Clinical benefits of Kefir explained
There may be particular benefits for readers, hmm hmm of a certain age.
Hello Fermented Fans,
On this post I would like to give a quick synopsis on the clinical benefits of kefir consumption through a search of the current medical literature available on PubMed.
First a little primer on kefir. Kefir starts as a kefir “grain” which is simply a dried biofilm mat of dormant microbial cells with yeast and bacteria comingled. These grains are added to milk and kept at room temperature in order for them to consume milk sugars and proteins, reducing the pH and creating a thick sour drink. The main bacterium active in this process are cells from the species Lactobacillus kefiranofaciens, while yeast from the genera Kluyveromyces and Kazachstania are also prevalent. The milks of cows, sheep, goats, and many other mammals is traditionally fermented, however kefir can also be made from milks of oats, rice and nuts. Kefir as a whole is more than the sum of its parts. Besides the nutritional benefits of the base milk, kefir also contains live microbes which can provide benefits to the intestine once ingested.
Now to the available data on the human health benefits of kefir consumption.
One 2015 study of forty osteoporosis patients in Taiwan found that patients given kefir-fermented milk supplemented with calcium carbonate for six months had a significant positive effect on bone mineral density of the spine and hip (as observed with x-ray), when compared with patients that consumed calcium carbonate alone. This was a double-blind study, meaning that neither the researchers nor the patients knew who was getting kefir until after the study was conducted.
In another controlled clinical trial from 2019, twenty-two patients with metabolic syndrome (a multi-factorial disease encompassing obesity, diabetes, heart and liver disease) were randomized to receive either kefir or unfermented milk for twelve weeks. Blood samples and blood pressure measurements were taken at the beginning and end of the study. Many markers of improved metabolism were found in the kefir supplemented group when compared to those who received milk alone, including improved insulin levels and decreased systolic and diastolic blood pressure.
In an uncontrolled (meaning all participants got kefir) clinical investigation published in 2020, scientists compared the cognitive performance to solve eight classical tests by thirteen Alzheimer’s patients at baseline versus after ninety days of daily kefir supplementation. Blood samples were taken at the beginning and end of the study. After the intervention period, a significant increases in the majority of the patients’ memory, visual-spatial/abstraction abilities, and executive/language functions was noted. This was accompanied by decreased blood markers of oxidative stress and DNA damage.
Although all of these studies have a small sample size there seems to be a case to be made for including kefir in traditional dietary recommendations, especially for those prone to bone density loss and cognitive decline. One thing I want to point out is there are numerous pre-clinical studies (animal studies) available that provide evidence that kefir consumption can provide specific mental and metabolic benefits. One interesting study published in 2021 tried to pinpoint which microbes present during fermentation might be responsible for some of these health benefits. The researchers in this study found that mice given a high fat diet for eight weeks became unhealthy as determined by cholesterol levels and weight gain. When mice on a high fat diet were given kefir fermented with both yeast and bacteria (traditionally made) a significant decrease was observed in plasma cholesterol and liver triacylglycerol, both markers of metabolic fitness of the animals. However, when they gave a different group of mice the same high fat diet and kefir that was fermented by yeast alone, or bacteria alone, no metabolic benefit was found. These results suggest there is a synergistic impact of yeast and bacteria on the health benefits of fermented kefir.
All in all, there are a handful of human clinical studies suggesting there are health benefits for kefir consumption, and there are many pre-clinical studies which support some of the molecular changes that occur after kefir consumption. More controlled clinical trials to understand how kefir consumption can alter the mental and metabolic profile of humans are warranted. Today, kefir is commercially produced by many dairy companies and is usually found in grocery stores as plain, or mixed with fruit and sugar. I would recommend any of you thinking of adding kefir to your diet to look at the ingredients list and choose one with low sugar content. If you are lactose intolerant, you should be able to drink milk-based kefir due to the fermentation of, and breakdown of lactose by the microbes during production. You can also get soy-milk based kefir and nut-based fermented milks as well.
You can also cheaply make your own kefir easily by ordering kefir grains online and fermenting your milk of choice. Just add the grains to the milk in a sealed container (not air-tight, but covered) and leave at room temperature out of direct sunlight. You can also add fresh milk to a partially filled bottle of kefir you purchased from the store and leave it on the kitchen counter for a few days and the milk will ferment. This can be done numerous times to continually have fresh kefir on hand without paying the premium at the grocery store. Just make sure you watch for any signs of off-colors or smells, especially around the mouth of the container. If it smells and looks like kefir (no colors other than white) and it tastes sour it is okay to drink.
Disclaimer: I am not a nutritionist or medical doctor and am not giving medical advice. The opinions above are my own and are not shared by the authors or publishers of the papers discussed herein. I do not claim ownership of any images.
Hope you enjoyed reading, and see you next time!