Alternative Fat Supplements: Are They Worth the Hype?

Part 2: Fatty15

In the world of nutrition, new “miracle” compounds are frequently making headlines, and with more and more online health influencers touting their latest all-curing supplements, it’s worth exploring the true efficacy of some of the fat concoctions. In Part 1, I covered omega-7s. Here, I’m looking into a lesser-known fatty acid that’s been getting a bit of online attention, because, when you come across claims like “the first essential fatty acid discovered in 90 years” [1] and “targeting six out of the 12 hallmarks of aging” [2], lots of you will be desperate to part with your hard-earned cash to reap the benefits of these lofty claims.

Pentadecanoic acid (also referred to as pentadecyclic acid) is a fatty acid with the chemical abbreviation C15:0. Commonly known as “Fatty15”, this odd-chain saturated fatty acid has 15 carbon atoms and is found in small amounts in dairy fat, fish, ruminant meats and some plants [3]. Unlike the more common even-chain saturated fats, such as palmitic acid and stearic acid, which have been linked to less favourable lipid profiles and negative health outcomes, in observational studies odd-chain saturated fats have been shown to be associated with a lower risk of type 2 diabetes, cardiovascular disease and overall mortality [4]. Researchers have suggested that this may be due to their unique role in metabolism and cellular health. But does the science around Fatty15 support its hype?

Claimed Benefits of Fatty15 Supplementation

Research has pointed to several health-protective effects of Fatty15. For example, it may help strengthen cell membranes, making them more resistant to stress and aging [5]. It may also have anti-inflammatory effects in that it may activate pathways that reduce chronic low-grade inflammation [6], a key driver of many of the non-communicable diseases. Some animal and early human studies have linked higher C15:0 levels with better cholesterol profiles, lower insulin resistance and healthier liver function. In addition, a few epidemiological studies have found that people with higher blood levels of C15:0 tend to live longer and have lower risks of chronic diseases [7].

Because many modern diets are lower in key dietary sources of full-fat dairy*, certain fish and ruminant meats, advocates have argued that supplementation of Fatty15 could restore beneficial levels. Plant sources include quinoa, jackfruit and acacia seeds, and tamarind kernels, none of which are foods that are regularly consumed in western cultures. While commonly eaten veggies like cabbage and cucumber have comparable amounts of pentadecanoic acid to other fatty acids, being poor fat sources, the absolute amounts of pentadecanoic acid ingested will be minute.

Is Supplementing with Fatty15 Worth It?

Despite intriguing findings, any claims made off the back of the evidence are premature. Most of the human data comes from observational studies; nothing yet points to it being pentadecanoic acid that’s driving any of the health benefits. Correlation does not equal causation. There could, for instance, be other factors in dairy or fish consumption at play. To date, very few randomised controlled trials have tested purified Fatty15 supplements in humans, without which we have no way of assessing the effective dose, long-term effects and safety.

As is usually the case with newly hyped supplements, there’s considerable marketing hyperbole at play. Claims like Fatty15 being the “first essential fatty acid in 90 years” are simply not substantiated. Sure, additional pentadecanoic acid might have some benefits, but there’s zero evidence to back up the assertion that pentadecanoic acid is “essential” in the way that we recognise the omega-3 fatty acid alpha-linolenic acid and the omega-6 linoleic acid as truly essential. In the absence of these nutrients, humans experience symptoms of frank deficiency.

There’s no strong evidence that Fatty15 supplementation is necessary in addition to consuming a well-balanced, nutritious diet. It may turn out that, sometime in the future, supplements are found to be useful, particularly in plant-based diets, but any claim to that effect will mandate much stronger evidence than what is presently available. For now, their benefits remain unproven, and pentadecanoic acid supplementation probably isn’t necessary for most of us.

That said, the evidence surrounding Fatty15 is interesting, and it’s certainly a nutrient I’ll be keeping my eye on. If more well-designed human trials are completed, we’ll be able to draw a clearer picture of their use as a supplement. As it stands, the hype is way outpacing the evidence. Until well-designed human trials confirm its benefits and safety, the Bayesian in me is telling me that it’s best to view Fatty15 supplements with cautious curiosity rather than as a sure path to better health.

*The butterfat in cow’s milk is the single major dietary source, comprising 1.2 per cent of the fat [8].

References
1. Venn-Watson, E. (2025) ‘The Groundbreaking Discovery & New Science Validating C15:0 as an Essential Fatty Acid’, Fatty15, 19 May. Available at: https://fatty15.com/blogs/news/the-groundbreaking-discovery-new-science-validating-c15-0-as-an-essential-fatty-acid (Accessed: 5 September 2025).
2. Venn-Watson, E. (2025) ‘Healthy Aging: 6 Longevity Tips for Graceful Aging’, Fatty15, 28 July. Available at: https://fatty15.com/blogs/news/healthy-aging-longevity-tips (Accessed: 5 September 2025).
3. (a) Hansen, R. P. et al. (1954) ‘The Occurrence of n-Pentadecanoic Acid in Hydrogenated Mutton Fat’, Biochemical Journal, 58(4), 516-17; (b) Dąbrowski, G. and Konopka, I. (2022) ‘Update on Food Sources and Biological Activity of Odd-Chain, Branched and Cyclic Fatty Acids –– A Review’, Trends in Food Science & Technology, 119, 514-29.
4. Venn-Watson, S. K. and Butterworth, C. N. (2022) ‘Broader and Safer Clinically Relevant Activities of Pentadecanoic Acid Compared to Omega-3: Evaluation of an Emerging Essential Fatty Acid Across Twelve Primary Human Cell-Based Disease Systems’, PLoS One, 17(5), e0268778.
5. (a) Jenkins, B. et al. (2015) ‘A Review of Odd-Chain Fatty Acid Metabolism and the Role of Pentadecanoic Acid (C15:0) and Heptadecanoic Acid (C17:0) in Health and Disease’, Molecules, 20(2), 2425-44; (b) Venn-Watson, S. et al. (2020) ‘Efficacy of Pentadecanoic Acid (C15:0) to Improve Health in Cell-Based and Animal Models of Metabolic and Inflammatory Disease’, Scientific Reports, 10, 8161.
6. ibid (5a-b).
7. (a) Khaw, K. T. et al. (2012) ‘Plasma Phospholipid Fatty Acid Concentration and Risk of Incident Coronary Heart Disease in Men and Women: The EPIC-Norfolk Prospective Study’, PLoS Medicine, 9(7), e1001255; (b) Forouhi, N. G. et al. (2014) ‘Differences in the Prospective Association Between Individual Plasma Phospholipid Saturated Fatty Acids and Incident Type 2 Diabetes: The EPIC-InterAct Case-Cohort Study’, The Lancet Diabetes & Endocrinology, 2(10), 810-18.
8. Smedman, A. E. et al. (1999) ‘Pentadecanoic Acid in Serum as a Marker for Intake of Milk Fat: Relations Between Intake of Milk Fat and Metabolic Risk Factors’, The American Journal of Clinical Nutrition, 69(1), 22-9.