In the overall landscape of long-term health interventions, gut health is still an often ignored or dismissed subject. This is despite the fact that we have scientific evidence suggesting a direct link between the gut microbiome and digestion, cardiovascular health, immune system, and mental wellbeing. More recently, research had begun to examine the possibility of gut bacteria also having an effect on our cognitive health and the development of neurocognitive conditions like dementia and Alzheimer’s.
The more we learn about the ways our gut influences the brain via the gut-brain axis, the deeper the connection between what we eat and who we are becomes. With all the knowledge we have about the benefits of gut bacteria, one question remains unanswered - how can we effectively translate these findings into actionable health advice?
Among the most promising candidates for improving gut health are probiotics. Some studies are suggesting that taking probiotics or possibly even eating probiotic-rich foods can improve cognition or even slow down the progression of Alzheimer’s disease. A recent meta-analysis reviewed 294 studies from 1984 to 2021 and found that probiotics do, in fact, have a beneficial effect on neurodegenerative diseases. Read on to find out the specifics.
Related Article: 4 Surprising Ways Your Gut Affects You
How taking probiotics can improve gut health
Did you know that more than half of the human body weight consists of microbes? A big percentage of these beneficial microbes - around 5 pounds (2.7 kg) worth of them - live in the intestines, forming the gut microbiome. Every person’s microbiome is different, and researchers are now trying to work out which strains of bacteria are the most beneficial for our overall health and cognition specifically.
Probiotics are believed to be beneficial bacteria, and they exist not only in the human body but also in many fermented foods. The photo below lists the common food source of probiotics, and our article titled 7 Probiotics that Boost Your Health, Besides Yogurt, goes through most of these foods in detail. The idea is that eating probiotic-rich foods or taking food supplements that contain probiotics introduces beneficial bacteria into the intestines, strengthens the gut microbiome, and pushes out any harmful bacteria that might have taken up residence in the gut.
Read more about the benefits of probiotics, prebiotics, and synbiotics in this guide - Prebiotics & Probiotics: Benefits, Differences, and Sources.
What about cognition and dementia specifically?
The intestines are rich in nerves that regulate your digestion through signals to the spine and brain. These nerves are called the enteric nervous system, or the gut-brain. Researchers believe that an irritated and “unhappy” gut can also impact the brain, and they know that this is true because they have observed that things like a diet high in sugar can impair cognitive abilities and cause brain fog.
Some scientists also suppose that a gut microbiome that’s unbalanced or insufficiently diverse, can contribute to neurodegenerative conditions like Alzheimer’s disease. It is also believed to contribute to a condition called mild cognitive impairment (MCI) - a state between dementia and normal cognition in aging adults. Both conditions are characterized by problems with memory, thinking, and language. To test the idea that diversifying the gut can improve these cognitive issues in older adults, researchers have patients take probiotics and examine their cognitive functioning.
The previously-mentioned review article examined a great number of such studies and concluded that “probiotic supplementation considerably improved cognitive function in the participants with MCI, but it only caused a modest cognitive improvement in those with Alzheimer’s disease.” Therefore, taking probiotics can slow down the progression of these neurodegenerative diseases, especially if introduced when cognitive changes only begin to appear.
In addition, the researchers point out that taking probiotics improved the diversity of fecal microbiota in patients with Alzheimer’s disease. It is known that Alzheimer’s patients have a reduced diversity of microbes in fecal matter. Let us remind you that Alzheimer’s disease affects 6 million Americans and is the leading kind of dementia in the US. The causes of this disease are still unknown, so any new information that can get researchers closer to being able to treat or prevent this condition is extremely valuable.
Is there a recommended dose of probiotics?
Since research in probiotics is still relatively new, health organizations around the world don’t list any specific guidelines on how much or how often one should take probiotics. That said, the review study lists that the minimal dose listed in most of the studies they looked at was 1 x 10⁹ CFU (probiotics are measured in Colony-Forming Units (CFU), which refers to the number of viable cells), or about 1 billion per day.
While this can be helpful if you’re taking probiotic supplements, it’s difficult to say how many probiotics you took if you get them through your diet. In this case, your best estimation is how you feel. If drinking too much yogurt or eating too many pickles makes you feel bloated or upset your digestion in any other way, lower the dose.
Lastly, let us point out that you shouldn’t start taking probiotic supplements on your own. Even though probiotics are generally considered safe, older adults who want to take probiotics for cognitive health are more likely to experience gastrointestinal upsets, infections, or skin rashes than others. Therefore, you shouldn’t start taking probiotics without your physician’s supervision.
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H/T: Medical News Today
