Modern transport, storage and distribution methods have transformed our eating habits, as well as our expectations around the availability and choice of food. Many of us grew up at a time when berries were only available during a short seasonal window – yet now, we expect to walk into any supermarket on any day of the year and find raspberries, strawberries or blueberries waiting for us.
As a frequent buyer of raspberries myself for their numerous benefits, this recently got me thinking about a fascinating essay I came across in The Forest Unseen about deer. When a deer is given food that is out of season, it gets indigestion and can actually die. Deer have a very different digestive system to us, and humans have certainly adapted to some degree – through drying, pickling, fermenting and storing food to see us through the winter months. But eating out of season still has an effect on our health, and I think we underestimate this.
The 2017 Nobel Prize in Medicine was awarded to three scientists for their ground-breaking discoveries on the circadian rhythm – our body’s internal clock – and how this biological rhythm governs everything from sleep patterns and hormone release to blood pressure and digestion. We all have some awareness of these inner rhythms. We’ve all experienced how terrible we feel when they fall out of sync – jet lag is the perfect example, as is that heavy, groggy feeling after a late night, even with a lie-in the next morning.
Eating out of season is a bit like jet lag for your digestion.
Our microbiomes and digestive enzymes don’t stay constant – studies show they shift not only with the time of day, but with the seasons too. In winter, for example, we produce increased levels of amylase, an enzyme present even in saliva, which helps us break down starchy foods like potatoes and grains.
Our bodies are essentially primed for what the season naturally offers. In his book Eat Wheat, Dr Douillard makes the interesting case that for some people, foods like bread may be perfectly fine – but only in winter, when digestive capacity is at its peak, and ideally in a long-fermented form such as sourdough.
Even the soil reflects the season. The microbes in the earth from which our fruit and vegetables grow change throughout the year, and this is most noticeable when we eat organic and local produce – food that connects us to the land and exposes us to beneficial bacteria that genuinely support our health.
There is something to be said for eating what is growing around you, at the time it is meant to be eaten.
References
Douillard, J., Eat Wheat: A Scientific and Clinically-Proven Approach to Safely Bringing Wheat and Dairy Back Into Your Diet (New York: Morgan James Publishing, 2017).
Haskell, D.G., The Forest Unseen: A Year’s Watch in Nature (New York: Viking Penguin, 2012).
