Secretes of fermentation

Fermented foods have become a trendy topic in recent years because they are made with natural food and many people believe in gastrointestinal health benefits contained in those food.

Fermentation is a process that requires a desirable environment and the presence of substrate (food for microorganism) for microorganism to be actively creating a metabolic change in food and beverages.

There is a great variety of fermented foods from around the world, such as, kefir, kombucha, kimchi, miso, sauerkraut, tempeh, semayi, natto, sourdough bread, etc. Something need to be noted that, active cultures or probiotics can only be found in some not all fermented food.

Research studies in fermented food benefits are considered as relatively new topics. The following listed health benefits associated with fermented food are based on limited study results. Thus, further investigations from high-quality clinical trials are needed to prove existence of those health benefits in fermented food.

Kefir

- A fermented milk drink originated from the Caucasus Mountains

Kefir, similar to yogurt, can be tolerated by people with lactose malabsorption due to the β-galactosidase expressing bacteria that decreases lactose content in the drink. (1)

Kefir may be beneficial as an adjunct treatment for people who are suffering from diarrhea, abdominal pain and nausea from H. pylori (Helicobacter pylori) infection. (1)

"Kefir possesses a myriad of bioactive properties to include anticancer, antimicrobial, anti-inflammatory, hypocholesterolemic, wound healing, antioxidant and gastrointestinal aiding properties(2)."Kefir is rich in B vitamins including B1, B2, B5, B6 and B12. Depending on the type of milk and microbiological flora used in making kefir, its vitamin content can be different. Contains partially digested proteins that can facilitate the absorption. (2)

Kombucha

- A fermented tea beverage originated in Northeast China

Some effects have been revealed in animal studies concerning "blood glycaemia, oxidative stress, diabetes-induced weight loss, chemically-induced nephrotoxicity, hypercholesterolaemia and indomethacin-induced gastric ulceration (1)." However, well-structured clinical trials are still needed to confirm the human health benefits of kombucha.

With proper brewing methods, kombucha is considered safe for healthy individuals who consume less than 4 oz per day. It is contraindicated in pregnant women and likely not ideal for people with pre-existing health conditions (3).

Sauerkraut

- Fermented cabbage originated from China and then became a popular German dish

A pilot study showed improved IBS symptoms severity and gut microbiota of patients with irritable bowel syndrome (IBS) (4). However, the limited study design failed to determine wether the improvement in symptoms was because of the raw cabbage itself or sauerkraut (1).

As a result, health benefits of fermented food remain as an area to be further explored by scientists. Lots of questions are still needed to be answered by credible research studies to reveal secrets of fermentation.

References:

1. Dimidi, E., Cox, S. R., Rossi, M., & Whelan, K. (2019). Fermented Foods: Definitions and Characteristics, Impact on the Gut Microbiota and Effects on Gastrointestinal Health and Disease. Nutrients, 11(8). doi:10.3390/nu11081806

2. Farag, M. A., Jomaa, S. A., El-Wahed, A. A., & El-Seedi, A. H. R. (2020). The Many Faces of Kefir Fermented Dairy Products: Quality Characteristics, Flavour Chemistry, Nutritional Value, Health Benefits, and Safety. Nutrients, 12(2). doi:10.3390/nu12020346

3. Kapp, J. M., & Sumner, W. (2019). Kombucha: a systematic review of the empirical evidence of human health benefit. Ann Epidemiol, 30, 66-70. doi:10.1016/j.annepidem.2018.11.001

4. Nielsen, E. S., Garnås, E., Jensen, K. J., Hansen, L. H., Olsen, P. S., Ritz, C., . . . Nielsen, D. S. (2018). Lacto-fermented sauerkraut improves symptoms in IBS patients independent of product pasteurisation - a pilot study. Food Funct, 9(10), 5323-5335. doi:10.1039/c8fo00968f