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Welcome to The Dr. Kumar Discovery, a health and wellness podcast hosted by Dr. Ravi Kumar, a board-certified neurosurgeon. This is the medical podcast for anyone who wants honest, evidence-based answers to the health questions that matter most. No corporate influence. Just a physician who reads the research, questions the dogma, and breaks it down in plain language so you can make better decisions about your own health.
Dr. Kumar is a practicing neurosurgeon who brings a surgeon's precision to topics most doctor podcasts only scratch the surface of. Each episode dives deep into the science behind metabolic health, cardiovascular disease, heart disease, hormones, nutrition, brain health, mental health, pain, inflammation, weight loss, aging, blood pressure, sleep, and longevity. Whether it's the truth about seed oils, the real data on GLP-1 drugs and weight loss, the science of cold water therapy, how light can heal the body, or why your testosterone is declining, Dr. Kumar goes straight to the peer-reviewed literature and tells you what the evidence actually shows, not what the headlines say. This is evidence-based medicine in plain English.
The show features three formats. Solo deep dives explore a single health topic from the ground up, covering everything from the biology to the practical takeaways you can use today. Expert interviews bring on leading researchers, clinicians, and forward-thinking voices in health and medicine for in-depth conversations you won't hear anywhere else. The Tribulations series tells the true stories behind medicine's greatest breakthroughs, from the discovery of penicillin to the invention of vaccines to a father's fight to save his son's life. These are the stories of the doctors, scientists, and patients who changed the course of medicine.
Topics covered on the show include testosterone and hormone optimization, sleep science, photobiomodulation and red light therapy, exercise with oxygen therapy, creatine, uric acid and gout prevention, gut health and probiotics, cardiovascular risk and Lp(a), cholesterol, PANDAS in children, PTSD and trauma, acetaminophen safety, glyphosate, foot health, and much more.
If you're tired of generic health advice and want to hear from a neurosurgeon who actually reads the studies, The Dr. Kumar Discovery is your podcast. New episodes drop regularly. Subscribe and join the discovery.
For show notes, references, and more, visit drkumardiscovery.com/podcast
[00:00:00] Dr. Ravi Kumar: Hey, everybody. Doctor Kumar here. So I knew the fluoride episode that I did earlier this week was gonna pique some interest. And I got a lot of really thoughtful questions. So I picked five of them that I thought would tie together a lot of the information I presented earlier in the week, and help you with some practical application of this knowledge. So let's get into it. Okay. First question. If the data is so questionable, why does the American Dental Association still recommend fluoridation? Okay. So this is a good question. The simple version is, that large medical and dental organizations move very slowly. And their positions reflect the science as it was understood five, ten, sometimes twenty years ago. In this situation, the ADA position on water fluoridation is essentially the same position that they have held since the nineteen fifties, when the original Grand Rapids data was the only data we had. The 2024 Cochrane review, the 2024 Federal toxicology analysis, the 2025 JAMA Pediatrics meta analysis, and the federal court ruling all happened in the last eighteen months. That is not enough time for a national organization to update a seventy five year old policy position. There is also a structural issue here. When an organization has spent decades publicly defending a policy as one of the greatest achievements of public health, reversing course is not just a scientific decision, it's a reputational and political one. This is not unique to dentistry. We saw the same lag with proton pump inhibitors, with hormone replacement therapy, with dietary fat recommendations. Medical dogma always moves slower than the data. That's why I keep coming back to the same theme on this show. Don't outsource your thinking to organizations. Read the data yourself and make informed decisions for your own family. The ADA's position will likely move as more data comes in and public sentiment changes. But it's important to remember that outdated advice from an authority is still outdated advice, and it does not override the actual peer reviewed studies that have been published in the last two years on this subject. Okay. Next question. I'm pregnant, and I drink municipal tap water. Should I be doing something differently? Okay. So the answer to your question is yes. In fact, the pregnancy data is the most concerning part of this entire conversation on fluoride, and it's not one I would recommend being passive about. There are two studies you should know about. The first was published in 2017, looking at a Mexican cohort of mothers and children. Higher maternal urinary fluoride during pregnancy was associated with lower IQ scores in their children measured years later. That data alone would not be enough to change practice. But then in 2019, a study was published in JAMA Pediatrics looking at a Canadian cohort. The Canadian women in this study were drinking water at the same fluoride levels we use in The United States, which is called optimally fluoridated water. The researchers still found that higher maternal fluoride exposure during pregnancy was associated with lower IQ scores in their children at ages three and four. The mechanism makes biological sense. Fluoride crosses the placenta, it crosses the blood brain barrier, the developing fetal brain is uniquely vulnerable to neurotoxins during pregnancy. We accept this with mercury, with lead, with alcohol, and their emerging evidence suggests we may need to accept it with fluoride too. The practical takeaway, if you're pregnant and on city water, get a reverse osmosis filter under your kitchen sink. They cost a couple $100, and remove fluoride along with other contaminants. Use that water for drinking and cooking. This is one of those situations, where I would rather you act on incomplete evidence and be overly cautious, than to go the other way and have been wrong. So if you can't get an RO system, drink bottled water. Drink it in the larger jug, so there's less plastic exposed to more water, and you should be fine. But an RO system is the gold standard for removing fluoride. The Brita filter that most people have won't do it. Okay. Next question. My pediatric dentist wants to apply fluoride varnish to my kids' teeth at every visit. Should I let them? Okay. This is a personal question that we all need to answer for ourselves based on our own view of the literature. But fluoride varnish at the dentist actually has solid evidence behind it. A 2013 Cochrane review of 22 trials found that varnish reduces decay in permanent teeth by about forty three percent, and in baby teeth by about thirty seven percent. That is a real effect, and it's bigger than fluoride toothpaste because the concentration is much higher and the application is professional. But here's the trade off and the risks that you need to know about. Fluoride varnish is a high concentration topical exposure. Some of that fluoride will absorb through the oral mucosa, and through any swallowing that happens during or after the application. For a child who already drinks fluoridated water, brushes with fluoride toothpaste, eats fluoridated processed foods, and now gets varnish twice a year, the cumulative dose is meaningful. My honest thinking on this is about risk stratification. If your child has high cavity risk, meaning they've already had cavities, they have poor enamel quality, or there's a strong family history, the cavity prevention benefit of varnish may outweigh the additional fluoride exposure. If your child has low cavity risk, brushes consistently, eats a low sugar diet, and uses hydroxyapatite toothpaste at home, the marginal benefit of varnish is much smaller, and skipping it seems reasonable to me. That's what we do for our kids. We don't let them get the fluoride varnish. So the practical takeaway is this. This is a conversation you have to have with your pediatric dentist, who's likely gonna push for fluoride treatment. Ask them what your child's cavity risk actually is. If they can't articulate on the specific reason your child needs varnish beyond it just being a routine thing that they do, you have permission to politely decline. It's your informed consent, remember, so you can decide whether they get it or not. Okay. Next question. Uh, I keep hearing that nano hydroxyapatite particles can absorb into the bloodstream. Is the toothpaste really safe? Okay. So this is a great question, and one that a lot of people are bringing up because the word nano makes everyone nervous, and and for good reason. Because nano particles are extremely small, and they can sometimes pass through biological barriers. But let's first get this out in the open. Hydroxyapatite is what your bones are made of. So if it gets into your bloodstream, it's biologically identical to a major component of your bones. Okay. So with that said, here's what the evidence actually shows. Nano hydroxyapatite has been used in toothpaste in Japan since the nineteen seventies, and has been used by NASA with no risks after fifty years of use, basically. The European Scientific Committee on Consumer Safety, which is one of the most cautious regulatory bodies in the world, formally reviewed nano hydroxyapatite in 2023 and concluded that it's safe in oral care products at concentrations up to 10%. And recently, they've adjusted that upward as well. And they specifically stated that particles that are rod shaped are safer, which is what all commercial dental products use. So the mechanistic reason that this works is safe and it's straightforward. Even if a few nanoparticles were absorbed, hydroxyapatite breaks down into calcium and phosphate, two compounds that your body uses constantly. There's no exotic foreign substance accumulating anywhere. Compare that to fluoride which crosses the blood brain barrier, and the placenta, accumulates in the bones over a lifetime, and behaves very differently inside the body than it does on the surface of the tooth. So I think the practical takeaway here is that nano hydroxyapatite is one of the most well studied fluoride alternatives available. The concentration that you want on the label of a toothpaste that's using nano hydroxyapatite is 10%. So just look for that as the active ingredient. Okay. Next question. Can I just drink bottled water instead of installing a filter? Yeah. This is good, and we talked about it just a little bit ago. Yes. In most cases, bottled water is generally low in fluoride, and the data is pretty clear on this. A study published in general dentistry in 2009 analyzed a 150 different bottled waters across multiple categories. Distilled bottled water averaged less than 0.01 per liter of fluoride. Drinking and purified bottled waters averaged less than 0.03. Compare that to tap water, which is zero point seven milligrams per liter of fluoride. And you can see why bottled water effectively removes most of your daily fluoride dose. The USDA national database puts the average fluoride content of bottled water around point one one milligrams per liter, which is a seventh of what is in tap water. The catch is that not all bottled waters are the same. Some bottled water is just repackaged municipal tap water from fluoridated cities. And a small percentage of brands actually have fluoride levels near fluoridated water supply levels. So you need to read the label or contact the company. Spring water, mineral water, distilled water, and reverse osmosis purified bottled water are typically your safest bets. That said, I personally think reverse osmosis at home is the better long term solution. It costs less than two years of bottled water for a family. It eliminates the plastic waste and the microplastic exposure from bottled water, which is on its own an emerging concern, and you have control over the sources. But if bottled water is what's accessible to you right now, especially during pregnancy, it is a reasonable solution. Okay. So that's it for this week, folks. I hope this filled some of the practical gaps from the main episode, and gives you what you need to make decisions for your own family. As always, none of this is medical advice, so take this information, ask better questions, and work with your own healthcare provider to figure out what makes sense for you. Okay, folks. Cheers, and I'll see you next week.