Unlocking oral-gut health optimization [Part 1 of the 21-day challenge]
The two-a-day nitrate-rich veggie challenge
Last weekend my teen daughter was desperate to find her wallet. She searched the house up and down and then called us in to help. I wasn’t home, but my husband started by asking when she had them last. He wanted her to start at the beginning.
Sure enough, he found her wallet on her bed, hidden under the covers. That day, she had come home, went straight to her room, and put it on her bed. And it was the last place she planned on looking.
When we think of gut health, we need to start at the beginning too. The food we ingest goes through a lot before it reaches the intestines. And science is discovering this is a missing key to optimizing gut health–especially for midlife women.
Welcome to our first midlife health challenge! Before we get into the challenge, let’s review important information so we understand our why for doing it.
Why gut health?
Interest in gut health’s relationship with heallth and disease has grown tremendously over the past few decades. More specifically, the trillions of microbes that inhabit it.
Dysbiosis, the disruption of these organisms, can weaken the immune system and raise the risk of various health issues. Through the gut-brain axis, the health of our GI tract also plays a key role in mental health.
This is vital at midlife because aging and hormonal changes (aging pause), increase the risk of microbial dysbiosis, thus negatively affecting health in a myriad of ways.
Additionally, these changes affect the absorption and utilization of micronutrients, further influencing health and well-being.
In view of this complex inter-kingdom relationship, it is conceivable that the disruption of the gut microbial ecosystem, either in number, diversity or functional capacity (i.e., dysbiosis) may have a major impact on human welfare and health.
- Rocha and Laranjinha, Free Radical Biology and Medicine, Volume 149, March 2020, Pages 37-43
Plus, my readers voted for gut health as the topic for the first midlife challenge. And I’m so glad because it’s the perfect starting place.
Let’s start at the beginning– the oral microbiome
The digestive tract contains the greatest number of bacteria among the trillions that live in the human body. But the second in line is the oral cavity.
Similar to the missing wallet story, most of the research first focused on the microbiome in the small and large intestines and not the starting point (the mouth).
Until recently, researchers believed that in healthy people, there was no overlap between the oral and intestinal microbiomes, and that 99% of the microbes that traveled from the mouth to the stomach died due to the acidic environment known as the mouth-gut barrier.
Researchers from European Molecular Biology Laboratory (EMBL) set out to question this assumption, analyzing 750 saliva and stool microbial communities from equal amounts of healthy people and individuals diagnosed with either colon cancer, rheumatoid arthritis, and type 1 diabetes.
The results showed that a significant number of oral bacteria, roughly one in three salivary microbial cells, colonize the gut in individuals, although individual amounts vary. The researchers conclude:
This puts oral-fecal transmission well in the range of other factors that determine human gut microbiome composition.
Meet your oral microbiome
The oral cavity has a diverse microbiota of 700 species. It’s home to aerobic and anaerobic bacteria, fungi, Archaea, and viruses that cover a space that is larger than the palm of your hand.
These organisms organize themselves into communities called biofilms and interact with each other, influencing both health and disease.
A healthy and diverse oral microbiome decreases the risk of oral and systemic diseases and, more recently, researchers have found that it affects the health of the gut. But when there is dysbiosis of the oral microbes, the opposite is true.
Having adequate levels of nitrate reducing bacteria (NRB) not only helps keep the bad guys at bay, but it also increases the ability of the body to make nitric oxide (NO), the magic midlife molecule, through the nitrate-nitrite-NO pathway. I go into detail in this post but here’s an excerpt:
After ingesting nitrates from food (excellent sources: leafy greens, celery, and beets) bacteria reduces nitrate to nitrite. Acid in the stomach further reduces nitrite to NO, where it then goes into circulation.
NRB species of bacteria include Veillonella, Actinomyces, Haemophilus, Rothia, and Neisseria. They exist in large concentrations on the dorsal of the tongue.
Decreased quantity of oral NRB increases pathogenic bacteria, raising the risk of chronic periodontitis and cardiovascular disease.
In a figure from 2023 series on mouthwash and the oral microbiome in the International Dental Journal, you can observe the difference between its functioning in a healthy state (eubiosis) versus when it's imbalanced (dysbiosis).
Inorganic nitrates to save the day
We can maintain healthy levels of NRB by boosting our dietary intake of nitrates. Nitrates are compounds of nitrogen and oxygen and 85% of nitrates in our diets come from vegetables.
The reputation of nitrates and nitrites is tarnished because of their presence in processed meat, which can produce cancer-causing N-nitroso compounds (NOCS) during digestion.
Yet nitrates from vegetables contain antioxidants (Vitamin C and E) and polyphenols suppressing the formation of NOCs, which is a key reason vegetables don’t carry the same risk.
Consuming nitrates from plant foods is associated with the following benefits:
Nitrates provide an alternative way to make NO. This is important as aging pause can decrease the body’s ability to make it.
NO has a well-established protective effect on the GI tract.
Nitrates help increase levels of NRB, which researchers have also linked to lower blood pressure and insulin resistance.
Adequate NRB, further improves oral health, salivary function, and optimizes Ph
Emerging evidence suggests that nitrates have a protective effect on the stomach by promoting gastric blood flow and increasing mucus production.
Researchers have proposed that nitrates, through the nitrate-nitrite-NO pathway, help regulate inflammation by reshaping gut microbes.
Nitrate Blockers
It’s important to quickly note factors that can impede dietary nitrates from working the way they should.
First, increased plaque, tongue coating, and oral diseases decrease the amount of NRB. Good oral hygiene and regular dental visits are a must.
Second is mouthwash made with chlorhexidine. Although it kills bad bacteria, it works like antibiotics do on the gut–it kills the good bacteria, too, as stated in this review on the subject:
The use of 0.12% CHX mouthwash may destroy more than 90% of oral nitrate-reducing bacteria with a resultant 85% reduction in the proportion of reduced nitrate. Several human studies have confirmed the association between the frequent use of antimicrobial mouthwashes and an increase in systolic blood pressure ranging from 2 to 5 mm Hg accompanied by a significant reduction in both salivary and plasma nitrite levels.
In fact, a three-year longitudinal study found that daily use of mouthwash was an independent risk factor for the development of pre-diabetes, diabetes, and hypertension, including those with no risk factors.
Last is the use of proton pump inhibitors and over-the-counter antacids. They pose an issue as they counteract stomach acid, which is necessary for the last step in the nitrate-nitrite-NO pathway.
These medications are supposed to be temporary, so if you are on them, work with a healthcare provider to find root cause behind digestive issues. It should not surprise us that a recent review linked their use with elevated blood pressure.
Now onto the challenge!
The two-a-day nitrate-rich veggie challenge
Nathan Bryan, a nitric oxide expert, has spent almost ten years advocating for nitrate to be recognized as a dietary nutrient. Unfortunately, most recommendations are still stuck on the risk of toxicity in processed meats and ignore the benefits to health from plant foods.
For instance, the WHO ADI for nitrates is only 0-3.7mg/kg body weight, which is about 222mg nitrate for someone about 60kg. According to a report by Bryan and Ivy, humans experience toxic levels at a dose of 22-23mg/kg body weight, which is approximately 150 times higher than what is typically used.
In the meantime, we can use common sense. Most people in the US get 40-100 mg/day of nitrates and it’s estimated that 5 servings of fruits and vegetables gets you to 157 mg.
Yet the DASH diet, which provides even more vegetables containing nitrate levels upwards of 1000mg! Experts and supplementation studies suggest around 300-400mg nitrates per day for optimizing health, but there are no official guidelines.
For this challenge, aim for two servings a day of nitrate-rich vegetables (middle to very high) with one being leafy green sources (spinach, arugula, and lettuce).
You can download my PDF of nitrate food sources and 21-day calendar to write notes and mark off the days.
The two-a-day nitrate-rich veggie challenge can be as easy as making a big spinach salad at lunch and including celery with peanut butter for a snack.
Or having arugula salad with dinner and roasted beets at lunch. Follow me on Instagram as I post some simple recipes all week.
Here’s a fun fact. Lettuce has more nitrates than kale, so add it to sandwiches and use it as wraps.
Also, remember to watch out for those nitrate blockers, so the nitrates you eat increase NRB and get turned into NO. One study has also shown that using a tongue scraper helped.
Don’t forget to share your experience in the comments. This can include a favorite recipe or strategy that worked for you!
Maryann, I just love all your work in this space! As a 50+ woman, I really appreciate your thorough research and deep dive explanations on this and so many other important health topics concerning older women-- so thank you! ❤
I do have a question concerning leafy greens... every day I include almost 1 cup of FROZEN spinach (or kale) into my smoothie, soup or sauce to boost my daily veggie intake. The frozen version of leafy greens in my freezer stay good SO much longer than a bag of fresh greens in the frig, which starts rotting in 3 days. :(
My question is: do frozen leafy greens contain as much nitrate (or near) the same amount as fresh leafy greens? {fingers crossed, lol!}