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In this episode, John Thomson Smith, a physician executive, explores the science of longevity and the critical role of healthspan in living a vibrant life. They discuss how tracking key biomarkers, such as VO2 max, heart rate variability, and telomere length, can empower individuals and clinicians to make data-driven decisions that enhance both daily vitality and long-term health. Whether you’re a health care professional or a patient seeking to optimize your well-being, this conversation offers actionable insights into the journey toward a thriving healthspan.
John Thomson Smith is a physician executive.
He discusses the KevinMD article, “Biomarkers: How to manage your body’s KPIs for longevity.”
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Transcript
Kevin Pho: Hi, and welcome to the show. Subscribe at KevinMD.com/podcast. Today we welcome John Thomson Smith. He’s a physician executive. Today’s KevinMD article is “Biomarkers: how to manage your body’s key performance indicators for longevity.” John, welcome to the show.
John Thomson Smith: Thank you, Kevin. Thank you for the invitation. It’s a pleasure.
Kevin Pho: All right, let’s start by briefly sharing your story and journey.
John Thomson Smith: Yeah, sure. Well, I’m actually an orthopedic surgeon by trade, and I’ve spent 20 years in clinical practice here in the U.K. in the NHS and private sector. During the pandemic, I started doing a lot more corporate work because we stopped operating for nearly two years with no need to get some nursing staff. I found myself working a lot with implant device companies in terms of product design, trying to have a greater global impact for patients. One of my personal interests is in the longevity space and sports medicine, healthy lifestyle, nutrition, et cetera. So I found myself working with a company called Rejuve.ai, which is a decentralized data platform. It’s a phone app application. We’re about to launch the definitive app any moment now—it’s a very exciting time—and we’re using AI-driven insights on a decentralized data platform to improve patients’ lifestyle and longevity, hence the outcome. I’m a senior medical advisor at Rejuve.
Kevin Pho: All right. So talk about your KevinMD article, “How to manage your body’s key performance indicators for longevity,” for those who didn’t get a chance to read it.
John Thomson Smith: Yeah, sure. Well, there’s certainly a lack of knowledge globally—both for physicians and patients alike—in terms of biomarkers, whether they’re physiological biomarkers such as your VO2 max or your heart rate variability, along with molecular biomarkers such as blood test analysis and blood profile. This is obviously a very hot topic at the moment with the advent of wearable devices and sensor technology. We’ve all got smartwatches, and these are key markers in terms of our health span and longevity. It’s a real pleasure to publish the article, and one of the aims of the company at the moment is really to increase awareness globally in terms of what we should be doing and the metrics that we should be tracking. So yeah, it’s a real pleasure to be involved with this space.
Kevin Pho: All right. So you mentioned a few of these biomarkers in passing—VO2 max, heart rate variability. Talk about some of these important biomarkers specifically: what they are and why we should know about them.
John Thomson Smith: Yeah, absolutely. Well, some of them are easier to measure than others. On a standard Apple Watch or Garmin, you’ll be able to assess your resting heart rate, and you’d be able to assess your respiratory rate on some devices, such as a WHOOP strap watch. More involved biomarkers, such as VO2 max, may need some specialist testing—for instance, a treadmill test or cardiovascular assessment.
Our aim with the app is actually to encompass all of these biomarkers into one usable app so that you can upload your blood profile—such as your blood glucose test, your cholesterol levels, your chronic inflammatory markers—and roll that together with physiological markers and even genetic testing to give you a much more accurate idea about biological age and longevity.
Kevin Pho: All right, so let’s say we have a standard Apple Watch and we want to measure our heart rate variability, for instance. Tell us what kind of medical prognosis or predictions one can make specifically from that marker.
John Thomson Smith: Yeah, great question, Kevin. Well, there’s vast evidence now that a high VO2 max or increased heart rate variability—or indeed even a low resting heart rate—is intrinsically associated with increased longevity. The reason why this is important is that if we have an awareness that these metrics could be improved, we can monitor and track things and potentially improve our health plan and life plan. So it’s really about raising awareness of these markers, but I can’t emphasize enough: it’s really the monitoring and the tracking of the trends associated with each individual’s biomarker that is important.
Kevin Pho: Talk about the evidence and some of the data behind that. Do you have any numbers that perhaps you can cite in terms of how much longevity one can gain if they have a favorable heart rate variability or a favorable VO2 max, for instance?
John Thomson Smith: Yeah, absolutely. In terms of anecdotal data, there is very good evidence that improving your VO2 max, or your heart rate variability, or improving your resting heart rate can certainly reduce your biological age. A great case example would be the very famous Bryan Johnson, who works in the longevity space. He’s the subject of a current Netflix documentary. He actually reduced his biological age by between five and seven years by improving his VO2 max and his cardiovascular parameters over a one- to two-year period. All of the evidence points toward these metrics improving one’s longevity.
Kevin Pho: And for those who aren’t familiar, just give us a 10- to 15-second primer as to what VO2 max is.
John Thomson Smith: VO2 max is essentially the maximum oxygen consumption or maximum oxygen-carrying capacity of an individual during high-intensity exercise. Traditionally, it’s been associated with athletic performance, and it’s certainly common in elite sports for people to have their VO2 max measured. But it’s actually the number one key parameter in terms of physiology and predictors of lifespan.
Kevin Pho: Are there any other biomarkers, other than the ones we talked about, that patients can measure themselves with commercial wearable devices?
John Thomson Smith: Yeah, absolutely. A common example now would be your blood glucose levels. Your blood glucose level and your insulin sensitivity is directly proportional to chronic inflammation systemically, which can be detrimental in terms of your health span and longevity. So monitoring your blood glucose and making sure that it’s within normal ranges is very, very applicable and also accessible now with modern techniques. That’s one that certainly springs to mind, along with the other ones that we’ve discussed.
Another very interesting product that is currently on the market is the Oura Ring, which has really focused on sleep hygiene and sleep health. That is often a metric that is forgotten in one’s lifestyle, yet is absolutely crucial for repair and regeneration at a systemic level. So I really like what they’ve done with the Oura Ring. But it’s really tying all these electronic things together and trying to create a complete package for that individual in terms of personalized care.
Kevin Pho: Now, you’re a physician and a medical advisor, of course, to a company. So what are you recommending patients do? Are you recommending patients get these wearable devices and measure all of these biomarkers? How many devices would they have to buy? What are you recommending for a typical patient who may be listening to you now, who wants to be a little bit more conscientious about measuring some of these biomarkers we’re talking about?
John Thomson Smith: Yeah, it’s a great point, Kevin, and I think it’s overwhelming, isn’t it, at the moment, in terms of the devices that are available. What we’ve tried to do at Rejuve is to allow access or connectivity to any of those devices. So if an individual has a Garmin or a Fitbit or a strap, that is inherently compatible with the app on your phone. You connect your wearable device, and with that, you can input any data you wish. So if you’ve had a recent blood profile at your family doctor or GP, you can input that data, and this will give you a more rounded picture in terms of your biological age and longevity.
In answer to your question, I would advise an individual who’s new to this to start slowly. Just stick to one device and one app, because you could end up with four or five different applications or four or five devices. So my advice would be to stick to one device—one wearable device that’s easy to use and has good functionality—and one application on your phone that you could use. Just keep things simple initially.
Kevin Pho: Now, of course, there are biomarkers that are measured through the blood. I’m a primary care physician here in the United States. What are some biomarkers that perhaps I should be thinking about for my patients I see in the exam room in terms of ordering specific blood tests or just having these biomarkers in the back of my mind if I wanted to promote longevity in my patients?
John Thomson Smith: Absolutely. So I think we can break that down into more common, sort of household names in terms of testing. We already mentioned glucose. A lipid profile is crucial, so the ratio of your good and bad cholesterol—the HDL and LDL. Inflammatory markers such as CRP, IL-6, or ESR in certain cases. These are acute-phase proteins, which give us a good indication in terms of chronic inflammation.
Also, hormones play a crucial part in longevity as well. So our sex hormone levels—whether it’s testosterone or estrogen—as well as your resting cortisol levels in terms of stress hormones, are important. Let’s not forget about endocrine function. Along with that goes thyroid testing as well.
Of course, the list is endless in terms of blood tests that we could request at a family doctor level. It’s mind-boggling, but those would be the most important. More comprehensive tests now do offer chronic inflammatory markers for biological age assessment and a genetic profile. This is something that’s very close to my heart at the moment. I’m trying to make those genetic tests more acceptable, affordable, and easy to understand for patients. I think that over the next five to ten years, we will see a real boom in genetic and epigenetic testing for patients to identify key parameters so that we can institute changes in lifestyle and intervention, in view of preventative health rather than treating disease.
Kevin Pho: Now, you mentioned over a dozen tests there. So do you recommend a blanket approach, or do you recommend targeting some of these tests based on the risk profiles of the patient in front of you? How would you approach these scores of biomarkers that you just have mentioned?
John Thomson Smith: Yeah, I think certainly it comes down to precision medicine or what I would call a tailored approach to each individual. If you say that to a 16-year-old adolescent, that’s a very different situation than a 75-year-old male. So I think we need to be aware of which patient is sitting in front of us; it may not be appropriate for everyone. There may also be an element of what the patient has requested and how much you want to do a deep dive into this.
I think you could break it down into a more basic assessment of biomarkers or a full phlebotomy across all of the tests, including the genetic profile and the epigenetics. So really, to answer your question, Kevin, it would be a tailored approach to each individual.
Kevin Pho: Give us some successful case studies of how some of the patients that you’re seeing or that your company is seeing are successfully integrating biomarkers into their lifestyle and how that’s positively moving the needle in their life. Give us some examples of what your vision would be like in an ideal case.
John Thomson Smith: Yeah, that’s a good point. So we’ve currently got around 10,000 users on our beta-test app, and we’re going to be finishing up in the next few weeks. What we’ve found is that the monitoring and tracking of the biomarkers and the health data for each individual provides a motivation factor. Whether it’s with a body mass index or a metric like VO2 max or a biological age factor, with improvements in that, it’s really the monitoring of the progress that’s the key motivating factor.
We’ve seen big changes in individuals even within 30 days. The goalposts are set around 30 days, 60 days, and 90 days—or one to three months—in terms of improvement. It’s really that feedback, as well, that is given through the application, through the artificial intelligence and machine-learning models that are presented. You can actively monitor the progress and institute almost real-time changes to that person’s lifestyle. That’s really a sort of blanket approach to what we’ve seen within the app and the feedback we’ve had. We’ve found that people have stayed within the app and want to continue to see that progress and improvement, which is really exciting.
Kevin Pho: We’re talking to John Thomson Smith. He’s a physician executive. Today’s KevinMD article is “Biomarkers: how to manage your body’s key performance indicators for longevity.” John, let’s end with some take-home messages that you want to leave with the KevinMD audience.
John Thomson Smith: Yeah, great. On a personal level, I would say for the physicians out there, keep your options and your horizons open. It’s very easy to become blinkered in your own clinical pathway and not see the bigger picture. We can have a much bigger global impact in terms of contemporary medical technology and incorporating those things into our practice. Thank you. And the real take-home message is to really try and focus on preventative health rather than treating disease, which is the way that we’ve been brought up as physicians—to treat the sick. But it’s really looking at precision medicines, personalized health plans, and prevention as the better cure. That’s really what we’re striving to do here at Rejuve.
Kevin Pho: John, thank you so much for sharing your perspective and insight, and thanks again for coming on the show.
John Thomson Smith: Thanks for the invitation, Kevin. It’s a pleasure. Take care.
