Among the many species that call earth home, there are trillions of microorganisms, many of which are still unknown or undiscovered. Some of the discovered microorganisms are known to be beneficial to humans while some are pathogens causing mild to deadly infections. Being outdoors and in contact with natural elements like mud, air and water (which are rich in microorganisms) can boost one’s immunity, say researchers. That makes it all the more vital that young children engage in outdoor play, not just to develop their physical attributes and fitness, but also their immunity.
Why outdoor play is important
Today, especially in cities, there’s hardly any green space for children to play. But no matter how limited the space is, it is necessary to engage them in physical activities which include sports, free play and outdoor exercises. It can enhance physical fitness, motor skills as well as cognitive and social development.
“Outdoor play helps the brain to rejuvenate and combat exhaustion,” says Dr Yogesh Kumar Gupta, consultant-paediatrics at Fortis Hospital, Bannerghatta, Bengaluru. “It enhances the ability to focus, particularly when surrounded by nature. Research conducted on children with ADHD [attention deficit hyperactivity disorder] showed that taking a 30-minute walk in the park improved their concentration levels compared to being in an artificial setting. Participating in outdoor activities amidst natural surroundings triggers the release of positive hormones such as endorphins and serotonin, which have mood-enhancing effects.”
Outdoor play and immunity
The diverse microorganism present in the natural environment can trigger one’s immune system, shaping immunological defence mechanisms. These processes are highly specific and regulated that help the body fight foreign pathogens.
“Our immune system function is shaped by microorganisms from our environment, from other humans and animals, which is then continuously modified by our diet or medicinal use,” says Dr Reena Jaybhaye, consultant rheumatologist and immunologist at Advanced Arthritis Rheumatism and Autoimmunity Centre, Kharghar, Mumbai. “On exposure to a broad variety of microorganisms, the immune system fine-tunes the balance between the attack and tolerance mechanisms, so that immune responses to self or harmless allergens is avoided.”
A child’s favourite play area would be the sand pit. The mess created reflects how much he or she enjoys the activity.
“There is a concept known as the “old friend hypothesis” (previously called the hygiene hypothesis) which suggests that playing in natural environments exposes us to mud, dust, sand and soil that contain helpful bacteria and microbes which have been present since the dawn of humanity,” adds Dr Gupta. “These microorganisms inhabit our skin and help to enhance our immune system by triggering certain responses that improve our overall immunity.”
Role of lymph in immunity
While playing in open playgrounds/parks, the movement involved is greater than while playing in a confined space, say, at home. This increases the lymph flow in the lymphatic system, which is closely linked to our immune system, since it contains specialised cells that assist us in combating infections.
“A consistent flow of lymph is necessary for its effective operation, which can be maintained through exercise and movement,” says Dr Gupta. “Exercise also encourages the secretion of specific hormones and factors that facilitate the movement of T cells [type of immune cells that help fight infections] into circulation.”
Vitamin D increases immune functions
Outdoor play exposes the child to sunlight, which aids in the production of Vitamin D. The ‘sunshine vitamin’ plays important roles in certain immune responses. One of the major cells which regulate an effective response to pathogens are the CD4+ T cells. “Vitamin D plays a crucial role in regulating CD4+ T-cell responses. Additionally, a deficiency of vitamin D has been linked to hypertension and depressive disorders,” adds Dr Gupta.
It is important to note that the benefits of spending time outdoors are not just confined to children. Adults should take time out for exercise, not just in gyms or indoor facilities.
“The hygiene hypothesis suggests that individuals who work outdoors, engage in manual labour or are exposed to nature (including dirt and mud) have stronger immune systems than those who are shielded from infection,” explains Dr Gupta. “This phenomenon is evident even in chronic complications such as asthma, Crohn’s disease and autoimmune disorders. These helpful bacteria are ubiquitous in the environment and assist in stimulating both respiratory and gut immunity, thereby contributing to the development of a healthier immune system.”
Takeaways
- The helpful bacteria or microorganisms present in the environment assist in stimulating both respiratory and gut immunity, thereby contributing to the development of a healthier immune system in children.
- Playing outdoors also increases lymph flow in the lymphatic system, which is closely linked to the immune system as it contains specialised cells that assist us in combating infections.
- An increased production of Vitamin D, aided by exposure to sunlight, helps in certain immunological reactions.
