R’s KOSO, the rare probiotic drink that contains Koji

What is Koji?

You might not know what Koji is, but chances are you have probably already consumed them, if you ever had miso soup, or anything containing miso, or shoyu (soy sauce) or even sake, the famous Japanese alcoholic drink. All of these things have one thing in common, which is they go through a fermentation process, and none of this would ever happen if it weren’t for Koji.

Koji is a traditional Japanese ingredient that is used in cooking, especially to enhance the flavoring of dishes, they are also known as the fungus or mold Aspergillus oryzae, which is commonly used in fermentation. Rice koji usually is made by mixing cultured Aspergillus oryzae with rice or other grains. During fermentation, these fungus release enzymes know as amylase and protease, which helps to breakdown macronutrient carbohydrates and protein, breaking them down to delicious amino acids, dominated by glutamic acid, which is known as the savory taste of umami. It usually has a savory, slightly nutty, sweet & salty taste to it. 

Koji can be used to ferment various types of legumes & grains, that’s why you might not know them specifically, but likely you have tried food that’s made by this little fungus.


Koji’s health benefits

With the growing amount of researches being done on fermented food such as kimchi, kombucha, Sauerkraut, and more, we are discovering more and more health benefits with this traditional food. Study has revealed that Koji contains high amount of glucosylceramide, these glucosylceramides are very important for our gut microbes, which in turn affects our health as a host. The study revealed that after ingesting Koji glucosylceramide, it was neither detected in the feces nor broken down by intestinal enzymes which suggest that our microbes likely digested these koji glucosylceramide instead. When ingestion takes place, there is an increase in  Blautia coccoides, this suggests that koji can have a role as a prebiotic, which these probiotics feed on. Since Blautia coccoides have been associated with health benefits, Koji might be the missing link in the health benefits of the Japanese diet, gut health, and longevity.

Another study evaluated the effect of fermentation with koji on the nutritional quality of food. Soybeans were fermented by koji Aspergillus oryzae vs the controlThe nutritional value of the fermented vs non-fermented soybean were compared through electrophoresis on the protein extracted from these soybeans. Collectively, fermentation increased the protein content and reduced the peptide size in the soybean. This suggests that the effect of fermentation may make soy foods more useful in the human diet as a functional food.


R’s KOSO with Koji

There are some of the drinks fermented by Koji, like Amazake and sake in Japan. R’s KOSO is also one of them. Conventional Koso drink that is commonly seen on the market are made by only lactic acid bacteria & yeast. R’s KOSO is not only made with lactic acid bacteria & yeast, but koji itself is also added as a key ingredient along with 100 other amazing ingredients. 

R’s KOSO is the only superfood supplement on the market that provides balanced nutrition, combining probiotics, prebiotics, and koji, which have proven to improve gut health and boost immunity. It is made from over 100 vegetables, fruits, and plants, including seaweeds and mushrooms, pine leaves, cedar leaves, persimmon leaves, octopus leaves, mulberry leaves), and Koji, all these nutritious ingredients undergoes about 1-year fermentation process to produce the R’s KOSO in a bottle. 



  1. Hong, K., Lee, C., & Kim, S. W. (2004). Aspergillus oryzaeGB-107 Fermentation Improves Nutritional Quality of Food Soybeans and Feed Soybean Meals. Journal of Medicinal Food, 7(4), 430-435. doi:10.1089/jmf.2004.7.430
  2. Dossou, S., Koshio, S., Ishikawa, M., Yokoyama, S., Dawood, M. A., Basuini, M. F., . . . Zaineldin, A. I. (2018). Growth performance, blood health, antioxidant status and immune response in red sea bream (Pagrus major) fed Aspergillus oryzae fermented rapeseed meal (RM-Koji). Fish & Shellfish Immunology, 75, 253-262. doi:10.1016/j.fsi.2018.01.032
  3. Hamajima, H., Matsunaga, H., Fujikawa, A., Sato, T., Mitsutake, S., Yanagita, T., . . . Kitagaki, H. (2016). Japanese traditional dietary fungus koji Aspergillus oryzae functions as a prebiotic for Blautia coccoides through glycosylceramide: Japanese dietary fungus koji is a new prebiotic. SpringerPlus, 5(1). doi:10.1186/s40064-016-2950-6
  4. Murakami H. Koji study. Tokyo: Brewing society of Japan; 1985. pp. 1–17.
Older Post
Newer Post
Close (esc)


Use this popup to embed a mailing list sign up form. Alternatively use it as a simple call to action with a link to a product or a page.

Age verification

By clicking enter you are verifying that you are old enough to consume alcohol.


Main menu

Shopping Cart

Your cart is currently empty.
Shop now
Liquid error (layout/theme line 311): Could not find asset snippets/elevar-body-end.liquid HTMLResult Skip Results Iframe EDIT ON