Fermented foods present health benefits that extend well beyond their basic nutritional value.
In the last few years, fermented foods have become a popular trend, especially in the natural healthy community. In fact, fermented foods have been around since Neolithic times, and many of us still remember our grandparents fermenting foods in the basement over the winter as a way to access produce during the cold months. Good thing, as it seems our ancestors were onto something: Not only does fermentation act a natural preservation process, but fermented foods present health benefits that extend well beyond their basic nutritional value, providing a dose of live bacteria to the intestines and generating additional compounds that have supplemental health benefits.
So, which fermented foods are supported by research to be beneficial for health?
Fermented Dairy: Yogurt and Kefir
Among the most widely studied of the fermented foods, yogurt and kefir seem to be the popular choice as a source of probiotics. Worried about lactose maldigestion? Yogurt and kefir contain the lactose digesting enzyme lactase, which survives gastric transit and is able to digest enough lactose to minimize or prevent symptoms in susceptible individuals, so most people tolerate them well.
Yogurt’s benefits are bountiful, as its consumption has been associated with improved bone mineral density, reduced hip fractures and improved weight management. Research shows that the greatest protection against obesity occurs with yogurt consumption equal or greater to seven servings per week, and there is a link between fermented dairy consumption and reduced risk of hypertension, cardiovascular disease, and type 2 diabetes.
The large variety of commercial yogurt products on the market today offer a wide selection, but also make it confusing when trying to choose a product with the most health benefits. Look for labels that advertise “live active cultures” and state the presence of particular species (i.e. Streptococcus thermophilus or Lactobacillus casei). The best avenue is to simply make sure the yogurt does not have any added sugars or flavors.
Kombucha is a fermented beverage originating in China, normally made by adding bacteria and yeast to a tea containing sucrose. Animal studies suggest that there are cholesterol-lowering and antioxidant effects of kombucha, but unfortunately at this time there are no human studies demonstrating these effects.
Like fermented dairy, it’s important to watch for added sugars, as a substantial quantity of sucrose may remain in kombucha at the time of consumption. A recent independent analysis reported that five out of eight brands of kombucha contained far more sugar than reported on the labels (“Sugars in Kombucha Tea,” 2016), so try to choose flavors that have less sugar originally. Also of importance: Microbial viability decreases over time, even when refrigerated, so be sure to consume your kombucha sooner rather than later.
Fermented Soy: Miso, Tempeh, Natto
There are several fermented soy products on the market that can diversify your fermented foods menu. Tempeh, a fermented soybean product, provides a source of isoflavones and has many health benefits, including alleviating oxidative stress, while miso, a fermented soybean paste, has been linked with reduced blood pressure. Natto, a traditional fermented soybean breakfast food, has been shown to improve insulin sensitivity, serum lipid and oxidative stress in overweight individuals with impaired glucose tolerance. In addition, fermented soy products have been associated with reduced bone loss in postmenopausal women, offering a dairy free alternative to yogurt for maintaining bone mineral density.
Based on what we now know, should we rely on fermented foods as our primary source of probiotics? Since many fermented foods contain bacterial amounts too low to provide the benefits seen in clinical trials, those who are looking for specific therapeutic benefits may not be successful with fermented foods alone. A probiotic supplement is the only way to achieve the dose and strain seen in clinical trials. However, the incorporation of fermented foods does support supplemental efforts, so for those mindful of maintaining overall health, fermented foods may be the perfect solution.
Ahmad, A., Ramasamy, K., Majeed, A. B. A., & Mani, V. (2015). Enhancement of β-secretase inhibition and antioxidant activities of tempeh, a fermented soybean cake through enrichment of bioactive aglycones. Pharmaceutical Biology , 53 (5), 758–766. https://doi.org/10.3109/13880209.2014.942791
Du, D. D., Yoshinaga, M., Sonoda, M., Kawakubo, K., & Uehara, Y. (2014). Blood pressure reduction by Japanese traditional Miso is associated with increased diuresis and natriuresis through dopamine system in Dahl salt-sensitive rats. Clinical and Experimental Hypertension (New York, N.Y.: 1993) , 36 (5), 359–366. https://doi.org/10.3109/10641963.2013.827702
Guarner, F., Perdigon, G., Corthier, G., Salminen, S., Koletzko, B., & Morelli, L. (2005). Should yoghurt cultures be considered probiotic? The British Journal of Nutrition , 93 (6), 783–786.
Ikeda, Y., Iki, M., Morita, A., Kajita, E., Kagamimori, S., Kagawa, Y., & Yoneshima, H. (2006). Intake of fermented soybeans, natto, is associated with reduced bone loss in postmenopausal women: Japanese Population-Based Osteoporosis (JPOS) Study. The Journal of Nutrition , 136 (5), 1323–1328.
Lee, S. C., Billmyre, R. B., Li, A., Carson, S., Sykes, S. M., Huh, E. Y., … Heitman, J. (2014). Analysis of a food-borne fungal pathogen outbreak: virulence and genome of a Mucor circinelloides isolate from yogurt. mBio , 5 (4), e01390-01314. https://doi.org/10.1128/mBio.01390-14
Martinez-Gonzalez, M. A., Sayon-Orea, C., Ruiz-Canela, M., de la Fuente, C., Gea, A., & Bes-Rastrollo, M. (2014). Yogurt consumption, weight change and risk of overweight/obesity: the SUN cohort study. Nutrition, Metabolism, and Cardiovascular Diseases: NMCD , 24 (11), 1189–1196. https://doi.org/10.1016/j.numecd.2014.05.015
McGovern, P. E., Zhang, J., Tang, J., Zhang, Z., Hall, G. R., Moreau, R. A., … Wang, C. (2004). Fermented beverages of pre- and proto-historic China. Proceedings of the National Academy of Sciences of the United States of America , 101 (51), 17593–17598. https://doi.org/10.1073/pnas.0407921102
Scourboutakos, M. J., Franco-Arellano, B., Murphy, S. A., Norsen, S., Comelli, E. M., & L’Abbé, M. R. (2017). Mismatch between Probiotic Benefits in Trials versus Food Products. Nutrients , 9 (4). https://doi.org/10.3390/nu9040400
Sugars in Kombucha Tea. (n.d.). Retrieved November 26, 2017, from http://naturproscientific.com/portfolio/sugars-in-kombucha-tea/
Taniguchi-Fukatsu, A., Yamanaka-Okumura, H., Naniwa-Kuroki, Y., Nishida, Y., Yamamoto, H., Taketani, Y., & Takeda, E. (2012). Natto and viscous vegetables in a Japanese-style breakfast improved insulin sensitivity, lipid metabolism and oxidative stress in overweight subjects with impaired glucose tolerance. The British Journal of Nutrition , 107 (8), 1184–1191. https://doi.org/10.1017/S0007114511004156
Tu, M.-Y., Chen, H.-L., Tung, Y.-T., Kao, C.-C., Hu, F.-C., & Chen, C.-M. (2015). Short-Term Effects of Kefir-Fermented Milk Consumption on Bone Mineral Density and Bone Metabolism in a Randomized Clinical Trial of Osteoporotic Patients. PloS One , 10 (12), e0144231. https://doi.org/10.1371/journal.pone.0144231