Moving Beyond Glucosamine: The Future of Functional Joint Care
In this practitioner spotlight, Dr. Darisa Espinal, naturopathic physician at Dr. Kara Fitzgerald’s New Frontiers Functional Medicine Clinic, shares her journey into functional medicine, the types of patients she supports, and how she integrates longevity medicine and root-cause care to help patients achieve optimal health and vitality.
Dr. Espinal, can you share your path to becoming a functional medicine doctor and how your training shaped your approach to patient care?
I actually started my journey working with a very experienced functional chiropractor. I spent a decade mentoring with her and learning the foundations of functional medicine before I went to naturopathic medical school. That clinical exposure planted the seed, but going through school and starting to work directly with patients deepened my understanding. After graduating from naturopathic school, I joined Dr. Fitzgerald’s clinic team and have been practicing functional medicine in an official capacity for about five years now, but the foundation has been in place much longer.
What really sets functional medicine apart from naturopathic medicine for me is how laboratory-driven it is. In those first few visits with a patient, you uncover so much; you get this comprehensive picture that you just don’t get in other models. I’ve continued to deepen my education through mentors like Dr. Fitzgerald and Dr. Litwin, and I’m always learning. That’s a core part of how I practice.
What inspired you to choose functional medicine over a conventional medical path?
It’s always been important to me that people have options. I don’t believe in a black-and-white approach to health care. There’s a lot of great work being done in conventional medicine, but I love that functional medicine allows us to use safe, effective tools that often tap into the basics – food, movement, mindset – and still make a profound difference.
I’ve seen so many lives transformed through my work, which is so deeply gratifying and keeps me very motivated. I apply this approach to myself and my daughter, too. It’s a lifestyle, not just a toolkit.
What types of patients and health conditions do you most often treat in your functional medicine practice?
I’ve developed a bit of a niche in pediatrics, not as a pediatrician, but I work with kids who have both acute and chronic conditions. I also see a lot of women in the perimenopausal and menopausal transition, and I work on hormone health, PCOS, and fertility. I feel grateful to have helped dozens of women achieve their fertility goals, with a success rate of over 95%.
Gut health is also one of our core strengths, with expertise in addressing SIBO, Candida, IBS, celiac disease, and general GI dysfunction. We’re often able to reduce flare-ups and help patients get regular, consistent bowel function. I also see patients with metabolic syndrome, cardiovascular issues, blood sugar dysregulation, cholesterol/triglyceride imbalances, and those navigating overweight or obesity.
And of course, many of our patients have multiple overlapping concerns. That’s where functional medicine really shines, because we’re not just managing symptoms, we’re addressing the terrain. When cases are complex (which they often are), I’m grateful to be part of an experienced clinical team where we can bounce ideas off each other and draw on the latest research. We spend a lot of time digging into scientific advances relevant to our cases, applying what’s shown to be effective in the research literature.
Case vignette – Meghan – Part 1: Recently, I worked with a patient (we’ll call her Meghan) with a history of weight loss resistance, sleep apnea, atrial fibrillation, elevated TSH, fibroids, and a partial hysterectomy. At the time she came to see me, she was most concerned about elevated liver enzymes and lipids in her recent labs, as well as her ongoing obesity and swollen ankles. Through a careful evaluation of her GI function/microbiome, food sensitivities, nutrients, SNPs, and markers of metabolic, thyroid and immune balance, we were able to identify and address her unique underlying issues. More on Meghan’s outcomes below…
How do you integrate longevity medicine and biological age testing into your functional medicine practice?
Longevity is deeply ingrained in functional medicine. I see it as one of our core tools. Functional medicine is, by definition, about slowing or reversing chronic disease and optimizing health because it focuses on the root cause of health or illness. When you do that, you’re working on longevity, whether you’re calling it that or not.
That said, there are patients who come to me specifically because they’re interested in maximizing their healthspan. Often, the measures they’ve been using indicate they’re in good health, but when we do a deep functional medicine dive, we almost always find areas for improvement. There’s always something to fine-tune, and we work on incremental, sustainable improvements over time.
Maximizing patients’ health automatically maximizes longevity. But for those patients, in addition to the foundational sweep of functional medicine investigations, I tend to pay attention to areas like methylation, SNPs (single-nucleotide polymorphisms), and biological aging markers. I’ve become very proficient at interpreting methylation SNPs, especially for patients with cardiovascular risk, family history of chronic disease, or signs of oxidative stress. Tools like DunedinPACE help us measure the pace of aging, and we use them to track a patient’s baseline state and how well our interventions are working.
Which functional medicine interventions most effectively slow the pace of aging and support longevity?
It depends on the patient, of course, and the full functional medicine approach works best. I often find that supporting methylation balance can have a measurable effect on biological age. We look at methylation patterns and make sure we have the right ratios. That includes ensuring adequate intake of methyl donors like B vitamins and choline, and supporting cofactors like glutathione. We also lean heavily on anti-inflammatory nutrients, especially things like sulforaphane, which has powerful epigenetic and detox benefits. But, the right approach for one person is not the right approach for another; it’s important to get proper guidance and be adequately monitored over time.
And again, we always circle back to the basics: food quality, exercise, sleep, and connection. Those are the things that make everything else work better. Functional medicine isn’t always about magic bullets – it’s about the synergy between systems, and the consistency of the care we provide.
What guidance would you give functional medicine practitioners on adding longevity medicine and biological age tracking to their practice?
Start with what you already know. I think there’s this misconception that longevity medicine requires some entirely new paradigm or toolset, but the truth is, if you’re practicing functional medicine well, you’re already doing longevity work. You’re identifying root causes, reducing inflammation, and balancing metabolic pathways. That’s the foundation.
Where it gets interesting is in the tracking. Tools like biological age clocks give you a way to measure the impact of what you’re already doing. They help validate that your interventions are working, and they also help uncover deficits that might otherwise go unnoticed in a “normal” lab workup. So I tell practitioners: don’t overcomplicate it. Layer these tools in where they make sense. You don’t need to use them with every patient, but they’re incredibly helpful when you’re working with people who are already relatively healthy but want to push the needle even further.
And honestly, patients love it. It reframes the conversation away from disease management and toward health optimization. It’s empowering. So don’t wait until you feel like an expert! Start where you are, and start shifting the lens of your work where it feels right.
Case vignette – Meghan – Part 2: Meghan responded well to a keto-leaning adaptation of the Younger You diet, together with a trial elimination of foods positive for potential immune sensitivity. This was layered with, among other things, a phased gut repair protocol and methylation-supportive nutrients. Regular check-ins with one of our nutritionists helped to smooth the dietary implementation and address any practical hiccups. As part of this process, Meghan discovered an apparent link between undereating and Afib, which she was then better able to manage. After six months, Meghan had lost a significant amount of weight and was feeling energetic. Her ankle swelling had receded and her sleep apnea had markedly improved. At 11 months, her liver enzymes were down (although the reduced ALT was still above the reference range cutoff), her thyroid peroxidase antibodies had dropped to just above normal (from 23 to 11 IU/mL), and her HbA1c was happily out of its previous prediabetic range. She reported that, although she was experiencing some plateauing of weight loss (and was continuing to work with our team on that), her clothes were fitting her differently “in a good way,” and she was no longer categorized as obese.
Thank you, Dr. Espinal, for sharing your thoughts with us!
Find out more about Dr. Espinal here. If you’re interested in working with Dr. Espinal or our other expert clinicians, please reach out to our clinic here.
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