Fermentation is all the rage these days, it seems. Whether it’s “gut-healthy” recipes that dominate your social media feed, “live culture” labels that stare back at you in the grocery store aisles or your best friend’s sourdough obsession, this fermentation craze has likely permeated your daily life. From homesteaders to political leaders, eating fermented foods is the hot new thing. But how new is it, really?
Long before influencers began touting “gut-healthy” sourdough bagels, and before Robert F. Kennedy Jr., U.S. secretary of health and human services, began speaking out about his diet consisting heavily of sauerkraut, many different cultures were engaging in fermentation practices. For thousands of years, humans have maintained diets that included fermented foods. Originally evolved to preserve food, fermentation has now become a social craze.
But what exactly is fermentation, and how does it work?
Fermentation is a process in which microbes break down food components to create various compounds — acids and alcohols — and ultimately produce energy. These microbes increase the food’s acidity, which prevents the growth of other microorganisms. This is why fermentation has its origins in food preservation and safety.
The microbes that carry out this process can be either naturally present or intentionally added to promote fermentation. Naturally present microbes carry out what we call wild or spontaneous fermentation. Examples of foods that use this process are sauerkraut and kimchi. Added microbes are used to grow culture-dependent ferments such as sourdough. You can add microbes using a natural or commercial starter culture, or through a process known as “backslopping,” where you add a small amount of previously fermented culture to the mixture. If you’ve ever made sourdough, adding your starter to the dough is considered “backslopping.” The increased accessibility of these starter cultures has sparked a resurgence in at-home fermentation.
When it comes to health benefits, the science is less clear. One major obstacle to research is the inconsistency of microorganisms that exist in any given batch of fermented food.
The health benefits of a given fermented food vary depending on the microorganisms present. So if these microorganisms differ between batches, it’s difficult to prove that there are consistent health benefits.
Probiotic is a term that often is central to discussions of the possible health benefits of fermented food. A probiotic refers to live microorganisms that positively affect an individual’s health when consumed. Scientifically, we tend to refer to a food’s probiotic potential because the formation of probiotic microorganisms largely depends on other properties of the food, such as the fermentation environment.
This isn’t to say there are no benefits to a diet that includes fermented foods. Kefir is a well-researched example. Kefir is a fermented milk drink that can be mildly fizzy. Researchers found that the drink may help eradicate Helicobacter pylori — a bacterium that causes common stomach infections — and help with lactose malabsorption (the failure to break down lactose molecules found in food).
There have been an array of studies examining the probiotic potential of fermented foods. Some have found fermented foods to help with weight management, some have found a reduced risk of cardiovascular disease and type 2 diabetes and others claim alteration of the gut microbiome. One literature review states that “reports have identified a lack of sufficient clinical trials, variation in the different fermented foods being investigated, and inconsistencies among ethnic groups.” Until new scientific studies can fill these knowledge gaps, the benefits of fermentation remain largely mysterious.
