I've long recognised that digging in the garden makes me feel good. No matter how tired or stressed I am, a few minutes with my hands in the earth and my mood improves. I had assumed the boost was due to being outdoors and active and doing something I love. But it may actually be tiny micro-organisms causing my good mood.
Unintentionally picking up a microbe called Mycobacterium vaccae can make us feel good. Scientific trials suggest this soil dwelling bacteria can decrease anxiety, improve our ability to learn and may work as an antidepressant.
We pick up this serotonin boosting bug by playing in the dirt or eating it with our fresh fruit and vegetables.
Mycobacterium vaccae is one of 10,000 or so species of microbes that may call your body home. And many of them are just as valuable, or more so. Some produce inflammation-fighting chemicals and others help regulate your immune response. Microbes also help you digest particular foods and assimilate nutrients.
We evolved with microbes. And it’s starting to look like we don’t function properly without them.
Scientists are only now starting to discover just how important microbes are for our health. Rob Knight in his book Follow your gut: the enormous impact of tiny microbes suggests that "microbes are not only more numerous than we thought ... they’re also more important than we ever imagined, playing a role in nearly all aspects of our health, even in our personality".
Rob writes that: "You are made up of about ten trillion human cells – but there are about a hundred trillion microbial cells in and on your body. Which means: you are mostly not you ... We are not individuals; we are ecosystems."
But there’s a problem. We’re destroying our useful microbiota by being stressed, overusing antibiotics, using antibacterial cleaning products, and indulging in processed food, artificial sweeteners, and sugar.
We also have fewer opportunities to pick up beneficial microbes. We’re playing or working in the dirt less. We try to sterilise our homes. And industrial-scale farming and widespread use of pesticides has depleted soil microbe diversity – reducing the chances of us picking up a diversity of good microbes from the foods we eat.
There are suggestions from researchers that our modern-day disconnection from soil microbes could help to explain the rapidly increasing frequency of food intolerances, allergies, asthma and diseases involving inflammation, such as diabetes, arthritis, and even depression.
So what can you do to boost your good microbes?
1. Play in the dirt. Dig in the garden. Don’t be afraid to get your hands dirty.
2. Grow your own food organically. Gobble a few carrots straight from the soil. You’ll likely pick up more beneficial bugs from a fresh barely cleaned homegrown carrot than from popping an expensive probiotic pill.
3. Buy fruit and vegetables that have been grown on small organic or family farms. You are more likely to pick up a greater diversity of beneficial microbes from fruits and vegetables grown without pesticides.
5. Repeat. The beneficial bugs we gain from playing in the dirt or eating homegrown food wear off after a while. A couple of weeks after contact with Mycobacterium vaccae – and it (and its feel-good feeling) is gone.
I like the idea of playing in the dirt being good for us.
It seems mud loving children know what's good for them.
Originally published in the Newcastle Herald Monday 18th May 2015.