Show notes
Dr. Lara Zakaria is joined by Stephanie Venn-Watson, DVM, MPH, to explore emerging research on pentadecanoic acid (C15:0), an odd-chain saturated fatty acid initially studied through research involving bottlenose dolphins.The conversation connects C15:0 with cell-membrane composition, lipid peroxidation, ferroptosis, iron metabolism, metabolic health, and steatotic liver disease. It also examines research on circulating C15:0 as a biomarker associated with cardiometabolic outcomes and early human trials of C15:0 supplementation. (Imamura 2018) (Sawh 2021) C15:0 has been proposed as a candidate essential fatty acid, however, that classification and a specific human “C15:0 deficiency syndrome” remain emerging hypotheses rather than established clinical diagnoses.Clinical TakeawaysFerroptosis is an iron-dependent form of regulated cell death. First characterized in 2012, ferroptosis involves iron-dependent lipid peroxidation and differs mechanistically from apoptosis and other forms of cell death. (Dixon 2012) Polyunsaturated fatty acids in phospholipids are particularly relevant substrates for ferroptotic lipid peroxidation. (Yang 2016)C15:0 is an odd-chain saturated fatty acid being studied for metabolic effects. Pentadecanoic acid, or C15:0, is found in dairy fat and smaller amounts in other foods. Higher circulating C15:0 has been associated with lower incidence of type 2 diabetes in prospective observational research, but these associations do not establish that C15:0 itself prevents diabetes. (Imamura 2018)Calling C15:0 an “essential fatty acid” remains an emerging scientific proposal. Experimental work has proposed C15:0 as a candidate essential fatty acid based on dietary exposure, biological activity, and associations between circulating levels and health outcomes. More research is needed before C15:0 can be treated as equivalent to the established essential fatty acids linoleic acid and alpha-linolenic acid. (Venn-Watson 2020) (Venn-Watson 2022) Metabolic hyperferritinemia is a recognized clinical framework, but it is not synonymous with ferroptosis or C15:0 deficiency. Metabolic hyperferritinemia describes elevated ferritin occurring with metabolic dysfunction. Ferritin is also an acute-phase reactant, so elevated values require evaluation in clinical context rather than being interpreted as tissue iron overload by themselves. (Valenti 2023)Human C15:0 supplementation evidence is early. Within this broader metabolic context, circulating C15:0 is an emerging biomarker of interest. In a small 12-week randomized, placebo-controlled trial in young adults with overweight or obesity, 200 mg/day oral C15:0 significantly increased circulating C15:0 concentrations. Exploratory analyses suggested that participants who achieved post-treatment circulating C15:0 concentrations above 5 µg/mL had greater reductions in ALT and AST and a greater increase in hemoglobin; these achieved-level findings were not definitive treatment effects and require replication in larger trials designed for liver and hematologic outcomes. (Robinson 2024)Diet and lifestyle remain the better-established foundation for metabolic and liver health. Dairy fat is the principal dietary source of C15:0, although circulating odd-chain fatty acids may also be influenced by endogenous production. (Weitkunat 2017) For people who avoid or tolerate little dairy, C15:0 supplementation is an emerging option that may be useful alongside high-fiber, Mediterranean-style minimally processed dietary patterns, regular exercise, metabolic-risk reduction, and appropriate evaluation and treatment of fatty liver disease or abnormal iron markers. (Chooi 2024)Guest: Stephanie Venn-Watson, DVM, MPHStephanie Venn-Watson is a veterinary epidemiologist whose research has included comparative medicine and the health of bottlenose dolphins cared for through the U.S. Navy Marine Mammal Program.Research involving dolphins identified similarities in metabolic and age-associated physiology that led investigators to study odd-chain saturated fatty acids, including C15:0 and C17:0. Her subsequent research has focused on the biological activity of C15:0 and the hypothesis that inadequate C15:0 may contribute to cellular vulnerability.Some of this research is connected with patents and commercial C15:0 products, making independent replication and larger human clinical trials particularly important when interpreting the findings.Clinician FAQ1. What is C15:0?C15:0, or pentadecanoic acid, is a 15-carbon odd-chain saturated fatty acid.It occurs in foods including dairy fat and has historically been studied as a biomarker related to dairy-fat intake. (Imamura 2018) More recent research is examining whether C15:0 itself has biologically relevant metabolic effects. (Venn-Watson 2020)2. Is C15:0 an essential fatty acid?Not yet by established nutritional consensus.C15:0 has been proposed as a candidate essential fatty acid, but this remains an emerging area of research. (Venn-Watson 2020) (Venn-Watson 2022) Linoleic acid and alpha-linolenic acid remain the conventionally recognized essential fatty acids in human nutrition.3. What is ferroptosis?Ferroptosis is a regulated, iron-dependent form of cell death characterized by damaging lipid peroxidation. (Dixon 2012)The process involves interactions among cellular iron, oxidizable membrane phospholipids, and antioxidant defense systems. Ferroptosis is being investigated across metabolic, neurologic, cardiovascular, liver, and cancer biology.4. Is high ferritin evidence that a patient is undergoing ferroptosis?No.Ferritin reflects iron storage but is also an acute-phase reactant. Elevated ferritin can occur with inflammation, liver disease, metabolic dysfunction, infection, malignancy, iron overload, and other conditions. (Valenti 2023) Ferroptosis cannot be diagnosed from serum ferritin alone.5. What is metabolic hyperferritinemia?Metabolic hyperferritinemia describes elevated serum ferritin occurring in the context of metabolic dysfunction.A published consensus framework proposes ferritin above 300 ng/mL in men or 200 ng/mL in women together with specified metabolic criteria, while excluding or reassessing alternative explanations for hyperferritinemia. (Valenti 2023) The framework also distinguishes hyperferritinemia from confirmed tissue iron accumulation. (Liu 2024)6. Does elevated ferritin mean a patient needs phlebotomy?Not necessarily.The metabolic hyperferritinemia consensus states that evidence supporting routine iron-depletion therapy is insufficient. (Valenti 2023) Phlebotomy should not be inferred from ferritin alone; evaluation of the cause of hyperferritinemia and, when appropriate, tissue iron burden is important.7. What foods contain C15:0?Dairy fat is one dietary source of C15:0, and C15:0 is also present in smaller amounts in some meats, fish, and other foods.Circulating odd-chain fatty acids are not exclusively determined by dairy intake. Research also suggests that endogenous pathways involving gut-derived propionate can contribute to odd-chain fatty acid production. (Weitkunat 2017)8. Does eating more full-fat dairy increase C15:0?Dietary dairy fat can contribute to circulating C15:0, but the health implications of increasing full-fat dairy cannot be reduced to C15:0 alone.Dairy foods contain multiple fatty acids, proteins, carbohydrates, minerals, and other components, and observational evidence differs by dairy-food type. (Imamura 2018) (Sawh 2021) Dietary recommendations should therefore consider the patient's overall diet and clinical context.9. What has human supplementation research shown?Human evidence remains limited.One randomized trial studied 200 mg/day of C15:0 for 12 weeks in 30 young adults with overweight or obesity and found increased circulating C15:0. (Robinson 2024) A separate randomized trial evaluated 300 mg/day as an addition to an Asian-adapted Mediterranean-style diet in women with fatty liver and reported an additional reduction in LDL cholesterol and an increase in Bifidobacterium adolescentis abundance. (Chooi 2024)Neither study establishes C15:0 supplementation as treatment for metabolic disease, ferroptosis, or metabolic hyperferritinemia.10. Can C15:0 levels be used as a clinical treatment target?A standardized clinical target has not been established.Thresholds such as 5 μg/mL or 0.2% of total fatty acids have been proposed and explored in C15:0 research, but they should not currently be treated as universally validated diagnostic thresholds for deficiency or treatment targets. (Robinson 2024) (Venn-Watson 2024) Timestamps / Key Moments00:00:18 Introducing C15:0, cellular aging, and ferroptosis00:02:19 Stephanie Venn-Watson’s background and dolphin research00:05:29 How C15:0 emerged from metabolomics research00:10:20 Alzheimer’s disease-like pathology in dolphins00:11:33 What C15:0 is and how fatty acids are classified00:18:18 C15:0, membrane stability, and lipid peroxidation00:19:25 Understanding ferroptosis00:24:34 Metabolic hyperferritinemia and clinical patterns00:27:37 Proposed C15:0 thresholds and metabolic research00:30:43 Dietary sources of C15:000:40:19 Measuring circulating C15:000:45:49 Human clinical research on C15:0Fatty acids and biological processes discussedPentadecanoic acid (C15:0)Heptadecanoic acid (C17:0)Odd-chain saturated fatty acidsSaturated fatty acidsPolyunsaturated fatty acidsLinoleic acidAlpha-linolenic acidEPADHACell-membrane lipidsLipid peroxidationFerroptosisReactive oxygen speciesMitochondrial functionIron metabolismFerritinClinical markers and conditions discussedFerritinTransferrin saturationHemoglobinRed blood cell distribution width (RDW)ALTASTGGTLipid peroxidationLDL cholesterolGlucoseInsulinMetabolic hyperferritinemiaInsulin resistanceType 2 diabetesMetabolic syndromeMASLDMASHIron overloadCognitive declineWant to elevate your practice?This episode is sponsored by Fullscript, a comprehensive care delivery platform designed to support whole-person, integrative healthcare. Fullscript helps practitioners bring supplement dispensing, lab ordering, patient education, and care planning into a centralized workflow.The goal is not to replace clinical judgment, but to support thoughtful, individualized care and reduce unnecessary administrative steps.For more practitioner education on supplement quality, metabolic health, and clinical decision-making, visit Fullscript Academy.DisclaimerThe views expressed on this podcast are those of the host and guest and do not necessarily reflect those of Fullscript or affiliated organizations. This episode is for informational and educational purposes only and is not medical advice.C15:0 research is evolving. C15:0 is not currently an established treatment for ferroptosis, metabolic hyperferritinemia, diabetes, MASLD, MASH, or neurodegenerative disease. Elevated ferritin has multiple potential causes and should be interpreted in clinical context. Patients should consult a qualified healthcare professional before changing their diet, supplements, iron intake, or treatment plan.ReferencesChooi, Y. C., Zhang, Q. A., Magkos, F., Ng, M., Michael, N., Wu, X., Brok Volchanskaya, V. S., Lai, X., Wanjaya, E. R., Elejalde, U., Goh, C. C., Yap, C. P. L., Wong, L. H., Lim, K. J., Velan, S. S., Yaligar, J., Muthiah, M. D., Chong, Y. S., Loo, E. X. L., … Eriksson, J. G. (2024). Effect of an Asian-adapted Mediterranean diet and pentadecanoic acid on fatty liver disease: The TANGO randomized controlled trial. American Journal of Clinical Nutrition, 119(3), 788–799. https://pubmed.ncbi.nlm.nih.gov/38035997/Dixon, S. J., Lemberg, K. M., Lamprecht, M. R., Skouta, R., Zaitsev, E. M., Gleason, C. E., Patel, D. N., Bauer, A. J., Cantley, A. M., Yang, W. S., Morrison, B., III, & Stockwell, B. R. (2012). Ferroptosis: An iron-dependent form of nonapoptotic cell death. Cell, 149(5), 1060–1072. https://pubmed.ncbi.nlm.nih.gov/22632970/Imamura, F., Fretts, A., Marklund, M., Ardisson Korat, A. V., Yang, W.-S., Lankinen, M., Qureshi, W., Helmer, C., Chen, T.-A., Wong, K., Bassett, J. K., Murphy, R., Tintle, N., Yu, C. I., Brouwer, I. A., Chien, K.-L., Frazier-Wood, A. C., del Gobbo, L. C., Djoussé, L., … Forouhi, N. G. (2018). Fatty acid biomarkers of dairy fat consumption and incidence of type 2 diabetes: A pooled analysis of prospective cohort studies. PLOS Medicine, 15(10), e1002670. https://pubmed.ncbi.nlm.nih.gov/30303968/Liu, W.-Y., Lian, L.-Y., Zhang, H., Chen, S.-D., Jin, X.-Z., Zhang, N., Ye, C.-H., Chen, W.-Y., Goh, G. B. B., Wang, F.-D., Miele, L., Corradini, E., Valenti, L., & Zheng, M.-H. (2024). A population-based and clinical cohort validation of the novel consensus definition of metabolic hyperferritinemia. Journal of Clinical Endocrinology & Metabolism, 109(6), 1540–1549. https://pubmed.ncbi.nlm.nih.gov/38124275/Robinson, M. K., Lee, E., Ugalde-Nicalo, P. A., Skonieczny, J. W., Chun, L. F., Newton, K. P., & Schwimmer, J. B. (2024). Pentadecanoic acid supplementation in young adults with overweight and obesity: A randomized controlled trial. Journal of Nutrition, 154(9), 2763–2771. https://pubmed.ncbi.nlm.nih.gov/39069269/Sawh, M. C., Wallace, M., Shapiro, E., Goyal, N. P., Newton, K. P., Yu, E. L., Bross, C., Durelle, J., Knott, C., Gangoiti, J. A., Barshop, B. A., Gengatharan, J. M., Meurs, N., Schlein, A., Middleton, M. S., Sirlin, C. B., Metallo, C. M., & Schwimmer, J. B. (2021). Dairy fat intake, plasma C15:0, and plasma iso-C17:0 are inversely associated with liver fat in children. Journal of Pediatric Gastroenterology and Nutrition, 72(4), e90–e96. https://pubmed.ncbi.nlm.nih.gov/33399331/Vacher, M. C., Durrant, C. S., Rose, J., Hall, A. J., Spires-Jones, T. L., Gunn-Moore, F., & Dagleish, M. P. (2023). Alzheimer's disease-like neuropathology in three species of oceanic dolphin. European Journal of Neuroscience, 57(7), 1161–1179. https://pubmed.ncbi.nlm.nih.gov/36514861/Valenti, L., Corradini, E., Adams, L. A., Aigner, E., Alqahtani, S., Arrese, M., Bardou-Jacquet, E., Bugianesi, E., Fernandez-Real, J.-M., Girelli, D., Hagström, H., Henninger, B., Kowdley, K., Ligabue, G., McClain, D., Lainé, F., Miyanishi, K., Muckenthaler, M. U., Pagani, A., … Zoller, H. (2023). Consensus statement on the definition and classification of metabolic hyperferritinaemia. Nature Reviews Endocrinology, 19(5), 299–310. https://pubmed.ncbi.nlm.nih.gov/36805052/Venn-Watson, S., Smith, C. R., Stevenson, S., Parry, C., Daniels, R., Jensen, E., Cendejas, V., Balmer, B., Janech, M., Neely, B. A., & Wells, R. (2013). Blood-based indicators of insulin resistance and metabolic syndrome in bottlenose dolphins (Tursiops truncatus). Frontiers in Endocrinology, 4, 136. https://pubmed.ncbi.nlm.nih.gov/24130551/Venn-Watson, S., Parry, C., Baird, M., Stevenson, S., Carlin, K., Daniels, R., Smith, C. R., Jones, R., Meegan, J., Simmons, J., Gomez, F., & Jensen, E. D. (2015). Increased dietary intake of saturated fatty acid heptadecanoic acid (C17:0) associated with decreasing ferritin and alleviated metabolic syndrome in dolphins. PLOS ONE, 10(7), e0132117. https://pubmed.ncbi.nlm.nih.gov/26200116/Venn-Watson, S., Lumpkin, R., & Dennis, E. A. (2020). Efficacy of dietary odd-chain saturated fatty acid pentadecanoic acid parallels broad associated health benefits in humans: Could it be essential? Scientific Reports, 10, 8161. https://pubmed.ncbi.nlm.nih.gov/32424181/Venn-Watson, S. K., & 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. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0268778Venn-Watson, S. (2024). The cellular stability hypothesis: Evidence of ferroptosis and accelerated aging-associated diseases as newly identified nutritional pentadecanoic acid (C15:0) deficiency syndrome. Metabolites, 14(7), 355. https://www.mdpi.com/2218-1989/14/7/355Weitkunat, K., Schumann, S., Nickel, D., Hornemann, S., Petzke, K. J., Schulze, M. B., Pfeiffer, A. F. H., & Klaus, S. (2017). Odd-chain fatty acids as a biomarker for dietary fiber intake: A novel pathway for endogenous production from propionate. American Journal of Clinical Nutrition, 105(6), 1544–1551. https://pubmed.ncbi.nlm.nih.gov/28424190/Yang, W. S., Kim, K. J., Gaschler, M. M., Patel, M., Shchepinov, M. S., & Stockwell, B. R. (2016). Peroxidation of polyunsaturated fatty acids by lipoxygenases drives ferroptosis. Proceedings of the National Academy of Sciences, 113(34), E4966–E4975. https://pubmed.ncbi.nlm.nih.gov/27506793/