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New study compares real kefir to a starter culture

by Nathan Pujol January 17, 2020 2 Comments

New study compares real kefir to a starter culture

A fascinating new study came out that demonstrated the power or kefir made by real grains. The study used mice, but the findings are still very relevant.

I really like this study as it compares kefir made from real grains to a commercial starter culture, similar to what you would find in yogurt or anything store bought that contains lab based probiotics.

Gastrointestinal Tract

They tested the feces of mice and found that the mice who were fed real kefir from real grains had elevated levels of that good kefir bacteria and yeast within those feces. This shows that it passed the harsh gastrointestinal transit and likely had wide-spread benefits.

The commercial starter culture (the culture that was NOT made from real grains), did not make it through the gastrointestinal tract – they shows similar results to the control group that were not fed any probiotics.


Fascinatingly, the commercial starter culture had higher markers of inflammation. The authors of the study, do not know why.

The mice that were fed real kefir did NOT have the higher inflammation. Another win for real kefir. Even though the kefir was stronger and more powerful than the commercial starter culture, it did not cause the same kind of inflammation.

There’s more and more research showing that simply combining probiotic strains in a lab is not very effective – and that’s the best case scenario. The worst case is that it may actually be damaging. Kefir grians are not lab based and their strong balance is natural.


Perhaps the biggest finding in this study is that the kefir actually stopped the feces from the mice from being toxic. There’s a mold in mice (Trichoderma koningii) that is pathogenic and carcinogenic.  However, the mice that ingested real kefir, shows no mold in their feces. Basically they had toxic free droppings. That’s incredible. I’m not exactly sure how that relates to humans, but it sure sounds good.

So here’s a crazy idea. If you are having trouble getting rid of mice, why not try feeding them kefir instead? They will no longer be toxic and they will have a beautiful shinny coat. Perhaps one day we can all live in harmony with mice?


As expected, the mice that were fed natural kefir showed a higher antioxidant status than the starter culture and the control. Kefir is well known for its antioxidant properties.

The also tested oxidative stress and found the lowest in the mice that were fed kefir. This marker indicates the level of toxicity which kefir being even lower than the control. The highest was the starter culture which is interesting. For some reason, both the inflammation and oxidative stress was higher in the mice that consumed the commercial starter culture.

Bottom Line

This is another fascinating study on the power behind kefir. In this study, mice were either fed kefir, a manufactured starter culture or neither.

The mice that were fed kefir showed higher levels bacteria and yeast in the feces which indicates that it survived the gastrointestinal tract. It also showed lower inflammation and higher antioxidant levels. It also completely irradiated toxic mold from the mice.

In comparison, the commercial starter culture (which had probiotics), did not significantly pass through the gastrointestinal transit and it actually caused higher levels of inflammation and oxidative stress. This is yet another reason to minimize commercial intake of probiotics and stick with probiotics that’s naturally been around for many hundreds of years – kefir.

Nathan Pujol
Nathan Pujol


Co-founder and author of Graduate degree in clinical psychology. Researcher with emphasis on the gut microbiome, fermentations and their connection to mental and physical well-being. He has 15 years of experience with making, sharing and teaching about traditional ferments.

2 Responses

Yemoos Nourishing Cultures
Yemoos Nourishing Cultures

January 30, 2020

Hi Tim – Anything made by real kefir grains would be that quality that has all those benefits. In store organic kefir is NOT that. They are typically made in a lab just like yogurt. They may share a couple strains with real kefir, but its not authentic kefir. They just pick a few bacteria type strains, mix them together and call it kefir. According to this study, its that type of commercial starter that has limited benefits and may actually cause inflammation.

Tim Washburn
Tim Washburn

January 30, 2020

Any suggestions for where to find kefir of this quality and would in store organic kefir preferably w/out sugar be good? Or should you stick with raw kefir?

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