Show Notes
A follow up Q&A to the nitric oxide deep dive earlier in the week with Dr. Nathan Bryan. Dr. Ravi Kumar picks five of the most thoughtful listener questions and does a mini deep dive on each, tying together the key themes from the full episode and filling in a few of the practical and biological gaps.
If you listened to the Nitric Oxide conversation with Dr. Nathan Bryan earlier in the week and walked away with more questions, this is the follow up. Dr. Kumar walks through whether two decades of mouthwash damage can actually be undone (it can, and fast), why eating your greens may not be enough in a world of soil depletion and nitrate variability, the clinical reality of long term acid suppression and how PPIs sabotage the entire nitric oxide pathway, why the cured meat cancer story most doctors learned in training is built on chemistry that the FDA fixed in 1972, and the symptom hierarchy that tells you when you are running low on nitric oxide. He closes with the converging evidence that fluoride in drinking water lowers children’s IQ.
In this episode, you will discover:
- Why two decades of mouthwash damage is reversible: Dr. Bryan’s team’s 2019 paper on 26 healthy people showed chlorhexidine twice a day for seven days predictably raised blood pressure and crushed the nitrate reducing bacteria. Within just a few days of stopping, blood pressure normalized and bacterial diversity rebounded, sometimes to a healthier baseline than the start
- What to actually do: Stop the mouthwash, switch off fluoridated toothpaste if you can, and wait about a week. Many people notice better energy and workouts within days. Newer nitric oxide friendly toothpastes and rinses are designed to support these bacteria instead of nuking them
- Why eating leafy greens may not be enough: Dr. Bryan’s 2015 retail vegetable survey across five US cities found nitrate content varied so much between regions that the authors said geographic differences may undermine any attempt to estimate dietary nitrate intake. Soil depletion compounds the problem: USDA data from 1950 to 1999 showed statistically significant declines in protein, calcium, phosphorus, iron, riboflavin, and vitamin C
- The case for targeted supplementation: If you use mouthwash, fluoridated toothpaste, or an antacid, the downstream conversion from nitrate to nitrite to nitric oxide is disrupted regardless of how much spinach you eat. Dr. Bryan’s framing: the two people who should supplement are people who are sick and want to get well, and people who are well and don’t want to get sick
- Why PPIs shut down nitric oxide production: Stomach acid drives the final step that converts salivary nitrite into nitric oxide gas. Shut down the acid, shut down the pathway. This is established biochemistry, not opinion. PPI users also show significantly higher all cause mortality than H2 blocker users, with risk increasing the longer they stay on the drug
- The low acid paradox: A lot of reflux is actually caused by low stomach acid, not high. Acid is what triggers the lower esophageal sphincter to close. When acid is low, the sphincter doesn’t close properly and what acid is there splashes up. So acid blockers can treat the symptom while worsening the root cause
- Why the 1956 cured meat scare is outdated: The original British Journal of Cancer paper showed nitrite cured fish could form nitrosamines, which are real carcinogens. But about 85% of dietary nitrate comes from leafy greens, not meat. If nitrate itself caused cancer, vegetarians would have higher cancer rates than meat eaters. They don’t, it’s the opposite
- What changed in 1972: The US government required nitrite cured meats to include ascorbic acid (vitamin C) or erythorbate, both of which block the chemistry that forms nitrosamines. Modern surveys confirm essentially undetectable nitrosamine levels in cured meats today, far below what the National Academy of Science reported in 1981
- The “uncured bacon” irony: No nitrite added bacon is made with celery powder plus a bacterial culture that converts the nitrate to nitrite anyway, just less controllably, often without the ascorbic acid that blocks nitrosamine formation, with shorter shelf life and double the price
- The symptom hierarchy of nitric oxide deficiency: Sexual dysfunction first, called the canary in the coal mine because the smallest blood vessels fail first. JAMA 2005 confirmed erectile dysfunction is an independent predictor of cardiovascular events. Then elevated blood pressure, insulin resistance, exercise intolerance, and at the far end, mild cognitive impairment progressing toward Alzheimer’s
- Why some researchers now call Alzheimer’s type 3 diabetes: A landmark 2008 paper by de la Monte and Wands laid out the case based on insulin resistance and hypoperfusion in the brain
- Nitric oxide really does decline with age: A 1994 JACC paper using ultrasound flow mediated dilation showed endothelial function declines progressively with age. A 2001 Hypertension paper directly measured nitric oxide bioavailability and confirmed it drops substantially with age. By the sixties or seventies, the average person is running on a fraction of what they had in their twenties
- The fluoride and IQ evidence is converging: The 2024 National Toxicology Program report linked fluoride exposure to lowered IQ in children. A 2025 JAMA Pediatrics meta analysis of 74 studies found a statistically significant inverse association that held up even when restricted to the highest quality studies. In September 2024, a federal court ruled that water fluoridation at US Public Health Service recommended levels poses an unreasonable risk to children’s health
Key Takeaways
- Twenty years of mouthwash damage is not a permanent sentence. The oral microbiome rebounds within days of stopping the antiseptic exposure
- In a world of soil depletion, regional nitrate variability, and ubiquitous downstream blockers (mouthwash, fluoride, antacids), targeted nitric oxide supplementation is a reasonable strategy for most people, even alongside a clean diet
- PPIs are blunt instruments designed for two to eight weeks of use. The downstream cost includes shutting off nitric oxide production and a measurable mortality signal. Many cases of reflux are driven by low acid, not high, so acid blockers can mask and worsen the underlying problem
- The cured meat cancer story most doctors learned in training is built on chemistry that the FDA addressed in 1972 by requiring ascorbic acid in nitrite cured products. Modern cured meats have essentially undetectable nitrosamine levels
- Sexual dysfunction is the earliest warning sign of endothelial failure and a documented predictor of cardiovascular events. If you’re over 40, on a standard American diet, using mouthwash, fluoridated toothpaste, or an antacid, you almost certainly need to address nitric oxide
- The science on fluoride and children’s neurodevelopment is no longer fringe. The NTP report, the JAMA Pediatrics meta analysis, and a federal court ruling are all pointing the same direction
If you have not yet listened to this week’s main episode with Dr. Nathan Bryan, Nitric Oxide: The Essential Molecule for Life & Longevity, start there. This Q&A builds directly on those concepts.
Restore Your Nitric Oxide: Shop Dr. Bryan’s nitric oxide releasing lozenges and oral care line at https://tidd.ly/4tsnbEI (use code KUMAR10 for a discount).
Transcript
[00:00 –> 00:23] Dr. Ravi Kumar: Welcome back to The Dr Kumar Discovery podcast. I’m Dr. Ravi Kumar. Earlier in the week, I interviewed Dr. Nathan Bryan on the biology of nitric oxide and how it fits into human health and wellness, and I got a bunch of very thoughtful questions. So I picked five of the best ones to do little mini deep dives on. I think this will tie together most of what we learned earlier. So let’s get into it.
[00:24 –> 00:44] Dr. Ravi Kumar: Okay. The first question is, I’ve been using mouthwash twice a day for 20 years. Is the damage permanent, or can my oral microbiome actually recover? This is a great question, and the good news here is that the answer is yes, you can recover, and it happens pretty fast. The key paper on this was published by Dr. Bryan’s team in 2019.
[00:44 –> 01:21] Dr. Ravi Kumar: They took 26 healthy people and did a baseline measurement of their blood pressure and their oral microbiome. Then they had everyone use chlorhexidine mouthwash twice a day for seven days, and predictably, blood pressure went up and the nitrate reducing bacteria took a big hit. But here’s the interesting part. Then they had everyone stop the mouthwash, and then they remeasured after just a few days. Within that short window, their blood pressure normalized, the bacterial diversity on the tongue actually came back, and in some cases, the community looked healthier than it was originally at baseline.
[01:22 –> 01:53] Dr. Ravi Kumar: These bacterial communities are remarkably resilient. They’re basically waiting for the chance to repopulate. So what this means practically for you is that you should stop using mouthwash and switch away from fluoridated toothpaste if you can, then wait about a week. Many people notice the difference in energy and workouts within days. And now, there are actually nitric oxide friendly toothpastes and mouth rinses that are being developed specifically to support these bacteria instead of nuking them, which is what happens with the traditional mouthwashes.
[01:53 –> 02:15] Dr. Ravi Kumar: This paper that I talked about is open access, so if you want to read it for yourself, just search Tribble, that’s T R I B B L E, Bryan, Tongue, Microbiome, 2019, and you’ll find it.
[02:15 –> 03:10] Dr. Ravi Kumar: Okay, next question. I already eat a ton of leafy greens, and I exercise regularly. Do I really need to supplement with nitric oxide? So this is a very common question. I had this question myself. In a perfect world, diet and lifestyle alone should be enough. The human body is designed to do its job when you give it what it needs. But here’s where reality doesn’t work with that concept. Dr. Bryan’s group published a paper in 2015 titled A Survey of Nitrate and Nitrite Concentrations in Conventional and Organic Labeled Raw Vegetables at Retail. So what they did is they basically bought 194 samples of broccoli, cabbage, celery, lettuce, and spinach from five major US cities. They brought them all back to their lab, and they measured the nitrate content. And the variability between these vegetables from different parts of the country was significant. The authors specifically noted that these geographic differences may actually undermine any attempt to estimate dietary nitrate intake because you just can’t predict what you’re getting.
[03:10 –> 04:08] Dr. Ravi Kumar: And then on top of that, soil depletion is a real problem. There’s a well cited analysis that tracked USDA nutrient data from 1950 to 1999 and found statistically significant declines in protein, calcium, phosphorus, iron, riboflavin, and vitamin C. The modern food supply is simply less nutrient dense than what our grandparents ate. So that being said, some people might be getting enough nitrate from food. But if you’re using mouthwash, if you’re using fluoridated toothpaste, or if you’re taking an antacid, you disrupt the downstream conversion steps that turn nitrate into nitrite, which turns into nitric oxide. Your body essentially can’t turn dietary nitrate into usable nitric oxide. So the foundation is still diet and lifestyle. I always believe that with everything. But you have to be realistic, and for most people in our modern environment, targeted supplementation makes a lot of sense.
[04:08 –> 04:42] Dr. Ravi Kumar: I really like Dr. Bryan’s quote on this. He said, there are two people who should supplement with nitric oxide supplements: people who are sick and want to get well, and people who are well and don’t want to get sick. That’s pretty much everyone. But still, I certainly wouldn’t be opposed to trying it naturally with the most nutrient rich vegetables you can find and then just seeing how you feel. I think that’s a reasonable strategy.
[04:42 –> 04:55] Dr. Ravi Kumar: Okay, next question. I’ve been on a PPI for acid reflux for years. Dr. Bryan said antacids block nitric oxide production. Am I stuck? Okay, this is a real clinical dilemma, and I want to be careful here. Please don’t stop any prescription medications without talking to your doctor first. This is educational and not medical advice.
[04:55 –> 05:42] Dr. Ravi Kumar: On that note, I did do a full podcast on GERD and how to wean off proton pump inhibitors when appropriate. That’s definitely worth a listen if you’re blocking your acid production with a drug. So let’s talk about the mechanism here. Your stomach acid is what drives the final step that converts salivary nitrite into nitric oxide gas. If you shut down the acid production in your stomach, you shut down that whole pathway. And this isn’t just Dr. Bryan’s opinion, this is actually established biochemistry. There’s also growing literature on the broader harms of long term PPI use. This is something I’ve talked about a lot. In fact, they’ve shown that PPI users have a significantly higher risk of all cause mortality compared to H2 blocker users, with the risk increasing the longer these people stayed on PPIs.
[05:42 –> 06:18] Dr. Ravi Kumar: PPIs were designed for short term use, originally two to eight weeks, but most people end up on them for years or decades. And then here’s one other thing you should probably know about acid production in your stomach. A lot of reflux cases are actually caused by low stomach acid, not high stomach acid. You see, acid triggers your lower esophageal sphincter to close. So when you have low acid, that sphincter doesn’t close and the acid splashes up into your esophagus causing pain. So acid blockers are essentially treating the symptom and worsening the root cause.
[06:18 –> 06:37] Dr. Ravi Kumar: So try listening to that episode I did on GERD and work with your doctor. Getting acid production back in your stomach can transform your whole body and bring nitric oxide production back online.
[06:37 –> 07:07] Dr. Ravi Kumar: Okay. Next question. My doctor told me cured meats cause cancer, and I should never eat bacon or deli meat. Dr. Bryan said the opposite. Who’s right? Okay, so this is a good question, and it’s a fascinating one, because it’s a perfect example of how medical dogma can persist long after the underlying science has been totally figured out. The origin of the cured meat scare traces all the way back to 1956, when a paper in the British Journal of Cancer showed that nitrite cured fish could contain compounds called nitrosamines, which are genuine carcinogens.
[07:07 –> 07:34] Dr. Ravi Kumar: Dimethyl nitrosamine, in particular, causes liver cancer in animal models, and that’s a real finding. Then in the 1970s and 1980s, nutritional epidemiology studies linked cured meat consumption to slightly higher rates of stomach and esophageal cancer. That’s the foundation of what most doctors were taught. And for years, I did not eat cured meat because I thought it would cause stomach and esophageal cancer. But the science has evolved substantially.
[07:34 –> 08:17] Dr. Ravi Kumar: Dr. Bryan published a rigorous risk benefit analysis in the journal Nitric Oxide in 2010, where he laid out several problems with the original hypothesis. First, about 85% of the nitrate and nitrite that we consume comes from green leafy vegetables, not cured meats. If nitrate itself were the problem, vegetarians would have massively higher cancer rates than meat eaters, but they don’t. It’s actually the opposite. And second, in 1972, the US government changed the code of federal regulations to require that nitrite cured meats include ascorbic acid, which is vitamin C, or its analog, erythorbate, which blocks the chemistry that forms nitrosamines in the first place.
[08:17 –> 08:54] Dr. Ravi Kumar: Studies looking at residual nitrite and nitrosamines in modern cured meats show essentially undetectable levels of nitrosamines. Dr. Bryan’s group has published multiple surveys confirming this, including a national survey of nitrite and nitrate concentrations in cured meat products that found levels substantially lower than those reported by the National Academy of Science back in 1981 when this whole scare was going on. And then third, your body concentrates nitrate in your saliva and reabsorbs it in your kidneys. Evolution doesn’t design elaborate machinery to recycle a toxin. It does that for nutrients.
[08:54 –> 09:35] Dr. Ravi Kumar: And here’s the irony, that uncured or no nitrite added bacon that a lot of health conscious people buy, including myself, is made with celery powder, plus a bacterial culture to convert the nitrate to nitrite synthetically. So it has nitrite anyway. It’s just made in a less controlled way, and usually without the ascorbic acid that blocks the nitrosamine formation, with more bacterial variability, shorter shelf life, and often double the price. The WHO classification of processed meats as carcinogens is based on old epidemiology that many in the field now consider fundamentally flawed.
[09:35 –> 10:03] Dr. Ravi Kumar: The science has moved, but the recommendations haven’t fully caught up. So, to be completely honest on this one, this definitely caught me by surprise. This is one of those examples where conventional dogma still had my mind trapped in flawed thinking because I hadn’t gone to the literature and looked it up myself. So investigate it yourself and be informed because doing that will unlock the truth on a lot of these things.
[10:03 –> 10:48] Dr. Ravi Kumar: Okay, so next question. How do I know if I’m actually nitric oxide deficient? Is there a test? This is a great question, and there are a few different angles here. First, listen to your body. Dr. Bryan described a hierarchy of symptoms, and there’s solid literature backing this order. The first sign is usually sexual dysfunction. He called it the canary in the coal mine, and that’s not hyperbole. There’s a well known study published in JAMA in 2005 showing that erectile dysfunction is an independent predictor of cardiovascular events because the small blood vessels of the sex organs are the first to show endothelial failure. Elevated blood pressure is next, then insulin resistance, then exercise intolerance, and at the far end, mild cognitive impairment progressing toward Alzheimer’s.
[10:49 –> 11:26] Dr. Ravi Kumar: In fact, some researchers now refer to Alzheimer’s as type 3 diabetes because of the insulin resistance and hypoperfusion in the brain. There’s a great paper by de la Monte and Wands in the Journal of Diabetes Science and Technology in 2008 that lays out this whole concept in detail. And second, there’s the question of whether nitric oxide really declines with age. And the short answer is yes, and this has been shown repeatedly. A foundational paper in the Journal of the American College of Cardiology in 1994 used ultrasound to measure flow mediated dilation, which is basically how well your arteries open up when blood flow increases.
[11:27 –> 12:10] Dr. Ravi Kumar: And they found that endothelial function declines progressively with age. Another important paper in Hypertension in 2001 directly measured nitric oxide availability and oxidative stress in humans and confirmed that nitric oxide bioavailability dropped substantially with age. By the time the average person hits their sixties or seventies, they’re running on a fraction of what they had in their early twenties. And lastly, if you’re over 40 and eating a standard American diet, using mouthwash, using fluoridated toothpaste, taking an antacid, and not exercising regularly, you’re almost certainly deficient. The science is clear on this, and in my opinion, you don’t really need a test to justify taking action.
[12:10 –> 12:52] Dr. Ravi Kumar: The interventions we talked about in the episode are safe and beneficial for essentially everyone. So start there. And one last topic that I thought was worth bringing up but I didn’t get a specific question on was that Dr. Bryan mentioned that fluoride in drinking water lowers children’s IQs, and this is based on the National Toxicology Program published report in 2024 that suggested this. It was followed up by a meta analysis in JAMA Pediatrics in 2025 that followed 74 studies and found a statistically significant inverse association between fluoride exposure and IQ, which held up when they restricted the analysis to only the highest quality studies.
[12:53 –> 13:13] Dr. Ravi Kumar: In September 2024, a federal court ruled that water fluoridation at the US Public Health Service recommended levels poses an unreasonable risk to children’s health. The science is converging on this, and if you want to read more about this, look up that JAMA Pediatrics paper because that’s a good starting point.
[13:13 –> 13:25] Dr. Ravi Kumar: Well, that’s it for today, folks. Keep the questions coming. And if you haven’t listened to that full conversation with Dr. Bryan, please take a listen. It’s one of my most favorite episodes so far. Okay, folks. Cheers, and I’ll see you next week.