Brain health: Probiotics, a healthy diet can support cognitive function

• A new review investigates whether influencing the makeup of the gut microbiome can improve brain health.
• In particular, it focuses on probiotics, prebiotics, dietary modifications, and faecal microbiota transplants (FMT).
• The authors concluded that modifying the gut microbiome may slow cognitive decline and improve brain health.
• This effect may be due to reduced inflammation in the brain, altered neurotransmitter signaling, and increased microbial metabolites.

If a nutritional or wellness trend becomes popular on social media, it’s best to remain skeptical. Most of the content shared is inaccurate at best and downright wrong at worst.

Gut health, however, bucks this trend. While gut microbes have become Internet darlings, evidence of their widespread importance in overall health continues to grow.

A new review on probiotics and cognitive health adds to this growing stack. The study appears in the Journal of Nutrition Research.

Although the authors call for more research, their results are positive. They found that modifying the gut microbiome may help older adults with early cognitive decline improve their thinking skills.

Overall, this is still a very young field, and much work needs to be done, but they concluded that “modulation of the microbiota is a promising therapeutic target that complements existing pharmaceutical and lifestyle interventions.”

A few decades ago, if someone had claimed that bacteria in the gut could slow cognitive decline or support mental health, it would have been considered fringe and likely raised a few eyebrows.

Today, it is not the least bit far. While understanding the exact relationship will take many years, it is now well within the realm of basic science.

Each of us harbors billions of microbes in our gut. They aid digestion, help us make vitamins, and produce an array of compounds that support our health.

We now know that they can communicate with the brain through several pathways, known as the gut-brain axis.

One of those lines of communication is the vagus nerve, which travels between the gut and the brain. Another is through compounds, such as short-chain fatty acids (SCFAs), that bacteria produce during fermentation of fiber.

SCFAs can directly stimulate the vagus nerve, but they can also travel through our bloodstream to the brain.

As we age, our cognitive abilities slow down. However, some decline faster than others, and some will eventually progress from cognitive decline to dementia.

As the population continues to age, understanding risk factors and lifestyle behaviors may become more important to reduce the burden. Some scientists are turning to the power of microbes.

Probiotics are live bacteria that, when consumed in sufficient amounts, provide health benefits. Anyone who has been to the store recently has likely seen probiotics in pills, shakes, toothpastes, and everything in between.

Overall, the evidence that store-bought probiotics support health is very weak, especially in people who are already healthy. Outside of some special cases—such as antibiotic-associated diarrhea—they have not shown much success in treating health conditions.

However, this is to be expected. There are hundreds of species of bacteria in the human gut, and each person’s microbiome is unique.

Even identical twins, who are essentially genetic clones, have distinct gut microbes. Therefore, it is not surprising that the addition of several types of microbes does not have a measurable effect for everyone.

However, this does not make the method useless. The more we know, the more likely we will find the strains, strains, or doses needed to produce specific benefits.

In addition to probiotic foods and drinks, other techniques are also popular. Prebiotics, for example, are essentially food for bacteria.

If you eat more prebiotics—such as dietary fiber—it will generally support the growth of “good” gut bacteria.

A recent review looked at a range of approaches to maintain cognitive health as we age: the use of probiotics, prebiotics, dietary interventions, and FMT. The authors also discuss the mechanisms through which it may be seen to protect cognitive health.

The review included data from 15 studies in 10 countries and more than 4,200 participants aged 45 or older. Here are their results:

The latter include B12, folate, choline and methionine. These compounds support functions such as gene expression and energy production.

Overall, the authors concluded that dietary interventions remodel the gut microbiome, increase production of SCFAs, and stabilize neurotransmitter networks.

They can improve cognitive health and reduce inflammation in the brain. This is important, because increasing evidence suggests that neuroinflammation plays a significant role Mental health disorders and cognitive decline.

In this category, the authors concluded that probiotics and synbiotics may improve verbal fluency and executive function, including working memory and cognitive flexibility.

They also found that these interventions increased gut microbiome diversity, which is a measure of microbiome health, and altered neurotransmitter pathways.

There are far fewer studies of FMT than other interventions, but the authors describe the results as “preliminary but surprising.”

The studies included in the review recruited people with Alzheimer’s disease. FMT was associated with faster changes in the gut microbiome than probiotics, synbiotics, or dietary interventions.

Importantly, the study also measured improvements in cognitive function and other measures of cognitive decline. However, further research is needed.

The results of this review are encouraging. They point to the possibility that we may one day modify the gut microbiome in such a way that we slow dementia and keep minds sharp as we age. However, we are not there yet.

The studies included in this review are mostly small and short-term.

Commercially available probiotics, as they currently stand, are not chosen solely because of their potential health benefits.

Instead, it is something that is considered safe for human consumption. This means that while some probiotics may improve brain health, they may not be available for sale.

As for FMT, it is not something that is easily accessible. This leaves dietary interventions, which we have more control over.

Today’s medical news spoke with Federica Amati, PhD, MPH, RNutr, about how to improve the health of our gut microbiome through food.

Amati, who was not involved in the review, is a medical scientist, registered public health nutritionist, and research fellow at the School of Public Health, Faculty of Medicine, Imperial College London, UK.

“In the UK and the US, most people don’t consume enough fibre. This directly affects the health of our gut microbiome: without fibre, our gut bacteria have nothing to eat,” she told us.

Fiber is found in essentially all plants, and Amati recommends eating 30 different plants a week. “This is important because there is a wide range of fiber types, and different microbes have different preferences. Consuming a range of plants ensures they are all supported,” she explained.

She also recommends limiting your intake of ultra-processed foods as much as possible. These products don’t have enough fiber to support the “good” microbes, but they have a long list of additives that can harm the microbes, and their sugar and fat content can also encourage the growth of “bad” gut bacteria.

Fermented foods are also a good choice. They naturally contain probiotics, often with a greater variety than commercially available probiotics. Fermented vegetables, such as kimchi or sauerkraut, are especially good because they are fermented plants, so they are naturally symbiotic.

– Federica Amati, PhD, MPH, RNutr