From Kimchi to Kefir: How Fermented Foods Benefit the Brain and Impact Longevity

Although probiotic supplements are currently all the rage and certainly have their benefits, we often forget about the original probiotics that have been consumed for millennia—fermented foods. Nearly every civilization and culture has utilized fermentation in some way, with the earliest records of this food preservation method dating back to 9,000 B.C. in the Middle East and Southwest Asia.

From the more mainstream foods like German sauerkraut and Greek yogurt, to the lesser-known—like the Nigerian fermented cassava flakes called gari or the Chinese fermented black beans called douchi—fermented foods are essential components of everyday cuisine all over the world. 

But far beyond being a way to preserve food in our pre-refrigerator eras, we now know that fermented foods also provide us with benevolent bacteria and compounds that not only benefit digestion, but also play a vital role in brain health, cognition, and even longevity.

Fermented Foods 101 

The most commonly consumed fermented foods and beverages include yogurt, kefir, kombucha, kimchi, sauerkraut, miso, pickles, and tempeh. However, there are hundreds of variations of fermented foods consumed by cultures worldwide.

The most common method of fermentation uses lactic acid-producing bacteria (LAB), which “eat” starch and sugar in foods and produce compounds like acids, gas, or alcohol. Lacto-fermented foods include kefir, yogurt, sourdough bread, sauerkraut, kimchi, and pickled vegetables. 

Although the probiotic strains and species found in each fermented food vary widely, the most common genera are Lactobacillus, Bifidobacterium, and Bacillus. 

Your Mind on Microbes: Fermented Foods and the Brain

If you’ve ever gotten a stomachache before an important presentation or had a disappearing appetite after receiving stressful news, you’ve experienced firsthand the relationship between your gut and brain. But in addition to its short-term effects on our emotions and mood, the gut-brain axis also significantly impacts cognition in the long run. 

Several studies have looked at the effects of fermented food consumption on brain health or cognition. In research from 2018, healthy middle-aged Japanese adults drank a Lactobacillus helveticus-fermented milk drink daily for eight weeks—a probiotic bacteria commonly found in kefir, buttermilk, and Parmesan cheese. The researchers found that those who drank the fermented milk had significant improvements in certain aspects of cognition, including attention and memory recall.

In another study, older adults with neurodegenerative conditions who drank probiotic-containing milk (Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium bifidum, and Lactobacillus fermentum) for 12 weeks also had improved cognitive function. Specifically, these adults had better scores on the MMSE (Mini-Mental State Examination), a set of questions that measures memory, thinking, communication, and understanding. The probiotic drinkers also had reductions in markers of inflammation and oxidative stress. 

Lastly, research with Indonesian adults has shown that higher consumption of tempeh (a fermented soybean product) was linked to better memory—but eating more tofu (a non-fermented soy product) was associated with worse memory. 

Although the direct mechanisms of why fermented foods are so beneficial to the brain are not entirely clear, animal studies have helped to elucidate these factors. The beneficial bacteria in these foods have been found to act on several areas of the brain, including suppressing neuroinflammation, reducing neural cell death, increasing neuron growth factors like BDNF, and upregulating antioxidant activity. 

Fermented foods are also a source of tryptophan—the precursor to serotonin, our primary “happy” neurotransmitter that affects both short-term mood and long-term cognitive function. When consumed, fermented foods also lead to the production of short-chain fatty acids in the gut, which can travel to the central nervous system and modulate neurotransmitter activity and promote memory consolidation.

Can Eating Fermented Foods Impact Longevity?

In addition to brain health, the consumption of fermented foods is also thought to support longevity. This association may be due to a myriad of factors, including their probiotic content, antioxidant and anti-inflammatory activity, or metabolic and neuronal effects. 

Although we don’t have many studies looking directly at fermented food consumption and lifespan, research from 2020 suggests that regular yogurt consumption is linked to lower mortality risk among women—especially when it took the place of red meat, processed meat, or non-fermented dairy.

Studies have also shown that semi-supercentenarians—people aged 105–109 years—have a significantly greater abundance of healthy bacteria in their guts, including Bifidobacterium, the probiotic found widely in fermented foods. 

Overall, fermented foods are an excellent way to get healthy probiotic bacteria without taking a pill—and may be a key factor for supporting both cognitive function and longevity as a whole. 

Reviewed by: Heather L. Makar

References: 

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Hogervorst E, Sadjimim T, Yesufu A, Kreager P, Rahardjo TB. High tofu intake is associated with worse memory in elderly Indonesian men and women. Dement Geriatr Cogn Disord. 2008;26(1):50-57. doi:10.1159/000141484

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