Fermentation inside us… wait, what???

Fermentation inside our bodies?? Did I read it correctly? 😯😯😯

Yes. You read it right, my friend. Fermentation occurs in our bodies too. I bet, when you hear the word fermentation you imagine this,

or this


But did you know that this process also happens in our body? And that it’s happening almost everyday? In this blog post, I will be discussing two types of fermentation that happen inside our bodies. One is common but the other one is quite uncommon. πŸ€”πŸ§ But I will first discuss the general information on fermentation. Okay, let’s begin.

What is Fermentation?

If you will check the dictionary (πŸ“•πŸ“—πŸ“˜ a must!), fermentation is a chemical process by which molecules such as glucose are broken down anaerobically (meaning, in the absence of oxygen). There are actually different ways to interpret this. It depends on what field you are discussing this (either in a biochemistry or food science point of view). Ahem! Whew! Science 😁. Let me explain things in an easier way.

In biochemistry, fermentation is the extraction of energy from macromolecules in the absence of oxygen. In food science, it is the process where in the chemical activity of a microbe affects the food or beverage in a positive and desirable way in the absence of oxygen. What does it mean and how does it work?

We all know that we need oxygen to survive. Basically, in science, our cells need oxygen to continue the process (it’s called β€œGlycolysis”). But there are also scenarios when oxygen is not available. Our cells cannot just stop from functioning just because oxygen is absent for some time. Hence, other pathways were developed (see how smart and complex our bodies are 😏). So what happens?

Glycolysis in its simplest process flow

Okay.. the figure above is what we call Glycolysis. It is a process happening in all living organisms wherein glucose (the simplest sugar (yes, from the food we eat)) is broken down to produce the Pyruvate guy πŸ‘¨. This pyruvate, in the presence of oxygen, goes to another pathway called Kreb’s Cycle to produce energy (the figure below). This is the reason why eating is important for all living organisms, including us. When we eat, we generate energy. Whenever we feel hungry, we feel we lack the energy to do things.

The Kreb’s Cycle in its super simplest process flow

But the problem is… what if Oxygen is not present? Just like the figure above, what will the Pyruvate guy do now? Where will it go? Okay.. let me be clear first. You do not necessarily need to eat at that moment to generate energy. Remember, it takes time for our food to be digested. During the digestion process, glycolysis, Kreb’s cycle and other important energy-generating processes happen but in the presence of oxygen.

The great thing about our body is that it knows what to do in case of any emergency 🚨. For example, whenever we exercise (just like the runner in the cover photo of this blog), we inhale lesser oxygen. Try running for 10-15 minutes. See whether your breathing changes. We gasp air as much as we can. As a result, we have lesser oxygen inside our body. Now there goes the scenario of our dear friend Pyruvate guy. Where to go? Somewhere where oxygen is not needed. 😌

Fermentation Avenue

So now, our friend just goes to another process called Fermentation. There are different kinds of fermentation depending on the type of organism. For microbes, the ever famous yeasts, Pyruvate is converted to ethanol and carbon dioxide. And yes my friends, these β€œwaste products” are one of the main ingredients of the famous beer 🍻.

And there goes our beer 🍺😁

For humans, fermentation happens during any physical activity just like what I mentioned earlier. Do you notice that whenever we exercise, or simply climb the stairs, we feel pain on our thighs? Yes? That’s fermentation. It is called heterolactic fermentation, a type of fermentation where lactic acid is produced. The pain we feel on our thighs and legs is the result of the accumulation of lactic acid. So the next time you do any physical activity and feel the pain, just say…

Oh my lactic acid!

There you go. Now you have a new scientific and geeky way of saying your thighs and legs hurt. πŸ˜… Also, please remember that even though fermentation happens in our body, we cannot produce other by-products like acetone and butyric acid. But………. some of us can produce ethanol! 😱😱😱

Have you heard of AUTO-BREWERY SYNDROME? 😳😳😳

Auto-Brewery Syndrome (ABS) is also called as Gut Fermentation Syndrome and Endogenous Ethanol Fermentation. It is a condition wherein an individual has elevated serum (blood) ethanol levels as a result of high carbohydrate intake (Cordell et al. 2019). This syndrome was first discovered in Japan in the 1950s to 1970s. But this has become widespread throughout several countries, however, ABS is poorly understood. Perhaps you never heard of this syndrome before.

The life of an individual with ABS πŸ˜”

In this paper published in 2019, Cordell et al. conducted case-control study involving 52 patients known to have a diagnosis of ABS. They found out that individuals with ABS have significantly different health lifestyles, diet and medical history. These individuals consumed less dairy products, less coffee or tea, have a higher aversion to starch, more sensitivity to food and have much higher amounts of yeasts in their gastrointestinal tracts. In fact, they have too much yeasts that these microbes are found in other systems such as integumentary.

The researchers presented important elements for the future ABS research. Much is left unknown about this syndrome, particularly on why these individuals have high level of ethanol. We can perhaps assume that it’s because of the presence of too much yeasts (and yes you may be right, a lot of fermenters present in their bodies 😱). Further studies are needed to confirm this.. but one thing is for sure.. our lifestyle can affect the natural flora in our bodies which may lead to either positive or negative way.

So that’s for today my friends! It’s a very basic explanation on fermentation but I hope you learned something today. I did actually πŸ˜…. Stay safe everyone! Adios, amigos!!!


Cordell BJ, Kanodia A, Miller GK. 2019. Case control research study of Auto-Brewery Syndrome. Glob Adv Health Med 8. Doi: https//doi.org/10.1177/2164956119837566

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