Analysis: humans and our non-human ancestors have been eating and evolving alongside fermented foods for a long time

By John Leech, Teagasc

Just how old is the art of fermentation and why should you be doing it too? Egyptians pioneered the fine art of beer brewing and bread leavening at least 4,500 years ago. Ancient Chinese were brewing mead 9,000 years ago according to evidence found in clay pots uncovered in Jiahu, China. While physical evidence from further back is lacking, we can look to evolution for insights into our long history with fermented foods.

From shrews getting drunk on fermented tree nectar and bees making bread to carrion beetles preserving their deceased dinners with yeast, research has proved that animals are no strangers to fermentation. However, humans and African apes are in a class of their own when it comes to fermented foods. As our common ancestor was frugivorous, they would have encountered high levels of alcohol in some of the fruit they gathered. We know our ancestors had evolved to consume fermented fruits as they boasted a keen sense of smell, sensitive to ethanol, which helped locate fallen fruit, and an enzyme that is 40 times more efficient at oxidizing ethanol than other animals.

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From RTÉ lyric fm's Culture File, Irish fermentation movement evangelist, April Danann on the wild yeasts of West Cork

Given that our last common ancestor with African apes was over 10 million years ago, our shared adaptations for fermented foods mean that these traits are at least that old too. The drunken monkey hypothesis (yes, that’s a real thing) suggests that it was our love for ethanol that drove our relationship with fermentation, and indeed, some of our primate cousins have shown a preference for 2-5% alcohol solutions over water. At least three species of primates are known to knock ripe fruit to the ground and return later to eat it, when the alcohol content is higher.

However, a new study suggests that the pre-digestion of food via fermentation is what made fermentation so important to us. As our ancestors left the trees and explored the savannahs, fermentation of tubers opened up an entirely new food resource, according to the study. Fermentation may have been so important, that it, and not fire, was what unlocked the extra nutrients we needed for our brain size to increase.

Now that we know that humans (and our non-human ancestors) have been eating and evolving alongside fermented foods for a long time, how important are fermented foods in our day-to-day lives? It is estimated that up to one third of all food consumed is fermented. This includes lots of products, like coffee, chocolate and alcoholic beverages.

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From RTÉ Lyric FM's Culture File, fermentation guru, Sandor Katz on teaching the world to stop worrying and love the microbe

Let’s backtrack a little bit. If we no longer need fermentation to access nutrients, why would these foods be important? Research in the last two decades has shown that the microbiome is very important to human health. The microbiome is the collection of microbes, bacteria, fungi and viruses mainly, that live on and within the human body.

Our own bodies contain many different microbial ecosystems, from our eyelids to our mouth, from our lungs to our gut. Each site has a unique community of microbes and performs important jobs for us. For instance, the gut microbiome helps us to digest our food, protect us from pathogens, and has been linked to a wide range of chronic diseases including Alzheimer’s, Crohn’s disease, diabetes, cardiovascular health, obesity and depression. It is a very complex ecosystem and figuring out if, how or what is causing a disease in such a diverse ecosystem is not easy.

However, one pattern that has emerged across studies on the microbiome is that diversity is best. The more species in the gut microbiome, generally, the healthier the individual is. By studying large populations of people, from many parts of the globe, we see that populations living a hunter-gatherer like lifestyle in non-industrialised parts of the world have higher microbial diversity than those of us living in the industrialised world.

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From RTÉ Brainstorm, a deep dive into the gut microbiome

In our world (Ireland), we sanitise everything. We pasteurise our food, we sterilize our homes, we take antibiotics when we are sick and we consume processed foods. These changes have been life saving for the most part, reducing our exposure to pathogens and making infectious diseases far less dangerous. However, it has come at a cost, and as a result of a relatively sterile environment, both our food and our living spaces, our industrialised microbiomes are not as diverse as our more traditional neighbours elsewhere on the planet. We also suffer from higher rates of chronic diseases, such as cardiovascular disease, type 2 diabetes and Alzheimer’s, all of which have been linked to the gut microbiome.

So are fermented foods important? In the context of the microbiome, the most interesting foods are the ones that contain live microbes when we eat them. Fermented foods are difficult to study for several reasons, largely because of the variable nature of their own microbiomes. However, evidence in recent years is growing, with studies showing that certain foods such as yoghurt, kimchi, sauerkraut and kefir have positive effects on certain disease outcomes, including type 2 diabetes, cardiovascular health, obesity and depression.

In the context of the microbiome, the most interesting foods are the ones that contain live microbes when we eat them

A study from earlier this year showed for the first time that daily consumption of fermented foods (and quite a few portions daily too) increased our microbiome diversity while lowering inflammation status. Chronic Inflammation is associated with a wide range of chronic illnesses. Fermented foods offer exposure to billions of live microbes daily, microbes that we no longer encounter due to our westernised environment.

More importantly, they come without the risks of infectious diseases, perhaps occupying the perfect position between traditional diversity and modern safety while helping to reduce chronic illnesses. Much more research is needed, but the role of fermented foods in health is becoming clearer by the day.

Dr John Leech is a MASTER research officer at APC Microbiome Ireland SFI Research Centre based at Teagasc


The views expressed here are those of the author and do not represent or reflect the views of RTÉ