There's a peptide your body already makes — has always made — that sits at the intersection of immunity, cellular repair, and aging itself. LL37. It's not exotic. It's not pharmaceutical. It's you, functioning the way you were designed to function. Scotch McClure's argument is elegant in its simplicity: aging, at its root, is what happens when your body loses its ability to produce enough of this peptide to maintain order. Homeostasis slips. Entropy wins. And you age faster than you should.
What makes this interesting isn't the synthetic version Maxwell Biosciences is developing — though that's worth watching. What's interesting is the implication buried inside the conversation. If LL37 production is influenced by sunlight, nutrition, and exercise, then the lifestyle choices we've been recommending for contrast therapy aren't just making you feel better. They may be directly supporting one of your body's core anti-aging mechanisms.
Cross-reference this with Dr. Mark Hyman's work on the Hallmarks of Aging, which we have extensively indexed in the knowledge base. The hallmarks describe cellular senescence, protein misfolding, and loss of proteostasis — the same terrain LL37 operates in. Heat shock proteins, which spike dramatically after sauna sessions, are molecular chaperones that refold damaged proteins. LL37 works upstream, helping the immune system identify and clear cellular debris before it accumulates into disease. Different mechanisms. Same goal: keeping order in a system that naturally drifts toward chaos.
The research on heat exposure and longevity shows a 66 percent reduction in Alzheimer's risk with regular sauna use. Alzheimer's is fundamentally a protein aggregation disease — misfolded proteins accumulating into plaques. If heat shock proteins prevent that accumulation, and LL37 supports the immune response that clears what gets through, you're looking at two complementary defense systems that both respond to lifestyle inputs.
McClure is careful here, and I respect that. He says outright that LL37 is not the "end all be all of forever young." That caveat matters. We've seen this pattern before in the longevity space — a promising molecule gets elevated to miracle status, supplements flood the market, and the nuance gets lost. LL37 fits into a system. It doesn't replace the system.
Before anyone waits for a synthetic LL37 product, focus on what McClure confirms raises natural production: sunlight exposure, quality nutrition, and regular exercise. Contrast therapy sits at the intersection of all three of these mechanisms — the physical stress of cold and heat mirrors the metabolic demands that signal your body to upregulate repair systems. You don't need to wait for a pharmaceutical intervention to start supporting what your body already knows how to do.
The surprising connection? Cold water immersion creates a significant stress response at the skin barrier — the same barrier where LL37 is most concentrated and most active. We don't yet have direct studies linking cold plunging to LL37 upregulation. But the mechanism is plausible, and the research direction is clear. The body doesn't distinguish between types of beneficial stress. It adapts. That's the whole point.