Dr. Kara Fitzgerald

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Sandy Hook, CT
Dr. Kara Fitzgerald

Actively engaged in award-winning clinical research on epigenetics & longevity. IFM Faculty & renowned international speaker.

Director of New Frontiers Functional Medicine & Nutrition Clinic. Subscribe to get latest content at www.drkarafitzgerald.com

12/22/2025

2025 was a remarkable year for functional and longevity medicine.

Across the clinic, the lab, and the research world, we saw breakthroughs that challenged assumptions, expanded our toolkit, and reminded us, again, that biology is dynamic and modifiable.

From early-detection biomarkers and cartilage regeneration research to new insights on mitochondria, immune resilience, nervous system regulation, and treatment-resistant depression, these were the ideas that sparked the biggest conversations in our community.

We also released new data on the Younger You™ protocol and explored how AI is reshaping clinical practice. And of course, the Functional Medicine is Longevity Medicine™ Masterclass brought together thousands of you for some of the most energizing dialogue we’ve ever hosted.

My team and I pulled everything into one place: The FxMed moments that “broke the internet” in 2025.
If you want a curated look at the science, stories, and clinical insights that defined the year (and a few you may have missed!), you’ll find the full roundup on the blog.

Here’s to a year of curiosity, thoughtful clinical practice, and evidence that continues to evolve.

Visit https://www.drkarafitzgerald.com/2025/12/07/2025-functional-medicine-highlights/ to read the article!

12/21/2025

Today marks the winter solstice, the longest night of the year, and a turning point that cultures have recognized for thousands of years.

From a functional medicine standpoint, this moment aligns with something very real in our biology. As light decreases, we see predictable shifts in circadian rhythm, melatonin production, cortisol patterns, neurotransmitters, mitochondrial function, and even immune activity. Many people feel this physically and emotionally, even if they don’t name it.

The solstice reminds us that these seasonal rhythms aren’t shortcomings; they’re biology. Our systems evolved to respond to changes in light, temperature, and energy demands. And when we honor those shifts rather than fight them, we often feel more grounded and resilient.

As the light begins to return, this can be a meaningful time to:
• Reassess your sleep rhythm and give it the stability it needs
• Bring intentional light exposure back into your morning
• Reconnect with nutrient density during a season when metabolism changes
• Create space for recovery and reflection, not just productivity
• Revisit practices that help regulate the nervous system during longer nights

For many, winter isn’t easy, but it is adaptive. And today reminds us that even in the darkest point of the year, biology is already moving toward renewal.

Wishing you a grounded, restorative solstice, and a season of health, warmth, and light.

12/20/2025

A new randomized trial reported a 39% lower risk of AFib recurrence in people assigned to drink one cup of caffeinated coffee daily, a fascinating contrast to the blanket “avoid caffeine” guidance many patients still receive.

My own mom was recently diagnosed with AFib and now sips a cup of weak decaf each morning… which, aside from being a deeply depressing ritual (in my opinion), made me wonder whether this advice is actually evidence-based.

This study suggests the story is more complex:
• Moderate caffeinated coffee was linked to fewer AFib recurrences
• PVCs are associated with caffeine, an important nuance clinicians should keep in mind
• Individual physiologic sensitivity still matters
• Nearly half of the coffee group still experienced recurrence
• Any change requires practitioner oversight, not self-experimentation

Bottom line: This doesn’t mean “everyone with AFib should drink coffee.” It does mean the old guidance may need updating, and that caffeine’s effects on cardiac electrophysiology are more individualized than we once assumed.

Biology is nuanced.Our recommendations should be too.

12/19/2025

A recent Mendelian randomization study found that higher circulating levels of the amino acid tyrosine are linked to shorter lifespan, especially in men. Phenylalanine (tyrosine’s precursor) also tracked with higher mortality in observational data, though its independent effect was less clear.

Important nuance: this paper is about endogenous amino acid levels, not a clinical trial of low-protein diets. Genetics, insulin resistance, neurotransmitter metabolism, inflammation, and overall diet quality all influence these levels. It does not mean that everyone should start restricting protein across the board, or that the already-too-low RDA is suddenly “high.”

From a functional medicine perspective, I see this as one more signal that context matters:
Chronically elevated amino acids in the setting of insulin resistance and metabolic dysfunction may be problematic.

At the same time, adequate high-quality protein is essential for muscle, bone, cognition, and healthy aging—especially in midlife and beyond, where the current RDA is likely insufficient for optimal function.

Rather than blanket protein restriction, we should be personalizing: looking at metabolic markers, body composition, activity level, age, s*x, and overall dietary pattern (fiber, phytonutrients, healthy fats).

Bottom line: this is a fascinating piece of the longevity puzzle, not a mandate to cut protein. I’d be cautious about long-term, high-dose tyrosine supplementation without a clear indication, and I’d continue to prioritize protein quality, metabolic health, and whole-diet context over single-nutrient fear.

Curious how you’re thinking about protein + longevity in your practice? Share your thoughts below.

12/17/2025

What happens in the mouth doesn’t stay in the mouth.

In this episode, I’m joined by Doctor Staci Whitman(board-certified pediatric dentist, IFMCP) for a deep, clinically relevant conversation on the oral microbiome, “leaky gums” (gingival permeability), and why oral inflammation is a systemic issue, not a silo.

We cover:
• Why the oral microbiome is established as early as preconception
• The “2,000 swallows/day” translocation concept
• Red complex pathogens and oral-systemic links
• Airway and mouth breathing as a driver of dysbiosis
• Hormonal transitions (puberty, pregnancy, peri/menopause) and oral tissue changes
• What functional medicine clinicians should be screening for in practice
• Why functional dentistry needs standards and what her Institute for Functional Dentistry is building

If you treat the gut, you need to assess the mouth. This episode connects the dots.

Head to https://www.drkarafitzgerald.com/2025/12/16/functional-dentistry-oral-systemic-health/ now.

12/16/2025

A new Immunity (2025) study from Purdue University identifies a metabolic root of Alzheimer’s, showing how the brain’s immune cells (microglia) can become overloaded with fat when exposed to amyloid-β.

This lipid buildup disrupts the brain’s natural cleanup system, preventing microglia from clearing amyloid plaques and accelerating neurodegeneration.

By blocking a single enzyme, DGAT2, researchers restored microglial function and the brain’s ability to clear plaques.

👉 This shifts the focus from targeting amyloid alone to supporting the metabolic health of the brain itself.

It’s a reminder that neurodegeneration is deeply intertwined with metabolism, inflammation, and cellular resilience — all areas where functional medicine shines.

🔬 Source: Prakash P. et al., Immunity, 2025. PMID: 40393454

12/15/2025

The MitoImmune trial adds an intriguing layer to what we know about immune aging: changes in mitochondrial quality may influence how effectively our immune cells function over time.

In this RCT, Urolithin A (Mitopure®) was associated with shifts linked to a more resilient immune profile, including an increase in naïve CD8+ T cells and improved mitochondrial signaling.

These mechanistic findings don’t establish clinical outcomes, but they do expand our understanding of how mitophagy and metabolic flexibility intersect with age-related immune decline.

As research evolves, the mitochondria continue to stand out as a meaningful focal point for exploring healthy longevity.

In partnership with Timeline Longevity, our latest blog breaks down more of the mechanistic pathways, limitations, and clinical considerations in the full blog.

Comment MITOIMMUNE and we’ll DM you the link or head to https://tinyurl.com/Mitoimmune-Study to read the full article.

As always, clinical decisions must remain individualized and practitioner-guided.

12/14/2025

A new Nature Communications paper used diffusion MRI from 4,216 people (ages 0–90) to map how brain “wiring” changes over the lifespan. Instead of a smooth curve, they found four major structural turning points around 9, 32, 66, and 83 years old.

These shifts in network topology were linked to changes in cognitive function and brain efficiency, suggesting that our brains move through distinct “epochs” of development and aging, not just one long decline.

Why it matters:
It reinforces that brain aging is non-linear – different ages may be more vulnerable (or more flexible) than others.
It supports what many clinicians observe in practice: periods when cognition, mood, and resilience shift more dramatically.
It raises good questions about when brain-supportive choices (sleep, movement, nutrition, connection, stress work) might matter most — even though this study didn’t test interventions.

🔍 Study at a glance
Human, multi-cohort diffusion MRI
Age range: 0–90 (mostly neurotypical adults and children)
Finding: 4 “topological turning points” in brain network organization at ~9, 32, 66 & 83 years
Design: Observational, cross-sectional (no treatment given)

This doesn’t tell us how you personally will age, and it doesn’t prove cause and effect. But it does give us a richer map of how brain structure appears to shift over time and a new framework for thinking about cognitive health and longevity.

As always, any decisions about prevention or treatment need to be individualized and guided by your healthcare team.

Source: https://doi.org/10.1038/s41467-025-65974-8

12/13/2025

When someone tells me they can’t sleep, or they’re wide awake at 3 a.m., I don’t reach for melatonin. I look for why.
Sleep issues are almost always hormonal or metabolic:

👩‍🦰 Premenopausal women: cortisol + blood sugar
👩‍🦳 Peri/postmenopause: shifting estrogen + progesterone
👨‍🦱 Men: sleep apnea + stress physiology

And remember, waking at 3 a.m. isn’t always “pathology.” If you can drift back to sleep, it may be normal physiology. If you’re wired, anxious, or sweating? That’s when we investigate.

Your sleep reflects your internal rhythm. When hormones, cortisol, and metabolism are in balance, deep rest follows.

✨ Want a personalized, root-cause approach to better sleep? Head to https://www.drkarafitzgerald.com/our-clinic/our-services/

12/12/2025

If winter hits you harder than everyone else seems to admit… you’re not broken.

You’re human, and your biology is responding to real environmental change.

Seasonal Affective Disorder (SAD) isn’t “just the winter blues.”

It’s shifts in serotonin, melatonin, circadian rhythm, inflammation, and even immune signaling. And it can feel like someone dimmed the lights inside you, too.

Here’s the hopeful part:
SAD is one of the most treatable mood disorders we see.

Your brain is exquisitely responsive to support.
✨ Get morning light (natural or a 10,000 lux lightbox)
✨ Move your body — even 10 minutes helps
✨ Nourish mitochondria + methylation (colorful plants, omega-3s)
✨ Keep a consistent sleep/wake rhythm
✨ Stay connected — isolation magnifies symptoms
✨ And please reach out if you’re struggling. Treatment works.

You’re not meant to suffer through winter.

You deserve to feel better, and your biology is more adaptable than you think.

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Sandy Hook, CT

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+12033049502

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http://www.drkarafitzgerald.com/

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