Welcome to Straight Talk on Health. I’m your host Dr. Chet Zelasko. Straight Talk on Health is a joint production with WGVU in Grand Rapids MI. I examine the practical application of health information. Nutrition. Exercise. Diet. Supplementation. I look at the science behind them, and let you know whether it’s something to consider or not. You can check out other things that I do on my website Drchet.com and sign up for my free emails.
If there is one thing we would all like for ourselves and others, it would be to retain as much of our memories as we can as well retain all of the things we’ve learned over our lifetime. Maybe we’d also like the ability to learn new things, like how to make a doll house for our granddaughter, how to bake our favorite dessert, even learn how to write code for a computer. In order to do that, we have to do the things we can to keep our brain functioning properly.
At this point, about 15% of older adults have mild cognitive impairment (MCI). By definition, MCI is a condition in which people have more memory or thinking problems than other people their age. The symptoms of MCI are not as severe as those of Alzheimer’s disease or a related dementia. People with MCI can usually take care of themselves and carry out their normal daily activities. However, MCI is the largest risk factor for the development of dementia or Alzheimer’s disease.
There are no specific risk factors for MCI. That could mean that there are most likely some genetic factors involved. However, some of the potential risks include concussions or other head trauma earlier in life, alcohol abuse, strokes, both hemorrhagic and obstructive, emotional issues such as depression, and even reactions to medications. It doesn’t mean that if you had one concussion earlier in life you will get MCI. However, as has been shown with repeated head trauma and concussions in football players, it is possible to accelerate MCI and dementia-like symptoms.
But you may not have known about this one. There is a known relationship between periodontitis and a decline in cognitive function. Periodontitis is an inflammation of the gums. Whenever you here a word with -itis at the end, it means inflammation, in this case, of the gums. Pockets form and bacteria can enter the blood stream. Bacteria can travel through the bloodstream under normal conditions but as long as favorable bacteria outnumber the negative, that can keep inflammation contained and limit damage in other parts of the body including the brain.
Researchers wanted to examine the difference in oral bacteria between 120 subjects, half of whom had MCI and control subjects who had normal cognitive function. They also wanted to test the difference between a sub-group who had the APOE4 gene and those that did not. The reason for the later comparison is that persons with the APOe4 gene have a greater risk of developing Alzheimer’s Disease before the age of 65 years. To say this was a complicated study, from the techniques used in assessing bacterial content of the mouth, the associated genes, and the statistical approaches used, is an understatement. Let me explain it in as simple terms as possible because the potential solution is absolutely understandable.
A little more about why the type of bacteria are important. Two potential reasons: Negative bacteria could enter the bloodstream due to periodontal disease and travel to the brain and cause problems. The other way that negative bacteria would wreak havoc is to replace the positive nitrate-reducing bacteria with a negative form of nitrate reducing activity. I know it seems like “Who cares?” as long as they do their job. It just makes a difference. If the potential for sending the nitrates to the brain to make nitric acid is impacted, that’s a problem. NO increases blood vessel dilation which is beneficial. Also, the NO is helpful to keep the synapses functioning and the cells viable. Also desirable.
Here's what they found. They found there was a greater prevalence of the oral Prevotella bacteria which was linked to the elevated genetic risk for dementia (APOE4) in individuals with MCI prior to dementia diagnosis. Could the presence of the bacteria indicate the presence of the gene in those who have not had genetic testing for that APOE4 gene? Perhaps but the test for bacteria is not commonly available while genetic testing for APOE4 is. They also suggest that interventions that can increase the oral production of Neisseria–Haemophilus and suppress the Prevotella-bacteria have the potential for delaying cognitive decline. More later.
They also found that the oral Por-phy-romonas genus was associated with MCI and that the abundance of Prevotella intermedia was a predictor of the APOE4 carrier status. That means that the association with this bacteria, prevotella, may indicate the APOE4 presence. The next finding is related to the positive-negative bacterial balance. The balance between two metabolic pathways for oral nitrate reduction, denitrification, and dissimilatory nitrate reduction to ammonia AKA (DNRA) was skewed toward DNRA in MCI. What does that mean? It leads to a potential solution for how cognitive decline could be delayed or prevented using prebiotic and dietary means.
Further, they suggest that there is a need to test dietary nitrate in individuals at the early stages of cognitive decline as an increase in dietary nitrate may help reverse the rise in oral Prevotella:Neisseria ratio. That may delay the onset of MCI and possibly AD. Okay. How about all of this in plain English.
What it means is that increasing vegetable intake, the primary source of nitrates in the diet. But that’s not all. You also have to increase whole grains as they contain prebiotics, which feed the healthy probiotics. At the same time, decreasing simple carbohydrates and sugars decreases the source of food for the negative probiotics. What kind of diet does that sound like to you? The ketogenic diet? Probably not as the lack of healthy carbohydrates may be too low to do any good. The one that comes to mind is the Mediterranean Diet or a localized version of it. It focuses on vegetables, fruits, whole grains, high fiber legumes and nuts. One more thing? Decreasing the intake of ultra-processed food and simple sugars also is beneficial for growing the positive bacteria. Eating that way could change the beneficial nitrate-reducing bacteria to help the brain use the nitrate to make NO. That’s the dietary way to protect your brain from MCI and potentially other brain damaging conditions as well. No matter how much we try to ignore it—your mother was right—eat all your veggies. I’ll throw one more thing in: take care of your teeth and gums by brushing regularly and flossing every day.
That’s it for this episode. If you like this podcast, please hit the like button and tell your friends and colleagues about it. Until next time, this is Dr. Chet Zelasko saying health is a choice. Choose wisely today and every day.
Reference: PNAS Nexus 2025:4 543
