune System (Continued)
Exercise and Immune System (Continued)
Heat Exposure and Immune System
Vitamin C, Zinc, and Natural Remedies
Zinc and N-acetylcysteine (NAC)
N-acetylcysteine (NAC) and Natural Remedies

Summary

Transcript

Colds and Flus

00:00 - 06:27

The podcast episode discusses colds and flus, including what they are and how they impact the brain and body.
It provides science-supported techniques to avoid getting colds and flus, although it acknowledges that it is impossible to completely avoid them.
The immune system is explained in a way that is accessible to everyone, regardless of their background in biology.
Behavioral tools for bolstering the immune system are discussed, along with various compounds that can enhance its function.
Common myths about treatments for colds and flus are debunked, with an emphasis on science-supported protocols and compounds.

Causes and Transmission of Colds

06:03 - 12:26

The common cold does not have a cure because it is caused by over 160 different types of viruses known as rhinoviruses.
Antibodies developed against one type of cold virus cannot effectively combat other types due to their different shapes.
Multiple colds can occur within a year or season due to exposure to different serotypes of the cold virus.
Cold temperatures do not directly cause the common cold; it is spread through breathing, sneezing, and touching surfaces contaminated with the virus.
The cold virus can survive on surfaces for up to 24 hours but does not necessarily infect individuals upon contact with the skin.
Skin acts as a barrier against most viruses and bacteria, providing protection against infection.
Cold virus particles are extremely small, around five microns in size, and can spread through sneezing but tend to fall onto surfaces rather than remain airborne for long periods.
Touching the eyes is one of the primary ways for the cold virus to enter the body, and people frequently touch their face and eyes throughout the day.

Transmission and Contagion of Colds

12:01 - 18:26

People often transmit the cold virus by touching their eyes and face throughout the day.
The common route of transmission for the cold virus is through coughing, sneezing, or blowing the nose into tissues and not washing hands afterward.
There are myths surrounding when people are contagious with a cold or flu, such as thinking they are no longer contagious after a certain number of days or until symptoms appear.
The cold virus is very small and can be transmitted through the air, skin-to-skin contact, and can survive on surfaces for up to 24 hours.
Touching the eye region is the most common way for the cold virus to enter the body, but it can also enter through other regions like the mouth and lips.
Different types of cold viruses cause different symptoms, ranging from mild to severe with varying degrees of fever.
Symptoms of a cold usually appear one to two days after exposure to the virus.
It's possible to avoid getting a cold even if exposed to a new serotype by having a strong immune system.
People are most contagious when they feel their worst but can still be contagious when starting to feel better. Generally, five to six days after peak symptoms, contagion decreases.
Continuing to experience sneezing and coughing means you're still contagious even if you've had a cold for several days.
People who continue going out while experiencing cold symptoms are likely spreading the virus unknowingly and should stay home as much as possible.
The financial, mental health, and physical health costs associated with getting a cold are significant. It can worsen existing health issues in individuals.
The flu virus has different serotypes categorized into A-type, B-type, and C-type based on proteins expressed on their surface.

Influenza and Flu Shots

18:06 - 24:40

Influenza, commonly referred to as the flu, is caused by different types of flu viruses that express different proteins on their surface.
The most common type of flu virus is in the A category and caused the Spanish flu pandemic between 1918 and 1920, which killed millions of people.
Flu viruses can be transmitted through human-human contact or by coming into contact with respiratory droplets containing the virus.
The flu virus can only survive on surfaces for about two hours before dying off.
Flu shots are vaccines specifically designed to combat specific strains of the flu virus present in a given season.
Studies have shown that getting the flu shot reduces the risk of contracting the most abundant strain of flu by about 40 to 60% and can also reduce symptom severity if one does get infected.
The effectiveness of the flu shot is limited to specific strains of the flu and does not protect against other forms of the virus or colds.
The decision to get a flu shot should be based on individual circumstances, such as exposure risk and potential transmission to vulnerable individuals.
Personal factors, such as lifestyle choices and overall health, may influence whether or not someone chooses to get a flu shot.
Keeping track of events preceding illness episodes can help identify patterns and potential triggers for colds or flus.

Immune System and Defense Mechanisms

29:56 - 36:09

The immune system has three major lines of defense: physical barriers, the innate immune system, and the adaptive immune system.
The physical barrier component includes the skin, mucosal linings, and liquids on the surface of the eyes.
The innate immune system is a generalized response system that deploys neurochemicals to combat viruses.
The adaptive immune system produces antibodies to specifically combat the serotype of virus that has infected the body.
Skin serves as an important physical barrier against viruses and produces chemicals that can neutralize and kill them.
Openings in the skin, such as the eyes and nostrils, have their own defenses against infection.

Mucosal Lining and Portals of Entry

35:52 - 42:09

The mucosal lining in your nose is sticky and traps viruses, but sometimes the viruses can infect other cells and tissues in your body.
The mucosal lining in your mouth and nose are different, but both help fight off bacteria and viruses.
Bacteria and viruses enter through the eyes, nose, or mouth, which are the primary entry sites for colds and flus.
People tend to touch their eyes or face after shaking someone's hand, possibly to unconsciously detect chemosignals from the other person.
Our olfactory system processes information about the other person's physiology and health when we touch our eyes or face after shaking hands.

Preventing Cold and Flu Infections

41:42 - 48:37

The olfactory system is not only responsible for conscious smelling, but also unconscious processing of chemosignals.
Touching other people or surfaces that have cold or flu viruses can bring the virus to our face, increasing the risk of catching a cold or flu.
Being mindful of the portals of entry for cold and flu viruses (eyes, nose, mouth) can help reduce the probability of getting sick.
While touch is important for social connection, being aware of hand-to-face contact can lower the risk of catching a cold or flu.
Using hand sanitizer after shaking hands can help prevent the transmission of viruses.
Once a cold or flu virus enters the body, the immune system launches a rapid response to attack and neutralize it.
White blood cells like neutrophils, natural killer cells, and macrophages are part of the innate immune system's response to viral infections.
The complement system in the bloodstream marks infected cells with an "eat me" signal to be destroyed by immune cells.
Infected cells release signals for help as they undergo damage from viral replication.

Innate and Adaptive Immune System

48:10 - 54:42

The innate immune system responds to viral infections by releasing cytokines, which help remove the infection and repair infected cells.
Cytokines cause physical swelling in the infected area, leading to edema and increased blood flow.
The innate immune system is fast and nonspecific, responding to various types of infections.
Exposure to a cold or flu virus may result in initial symptoms like fatigue or malaise due to the innate immune system's response.
The severity of a cold or flu infection depends on whether the innate immune system can fight off the virus effectively.
Taking steps to support the innate immune system can increase the chances of preventing a full-blown cold or flu.
The adaptive immune system is another layer of defense that creates specific antibodies against pathogens.

Adaptive Immune System and Exercise

54:15 - 1:01:25

The adaptive immune system creates antibodies specifically targeted at the intruder that infected your cells.
Antibodies produced by the adaptive immune system can neutralize specific strains of cold or flu viruses.
The adaptive immune system has two phases: first, it produces IgM antibodies that approximate the shape of the virus, and then it produces more specific IgG antibodies.
The innate immune system launches a generalized attack on viruses, while the adaptive immune system produces antibodies specific to the virus.
The adaptive immune system acquires a memory of successful battles with viruses and can quickly produce antibodies if reinfected.
The lymphatic system collaborates with the vascular system to filter cells and produce chemicals that help combat infections.
Exercise of sufficient intensity and duration can recruit or increase the activity of the innate immune system, even in the absence of an infection.
Improving the function of our immune system involves various strategies such as getting enough rest.

Sleep, Exercise, and Immune System

1:06:56 - 1:13:42

Getting enough quality sleep is crucial for maintaining and enhancing the function of the innate immune system.
Exercise, when done in specific types, durations, and intensities, can help bolster the innate immune system.
Adequate nutrition is important for supporting the immune system, while caloric deficits or extended fasting can compromise its function.
Chronic stress can reduce the functioning of the innate immune system, but short bouts of stress that don't impede sleep can actually enhance immune function.
Cortisol, when elevated early in the day and within certain thresholds, plays a role in activating natural killer cells and deploying interleukins to combat infections.
Inflammation response is an important component of the innate immune system to fight infections effectively.
Maintaining a healthy gut microbiome is essential for optimal immune function.
The gut microbiome exists not only in the gut but also on the surface of eyes and nasal passages. The nasal microbiome seems to be particularly effective at combating cold and flu viruses.

Gut Microbiome and Immune System

1:13:15 - 1:19:39

The microbiome in the nasal passages is different from the microbiome in the mouth and is effective at combating cold and flu viruses.
Being a nasal breather promotes a healthy nasal microbiome and protects against upper respiratory tract infections.
Nasal breathing heats the air differently than mouth breathing, reducing the likelihood of cold or flu viruses infecting the nose.
The gut microbiome plays a crucial role in supporting the immune system.
Consuming two to four servings of low sugar fermented foods per day, such as sauerkraut and kefir, supports the diversity of microbiota along the entire length of the gut microbiome.
Avoid high-sugar fermented foods as they can create other health issues.

Fermented Foods and Immune System

1:19:10 - 1:25:48

Consuming two to four servings of low sugar fermented foods per day is one of the best ways to promote a healthy gut microbiome and support the innate immune system.
Swishing water around in your mouth and swallowing it before brushing your teeth can potentially improve the function of your gut microbiome by providing substrate for the microbiota in your digestive tract to thrive.
Quality sleep, supporting the gut microbiome, and exercise are important for bolstering the innate immune system.
Exercise can enhance the immune system, but certain intensities and durations of exercise can make us more vulnerable to colds and flus.
If you're feeling rundown or experiencing whole body malaise, it's best to rest, take a hot shower or bath, and get extra sleep as pushing yourself into intense activity may compromise the function of your innate immune system.

Exercise and Immune System

1:25:40 - 1:32:15

Activation of the innate immune system during sickness affects sleep patterns and can lead to feelings of sleepiness and malaise.
Exercise can strengthen the innate immune system and help combat colds and flus.
The appropriate intensity and duration of exercise is important for boosting the output of the innate immune system.
Exercise sessions that are 60 minutes or less, intense but not all-out effort, promote the exchange of components between blood and lymphatic systems, increasing circulation within the innate immune system.
Regular exercise of sufficient intensity can ramp up baseline activity of the innate immune system for many hours after exercise, improving its ability to fight infections.
Walking briskly for about 60 minutes a day increases T cell function, natural killer cell activity, macrophage function, cytokines (mildly), and stress hormones.
Running a marathon leads to a different pattern of immune response compared to one hour of exercise. Marathon runners experience severe immune compromise with reduced T-cell function, diminished natural killer cell activity, high levels of stress hormones and inflammatory molecules.

Exercise and Immune System (Continued)

1:31:49 - 1:38:32

Exercise can have both positive and negative effects on the immune system.
Running marathons or half marathons can temporarily weaken the immune system, making individuals more susceptible to colds and flus.
Regular exercise, even for as little as 20 minutes per day, can improve the innate immune response.
High-intensity training for shorter durations (such as 12 minutes) can also enhance the innate immune system function.
It is recommended to combine cardiovascular training and resistance training for overall health and immune system function.
Exceeding 75 minutes of exercise in a single session may increase the risk of getting sick.
Lack of sleep and excessive exercise are common precursors to getting a bad flu or cold.
Moderation is key when it comes to exercise duration and intensity to maintain a healthy immune system.
Exercise should not be used as a substitute for sleep, but if sleep-deprived, exercising early in the day may help offset some negative effects.

Exercise and Immune System (Continued)

1:38:08 - 1:44:53

If you can't go back to sleep after a night of sleep deprivation, doing some exercise at reduced intensity and duration can help offset the negative effects.
Ingesting carbohydrates after exercise can reduce inflammation induced by exercise, especially if training fasted. Complex carbohydrates like rice, oatmeal, pasta, and fruit are recommended.
It's fine to consume caffeine before exercising in the morning for an energy boost. However, if exercising for longer than 60 minutes while fasting and consuming caffeine, it's advisable to have complex carbohydrates and fruit within 45 minutes to prevent prolonged inflammation.
Deliberate heat exposure, such as using a sauna, can improve the function of the innate immune system and help combat colds and flus. Heat exposure triggers adaptations that lead to increased well-being.
A study compared athletically trained and non-trained men in sauna sessions. The protocol involved 10 sessions with three rounds of 15 minutes each at temperatures between 176 and 210 degrees Fahrenheit. Cool showers were taken between rounds.
Sauna sessions resulted in an increase in cortisol concentration after each session due to the stressor effect of heat.

Heat Exposure and Immune System

1:44:32 - 1:51:30

Sauna sessions result in a statistically significant increase in cortisol concentration after the first and tenth session.
Heat in the sauna acts as a stressor, causing a cortisol response.
Athletes who are trained and used to high heat conditions require a stronger stimulus or more sauna exposure to see increases in innate immune response compared to non-trained individuals.
Regular sauna practice of three rounds of 15 minutes, with breaks in between, can help boost the activity of the innate immune system and potentially keep colds and flus at bay.
It is important to consider safety when using saunas and not harm oneself.
If feeling rundown or experiencing symptoms of a cold or flu, it is advisable to limit stress on the body, rest, and allow the immune system to combat infections.
Some common remedies for colds and flus include taking garlic, echinacea, vitamin C, and zinc.
High doses of vitamin C (6,000 to 8,000 milligrams per day) may delay the onset or shorten the duration of a cold but can cause gastric distress for those not accustomed to high vitamin C intake.

Vitamin C, Zinc, and Natural Remedies

1:51:17 - 1:57:35

Taking high doses of vitamin C (6 to 8 grams) may cause gastric distress for most people.
A recent paper titled "Retraction" retracted a meta-analysis that showed a small improvement in cold and flu outcomes with vitamin C supplementation due to data analysis flaws.
Getting sufficient amounts of vitamin C from food intake or supplements is likely enough, and high doses may not be effective for treating or preventing colds and flus.
Supplementing with 1,000 to 2,000 IU of vitamin D per day is probably safe for most people and can help maintain sufficient levels in the body.
People with low levels of vitamin D are more prone to respiratory tract infections, but deficiencies may not be the sole reason for this correlation.
Sunlight exposure increases vitamin D levels and has other benefits related to immune system function.
Most people can benefit from supplementing with 1,000 to 2,000 IU of vitamin D, but some individuals may require higher doses based on a blood test.
Overdosing on vitamin D can be detrimental if already having sufficiently high levels in the system.
Vitamin D alone is unlikely to fully protect against colds and flus but is beneficial as part of overall nutrition and supplementation.
Supporting the gut microbiome through low sugar fermented foods or probiotics can also support the innate immune system.
Echinacea has limited evidence in preventing colds and flus, but it is generally safe to use.

Zinc and N-acetylcysteine (NAC)

1:57:10 - 2:03:22

Taking Echinacea regularly at high doses can potentially impede the function of the innate immune system, reducing white blood cell count and natural killer cells.
If you want to take Echinacea, it is suggested to reserve it for when you're starting to feel rundown or during winter months when you're prone to cold and flu infections. Avoid taking it continuously throughout the year or for more than four weeks.
Supplementing with zinc has been shown to combat colds and flus, but dosages matter. Taking less than 75 milligrams of zinc won't be effective. You need to take 100 milligrams or more, preferably divided into two doses with a meal.
Older people may benefit from supplementing with zinc, while children under 15 should avoid excessive zinc supplementation. Pregnant women should consult their doctor before taking zinc.
Supplementing with zinc at a dosage of 90 to 100 milligrams per day can lead to three times faster recovery from a cold.
Zinc is low cost, generally safe when taken with food, and can help stave off colds and reduce their duration.
The benefits of zinc have been studied more for treating colds rather than flu specifically, but there's no reason why you wouldn't take zinc if you had the flu. Consult your physician before making any changes to your supplement regimen.
N-acetylcysteine (NAC) is a precursor to glutathione, which is involved in reducing reactive oxygen species and reactive nitrogen species that increase under conditions of infection.
NAC is used as a mucolytic substance in clinics for conditions like cystic fibrosis. It helps loosen mucus in different cavities of the body, including the lungs and nasal passages.
Taking NAC at a dosage of 600 to 900 milligrams

N-acetylcysteine (NAC) and Natural Remedies

2:02:52 - 2:05:44

N-acetylcysteine (NAC) is a powerful mucolytic that can relieve sinus pressure and congestion.
NAC can be used as an alternative to over-the-counter decongestants, which can cause rebound congestion and have potential habit-forming effects.
A 1997 study showed that people who took NAC had a significantly lower probability of contracting influenza.
Some clinicians, including Dr. Schwelt, take NAC as a preventative measure against colds and flus.
NAC increases glutathione levels, which is beneficial for overall health.
N-acetylcysteine is still available over the counter in the US, despite previous attempts to remove it from sales due to unsupported claims.
The recommended dosage of NAC is about 1200 milligrams per day divided into two doses of 600 milligrams each.
It is important to note that more randomized controlled trials on NAC are needed before making definitive conclusions about its effectiveness.
There are other natural remedies and techniques that can be used to manage colds and flus if one chooses not to take NAC.