Abstract: Fermented foods have been a well-established part of the human diet for thousands of years, without much of an appreciation for, or an understanding of, their underlying microbial functionality, until recently. The use of many organisms derived from these foods, and their applications in probiotics, have further illustrated their impact on gastrointestinal wellbeing and diseases affecting other sites in the body. However, despite the many benefits of fermented foods, their recommended consumption has not been widely translated to global inclusion in food guides. Here, we present the case for such inclusion, and challenge health authorities around the world to consider advocating for the many benefits of these foods.
Alex’s Notes: Many governmental agencies have food policy and nutritional recommendations, and most of these are based on reductionist thinking and nutritionism, although not all are. As a result, guidelines do not reflect traditional eating behaviors of the populations being governed, nor do they appreciate the benefits of foods consumed by generations before. Fermented foods are a perfect example, as the process of fermentation has long been used to prevent food spoilage.
Fermentation is a process whereby microorganisms convert sugars such as glucose into other compounds such as alcohol and vinegar. Bacteria are primarily responsible for producing lactic acid and other volatile molecules, while yeast is responsible for producing alcohol. Both operate under anaerobic conditions (no oxygen present). There are many different species of bacteria used in this process that contribute to the unique flavors and textures of the fermented products, with the most common products being yogurt, sauerkraut, kimchi, kefir, and pickling.
Initially, many foods underwent fermentation naturally, but today these foods are created with starter cultures and processes that have become more automated and reproducible. Yogurt is now easily available on the market and often advertises the probiotic bacteria used to create it, whereas traditionally one would have left raw milk on the counter to curdle. This is also similar to how cheese was made. Similarly, globalization has allowed for the transport of foods and ideas across nations, allowing kimchi to no longer be restrained to its South Korean home. Yogurt originated in Greece & Turkey, and kefir in Russia, but these foods are widely available on the other side of the planet.
Despite all this, the only governmental nutritional guide to promote fermented foods is the National Institute of Nutrition’s Dietary Guidelines for Indians, which specifically states that pregnant women should “eat more whole grains, sprouted grains, and fermented foods.” In other guidelines, when fermented foods such as yogurt are recommended, it is because of their nutritional content rather than fermentative status. Unfortunately, this absence of a recommendation may lead some into believing that these foods are not beneficial when nothing could be further from the truth.
A handful of large cohort studies in The Netherlands and Sweden have found that increasing consumption of fermented dairy products was associated with a significantly reduced prevalence of bladder cancer and cardiovascular disease. Similarly, intake of milk and fermented dairy was significantly inversely associated with periodontal disease in Danish adults, but cheese and other dairy foods were not.
These associations can be explained most likely through immune and metabolic effects of fermented dairy products.Fermented milk supplemented with probiotics can improve intestinal health, humoral and cell-mediated immunity, and salivary and fecal antibodies. Some evidence even suggests this can help reduce the duration and severity of respiratory infections. This is of course only one example, and other studies have found improvements to vaginal, bladder, bone, liver, body mass, and skin health. It should be noted that these studies use strains of bacteria common in the fermentative process, not fermented foods themselves. However, seeing how a one-ounce serving of sauerkraut contains more than one trillion probiotic bacteria, it stands to reason that fermented foods beat out supplements.
In vulnerable populations, probiotics continue to shine. Randomized trials in infants demonstrate their ability to reduce the risk of allergies, and more importantly, demonstrate their safety in this population. Daily consumption of probiotic yogurt has also been suggested to preserve insulin sensitivity in pregnant women, and has been associated with a reduced incidence of type-2 diabetes. More interesting, we know that the microbiome plays a role in arthritis, and fermented milk has indeed been shown to alleviate symptoms.
Of course not everyone consumes dairy. Kimchi, a popular side dish originating in Korea, has been associated with numerous health benefits, including prevention of cancer and obesity, reduction in cholesterol levels and immune system promotion. Another study found that consumption of fresh and fermented kimchi for eight weeks improved glucose tolerance in pre-diabetic individuals, as well as reducing body weight, waist circumference, and insulin resistance.
Fermented foods are a historical dish consumed all over the world by our ancestors. They provide important and beneficial bacteria for out guts in quantities & diversity far greater than anything that can be found inside a pill (except perhaps one of those new fecal transplant pills). Consumption should be encouraged, if not by governmental agencies, then by health professionals everywhere else. So find a brand or style of kimchi, yogurt, sauerkraut, etc. that you enjoy and eat some daily.