If you like yogurt, kimchi, sauerkraut, or other fermented foods, it’s not just your taste buds that are getting a treat. A new review that looked at fermented foods found that consuming them may be linked to improved brain performance. It’s not exactly shocking that there may be an association between brain health and the foods you eat, considering what we know about the gut-brain connection. But the research into the impact of fermented foods on the health of microbiota was significant enough to warrant more cognitive-focused research on the topic.

Why research fermented foods?

The review, which was published in the journal Neuroscience & Biobehavioral Reviews, looked at:

• the different types of fermented foods

• fermentation techniques

• the ability of fermented foods to affect the microbiota-gut-brain axis

• knowledge gaps and the challenges of conducting studies with humans

Why study fermented foods in particular? Because they contain bioactives from the original food (e.g., dietary fiber, polyphenols), probiotics (i.e., healthy bacteria), and post-biotics (metabolites created by the bacteria). These components can either contribute to the gut bacteria or stimulate action on the gut-brain axis.

“The net effect is to contribute to a healthier gut bacteria ecosystem that activates brain pathways,” explains Dr. William Li, author of “Eat to Beat Your Diet: Burn Fat, Heal Your Metabolism, and Live Longer.” “While research on exact bacteria-to-brain/brain-to-bacteria effects are still in their infancy, this gut-brain connection is associated with a wide variety of brain functions, such as memory, cognition, anxiety, depression, and overall mental health and wellness. There are many compelling correlations showing that dysbiosis (abnormal gut microbiome composition) is associated with depression, anxiety, dementia, Parkinson’s disease, and other neurodegenerative disorders.”

The Gut-Brain Connection

The published review noted that fermented foods directly impact the enteroendocrine system. Cells in this system produce a variety of gut hormones that play a role in coordinating digestion, food absorption, insulin secretion, and appetite. They affect hormones such as serotonin, ghrelin, neuropeptide-Y, and GLP-1. And although it’s known that prebiotics and probiotics increase the amount of GLP-1, more research is needed to understand how appetite is affected by fermented foods.

“Substances produced in the gut by bacteria can travel or send signals up large nerves, such as the vagus nerve, directly to the brain,” says Dr. Li. “[This can] trigger different brain activities that can alter mood, behavior, memory and cognition.”

Limitations of the review

There’s so much more to learn about the gut-brain connection, as well as the benefits of fermented foods, and the review mentions some of the limitations of current research. Here are a few examples:

• Clinical studies might not capture sex-specific differences.

• Clinical studies might not account for the diversity of the subjects’ diet, lifestyle, behavioral or genetic factors.

• Fermented foods differ across regions in terms of production, the storage environment, and how they’re consumed.

• Studies that involved a single bacteria don’t capture the full extent of the impact of fermented foods because of the various metabolites, bacteria and other small molecules present in the food that could also be playing an important role.

• Some of the research that the narrative review covered had poor methodology (e.g., inadequate controls), which the authors of the review pointed out.

MBJ

Wendy Burt-Thomas writes about the brain, mental health and parenting.

Check out the research:

https://www.sciencedirect.com/science/article/pii/S0149763424000307?via%3Dihub