I ferment, therefore I am

An expert panel of global scientists meet and discuss fermentation at its finest

Hello again fermentationists,

Today I have the pleasure of summarizing a review article published by the esteemed scientific journal Nature and co-authored by my graduate studies advisor Dr. Maria Marco. This review article focuses on the definition of fermented foods, the role of fermented foods in the human diet, and recommendations for the inclusion of fermented foods in government-approved dietary guidelines. This paper is especially interesting, because it actually evolves from discussions and presentations from the world’s leading scientific experts on fermentation that were given at the annual meeting of the International Scientific Association for Probiotics and Prebiotics in 2019 in Antwerp Belgium. I have attended this meeting in years past, and I loved getting to know some of the authors listed on this paper, as well as the passion these experts have for advancing the science of fermented foods and drinks. 

First off, let us work with some definitions to get everyone on the same page. For these I am directly citing the ISAPP website and I encourage you to explore this page as needed for any lingering questions. 

Prebiotics: a substrate that is selectively utilized (eaten) by host microorganisms conferring a health benefit. Often, prebiotics are types of soluble fiber that the human body cannot digest, which serve as ‘food’ for beneficial microbes that already live in your small and large intestine or elsewhere in your body.

Probiotics: live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. The word probiotic is often used incorrectly to refer to any live microorganisms—but ISAPP scientists have agreed that the term should be restricted to microorganisms that have been empirically tested and shown to provide a health benefit.

Fermented foods and beverages: foods made through desired microbial growth and enzymatic conversions of food components.

Hello fermentation, my old friend

It is without a doubt that humans have only survived on Earth this long because of fermentation. The very first fermentations probably occurred quite accidentally, however they must have eventually been promoted, as we have evidence of fermentation vessels dating back thousands of years. The main reason fermentation initially flourished was because it was seen as a method to preserve foods during times of famine. Fermentation associated microorganisms can secrete various organic acids, and other small molecules which directly inhibit the growth of food-spoilage microorganisms. The fermentation process has allowed for humans to provide a stable source of safe food and drink for millennia. This is especially true for sources of liquid that otherwise wouldn’t have been potable. The ISAPP researchers specifically singled out the fermentation of dairy as the prime example of how humans learned to preserve foods for longer time periods and how the savory tastes created by fermentation also promoted fermenting microorganisms to stick by our side.

From the paper--

“… the human attraction to flavour-potentiating nucleotides and amino acids that are enriched in certain fermented foods, such as soy sauce and miso, could have evolved as a result of the safety and nutritional benefits of those foods in early human diets”

This sentence is essentially saying that because fermented foods have health benefits and are safe to eat, humans have evolved to enjoy their taste, which to be honest blows my mind.

Fermentation defined

The authors here reiterate the definition of fermented foods as a biological process that is desirable, and contrast that to food spoilage which is still a biological process, but that occurs through undesirable microorganism contamination. 

A general list of fermented foods and drinks is given in Box 1 which includes familiar fermented favorites like yoghurt and kefir, but also (depending on where you are from) exotic food and drink like boza and bushera. It is important here to note that not all fermented foods contain live microorganisms at the time of consumption, and that not all fermented foods have health benefits. In particular, we know alcohol is produced through fermentation, and we also know excessive alcohol consumption is associated with severe health consequences. 

If you go to your local grocer you are destined to see the word probiotic scrawled across any number of products. But as the authors point out here, you should not be fooled into automatically thinking that these products have any proven health benefits. 

From the paper--

“These declarations might reflect efforts by manufacturers to communicate to consumers that living, health-promoting microorganisms are present in the product. However, the term ‘probiotic’ should only be used when there is a demonstrated health benefit conferred by well-defined and characterized live microorganisms. The health benefit must, at least in part, be due to the live microorganisms and must extend beyond any nutritional benefit of the food matrix.”

This means that due to current United States marketing guidelines there is nothing to stop businesses from using the word probiotic, even when there is no evidence for the health benefits the term denotes. It is much harder to get away with using the word probiotic in Europe.

Which bugs are doing all the heavy lifting in fermentations anyways?

Due to the broad definition of fermented foods and the variety of food sources that can be fermented, it should come as no surprise that there are a whole host of fungi and bacteria which actually do the fermenting. By far the most common bacteria involved in fermentation are the lactic acid bacteria, so named due to the production of lactic acid as a by-product of their metabolism. Other less common bacteria involved include acetic acid producing bacteria and members of the species Bacillus. Bread and alcoholic fermentation are predominantly carried out by yeast which are members of the species Saccharomyces. Some other fungi you may be aware of are members of the species Penicillium which are responsible for the blue stank in bleu cheese. 

The fascinating thing with most spontaneous fermentations (that is fermentations where no microbes were added purposefully by humans) is that a complex ecosystem of microbes may develop with multiple species of bacteria and fungi partaking in a give and take economy. Some bacteria may produce an enzyme that can cut a certain sugar and then parts of that sugar are shared with a different species, or a fungus may be able to break down the hard cell walls of a plant material to give access to other microbes to the goodies inside. These types of ecosystems within foods are now being explored as model experiments through cutting edge nucleic acid sequencing technologies, so that we can better understand how our foods actually get fermented. In the end though, certain bacteria seem to be able to win out and dominate a particular fermentation, especially members of the species Lactiplantibacillus (formerly Lactobacillus plantarum) when involved in vegetable fermentations. 

Healthy gut, healthy life

There is a growing body of evidence suggesting fermented foods have direct benefits to human health. The main winner in this arena is yoghurt or other fermented dairy which has been clinically tested (clinically meaning humans were given a fermented food or a placebo and then researchers measured a certain aspect of health), to be “associated with reductions in adiposity factors (body mass index, waist circumference), type 2 diabetes mellitus and cardiovascular disease”. In other words, we do know for a fact there are at least some benefits from including fermented dairy products into our diets. There is overall less evidence for other fermented foods like kimchi, sauerkraut etc, but more researchers are itching to put these foods on the clinical trial map as well. It should be noted that these studies have a long way to go and there are inherent challenges with creating a placebo of a fermented food (think of eating a cucumber versus eating a pickle) and making sure humans in these trials follow the rules, but we are heading in the right direction.

But now you are asking, Dustin how are these fermented foods impacting my health? Well, the authors do a wonderful job of explaining the potential benefits and provide a nice infographic as well. 

To paraphrase: Health benefits of fermented foods include the transformation of raw ingredients to synthesize higher nutritional value through the production of bioavailable organic acids, vitamins, and other molecules that are not present in the unfermented base food. There is also evidence that fermentation microorganisms lead to detoxification of some undesirable  molecules naturally present in foods like phytic acid. Besides this, the microorganisms present in the fermented food themselves have the potential to interact with the resident intestinal microbiota and your own intestinal cells to promote health. The main route of direct benefits from the microorganisms may be through the interaction with the intestinal immune system, where these bugs can lead to a more accepting immune response that limits inflammation and in turn leads to overall better health. 

One astounding excerpt from the article states that as much as 70% of your immune system is actually located in the gut. Think of your intestine as a gatekeeping paramilitary force that yearns to destroy any threats, both foreign and domestic. While this is a great thing usually, sometimes this overzealous crew can go overboard and do damage to your own cells. Having the microbes that are inherent to fermented foods, (think lactic acid bacteria especially), in the gut can actually signal to your immune system to stand down and only attack things that warrant a response. In this regard, clinical studies are yet to prove anything definitive, but there are some interesting associative evidence showing a correlation between higher fermented food intake and lower risk of allergy and asthma development in children.

Dietary recommendations from the government, not in my colon!

There is a sad truth known by many in the United States that the food pyramid created so long ago was actually just a marketing tool to get people to eat more corn and other cereal grains. Why? Because the whole middle of the country is basically an endless farm. Now, don’t get me wrong corn is great and all, and can actually be a part of a healthy diet, but we should also look into the science of diet and what makes up a whole balanced meal. One aspect of dietary guidelines that is almost completely absent in most countries is fermented foods. In fact, as the authors note, the only country to actually encourage fermented foods as part of dietary guidelines is India and only during pregnancy. There is some brief mention of yoghurt and kefir in USA and Canadian dietary guidelines, but only under the section of dairy intake. Overall there should be a greater emphasis on supplying consumers with current scientific evidence on potential benefits of certain fermented foods and ways to incorporate them into a balanced diet. 

From the previous paragraphs I have tried to convince you that there is at least one fermented food or drink that you can add to your diet that will predictably lead to an improvement in some aspect of your health. This is not an anecdotal story about how my aunty Virginia ate some Kimchi once and lost 5 pounds. This is coming from real data backed scientific studies with real humans. Therefore, the ISAPP researchers conclude that “Owing to the high levels of live, potentially health-promoting microorganisms in many fermented foods, these foods have been advocated for inclusion in dietary recommendations”. Of course being careful and diligent researchers, they also state there is an urgent need to continue profiling the distinct nutritional value of fermented foods, what type of microbes are present and how they interact with the human body to make the case for consumers and governments to finally jump on board the fermentation train. 

Conclusion

All in all, fermented foods and drinks have and always will be an important part of the human experience. I for one wouldn’t have it any other way, and stand in awe of the intricate relationship we have built with the unseen microscopic world. There are still many aspects of fermentation science that need to be demystified, but we have the tools, we have some of the brightest minds on the planet using them, and we can all surely benefit from encouraging a little desirable microbial growth of our own. 

Thanks and see you next time, 

Disclaimer: The opinions expressed in my articles are my own and do not reflect those held by the authors or publishers of the articles discussed herein. I do not claim ownership of any of the data, or images presented.