I recently enjoyed a farm-to-table meal in the Malibu hills. We nibbled garden-fresh veggies and berries straight from the bush. After all, what’s a bit of dirt?A lot, apparently. A hypothesis suggests that microbes that co-evolved with us are our ‘old friends’; they protect against a wide spectrum of immune-related disorders. Some of these are present in soil and can be inhaled when out in nature. This might be why spending childhood on a farm is good for our lifelong health. Getting licked by the family dog, having siblings, and eating vegetables are also health-protective. If the veggies are organic—fertilized with manure and compost instead of simple ammonium nitrate—it’s even better. Why? Each of these up our microbial diversity.
Exposure to animals, soil, and environmental microbes clearly impacts the gut microbiome: If the outside world has rich biodiversity, the internal environment will likely reflect greater diversity too.It wasn’t surprising that my dinner mates weren’t germaphobes. Seasoned health writers, we have been ‘exposed’ to the original ‘hygiene hypothesis’ for decades: we know exposure to some microbes is healthy. Turns out, exposure to more may be even better. The human microbiome—in other words, the combination of all the bacteria, archaea, viruses, fungi and worms and other eukaryotes that inhabit the body—are more protective and adaptive when they are diverse.
Diversity and balance in our microbiomes are easier to achieve when our diet and the ecosystem we inhabit are balanced and diverse too. Ecological health is healthy.Although ‘modern’ processed diets play a role in our dwindling gut diversity, it is important to acknowledge that moving away, often literally, from natural environments affects us in detrimental ways. Pediatric gastroenterologist Dr. Eric Benchimol states that children living in rural households experience a protective effect against IBD (irritable bowel diseases like Crohn’s and colitis). The effect is apparent if they live there at 10 years old, but even stronger if they spent their first 5 years there. Conversely, living in airtight, highly germ-free, concrete environments is a risk factor for developing certain diseases. I take a personal interest in this as I was born in a high-rise and live in one now.
We now know that urbanized living may create an increase in cases of fevers and allergies, as well as IBD and autoimmune diseases like type 1 diabetes and multiple sclerosis.These diseases are highest in highly urbanized and industrialized countries like the US and Canada. We also eat a diet too low in fresh plant foods and too high in emulsifiers. As a result, a few bacterial species dominate. Our guts are very different from the diverse microbiomes of people living in less developed places.
Now, no one is suggesting that we were better off before sanitation. But extremes in anything, even hygiene, suggest a looming pendulum swing.Lifestyle factors that create less healthy, less diverse microbiomes include many that come with industrialization:
- antibiotic use, ingestion, or exposure
- foods that lack fiber or use synthetic emulsifiers
- stress, artificial lights, and lifestyles that disrupt circadian rhythms
- pollution, medications, and toxicants
- lack of exposure to green space, animals, and soil