“Is Fatty15 Legit” Series: Is C15:0 really an essential fatty acid?

If you’re here, chances are that you recently heard about fatty15, a healthy aging supplement containing C15:0. And you may be wanting to know if this supplement is legit.

In this series, we help answer some of the most common questions about the science behind fatty15. We also address misconceptions and misinformation about fatty15 that are coming from folks who aren’t living and breathing C15:0 science 24/7. To help you dive even deeper, you can visit DiscoverC15.com/resources to read the cited peer-reviewed studies.

Is C15:0 really an essential fatty acid?

Yes, C15:0 really is emerging as an essential fatty acid. 

First up, an essential fatty acid is a nutrient that our bodies must have to maintain physiological health, but of which our bodies don’t make enough. There have long been two well-accepted essential fatty acids: linoleic acid (an omega-6 fatty acid) and alpha-linolenic acid (an omega-3 fatty acid), which were discovered as such by Dr. George and Mildred Burr back in 1929 and 1930 [1].

During 2020, fatty15’s co-founder, Dr. Stephanie Venn-Watson and Dr. Edward Dennis (who was the Editor-in-Chief of the Journal for Lipid Research for 15 years and has over 400 peer-reviewed publications), published a peer-reviewed paper in Nature’s Scientific Reports laying out the evidence that C15:0 met the criteria of an essential fatty acid [2]. Since then, independent research teams from Canada, France, China, and Australia have published their own studies that are revalidating C15:0 as an essential fatty acid:

• Using the same gold-standard study that Dr. George and Mildred Burr used to discover the first two essential fatty acids, Ciesielski et al. gave pregnant rats a C15:0 deficient diet and showed that the offspring had poor body growth and evidence of nutritional deficiency syndrome [3]. When C15:0 was given to half of these neonates, only those who received C15:0 had resolved healthy body growth. C15:0 was as effective at fixing its nutritional deficiency as linoleic acid (one of the long-known essential fatty acids). 

• In another study, Ruan et al. evaluated numerous fatty acids using early developing worms starved of all nutrients [4]. Only five fatty acids demonstrated the ability, on their own and in the absence of any other nutrient, of restoring normal development; one was C15:0 and another was linoleic acid.  

• In a separate paper, Ciesielski et al also reviewed the published literature around C15:0 in humans and the criteria for essential fatty acids and concluded (referring to “PDA” for pentadecanoic acid and “EFA” for essential fatty acid): “Thus, considering these elements, PDA is currently meeting the described criteria of an EFA [5].”A similar conclusion was made by Dornan et al. in their paper published in 2021 [6].

• There are now also a growing number of human studies, including those published by George et al. and Yuan et al., which are building evidence that C15:0 is needed to support healthy pregnancy, healthy fetal development, and healthy growth and cognitive development in infants and children [7,8,9].

• The importance of C15:0 to early development is further backed by a study by Duan et al., showing that piglets (a model for human infants) fed milk replacers fortified with C15:0 had improved daily growth, gut health, and mitochondrial function [10]. The authors conclude that current human infant formulas, most of which lack C15:0, may need to be fortified with C15:0 to support healthy infant development.

Based on validation by multiple independent research teams throughout the world, including use of gold-standard studies, C15:0 is emerging as the first essential fatty acid to be discovered in over 90 years. 

What the skeptics say

In one video, a scientist talking about essential fatty acids incorrectly states that “there is no evidence that C15:0 meets these criteria, by any stretch of the imagination”. He then goes on to explain that animal studies would be needed in which C15:0 was removed from the diet, which induced a nutritional deficiency syndrome, and restoring C15:0 fixed the problem - not realizing that these studies had already been done and published. Additionally, some scientists have mistakenly stated that since the body can make some small amounts of C15:0, it is not essential.

Setting the record straight

As shared above and in addition to Venn-Watson et al.’s initial published discovery of C15:0 as an essential fatty acid in 2020, multiple independent researchers have published peer-reviewed papers that provide evidence, including gold-standard studies, that C15:0 meets the criteria of an essential fatty acid. This includes independent researchers concluding that, while our body can make some C15:0, it cannot produce enough to maintain healthy levels.

In summary

Essential fatty acids are defined by specific and well accepted criteria agreed upon by the lipid research community. To date, the discoveries of novel essential fatty acids have been made by initial research published in the peer-reviewed literature from a single team. That discovery is then challenged by other independent researchers over time who independently conduct their own studies, including gold standard studies for nutritional deficiencies, and either support or refute whether a fatty acid is essential. There is no single body that determines whether a fatty acid is essential.

As described above, this process has been underway for C15:0, in which there are now multiple independent teams throughout the world who have similarly concluded that C15:0 meets the criteria of an essential fatty acid.

Cited peer-reviewed studies

[1] Mukhopadhyay (2012) J Biol Chem 287, 35439-35441

[2] Venn-Watson et al. (2020) Sci Rep 10, 8161

[3] Ciesielski et al. (2025) J Nutr Biochem 137:109814

[4] Ruan et al. (2024) PLOS Biol 22,e3002841

[5] Ciesielski et al. (2024) Biochimie 227,123-129

[6] Dornan et al. (2021) J Am Oil Chem Soc 98, 813-824

[7] George et al. (2021) Nutrients 13, 4183.

[8] George et al. (2023) Proceedings 84, 9.

[9] Yuan et al. (2025) Eur J Clin Nutrition 79:320-328.

[10] Duan et al. (2025) J Nutr 155, 1298-1310.