ICN 2017, Buenos Aires, Argentina

What are the health benefits of fermented dairy foods?

Yogurt-health-fermented foods

The 5th Yogurt Summit took place on October 18th, 2017 in Buenos Aires, Argentina. This fifth edition attracted a wide international audience with attendees from all over the world. This unique community of scientists came together to discuss the importance of fermented foods in global health. Robert Hutkins (University of Nebraska, USA) explored the interactions between ingested microorganisms and the gut microbiota, and the way exogenous microorganisms can change the gut environment.

For many years, humans have known that bacteria and other microorganisms are capable of transforming food substrates, making them both tasty and nutritious. More and more, chefs and other food makers are putting bacteria to work to produce fermented foods and the result is delicious. Apart from flavor, though, are there other reasons to seek out fermented foods? Scientists around the world are trying to answer this question by studying the possible health benefits of consuming live cultures.

What are fermented foods?

Fermentation is the process of deriving energy from the oxidation of organic substrates such as glucose, where the electron acceptor is an organic compound. Therefore, a food-friendly definition of fermented foods could be: the conversion of raw foods into fermented foods by microorganisms. Why have fermented foods been so popular for 10,000 years? In part, this is because products like fresh yogurt, aged cheese, and spicy kimchi have aromas and flavors unlike any other foods. There is also, of course, the intoxicating appeal of a fine wine, craft beer, or single malt scotch. Another reason for the popularity of fermented foods is the health benefits associated with many of these products. Wine, chocolate, and coffee, for example, are rich in natural antioxidants that promote heart health and fight disease. However, for many consumers, it’s the live bacteria that matters most. That’s because many of the bacteria found in fermented foods are associated with gut health and other benefits.

What are the health benefits of fermented foods?

Hutkins listed many potential reasons to add them to your diet. For example, epidemiological studies have shown that yogurt consumption is generally associated with reduced risks of type 2 diabetes (T2D), metabolic syndrome, and heart disease, and improved weight management. Although these products are good sources of protein, calcium, and other nutrients, the live microorganisms present in these products are now considered responsible for many of these health benefits. Included are the yogurt starter culture organisms, Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus, as well as strains of Bifidobacterium and Lactobacillus added specifically for their probiotic properties. One study found that fermented milk eased symptoms of irritable bowel syndrome, possibly due to beneficial changes in gut bacteria that such foods bring. Other fermented foods appear to relieve the diarrhea that people often suffer from after taking antibiotics. Hutkins also presented the latest areas of research on the microbiota-gut-brain axis, suggesting that probiotics and prebiotics could influence behavior.

How do we explain these healthy effects of fermented foods?

According to Hutkins, the transformation or change in the food brought about by microorganisms can explain the effects of fermented foods. More specifically, it’s probably the microorganisms that reach the gut and produce beneficial end products that are involved in these healthy effects. Actually, there is increasing evidence that food-borne bacteria contained in fermented products are biologically active in the colon… And such activities might be part of the mechanisms underlying beneficial effects. Several studies support the concept that fermentation can be leveraged to re-engineer the gut microbiome and improve dysbiosis-related diseases. One major topic of research for establishing a role for these organisms is the well-known phenomenon of colonization resistance.  The healthy human gastrointestinal tract contains a diverse, complex and stable microbiota that is resistant to colonization by exogenous microorganisms. These could include pathogenic organisms as well as bifidobacteria and lactobacilli that are added to fermented milk products as probiotics. However, recent research reported that regular consumption of yogurt appeared to increase the numbers of Lactobacilli in the gut. The microbial diversity in the gut also appears to slightly increase with yogurt consumption in some subjects. These findings suggest that bacterial species and functional genes absent in the gut microbiome of individual humans can be reestablished, providing opportunities for precise and personalized microbiome reconstitution. Another ongoing area of investigation for food scientists is to find out whether the method of delivering live microorganisms, otherwise known as the ‘food matrix’, matters for how the bacteria survive—and for how they contribute to health. The matrix can affect viability and survival of the organisms, such that some foods may be more-or-less hospitable than others,” explains Hutkins.

Don’t get confused between all fermented foods!

In his conclusions, Hutkins reminds us that not all fermented foods contain live organisms. Beer and wine, for example, undergo steps that remove the organisms (like yeast that allows fermentation). Other fermented foods are heat-treated and the organisms are inactivated. Bread is baked and sauerkraut is often canned. So, while these foods may be nutritious, they do not have probiotic activity, unlike yogurt, kefir or any other fermented dairy foods with added probiotics. We must also be mindful of the fact that a lot of fermented foods do not necessarily have any probiotic functions. By definition, probiotics must ‘confer a health benefit’. That means the probiotic must have been characterized and have clinical evidence of a health benefit. Cultures are not probiotic unless they have met this requirement. Therefore not all fermented foods can be qualified as probiotic, and not all probiotics take the form of fermented foods.