As the old saying goes, "He who returns from a journey is not the same as he who left." Travel broadens your horizons, introduces you to new cultures, and provides a break from everyday routines. 

However, exploring the world also changes you on a cellular level – specifically through your immune system. Whether you're navigating busy airports, adjusting to different time zones, or simply trying new foods, your immune system is constantly adapting to these changes.

To avoid getting sick on your trip, you need to understand how travel affects your immune defenses and take proactive steps to make the most of your adventures. Here's what to know.

The challenges of an immune system on-the-go

Traveling can take a toll on your immune system in several ways:

  • Poor sleep. Long hours on the road, jet lag, uncomfortable hotel beds – it's not always easy to sleep well on a trip. But sleep disruptions can impair the function of T-cells, which are crucial for the body's immune response.1 Without adequate sleep, your body also produces fewer cytokines, a type of protein that targets infection and inflammation.2,3 This helps explain why people who regularly get less than 7 hours of sleep each night are more likely to have upper respiratory infections.2,4
  • Stress. Even the most well-planned vacations have stressors, from lost luggage to being separated from a pet. When you're stressed, your body produces cortisol, a hormone that, in high levels, can suppress the immune system and make you more likely to get sick.5,6
  • Meeting unfamiliar germs. Traveling exposes you to a wide range of new pathogens, from unfamiliar bacteria in local food and water to viruses circulating in crowded places like airports and public transport. Your immune system may not be prepared to handle these foreign invaders, increasing the risk of infection.
  • Changes to diet and hygiene habits. More than 70 percent of your immune system is in your gut, which means that unfamiliar cuisines that upset your digestive system can also make you more susceptible to illness.7 Picking up new bacteria – say, from gas-station restrooms or street food vendors – can wreak havoc on your gut microbiome, which plays a crucial role in immune function.7
  • Lower oxygen and air pressure on airplanes. Even short flights expose you to lower oxygen levels and reduced air pressure, which can stress your body and immune system.8 The cabin air in airplanes is also recirculated, increasing the likelihood of pathogen transmission among passengers – especially on crowded flights.9
  • Dehydration. There's a reason flight attendants wheel out the drink cart shortly after takeoff: Dehydration is a common issue during travel, especially on long flights and car rides, or in hot climates. It can weaken your immune system by affecting the production of saliva and mucus, both of which contain antimicrobial agents that protect against infection.10 Dehydration also impairs the function of your lymphatic system, which is crucial for transporting immune cells throughout your body.11

Plot twist: Travel can also boost your immune system

Think travel is only about catching colds? Think again – the right getaway could also be the ticket to boosting your immune system.

Sometimes new microbes from unfamiliar environments can stimulate your immune system, encouraging it to adapt and strengthen. This process, known as microbial diversity exposure, helps to build a more robust immune response.12 It's like getting a vaccine, which works by exposing the immune system to a controlled amount of a pathogen to build immunity.

Plus, a well-earned vacation can offer plenty of physical and mental health benefits. The immune system responds to exercise – like wandering city streets or hiking in nature – by producing more anti-inflammatory cells.13 Exploring new places and experiencing different cultures can also reduce stress, anxiety, and depression, all of which are known to weaken the immune system.5

Travel hacks for a strong immune system

Your travel choices can mean the difference between an immune-boosting or immune-busting trip, so prioritize your health along the way. Here are some practical tips:

  • Commit to a pre-trip immunity boost. Get your immune system in top shape before you travel by exercising, eating well, and managing your stress. Supplements like Echinacea, vitamin C, and vitamin D can help support your immune function.*14 
  • Pack a water bottle. Keeping your body well-hydrated helps maintain a robust immune system, ready to fend off any potential threats. Drink plenty of water, avoid excessive caffeine and alcohol, and eat hydrating foods like cucumbers, melons, tomatoes, and broccoli (all of which are full of immune-boosting vitamins as well). 
  • Fly smart. Grab some juice when the drink cart rolls up and move around during the flight to boost circulation. Use nasal sprays or humidifiers to keep your mucous membranes moist – they're your first line of defense against airborne pathogens. If jet lag has you down, try taking melatonin to reset your circadian rhythm.*15
  • Stay nourished. Try to maintain a balanced diet rich in fruits and vegetables. Remember, it's okay to have treats while traveling – that's what vacations are for! – but aim for balance and moderation.
  • Keep it fresh. Practice good hygiene, like frequent hand washing and using hand sanitizers, and be cautious about what you eat and drink. Staying vigilant about these practices can help bolster your immune defenses against unfamiliar threats. 

As you set off on your next journey, remember that travel is not just about exploring new places – it's also a journey for your health. Pack wisely, nurture your immune system with healthy habits, and savor every moment. Your adventure awaits.

A word from Thorne

Thorne offers an array of immune supportive supplements.* If you tend to get sick when you travel, consider starting to give your immune function a boost prior to walking out the door, then throw some support in your suitcase. 

And remember – 70 percent of your immune system is in your gut. For more information on keeping your gut healthy while traveling, check out this recent Mayo Clinic article here on Take 5 Daily. 

And finally, Thorne’s Travel Bundle contains melatonin for sleep support, a formula to support electrolyte balance, and a probiotic for gut immune support.*

References

  1. Martínez-Albert E, Lutz ND, Hübener R, et al. Sleep promotes T-cell migration towards CCL19 via growth hormone and prolactin signaling in humans. Brain Behav Immun. 2024;118:69-77.
  2. Besedovsky L, Lange T, Haack M. The sleep-immune crosstalk in health and disease. Physiol Rev. 2019;99(3):1325-1380.
  3. Desai D, Momin A, Hirpara P, et al. Exploring the role of circadian rhythms in sleep and recovery: A review article. Cureus. 2024;16(6):e61568.
  4. Robinson CH, Albury C, McCartney D, et al. The relationship between duration and quality of sleep and upper respiratory tract infections: a systematic review. Fam Pract. 2021;38(6):802-810.
  5. Shah K, Kumari R, Jain M. Unveiling stress markers: a systematic review investigating psychological stress biomarkers. Dev Psychobiol. 2024;66(5):e22490. 
  6. Noushad S, Ahmed S, Ansari B, et al. Physiological biomarkers of chronic stress: a systematic review. Int J Health Sci. 2021;15(5):46-59. 
  7. Wiertsema SP, van Bergenhenegouwen J, Garssen J, et al. The interplay between the gut microbiome and the immune system in the context of infectious diseases throughout life and the role of nutrition in optimizing treatment strategies. Nutrients. 2021;13(3):886.
  8. Hinkelbein J, Jansen S, Iovino I, et al. Thirty minutes of hypobaric hypoxia provokes alterations of immune response, haemostasis, and metabolism proteins in human serum. Int J Mol Sci. 2017;18(9):1882. 
  9. Herbig B, Norrefeldt V, Mayer F, et al. Effects of increased recirculation air rate and aircraft cabin occupancy on passengers' health and well-being – results from a randomized controlled trial. Environ Res. 2023;216(Pt 4):114770.
  10. Sheng YH, Hasnain SZ. Mucus and mucins: the underappreciated host defence system. Front Cell Infect Microbiol. 2022;12:856962.
  11. Lacey J, Corbett J, Forni L, et al. A multidisciplinary consensus on dehydration: definitions, diagnostic methods and clinical implications. Ann Med. 2019;51(3-4):232-251.
  12. Zheng D, Liwinski T, Elinav E. Interaction between microbiota and immunity in health and disease. Cell Res. 2020;30(6):492-506.
  13. Nieman DC, Wentz LM. The compelling link between physical activity and the body's defense system. J Sport Health Sci. 2019;8(3):201-217.
  14. Crawford C, Brown LL, Costello RB, et al. Select dietary supplement ingredients for preserving and protecting the immune system in healthy individuals: a systematic review. Nutrients. 2022;14(21):4604.
  15. Complementary health approaches for travelers. National Center for Complementary and Integrative Health. https://www.nccih.nih.gov/health/complementary-health-approaches-for-travelers. [Accessed July 10, 2024.]