At the 2016 meeting of the International Scientific Association for Probiotics and Prebiotics, Professors Robert Hutkins (University of Nebraska) and Maria Marco (University of California – Davis) convened a workshop on “Prebiotics and Probiotics in Fermented Foods.” Along with global academic experts invited to the discussion and a representative from the National Dairy Council, Dr. Chris Cifelli, they focused on evidence that fermented foods might contribute to human health.
Why fermented foods? Fermented foods were listed as the 4th biggest food trend for 2016 by Whole Foods. Scientists studying the human microbiome suggest that healthy diets should include fresh fermented foods to transiently bolster the live microbes in your gut. A majority of family physicians advise patients to eat yogurt containing live active cultures for its health benefits.
There are likely hundreds of different fermented foods globally, each with different starting ingredients, processing conditions and fermentation microbes. But how much do we really know about the health benefits of these foods? The evidence for most of these fermented foods such as kimchi, natto, pickles and sauerkraut, with regard to their health benefits is in its infancy. (We know much more about yogurt, since it is the subject of many observational studies and controlled intervention trials.)
Fermented food has benefits beyond those present in the pre-fermented food. Depending on the raw materials and the microbe(s) responsible for the fermentation, the fermentation process can inhibit pathogens, increase vitamin content, produce functional byproducts of growth (peptides and prebiotics), improve digestibility and even detoxify raw foods.
But still emerging for most fermented foods is evidence that foods, perhaps due to the live microbes they contain, may play a role in expanded benefits such as downregulation of inflammation, improved immune response, or in metabolic benefits such as reduced cardiovascular disease or diabetes risk.
However, not all fermented foods contain live microbes when consumed. Sour dough French bread, coffee, wine, and fermented vegetables that are pasteurized such as some sauerkraut, olives and pickles are lacking the rich compliment of microbes responsible for their transformation.
Studying the benefits of fermented foods has challenges. Differentiating if benefits are due to the chemical transformation of the food or to the live microbial content of the food may be difficult to determine. Often fermented foods have an undefined, mixed microbial content, while carefully controlled studies would require a food with a well-defined and quantified microbial composition.
Important to the probiotic field is the fact that scientists make a distinction between fermented foods and probiotics. Not all fermented foods contain probiotics. They MAY. But in order to be a probiotic, a live microbe must be studied and shown to have health benefits. Many fermented foods do not reach that level of evidence. (ISAPP infographic on fermented foods)
It is likely that over time we will better understand the benefits of the wide array of fermented foods that exist. But without fermented foods, people in modern, westernized environments would ingest few live microbes. Feeding your intestinal immune system and your gut with live microbes may be a strategy for health.