The Science Behind C15:0

Healthy Aging

A Quick C15:0 Catch Up

Well, it’s officially here, everyone! Simon & Schuster will be releasing The Longevity Nutrient on Tuesday, March 25th. This book tracks our 20-year scientific journey – starting with an unexpected discovery of C15:0’s health benefits  while helping dolphins – which has culminated in a movement to improve global health. And dare we say, humanity?

In this series of Science Says!, we have been providing a behind-the-scenes science peek relevant to each of the book’s chapters – from surprising dolphin discoveries to longevity molecule must-haves, from how essential fatty acids are discovered to the many ways C15:0 works, from how a newly found nutritional deficiency accelerates aging to how fixing and optimizing our C15:0 levels can slow aging to help us live healthier, longer.

In this The Longevity Nutrient book launch week, let’s do a quick catch-up on a whole lotta C15:0 science. Consider this issue your cliff notes to the book.

Helping dolphins revealed a secret to healthy aging.

During 2005-2012, while caring for older Navy dolphins, we published a series of peer-reviewed papers demonstrating parallels between aging dolphins and aging humans. Just like us, about 1 in 3 older dolphins developed chronic inflammation, elevated cholesterol and triglycerides, insulin resistance, liver iron overload, and fatty liver disease.

We used an advanced technology, called metabolomics, to study thousands of small molecules present in the dolphins’ archived serum, as well as their all-fish diets.

The top dietary predictor of the healthiest aging dolphins? As we published in PLOS ONE, the top predictor of healthier dolphins was higher dietary and circulating levels of C15:0 (aka pentadecanoic acid).

Today, we know that C15:0 does a lot of good things to support our long-term health and wellness. To start, C15:0 is a sturdy fat that plays a core role in strengthening our cell membranes and protecting us (and dolphins) against age-related breakdown.

C15:0 is discovered as the first essential fatty acid to be found in over 90 years.

After that initial discovery in dolphins, we moved pure C15:0 into the lab to conduct 8 studies over 3 years. As published in Nature’s Scientific Reports, these studies showed that C15:0 was not only an active and beneficial fatty acid, but that it met the rare criteria of an essential fatty acid.

As a reminder, essential fatty acids are nutrients that our bodies need to maintain our baseline health. Since our bodies don’t make enough of these fatty acids on their own, we have to get adequate amounts from our diet.

Since that initial publication in 2020, three additional independent teams in Canada, China, and France have conducted their own studies revalidating C15:0 as an essential fatty acid, including two gold-standard studies:

• Ciesielski et al. (2025) gave pregnant rats a C15:0 deficient diet and showed that the offspring had poor body growth and evidence of nutritional deficiency syndrome. When C15:0 was given to half of these neonates, only those who received C15:0 had resolved healthy body growth.
• Ruan et al. (2024) evaluated numerous fatty acids using early developing worms starved of all nutrients. Only a small handful of fatty acids demonstrated the ability, on their own and in the absence of any other nutrient, of restoring normal development. Yep, one of those was C15:0.

These and many other studies all support C15:0 as the first essential fatty acid to be discovered in over 90 years, since omega-3 (alpha linolenic acid) and omega-6 (linoleic acid). You go, C15:0!

C15:0 supports our whole body health and wellness.

The scientific support behind C15:0’s health benefits are backed by studies demonstrating C15:0’s mechanisms of action, dose-response cell-based activities, efficacy in relevant animal models, large scale epidemiological studies, and clinical trials. Let’s walk through liver health as just one example:

• First, C15:0 activates key receptors, called PPARɑ and PPARδ. These receptors are master balancers of our metabolism and immune responses – and are also known to help to keep our livers healthy.
• Second, in human cell-based systems mimicking angry livers, C15:0 effectively calmed proinflammatory cytokines and fibrosis (aka scarring).
• Third, daily C15:0 supplementation helped to support healthy livers in multiple models of fatty liver disease.
• Fourth, in a placebo controlled clinical trial, people supplemented with C15:0 who achieved sufficient C15:0 levels ( > 5 ug/ml) demonstrated improved liver function within 12 weeks.
• Finally, across multiple epidemiological studies, people with higher C15:0 levels consistently have healthier livers.

In The Longevity Nutrient, we cover similar supporting evidence for C15:0’s benefits to our long-term metabolic, heart, red blood cell, and gut health. Yep, whole body health and wellness.

Introducing C15:0 as a leading longevity nutrient.

As described in the book, we now know that C15:0 checks off the 7 must-haves of a longevity nutrient. For example, C15:0:

1. Targets the Human Longevity Regulating Pathway. C15:0 activates AMPK and inhibits mTOR, which are the heart of the human longevity pathway (and also targeted by metformin and rapamycin, two leading longevity compounds).
2. Reverses Key Hallmarks of Aging. C15:0 reverses multiple hallmarks of aging at the cellular level, including evidence of reversing inflammaging, mitochondrial dysfunction, cellular senescence, poor cellular signaling, gut dysbiosis, and epigenetic alterations.
3. Has Evidence of Slowing Our Aging Rate. By strengthening cells, C15:0 protects against declining hemoglobin and raised red blood cell distribution width (RDW), two key markers of accelerated aging rates. Liu et al. showed that that people with higher C15:0 in their lipids had a younger biological age than their chronological age.
4. Demonstrates Clinically Relevant Benefits within Months. In both relevant animal models and human clinical trials, C15:0 directly improved liver, cholesterol, red blood cell, and gut microbiome health within 12 weeks.
5. Has Evidence of Protecting Long-Term Health. All the above helps to explain how many (many) prospective cohort studies have shown that people with higher C15:0 levels have better long-term metabolic, heart, and liver health.
6. Is Feasible to Take Over Decades and Decades. As a component of dairy fat, C15:0 has been accessible to humans since, well, humans have existed.
7. Is Safe to Take Over Decades and Decades. As an essential and natural nutrient, C15:0 is also remarkably safe.

Thus, a quick summary of how C15:0 became The Longevity Nutrient.

A deficiency syndrome.

Lastly, as we covered last week, there is an urgent need to understand how global nutritional deficiencies in C15:0 are impacting our health, including evidence that Cellular Fragility Syndrome is accelerating aging – especially among younger people. We published this nutritional deficiency syndrome in the peer-reviewed journal, Metabolites, including the detailed pathophysiology of how nutritional C15:0 deficiencies weaken our cell membranes, which result in ferroptosis, a new form of cell death that accelerates aging and affects our metabolic, liver, and heart health.

Just as importantly, these C15:0 deficiencies are fixable.