A NOvel Approach to Improving the Oral Microbiome
The fascinating part of the story to follow is how much health benefit can be gained from only 10 days of consuming one superfood.
Nitric oxide (NO), which is produced in our bodies, is required to regulate vascular tone and neurotransmission. “Nitric oxide is produced by nearly every type of cell in the human body and one of the most important molecules for blood vessel health. It's a vasodilator, meaning it relaxes the inner muscles of your blood vessels, causing the vessels to widen. In this way, nitric oxide increases blood flow and lowers blood pressure.” (Source)
Reduced nitric oxide production is a benchmark of aging, and corresponds with impairment to the cardiovascular system and cognitive function. Precursors to nitric oxide are used therapeutically to treat a variety of ailments including erectile dysfunction, delayed-onset muscle soreness, hypertension, and symptoms of type 2 diabetes. The most commonly used precursors for nitric oxide production are L-citrulline, L-arginine, Pycnogenol, Neo-40, and beet juice.
Herein, we are going to examine a study done on beet juice, which showed benefits far beyond simply raising nitric oxide levels in the body.
When we eat a diet rich in vegetables, the good bacteria in our mouth takes the inorganic nitrate found in such foods, and turns it into nitrite, which then acts as a precursor to nitric oxide. Now, it has been well established that an unhealthy oral microbial community (oral microbiome), and poor dental health, are linked to “impaired cardiovascular and metabolic health”.
However, since the scientific community still has little understanding of how the oral microbiome can influence our health so dramatically, new studies are underway to explore this relationship. The study we are going to examine here, started with this idea: “One mechanism by which the oral microbiota may influence human health is its contribution to the production of the signalling molecule nitric oxide (NO), which regulates vascular tone, mitochondrial respiration and neurotransmission among many other functions.”
They go on to point out the proven health benefits to be found in the “Mediterranean diet”, and the “DASH” (Dietary Approaches to Stop Hypertension) diet, both of which are rich in vegetables that are “abundant in dietary nitrate”. Those proven health benefits include reduced blood pressure, improved skeletal muscle contractility and exercise efficiency, and enhanced brain and cognitive function. And this conversion of dietary nitrate into nitric oxide, via oral bacteria, is particularly important since the normal pathways for producing NO internally decline as we age, leading to “the development of arterial hypertension, reduced physical and cognitive functional capacity, and increased morbidity”.
According to the authors of this study, the link between the state of our oral microbiome and NO production has been established by “studies showing that use of bactericidal mouthwash acutely reduces systemic NO bioavailability and elevates blood pressure, and that chronic, frequent use of mouthwash is associated with elevated risk for type II diabetes”.
Isn’t that interesting? Clearly information to take into account when choosing a mouthwash (i.e. don’t use one that is antibacterial, but rather, if you must, use a mouthwash that simply freshens the breath).
“The purpose of this study was to determine 1) which co-occurring modules of bacteria in the salivary microbiome of healthy older people were sensitive to dietary nitrate intake, 2) which co-occurring oral microbiome modules correlated with cognitive and physiological traits across dietary interventions with placebo and nitrate, and, 3) which nitrate-sensitive modules represent key biomarkers, and thus probiotic targets, for enhancing cardiovascular and cognitive health.”
Thirty older people were followed for 10 days, in which some were given “dietary inorganic nitrate (nitrate-rich beetroot juice) or placebo (nitrate-depleted beetroot juice) supplementation in a randomised, placebo-controlled crossover design”. There are a variety of oral microbiome “modules”, or clusters, found consistently across a wide variety of people, irrespective of age and ethnicity: “The most consistently identified modules include the Prevotella-Veillonella, Neisseria-Haemophilus, and Streptococcus-Rothia clusters.”
The study we are examining here was considered to be successful because they “showed that it was possible to manipulate the relative proportions of these ‘universal’ oral microbiome clusters via a simple, short-term dietary nitrate supplementation in a population of 70–80 year-old individuals who followed their habitual omnivorous diet throughout the study”.
What specifically happened to the oral microbiome, after 10 days of receiving beet juice, was that “the Prevotella-Veillonella cluster was diminished, while the Neisseria-Haemophilus and Streptococcus-Rothia clusters thrived”.
Now, what does this mean in layman’s terms?
Well, the Prevotella-Veillonella module has been associated with negative health states including systemic inflammation, gum disease, pneumonia, and dysbiosis (digestive disturbances including gas, bloating, constipation, or diarrhea). So, clearly, reduction in this oral microbiome cluster is a good thing. And, if the Prevotella-Veillonella module is the bad guy, the other two are the good guys.
For example, those with a healthy amount of Neisseria-Haemophilus clusters have good gum health (remember poor gum health is associated with a variety of diseases), and a lower body mass index (they are of a healthy body weight). Neisseria-Haemophilus clusters are found in abundance in those who are young, those who do not smoke tobacco, and in vegans (due to their high intake of nitrate containing foods, specifically vegetables).
“Collectively, this ecosystemic shift following dietary nitrate supplementation away from Prevotella-Veillonella and towards dominance by Neisseria-Haemophilus and Streptococcus-Rothia modules, may have positive implications for oral and systemic health.”
This shift in bacterial dominance in the oral microbiome was accompanied by “beneficial changes in systemic NO bioavailability, blood pressure, O2 cost of walking, and sustained attention that were indicative of improved cardiovascular, metabolic and cognitive function”. (The “O2 cost of walking” is a measurement of physical health: the less oxygen you require for exercise the healthier you are.)
As well, the beet juice, and corresponding improvement in the oral microbiome, led to a decrease in relative abundance of pathogenic Clostridium difficile bacteria. C. difficile is a bacterium that causes severe diarrhea, and can lead to colitis. Most cases occur following antibiotic use and it can be life-threatening in some people. In fact, one in 11 people over age 65 diagnosed with a C. difficile infection, die within one month. (Source)
This would suggest that following antibiotic use it would be a good idea to consume beet juice (for around 10 days).
For a scientist, “the first signs of cognitive decline predominantly manifest as deficits in executive function, sustained attention, and information processing speed”. In this study, even within the brief 10 day period, those receiving beet juice showed improved sustained attention. And, those with reduced Neisseria-Haemophilus clusters had poorer information processing speed. Furthermore, “the known periodontal pathogens Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia that have emerged as correlates of cognitive decline and Alzheimer's disease...diminished after nitrate supplementation”.
All of which indicates that improving the oral microbiome may be a form of intervention that can be used to delay the progression of cognitive decline. And, since attention improved after only 10 days on beet juice, it may very well also serve to reverse some of the symptoms of cognitive decline. (Study)
This study concluded by suggesting that we cannot waste too much time focussing on single bacterium, “because the gene expression and signalling cascades of a given bacterial species are modulated by its co-inhabitants in the collective microbial ecosystem”.
Thus, we need to ensure a wide range of good bacteria thrive in both our gut and oral microbiomes, along with supporting them through the use of prebiotics (soluble fiber, Lactospore, fermented foods), and nitric oxide producers like beet juice.
The study we have examined here, while quite detailed, did not disclose the amount of beet juice the subjects consumed. So, I looked elsewhere for a clue and found that, according to Healthline.com, “one study showed that drinking 3.4 ounces (100 ml) of beetroot juice significantly increased nitric oxide levels in both men and women”. Therefore , a safe bet would be about half a cup of beet juice once or twice per day.
Dried beet juice powders are available for the convenient approach. For example Salus makes a crystalized organic beet juice product that is of the highest quality. (I mention quality here because almost all fruit and vegetable juices that are dried, are spray dried onto a medium that is usually maltodextrin, a form of sugar.) Another company, Biotta, has a bottled beet juice, from Europe that is absolutely delicious (whereas the beet crystals are okay but not exciting, tastewise).
Of course, fresh beet juice is ideal, as here we also take advantage of the live enzymes (not present in dried or bottled products). However, beets can be prone to contamination with mold, so to be on the safe side, I advise soaking the beets in a 3% solution of hydrogen peroxide for about 5 minutes (or if you do not want to use up that much peroxide, just wipe each beet down with peroxide and let them sit for the same amount of time). Then rinse with water before juicing.