Long before probiotics became the darlings of the microbial world, cultures throughout history and across the globe were celebrating fermented foods. Born as a preservation method and used for millennia, the Neolithic tradition of fermentation has sparked modern use of and interest in probiotic microbes.
Most research focuses on fermented dairy products. However, vegetables such as cabbages, carrots, garlic, soybeans, olives, cucumbers, onions, turnips, radishes, cauliflower and peppers, in addition to fruits such as lemons or berries, offer novel flavors and textures—partly explaining why home fermentation, and particularly lactic acid fermentation, is becoming an increasingly popular trend. Whether keepers of culinary tradition, those interested in potential health benefits or folks who simply enjoy trying new foods, fermentation enthusiasts are bringing new life to this ancient practice. Lactic acid fermentation, or lacto-fermentation, is among the most common methods and one of the easiest to experiment with at home. It is an anaerobic process whereby lactic acid bacteria, mainly Lactobacillus species, convert sugar into lactic acid, which acts as a preservative. Salt plays a pivotal role in traditional fermentation by creating conditions that favor the bacteria, preventing the growth of pathogenic microorganisms, pulling water and nutrients from the substrate and adding flavor.
The earliest record of fermentation dates back as far as 6000 B.C. in the Fertile Crescent—and nearly every civilization since has included at least one fermented food in its culinary heritage. From Korean kimchi and Indian chutneys to the ubiquitous sauerkraut, yogurt and cheese, global cultures have crafted unique flavors and traditions around fermentation.
In some cases, fermentation is a critical component to food safety beyond preservation. In West African countries, garri is an important food source. It is made from the root vegetable cassava, which contains natural cyanides and, if not properly fermented, can be poisonous. Other foods, such as the Tanzanian fermented gruel togwa, have been found to protect against foodborne illnesses in regions that have poor sanitation.
Asian civilizations in particular have a history of fermenting a wide variety of foods—Japanese natto (soybeans), Vietnamese mám (seafood), Chinese douchi (black beans), Lao pa daek (fish sauce), Korean banchan (side dishes)—that remain essential components of their everyday cuisine. Fermented foods are also used in Eastern cultures for medicinal purposes, which may be of particular interest to registered dietitians who practice “food as medicine.” Links between fermented foods and health can be traced as far back as ancient Rome and China, and remain an area of great interest for researchers in modern times.
The Science of Probiotics
Evidence-based reviews indicate that certain strains of probiotics contribute to the microbial balance of the gastrointestinal tract—supporting the immune system and reducing inflammation in the gut. Health conditions that can benefit from probiotics therapy include diarrhea, gastroenteritis, irritable bowel syndrome, inflammatory bowel disease and cancer.
However, exactly which probiotic strains, appropriate dosages and fermentation profiles are still being investigated. According to “Probiotics and Prebiotics in Dietetics Practice” in the March 2008 Journal of the Academy of Nutrition and Dietetics, the challenge in developing clinical recommendations for probiotics therapy is not a lack of scientific literature, but a lack of consolidated research and consistency across studies with respect to bacterial strains, dosages and populations. Nonetheless, the authors write that “although documenting efficacy of probiotics is still emerging, a growing number of consumers and health-care professionals are interested in trying probiotics,” and that people might “also be interested in increasing the levels of live active cultures in their diet. Such diets have not been evaluated strictly, but could be recommended based on the emerging body of evidence that a variety of probiotics is beneficial.”
In addition to supporting human health, Lactobacillus and other bacteria may protect against foodborne illness by inhibiting and eradicating foodborne pathogens, including Listeria monocytogenes, Staphylococcus aureus and Bacillus cereus. The inhibition of pathogenic bacteria may be due in part to pH, as well as antimicrobial bacteriocins produced by Lactobacillus to inhibit other competitive strains, including foodborne pathogens. While these findings support fermentation as a safe method of preservation, and consumption of fermented grain has been associated with decreases in foodborne illness, more research is needed.
An Integrative Medicine Perspective
A basic tenet of integrative nutrition is that digestive dysfunction is at the root of most maladies. Research has suggested that an imbalance of beneficial-to-pathogenic bacteria and yeasts can disrupt the delicate intestinal barrier, which constitutes the body’s first line of defense against ingested pathogens. One strategy used by RDs in integrative medicine is the reintroduction of beneficial bacteria to improve digestive function and rebalance the intestinal flora. While probiotic supplementation is widely utilized, many prefer using a “food first” approach by recommending naturally fermented foods.
Small Batches vs. Large-Scale Production
Traditional lacto-fermentation utilizes the microflora present on vegetables and a lactic acid bacteria starter culture (whey). Once upon a time, all pickles were naturally fermented through lacto-fermentation, which is why some people use the terms “pickled” and “fermented” synonymously. In modern times, this is no longer the case. In large-scale food manufacturing practices, vegetables are washed in diluted chlorine solutions to destroy or inactivate existing microflora, and acetic acid (which, along with water, is a main component of vinegar) is used instead of lactic acid. Of the few commercially available pickles that are lacto-fermented, most are heat processed or pasteurized to create a sterile product. Others are “desalted” or rinsed, likely removing any beneficial bacteria that may have been present.
If it’s health benefits you seek, lacto-fermented foods work best from both quality and food safety perspectives when produced in small batches, although there are small-scale operations that pride themselves on reinvigorating the fermented food market (look for them at gourmet stores, farmers markets and Asian shops). Meanwhile, home fermentation enthusiasts continue to look to the past as the wave of the future.
- Wild Fermentation: The Flavor, Nutrition, and Craft of Live-Culture Foods (Chelsea Green Publishing 2003)
- Making Sauerkraut and Pickled Vegetables at Home: Creative Recipes for Lactic Fermented Food to Improve Your Health (Alive Books 2002)
- Preserving Food without Freezing or Canning: Traditional Techniques Using Salt, Oil, Sugar, Alcohol, Vinegar, Drying, Cold Storage, and Lactic Fermentation (Chelsea Green Publishing 2003)