November 14th, 2012 by Digestive Detective
A cornerstone of the diets of many traditional cultures, fermented foods have historically been revered for their health-promoting and medicinal properties. Modern science is now beginning to pay that same reverence to the constituents of beneficial bacteria found in fermented foods that serve to enhance the microbial environment of the human gut. Individuals in the “real food movement” and holistic nutrition arena have already begun touting the benefits of fermented foods for these same benefits and incorporate fermented foods into their own diets with an emphasis on their ability to promote greater overall wellness.
Fermented Foods and The Gut
From a modern scientific perspective, fermented foods are primarily being studied for their functional compounds and potential application in disease management. A growing appreciation for the complex internal environment of the gut and microbiota that reside within the human body has lead researchers to look to the influence of this microbial environment on human health.
Gastrointestinal and immune function are at the forefront of this research with the knowledge that the human gut is home to approximately 100 trillion microorganisms. Over 400 known diverse bacterial species populate the gut and serve to aid in nutrient digestion and absorption as well as modulation of the immune system. Researchers believe that we evolved with these microorganisms in a symbiotic relationship; therefore, the introduction of bacterial-rich, fermented foods serves as a key environmental input as the components are evolutionarily familiar to us. Disregulation of the gut microbiota via antibiotic overuse, ingestion of toxins and highly processed food sources can result in a decrease in microbial diversity and dysbiosis or imbalance of beneficial to deleterious bacteria. The resulting effect can produce a gastrointestinal environment that is more prone to pathogenic infection, malabsorption of nutrients, inflammation, and intestinal permeability. Intestinal permeability is characterized by a loosening of the tight junctions along the mucosal barrier of the small intestine that decrease the barrier’s competency to prevent macromolecules from passing from the gastrointestinal tract into general circulation. Intestinal permeability is now believed by many researchers to be at the crux of a variety of disease processes with particular attention being observed in relation to autoimmune disorders. In their analysis of the role of intestinal permeability in relation to autoimmunity (celiac disease and type 1 diabetes) researcher and mucosal biology expert Alessio Fassano, MD and colleagues from the University Groningen in the Netherlands, noted:
“There is growing evidence that increased intestinal permeability plays a pathogenic role in various autoimmune diseases including [celiac disease] and [type 1 diabetes]. Therefore, we hypothesize that besides genetic and environmental factors, loss of intestinal barrier function is necessary to develop autoimmunity.”
This finding and ones like it highlight the impact of healthy gut microbiota and mucosal environment on the key physiological functions of assimilation and energy production as well as protection. Protection is influenced due to the ability of gut permeability and dysfunction to result in hyperactive immune response. Fermented foods often provide a dual benefit to the consumer when it comes to gut health & immune function via the beneficial bacteria derived through the fermentation process as well as the often associated high fiber content of such foods. Ingesting pro-biotic rich fermented foods such as kefir, natto, sauerkraut, kimchi, miso, yogurt, etc. helps repopulate the microbiome and the fiber found in many of these foods enhances digestion and elimination.
These familiar cues and mechanisms from micro-organisms highlight fermented foods ability to confer upon the eater an appraisal of physiological needs and associated responses. The resulting effect from these responses, in the case of immune function/modulation, is an improvement to our cellular and systemic resilience against internal stress (foreign pathogens) and external stress.
Antioxidant Capacity, Blood Sugar Regulation and Cardiovascular Health
In addition to their application in promoting gastrointestinal and immune health, fermented foods, especially fermented vegetables, have shown promise in clinical studies through the promotion of antioxidant status, blood glucose regulation and cardiovascular benefits.
Researchers from the Institute of Bioscience, Universiti Putra Malaysia, studied the potential of fermented mung beans to reduce the risk of diabetes in Asian populations. Using a mice model, researchers tested blood glucose response in glucose- and alloxan-induced hyperglycemic mice. Results showed a significant decrease in blood sugar levels, as well as serum levels of cholesterol, triglycerides and low-density lipoprotein. At the same time, insulin secretion and antioxidant level were significantly improved in the plasma of the fermented mung bean-treated group.
In another study, researchers examined hypertension and the propensity for fermented foods, in this case probiotic-fermented purple sweet potato yogurt (PSPY), to inhibit cardiac hypertrophy. In the experiment, researchers divided rats into four control groups: sterile water, captopril and 2 PSPY groups with different doses (10 and 100%) for 8 weeks. Examining changes in myocardial architecture and key molecules of the hypertrophy-related pathway in the excised left ventricle after 8 weeks of protocol admission, researchers concluded:
“The protein levels of the hypertrophic-related pathways were completely reversed by the administration of PSPY. PSPY may repress the activation of ANP and BNP which subsequently inhibit the dephosphorylation of the nuclear factor of activated T-cells, cytoplasmic 3 and ultimately prevent the progression of cardiac hypertrophy.”
Finally, a study published in the Journal of Applied Microbiology evaluated the potential of fermentation of Sargassum in enhancing anticoagulant and antioxidant properties. The application of marine lactic acid bacteria to the seaweed effectively maximized culture viability and the sample exhibited maximum anticoagulation activity and antioxidant activity. Researchers noted these results as significant as they provide a wide range of possibilities for developing functional foods from seaweed species.
These studies and ones like these encourage researchers to continue their work of examining the health promotion potential and disease management properties of not simply the beneficial bacterial species and individual, isolated compounds of fermented foods but the whole foods themselves as functional, therapeutic tools.