A longevity expert's reality check: What actually works (and what doesn't)
Dr. Matt Kaeberlein has spent 20 years studying aging and says most of the expensive tests and supplements being marketed today aren't worth it.
The longevity industry has exploded in recent years, offering biological age tests, specialized supplements, microbiome analyses, and optimization protocols—all promising to help you live longer and healthier. But which of these interventions are backed by solid evidence, and which are premature at best?
Dr. Matt Kaeberlein has spent over 20 years studying the biology of aging as a professor emeritus at the University of Washington. Unlike many voices in the longevity space, he has no products to sell—just decades of laboratory research and clinical observation to draw from. His perspective cuts through the hype to focus on what the science actually shows.
"I feel super lucky that I sort of stumbled into it," Dr. Kaeberlein reflects on entering the aging field during what he calls "a golden age for the science of longevity" in the late 1990s and early 2000s. Since then, he's watched rigorous research evolve into a consumer marketplace where evidence doesn't always keep pace with marketing claims.
The bottom line: Most interventions that work for longevity aren't exotic or expensive—they're the fundamentals of healthy living. Understanding what's proven versus what's promising can help you focus your efforts where they'll have the greatest impact.
Reality Check #1: Biological Age Tests Aren't Ready for Prime Time
Epigenetic biological age tests generate enormous excitement by promising to reveal your "true" biological age and track how quickly you're aging. The science behind them is real—in research settings, epigenetic markers can predict mortality risk and health outcomes. The problem is translating that research into reliable consumer products.
"I don't recommend that people get them unless you just want it for entertainment value," Dr. Kaeberlein explains. "I don't think you can have confidence that the numbers are actually giving you are useful at this point."
The gap between research and consumer products comes down to standardization and quality control. Different companies test different epigenetic marks, making results incomparable across platforms. Even within the same company, Dr. Kaeberlein notes that repeated tests on samples taken the same day "can get a 20-year difference."
There's also a terminology issue. These tests claim to measure "biological age" but actually measure something different: features correlated with mortality risk or current health status. "None of them measure biological age," Dr. Kaeberlein clarifies. "They all measure features that are correlated with either risk of dying, mortality, or health status."
Perhaps most importantly, even if these tests were accurate, they don't provide insights beyond what more established testing can reveal. A comprehensive metabolic panel, body composition scan, and functional fitness assessment cost less and provide more actionable information about where to focus your health efforts.
Reality Check #2: Most Longevity Supplements Lack Strong Evidence
Dr. Kaeberlein's personal supplement regimen might surprise people: beyond vitamin D and omega-3s (both measurable via blood work), he takes creatine. That's it.
This minimalism isn't from ignorance—it comes from deeply understanding both the biology of aging and the evidence behind various supplements. "I tend not to add supplements that I take unless I'm really confident that it's likely to have value or it's something that I can measure on a blood test," he explains.
The challenge with supplements is biological complexity. "If you think about the human body, our body is one of the most complicated biological machines that's out there," Dr. Kaeberlein notes. Adding compounds without clear deficiencies or strong evidence is more likely to cause unintended effects than optimization.
Take NAD boosters like nicotinamide riboside—initially reported to extend lifespan in laboratory animals but "wasn't subsequently able to be reproduced" in follow-up studies. Or resveratrol, which Dr. Kaeberlein calls "the most debunked longevity intervention of all time." When researchers analyzed all published studies on resveratrol and lifespan in animals, "the average or median effect was zero."
This doesn't mean supplements never have value. Creatine, for instance, has solid evidence for supporting muscle function and potentially offering protective effects beyond muscle mass. But the evidence bar should be high, especially given the lack of regulation in the supplement industry.
Dr. Kaeberlein puts creatine "in the next level down" from lifestyle interventions—"I believe that for a lot of people it can have sort of an incremental value especially if you're living a relatively healthy lifestyle and doing resistance training regularly."
The key word: incremental. No supplement comes close to the impact of lifestyle factors.
Reality Check #3: Microbiome Tests Don't Provide Clear Action Steps
The gut microbiome genuinely matters for health, but that scientific reality has generated consumer tests that often overpromise. Like biological age tests, direct-to-consumer microbiome tests face issues with standardization and interpretation.
"I know most of the best microbiome researchers in the world and I have yet to have one tell me that they think these direct to consumer microbiome tests are useful or a good idea," Dr. Kaeberlein shares.
The problem isn't that microbiome analysis has no value—it's that the broad wellness tests marketed to healthy people don't yet provide actionable insights beyond what you'd learn from basic health principles. Some companies compound this by pairing tests with proprietary supplements, using pseudoscientific framing to suggest you need specific products based on your "good and bad bacteria."
Dr. Kaeberlein draws a distinction: "There are a small percentage of people who have specific conditions in their gut where specific microbiome tests are valuable." These clinical tests for particular pathogens or conditions differ from general wellness microbiome analyses.
For most people focused on gut health, the proven interventions—eating diverse plant foods, limiting processed foods, managing stress—will have more impact than any test result.
Reality Check #4: Getting the Basics Right Matters More Than Optimization
Perhaps the most important insight from Dr. Kaeberlein's research is about priorities. In the longevity space, there's enormous focus on optimization: perfecting supplement stacks, fine-tuning fasting windows, tracking every biomarker, maximizing zone 2 training.
But for most people, this focus on optimization comes before mastering fundamentals. "I think that's fair," Dr. Kaeberlein agrees when asked if lifestyle interventions rank highest. "I sort of think of these in buckets of things that move the needle, big levers. And that's where the lifestyle falls. Those things work and we know they work."
The big levers are unsexy but proven:
- Nutrition: "I think given what we know today, it would be hard to argue that a plant-forward diet where you're not eating red meat every day and you're not eating highly processed foods every day, a lot of them, is a good place to be."
- Protein: Moderate intake around 0.6-1.0 grams per pound of body weight provides benefits without the potential downsides of very high protein diets. "Do I eat protein bars once in a while? Yeah, I eat protein bars once in a while, but I'm not eating eight protein bars a day."
- Exercise: Both resistance training (especially if you're undermuscled) and cardiovascular fitness matter. But the specifics matter less than consistency. "You should lean into that and say, 'What kind of exercise can I do that I enjoy or that I can envision myself doing for the next 10 years?'"
- Sleep, stress, and relationships: These interconnected factors affect everything from hormone balance to inflammation. "How are your relationships? How is your mental health?" Dr. Kaeberlein asks. "Assessing your emotional health, your relationship health, I think is part of the equation."
The point isn't perfection—it's getting these fundamentals consistently right. Everything else provides marginal gains at best.
What to Focus On Instead
Rather than expensive tests and supplement stacks, Dr. Kaeberlein recommends what he calls "the foundation":
- Functional assessments of strength and cardiovascular fitness provide concrete data about your current capabilities and where to focus training efforts. A DEXA scan reveals body composition, including muscle mass, fat distribution, and bone density—all crucial for long-term health.
- Lifestyle optimization across nutrition, exercise, sleep, stress management, and social connection forms the core. These aren't exciting or high-tech, but they're the only interventions proven to significantly impact health span.
- Targeted interventions based on specific, measurable issues. If your vitamin D is low, supplementation makes sense. If you have insulin resistance, dietary changes targeting that specifically will help. This personalized approach beats throwing supplements at problems you haven't identified.
Dr. Kaeberlein acknowledges a cultural barrier: "Unfortunately, in the United States especially, we have been psychologically trained that if medical insurance doesn't pay for it, I'm not going to do it. You got to get over that." Basic preventive testing and interventions often cost less than the marketed longevity products—and they actually work.
The Path Forward
The longevity field is evolving rapidly, with promising research on interventions like rapamycin (which Dr. Kaeberlein discusses as the most robust longevity intervention in animal studies) potentially translating to human applications. But we're not there yet with most interventions being marketed today.
What's proven and available now? The fundamentals. "Those things work and we know they work," Dr. Kaeberlein emphasizes about lifestyle interventions.
This is actually good news. The tools for improving your health span don't require expensive tests, specialized supplements, or optimization protocols. They require commitment to doing the basics well: eating quality food, moving regularly, sleeping adequately, managing stress, and maintaining strong relationships.
The longevity revolution isn't being sold online—it's happening in your daily choices about how you eat, move, sleep, and connect with others.
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