It wasn’t so long ago that my parents would “force” us to go play outside. And it seemed to be the norm—at least in my neighborhood—because before long, a dozen kids would be running around, exploring, and playing together. What used to be second nature now feels a bit rare, as both kids and adults spend most of their time indoors. ¹,² However, summer’s here, and it’s the perfect time to reconnect with the outdoors—and soak in all the benefits that come with it. Whole-Body Health: From Physical to Mental Well-Being. Why go outside, really? Because it’s good for you—plain and simple. Nature has been shown to support both physical and mental health. For instance, green spaces like parks and forests naturally encourage physical activity, which helps improve motor skills, build muscle, support heart health, and maintain a healthy weight. ³,⁴ Spending time in nature also helps reduce stress and anxiety. According to the stress reduction theory, our brains are wired to feel calm and safe when surrounded by natural environments—because we evolved in them. Several studies back this up, showing that spending time in nature lowers levels of cortisol, the stress hormone. ³,⁴ A Dose of Sunshine = A Boost of Vitamin D Of course, we can’t talk about the outdoors without mentioning the sun—our main natural source of vitamin D. And that’s a big deal, especially since many people living in the Northern Hemisphere have low levels of this essential nutrient. When our skin is exposed to UVB rays—in moderation, of course—it produces vitamin D. This vitamin helps build and maintain strong bones, cartilage, and teeth. It also plays a key role in activating our immune system, helping regulate genes involved in fighting infections. 5 Bonus: Getting Outside Might Even Support Your Microbiome Our microbiome—the trillions of microorganisms living on and in us, especially in our gut and on our skin—plays a vital role in our health. And while research is still evolving, one thing is clear: a healthy microbiome is a diverse one. So how can the great outdoors help with that? One lesser-known benefit of vitamin D is its impact on gut health. Evidence is growing that it helps balance the gut environment. It does this by strengthening the intestinal barrier—essentially helping “seal” the spaces between gut cells to prevent bacteria and toxins from sneaking through. ⁶ Some studies have shown that vitamin D supplementation can influence the composition of the gut microbiome. ⁷,⁸ In fact, one pilot study found that repeated exposure to UVB light increased microbial diversity in the guts of healthy women with vitamin D deficiency. ⁹ These findings suggest that maintaining optimal vitamin D levels may help support a more balanced, diverse gut microbiome—possibly by regulating the immune system and maintaining the gut’s protective barrier. Natural Spaces—Forests, Soil, Vegetation, Bodies of Water—Real Microbial Goldmines. Forests, soil, plants, water—natural environments are teeming with microorganisms that can enrich our own microbial communities. According to the biodiversity hypothesis, the reduced microbial diversity in today’s highly urbanized and sanitized environments may be contributing to rising rates of chronic, allergic, and autoimmune diseases. On the flip side, exposure to diverse natural ecosystems may help promote a healthier, more varied microbiome—leading to better overall health. ¹⁰ One intervention study in daycare centers explored this idea. Researchers compared three types of settings: nature-oriented daycares, conventional urban daycares, and urban daycares with nature-enriched playgrounds (think forest soil and moss added to the yard). After just 28 days, children in the nature-enriched group had more diverse skin microbiomes—closer to those in nature-based programs. Gut microbiomes and immune responses also shifted toward a healthier, more anti-inflammatory state. ¹¹ In a similar study, preschoolers who spent 10 weeks doing outdoor activities showed reduced stress—particularly less frequent anger—and better serotonin balance in the gut, along with microbiome changes. ¹² Another large-scale study of over 9,500 people across 34 countries found that greener living environments were associated with richer microbial diversity on the skin and in the gut, including higher levels of beneficial bacteria like Lactobacillus and Bifidobacterium. ¹³ While still limited, current research suggests that exposure to nature can positively modulate the diversity of our gut and skin microbiota. Bottom line? Go outside—your body (and microbiome) will thank you. Whether it’s just for fun, to feel better physically or mentally, or to give your microbiome a gentle boost, there’s never been a better time to get outside. So, enjoy the fresh air this summer… and maybe keep up the habit all year long! References: 1.Environment and Climate Change Canada. 2022. Indoor air quality 2.Cision. 2017. Survey Reveals Today’s Kids Spend Much Less Time Outdoors Than Their Parents Did - and Societal Pressure Regarding Children’s Activities Isn’t Helping. Nature Valley Survey. 3.Jimenez, M.P. et al. 2021. Associations between nature exposure and health: A review of the evidence. Int J Environ Res Public Health. 18(9):4790. 4.Twohig-Bennett, C. & Jones, A. 2018. The health benefits of the great outdoors: A systematic review and meta-analysis of greenspace exposure and health outcomes. Environ Res. 166:628-637. 5.Brown, G. et al. 2024. Vitamin D and immune system. Adv Food Nutr Res. 109:1-41. 6.Wang, J. et al. 2024. Contemporary Perspectives on the Role of Vitamin D in Enhancing Gut Health and Its Implications for Preventing and Managing Intestinal Diseases. Nutrients. 2024. 16(14):2352. 7.Bellerba, F. 2021. The Association between Vitamin D and Gut Microbiota: A Systematic Review of Human Studies. Nutrients. 13(10):3378. 8.Singh, P. 2020. The potential role of vitamin D supplementation as a gut microbiota modifier in healthy individuals. Sci Rep 10: 21641. 9. Bosman, E.S. 2019. Skin Exposure to Narrow Band Ultraviolet (UVB) Light Modulates the Human Intestinal Microbiome. Front Microbiol. 10:2410 10.Haahtela T. A. 2019. biodiversity hypothesis. Allergy. 74(8):1445-1456. 11.Roslund, M.I., et al. 2020. Biodiversity intervention enhances immune regulation and health-associated commensal microbiota among daycare children. Sci Adv. 6(42):eaba2578. 12.Sobko, T., et al. 2020. Impact of outdoor nature-related activities on gut microbiota, fecal serotonin, and perceived stress in preschool children: the Play&Grow randomized controlled trial. Sci Rep 10, 21993. 13.Zhang, Y.D., et al. 2023. Association between Residential Greenness and Human Microbiota: Evidence from Multiple Countries. 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