Most of us consume fermented foods on a daily basis, whether it’s yogurt, kombucha, sauerkraut, bread, olives, cheese, beer or wine. This dietary habit isn’t new: humans have had a relationship with fermentation for thousands of years, and for good reason. Modern research is finding that the process of fermentation may benefit our health. That doesn’t mean you should grab the nearest six-pack and guzzle it down, but there are a few good reasons to add more fermented foods to your diet, which we'll explore in this post. What is fermentation? Fermentation is the process of converting carbohydrates into alcohol or organic acids using microorganisms—yeasts or bacteria—under anaerobic (no oxygen) conditions. Perhaps the most widely known example is the conversion of sugar into ethanol, producing alcoholic drinks like wine, cider and beer. But similar processes occur in bread making (yeast produces carbon dioxide) and in preserving foods such as yogurt, sauerkraut and kimchi through the production of lactic acid. During fermentation, end products of bioactive and bio-available compounds are created, which are full of nutrients. They confer health benefits by adding vitamins, increasing the bioavailability of minerals and vitamins, contributing probiotic microorganisms, or simply by making an inedible food into an edible staple. History of fermentation At its most basic, fermentation is a form of biological food preservation. Fermented foods can, in fact, be considered the first "processed food," for the chemical processes that occur during fermentation both improve shelf life and increase taste profiles. Seven thousand-year-old jars containing remnants of wine have been discovered in the Zagros Mountains of Iran. Yogurt's creation has been attributed to Neolithic herdsmen in Central Asia around 6,000 B.C. They likely began the practice when, after milking their animals, they put the milk in the animal-stomach carrying containers they used. Natural enzymes in these containers curdled the milk—essentially making yogurt. The curdled milk kept longer and, it is believed, the people preferred the taste, continuing the practice. Over the centuries, that process evolved into the commercial yogurt making we know today.
How do fermented foods benefit me? Studies have found a correlation between the consumption of fermented foods containing live microorganisms and better health outcomes, including improvements in immune function, decreased incidence of irritable bowel syndrome and overall mortality, reduced rates of obesity, lowered blood pressure and cholesterol levels, improved bone mass in patients with osteoporosis, and even increased attention span. While more studies are needed to prove how many of these benefits can be directly attributed to fermented foods, it does appear that this ancient technique may provide a path to better health. Probiotics and live bacterial cultures Probiotics are defined as live microorganisms in food, which confer a health benefit on the host’s gut microbiota (the microorganisms inhabiting the digestive tract). As scientists have begun to more fully understand the human gut microbiome (the genetic material within the microbiota) and its role in human health, they’ve started to look closely at food ingredients and how they impact the intestinal microbiota—also sometimes referred to as “intestinal flora.” Given the genetic similarity between probiotics and the living microorganisms found in fermented foods, much attention is now focused in this area. Diet is one of the primary influences on the human gut microbiota. Many food-ingested bacteria can temporarily join this microbiota, possibly impacting the behavior of the resident gut microbial community. Some studies have found that many of the live organisms in fermented foods survive digestion and have probiotic effects within our gut. However, not all fermented foods contain probiotics or live organisms: beer and wine, for example, undergo steps that remove organisms like yeasts that allow fermentation. Other fermented foods are heat-treated and the organisms are inactivated. Bread, for instance, is baked and some sauerkraut is canned, killing the live organisms. So while these foods may be nutritious, they do not have probiotic activity. That said, many fermented foods do contain live organisms, including non-heated sauerkraut and kimchi, yogurt, kombucha and other fermented dairy foods (like cheeses), and many of the European-style dry fermented sausages. Our modern lifestyle can deplete our beneficial bacterial makeup. Antibiotics in our foods or in prescription form can cause the “good” bacteria in our intestines to die off. Eating fermented foods containing live cultures can help re-colonize the intestines. While eating probiotic-rich fermented foods may not lead to a complete change in your gut microflora, these live cultures can help supplement the bacteria already present and fill in for missing beneficial bacteria until your gut is healthy. While the health benefits of probiotics continue to be studied, it is generally accepted that consuming live bacterial cultures in fermented foods can be recommended.
Pre-digestion enhances the nutrient profile
The process of fermentation pre-digests foods, making them nutritionally more bioavailable. The bacteria and fungi are essentially doing your body’s work for you, while also increasing the bioavailability of minerals, some B vitamins (riboflavin, niacin, thiamin) and creating unique micronutrients that have been found to have health benefits. For example, the fermentation of cabbage creates compounds known to be anti-carcinogens. Many people who are lactose intolerant can eat yogurt because the bacteria in this fermented milk product buffers the acid content of the stomach and allows for easier digestion.
Fermentation can not only make an inedible food edible, but also more nutritious. As an example, cassava root, a high-cyanide tuber, can be detoxified if peeled, chopped and soaked in water. Similarly, soaking certain nuts to remove bitter compounds (and thus fermenting them), makes them edible. Fermentation reduces the phytic acid content in food and improves the nutritional value of cereal grains, seeds and some legumes. The chief concern about phytates is that they can bind to certain dietary minerals including iron, zinc, manganese and, to a lesser extent, calcium, and slow their absorption.
The bottom line:
Add fermented foods to your diet on a daily basis. It is not yet clear how much we need to consume to receive benefits, so incorporate these foods as you like.
Read the labels: live and active cultures will be listed on the label under the ingredients; for example: B. lactis, L. acidophilus, Lactobacillus lactis.
Shop in the refrigerator aisle: fermented foods that are shelf-stable (in unrefrigerated jars or cans ) likely do not have active cultures.
Best choices include:
Active culture yogurt (Greek and Icelandic or other low-sugar brands that are clearly labeled as containing live active cultures)
Kimchi. Use it on roasted potatoes or other veggies for a probiotic boost
Sauerkraut (homemade or from the refrigerator aisle)
Kombucha (choose brands with live and active cultures and probiotics; GT’s and Revive are my favorites as they clearly list the cultures on the label)
Fermented vegetables. Remember that “pickled” does not mean fermented. Look for products with the active cultures on the label; they will always be refrigerated. Even better: ferment your own!
Brew your own Beet Kvass, a traditional Russian beverage that just may steal the spotlight from kombucha
The research continues, but for now, it appears that the fermentation process is good for our health and well-being. Who knew those ancient herdsmen would be setting the stage for a nutrient revolution in the 21 century?
Alba-Lois, L. & Segal-Kischinevzky, C. "Yeast Fermentation and the Making of Beer and Wine." Beer and Wine Makers. Nature Education3(9):17 (2010).
Gupta, R. et al. "Reduction of phytic acid and enchancement of bioavailable micronutrients in food grains." Journal of Food Science Technology. 2015 Feb; 52 (2): 676-684.
Katz, Sandor. The Art of Fermentation. White River Junction, VT: Chelsea Green Publishing, 2012. Print.
Marco, M., Heeney L., Dustin et al. "Health Benefits of fermented foods: microbiota and beyond." Current Opinion in Biotechnology, 44:94-102 (2017).
Teoh, A., Heard, G., and Cox, J. "Yeast Ecology of Kombucha Fermentation." International Journal of Food Microbiology. 95 (2004) 119-126.
"Everything You Always Wanted to Know About Fermented Foods." Science-Based Medicine. Oct. 30, 2015. sciencebasedmedicine.org/everything-you-always-wanted-to-know-about-fermented-foods/#h.2bn6wsx
Kombucha Culture Podcast: gastropod.com/kombucha-culture/
"Report on Joint FAO/WHO Expert Consultation on Evaluation of Health and Nutritional Properties of Probiotics in Food Including Powder Milk with Live Lactic Acid Bacteria." FAO/WHO (2001). www.fao.org/3/a-a0512e.pdf
Khristine Holterman, MSN
Khristine Holterman is a nutritionist who worked in clinical research before becoming a consultant to clients for wellness, weight-loss and cardiovascular health. She has an undergraduate degree from Stanford University and an MS in Nutrition from Boston University. She has taught nutrition and fitness classes at local schools and has written about nutrition-related topics for local publications. She has a strong interest in sustainable food systems and the impact of diet on our bodies and our environment, and she is an advocate for locally grown and sourced food.
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