The Science Behind Kefir: A Powerful Probiotic Superfood for Health

In the United States, there is a growing emphasis on preventive wellness, leading to a renewed interest in traditional fermented foods like kimchi, kombucha, and kefir. Among these, kefir stands out due to its intriguing origins and unique microbial composition.

Origins and Historical Significance

Kefir, a slightly effervescent beverage made from goat or cow milk, is believed to have been created thousands of years ago by nomadic herders in the Caucasus Mountains. Its name derives from the Turkish word ‘keyif,’ which translates to ‘feeling good,’ hinting at its long-recognized health benefits.

Historians theorize that the first kefir was likely produced when Caucasian herders stored milk in bags made from goat or sheep stomachs filled with enzymes, leading to the milk’s fermentation and coagulation into gelatinous orbs. This process resulted in a product that could outlast fresh milk, prompting efforts to replicate it.

Microbial Complexity and Health Benefits

This probiotic-rich drink is known to enhance the immune system, alleviate gastrointestinal issues, and aid in metabolic regulation. Consequently, health professionals across the U.S. are increasingly recommending kefir for patients facing intestinal disorders or recovering from intense medical treatments. Recent market analyses predict that global kefir sales could nearly double from 2023 to 2033, potentially reaching a staggering $4.1 billion.

But what makes kefir so beneficial? According to Rafael Jimenez-Flores, a leading researcher in dairy foods at Ohio State University, the complex interplay between lactic acid bacteria, acetic acid bacteria, yeast, and lactose offers multiple health advantages. His ongoing studies indicate that this unique combination acts as a powerful probiotic within the gut, effectively combating harmful bacteria.

“The grains function like a factory, continuously shedding Lactobacillus kefiranofaciens to maintain lactose fermentation,” explains Jimenez-Flores.

Jimenez-Flores initially did not set out to explore kefir’s microorganisms and their health implications. However, he learned from a colleague that patients undergoing extensive antibiotic treatments reported quicker recovery times when consuming kefir. ‘Antibiotics and radiation treatments significantly alter your microbiota,’ he explains.

His former student, Brianda D. González-Orozco, now with Daisy Brand, discovered that kefir’s unique lactic acid bacteria and other microbes produce antimicrobial substances like bacteriocins, organic acids, and hydrogen peroxide. These compounds can disrupt pathogenic bacteria’s cell membranes and interfere with protein synthesis in common foodborne pathogens such as Escherichia coli and Salmonella.

Moreover, kefir boasts antiviral, antioxidant, antidiabetic, and antiallergenic properties. Jimenez-Flores attributes some of these benefits to oligosaccharides produced during its fermentation process. These short carbohydrate chains absorb toxins and prevent their absorption in the intestines, while polysaccharides contribute to the repair of intestinal mucosa.

Making and Understanding Kefir at Home

An added advantage of kefir is that it significantly reduces lactose content due to its fermentation process. The beneficial bacteria in kefir aid in lactose absorption, minimizing the effects associated with lactose intolerance.

To create authentic kefir at home, one needs just two ingredients: whole milk (from any common animal source) and kefir grains, which can be easily ordered online or found in health food stores. These grains are not cultivated from plants or animals; their exact origins remain somewhat of a mystery.

To make kefir at home is straightforward: simply add a tablespoon of grains to a quart of fresh milk and let it ferment for 24 to 72 hours for desired taste and tanginess. After fermentation, strain the liquid to separate the grains, store the liquid in the refrigerator for consumption, and reuse the grains for subsequent batches.

Kefir grains multiply during fermentation, often leading home brewers to share or dispose of excess grains. Many commercial kefirs also incorporate fruits and sugars, deviating from traditional recipes. However, the transformation of milk into kefir is a complex process involving more than just simple fermentation.

Distinct Fermentation Compared to Yogurt

Unlike yogurt—which relies solely on lactic acid bacteria like Streptococcus thermophilus and Lactobacillus bulgaricus—kefir’s fermentation process is more intricate. It involves solid-state fermentation combined with fluid fermentation using various bacterial strains including Lactobacillus kefiranofaciens.

Research has shown that as bacteria in kefir grains interact with milk, they produce a diverse range of bacterial strains. “The grains function like a factory, continuously shedding Lactobacillus kefiranofaciens to maintain lactose fermentation,” Jimenez-Flores explains.

This means that the fermentation occurring within the grains differs from that outside them. Kefir represents a symbiotic collection of lactic acid bacteria, acetic acid bacteria, and yeast bonded to a polysaccharide-protein structure resembling cauliflower.

“Unfortunately, replicating the exact balance of bacteria and yeast found in traditional kefir on a commercial scale is nearly impossible,” says Jimenez-Flores.

As a result, many companies use defined microbial mixtures in their products. While these may closely resemble authentic kefir, they often fall short of capturing its full essence.