04 September 2017

Fermented Foods

I'm not into food fads. Not at all. But I am intrigued by a recent documentary I heard about fermented foods. Foods transformed by microorganisms are very common: cheese, wine, beer, yoghurt, pickles, soy sauce, etc. But in most of them, the bugs are either dead or we kill em.

Yogurt, sauerkraut, tempeh, blue cheeses, and other foods contain living microorganisms: bacteria and fungi (including yeasts).

Giving rise to the joke.

Q. What is the difference between yogurt and {country X that you wish to ridicule}? 
A. Yogurt has a living culture. 

And the idea is that these bugs take up residence and help make us healthy.

One of my great science heroes is microbiologist Lynn Margulis (d. 2011), one of the great scientists of the 20th Century. Margulis established that the mitochondria which live in all of our cells were once free living bacteria. She emphasised the role of symbiosis in evolution (in contradiction to the fetishisation of competition amongst male biologists). This has been one of the strongest influences on my thinking about the world: the importance of symbiosis, hybridization, communities, and cooperation. We are not only social animals, but in fact, we are colonies of cells, with many different symbionts living in our gut. A colony of colonies.

For many decades the existence of bacteria and fungi living in our gut, as symbionts, not pathogens was scarcely acknowledged. In the last ten years or so it has started to dawn on the world of biology that Margulis was on to something big. These intestinal flora are not passive hitch-hikers. They are actively involved in homoeostasis - the collection of processes by which we maintain our internal milieu at the optimum for life.

We now know, for example, that gut microbes participate in and contribute to our immune system. They are involved in processes that govern blood-sugar. And so on. Our gut is full of symbionts - a mutually beneficial association. Thousands of species of them and in vast numbers (perhaps as many as 100 of their cells for every cell in our body, though this figure has been challenged).

I think most people are probably aware that yoghurt has this reputation for repopulating the gut with healthy bacteria. But now expand that out to every food with living bugs. And keep in mind that the gut contains a community of bugs, all "communicating" and working together. Thousands of species are involved. And it seems the more the merrier.

I'm certainly not conducting a scientific experiment, but as part of an effort to eat healthily, I'm now regularly including sauerkraut in my diet and some soy-based yoghurt. The sauerkraut is a bit of an acquired taste, but tastes can be acquired with repeated exposure (like olives). And actually, sauerkraut is *very* easy to make so I might have a go at it.

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