The Path to Essentiality: Omegas & C15:0

September 27, 2026

Welcome to Issue 188 of Science Says! Our weekly newsletter where you’ll learn the latest healthy aging and C15:0 research news that our team of doctors, scientists, and experts are most excited about—without having to go search for it.

Eric and Steph
Co-Founders, Doctors, Nerds

What Dr. Stephanie Venn-Watson, our co-founder and author of The Longevity Nutrient and over 80 peer-reviewed scientific publications, is reading.

Healthy Aging

Who determines that a fatty acid is essential?

Back in 2020, we published a paper in Nature’s Scientific Reports proposing C15:0 as an essential fatty acid – which would make C15:0 the third-ever discovered nutrient in this exclusive category. Today, there are 150+ studies supporting C15:0’s health benefits, 144+ of which are by independent teams. A common question we get is, who determines that a fatty acid is essential? This week, we cover how fatty acids earn the rare title of essential.

Sounds great, but remind me – what is an essential fatty acid?

Good question! An essential fatty acid is a fatty acid that our body requires to maintain baseline physiological health, but it doesn’t make enough of that molecule on its own. This means it is essential to get this fatty acid through our diet in order to achieve and maintain healthy levels.

Prior to our discovery, there were two known essential fatty acids (EFAs):

Linoleic acid (LA), an omega-6 fatty acid
Alpha linolenic acid (ALA), an omega-3 fatty acid

But who determines that a fatty acid is essential?

Well, for LA and ALA, Dr. George and Mildred Burr conducted a series of rodent studies in 1929 and 1930 showing that these fatty acids met the criteria of essentiality.

First, they showed that a diet absent of fat led to:

A distinct deficiency-driven disease
Poor ovulation
Poor growth
Cured disease by restoring fats in the diet

Source: Burr and Burr (1929)

Next, they showed that specific fatty acids within fat were required to:

Avoid deficiency-driven disease
Support healthy ovulation and reproduction
Support healthy growth
Cure disease by restoring specific fatty acids in the diet

Source: Burr and Burr (1930)

As such, LA and ALA were deemed “essential fatty acids”. And that was that.

While this may not sound mindblowing now, these were huge discoveries. Back then, it was believed that fats only provided calories, with no further benefits. The Burrs’ claim that specific fatty acids not only had health benefits, but that they were essential was met with fervent rejections from members of the nutrition community. Specifically, Lafayette B. Mendel, a nutritionist, was the loudest descending voice. Since the Burrs were not well known, the mainstream community followed Mendel’s dissent.

Since then, the overall body of peer-reviewed research has supported that LA and ALA (paired with its metabolites, EPA and DHA) are essential fatty acids that contribute to broad aspects of human health, and the Burrs have long been proven right.

C15:0’s path to essentiality

Fast forward almost a century later, and a similar path has been set for C15:0 (also called pentadecanoic acid).

Thanks to the Office of Naval Research funding, we published a series of studies and supporting literature in Nature’s Scientific Reports supporting that C15:0 meets the criteria of an essential fatty acid. This paper’s senior author was Dr. Edward Dennis, a respected leading academic scientist in the lipid community and Editor-in-Chief for the Journal of Lipid Research for 15 years.
We subsequently published evidence and the detailed pathophysiology of a nutritional C15:0 deficiency syndrome in humans (and dolphins) involving ferroptosis – a newly discovered form of cell death discovered by Dixon et al. at Columbia University – as well as dysmetabolic iron overload syndrome and nonalcoholic fatty liver disease.
This same pathophysiology in humans was formally described as “Metabolic Hyperferritinemia” in a 2023 consensus statement published by Valenti et al. in Nature Endocrinology.

Since our landmark paper, which has been cited in 245 peer-reviewed papers to date, numerous independent teams have continued to support the emergence of C15:0 as an essential fatty acid.

Ciesielski et al. repeated the Burrs’ hallmark rodent model studies with C15:0, and showed that C15:0 did as well as LA in restoring essential fatty acid deficiencies. This team also published a review paper on human studies supporting that C15:0 is emerging as essential.
Similarly, a team in Canada published a paper concurring that C15:0, as an odd-chain fatty acid, is essential.
Aabis et al. conducted a series of studies with a rodent model of C15:0 nutritional deficiency, ferroptosis, and metabolic hyperferritinemia – and reconfirmed that C15:0 had broad beneficial effects across multiple pathways.
Using C. elegans as a model, Ruan et al. showed that absent all nutrients, C15:0 alone restored normal neurodevelopment in postembryonic nematodes.
Duan et al. showed that piglets fed a C15:0-supplemented formula resulted in improved body growth, gut health, and mitochondrial function that matched those fed sow’s milk.
Numerous studies have shown that human infants receiving more C15:0 in the womb and through breastmilk have better body growth and brain development. Further, higher C15:0 has been associated with better ovarian, reproductive, and pregnancy health in women. This matches animal studies showing that C15:0 directly improves placental vasculature and fetal development.

Importantly, despite six years passed and hundreds of papers citing our hallmark studies, there have been no outright disputes of C15:0 as an emerging essential fatty acid in the peer-reviewed scientific literature – the appropriate forum where the breadth of C15:0’s beneficial role will continue to play out. The science of C15:0 is now in the world’s hands, and it has been exciting to see this body of research grow. Thanks for being with us on this incredible journey, and a big thanks to the Navy (including you, dolphins!). Have a great week, everyone.