Breaking down the microbiology world one bite at a time
Kefir – A fermented drink with many health benefits
Kefir as an antiobesity food – Fact or Fad?
Social media and mainstream media are well-known for influencing various aspects of our life such as fashion and promoting various fads and trends. Recently, there has been a rise in the influence of social media trends related to nutrition and health, such as the keto diet, intermittent fasting or kombucha. These dietary trends and foods are marketed to have various health benefits or weight loss/gain propensities; however, often these claims and trends are not supported by the scientific evidence and may even be harmful in the long run.
One food that is often promoted by social media or blogs for its dietary and/or weight loss advantage is kefir. Kefir is a fermented dairy beverage, similar to yogurt, made using probiotic bacteria and yeast from kefir grains. Therefore, it is a good dietary source of probiotic lactic acid bacteria (PLAB). Many research studies in animal models, especially mice and rats, demonstrated that PLABs improved obesity induced by a high-fat diet, as well as various metabolic disturbances associated with it. Consistently, recent research in mouse models demonstrates that kefir reduces metabolic disturbances associated with the high-fat Western diet such as obesity, inflammation and fatty liver disease. These are very promising initial results suggesting the possibility of even treating various metabolic diseases using kefir or kefir PLAB-derived probiotics, postbiotics or parabiotics (inactivated bacterial cells or isolated parts of the cells) (Figure 1). However, significant research is currently being done and still needs to be performed to further explore the health benefits and short-/long-term side effects of kefir or any pro-, post-, or para-biotics derived from it in both preclinical animal trials and clinical trials in humans prior to promoting their widespread use in the society.
In a recent study, Kim et al. (2021) explored the antiobesity health benefits of cellular components of a kefir PLAB, Lactobacillus kefiri DH5. In particular, they were interested in L. kefiri DH5’s surface layer proteins (SLPs), which are the glycoprotein components of the bacteria’s cell envelope, and are able to bind to/interact with host cells and trigger an immune response. One type of immune response is related to inflammation, resulting in either a pro-inflammatory or anti-inflammatory response depending on the trigger and its interaction with the host. Inflammation, in turn, is related with the development of obesity and metabolic dysfunctions. Therefore, bacterial components that trigger an anti-inflammatory response or activate anti-inflammatory genes in the host could potentially also reverse or prevent the development of obesity.
Kim et al (2021) performed a short-term 6-week study on mice that are fed a high-fat diet, supplemented with either a L. kefiri DH5 SLP or a placebo as a control. Over the study period, they found that the SLP supplemented mice had a lower weight gain and overall better metabolic functioning than the control mice. However, mice in both groups still gained weight as a result of the diet. Additionally, they also found that the SLP supplemented mice had lower expression of multiple pro-inflammatory genes in comparison to the control. These results show that L. kefiri DH5 SLP played a role in preventing weight gain and an inflammatory response in the high-fat diet fed mice, but it should be noted that it did not completely prevent weight gain or obesity. A lot more research in the area is still required to fully understand kefir and its derivatives’ anti-obesity properties and spectrum of health benefits.
Link to the original post: Eseul Kim, Hyeon Gyu Lee, Sanghoon Han, Kun-Ho Seo, and Hyunsook Kim. Effect of Surface Layer Proteins Derived from Paraprobiotic Kefir Lactic Acid Bacteria on Inflammation and High-Fat Diet-Induced Obesity. Journal of Agricultural and Food Chemistry 202169 (50), 15157-15164DOI: 10.1021/acs.jafc.1c05037
- Kim, D.-H., Jeong, D., Kang, I.-B., Kim, H., Song, K.-Y., & Seo, K.-H. (2017). Dual function of lactobacillus kefiri DH5 in preventing high-fat-diet-induced obesity: Direct reduction of cholesterol and upregulation of PPAR-α in adipose tissue. Molecular Nutrition & Food Research, 61(11), 1700252. https://doi.org/10.1002/mnfr.201700252
- Kim, D.-H., Kim, H., Jeong, D., Kang, I.-B., Chon, J.-W., Kim, H.-S., Song, K.-Y., & Seo, K.-H. (2017). Kefir alleviates obesity and hepatic steatosis in high-fat diet-fed mice by modulation of gut microbiota and Mycobiota: Targeted and untargeted community analysis with correlation of biomarkers. The Journal of Nutritional Biochemistry, 44, 35–43. https://doi.org/10.1016/j.jnutbio.2017.02.014
- Plaza-Diaz, J., Ruiz-Ojeda, F. J., Gil-Campos, M., & Gil, A. (2019). Mechanisms of action of probiotics. Advances in Nutrition, 10(suppl_1). https://doi.org/10.1093/advances/nmy063
- Seo, K.-H., Jeong, J., & Kim, H. (2020). Synergistic effects of heat-killed kefir paraprobiotics and flavonoid-rich prebiotics on western diet-induced obesity. Nutrients, 12(8), 2465. https://doi.org/10.3390/nu12082465
- Teame, T., Wang, A., Xie, M., Zhang, Z., Yang, Y., Ding, Q., Gao, C., Olsen, R. E., Ran, C., & Zhou, Z. (2020). Paraprobiotics and postbiotics of probiotic lactobacilli, their positive effects on the host and action mechanisms: A Review. Frontiers in Nutrition, 7. https://doi.org/10.3389/fnut.2020.570344