Pentadecanoic Acid (C15:0) Statistics: Key Research Numbers in 2026

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This page collects the key numbers from published research on pentadecanoic acid (C15:0), each tied to the population or system it came from. It includes null and conflicting results alongside the positive ones, because a list of only good news would mislead.

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Most human evidence is observational, so those entries say “linked to” and not “causes.” Cell and animal results are labeled as such. Company statements appear only as the company’s own claims.

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Key Takeaways

  • Higher blood C15:0 is linked to lower type 2 diabetes risk in several pooled analyses, for example a risk ratio of 0.82 in an umbrella review of 1,226,322 participants, but the evidence was graded only suggestive (class III).[1]
  • A genetic test found no evidence that C15:0 causally affects blood pressure, heart rate or hypertension.[2]
  • Among the studies summarized here, one randomized trial tested pure C15:0 capsules alone, in 30 young adults with overweight or obesity.[3]
  • Blood C15:0 is an imperfect marker of dairy intake: a meta-analysis found a correlation of r = 0.33 with dairy fat intake.[4]
  • Much of the cell and animal work comes from or alongside groups with commercial interests, and none of it shows an effect in people.[5]

Blood Levels and Diet

Blood C15:0 is widely used as a marker of dairy fat intake, but typical levels are low and the link to what people report eating is only moderate. For where C15:0 comes from, see our guide to natural food sources of C15.

  • In a preprint (not peer reviewed) of 4,069 US adults in NHANES 2011 to 2014, average serum C15:0 was 23.33 µmol/L (SD 11.49).[6]
  • In 826 healthy young Canadian adults, mean plasma total-lipid 15:0 was 17.8 µmol/L (SD 6.7), with reported percentile values of 10.8 and 26.3 µmol/L.[7]
  • A review reports that odd-chain fatty acids such as C15:0 and C17:0 represent 1% and 0.5% of total milk fatty acids, respectively.[8]
  • The same review estimates that one 200 ml serving of semi-skimmed milk provides about 20 mg of C15:0 and 10 mg of C17:0.[8]
  • In a crossover study of 11 healthy volunteers, test portions held about 0.3 g of C15:0 in 600 mL of milk and 0.3 g in 100 g of cheese.[9]
  • Freshwater fish also contain C15:0, at about 0.4% of total fatty acids across twenty-seven species, according to a review.[8]
  • A meta-analysis found plasma or serum C15:0 correlated with dairy fat intake at r = 0.33 and with total dairy intake at r = 0.20.[4]
  • In 246 free-living Dutch adults, plasma C15:0 correlated only weakly with total dairy intake (rs = 0.17) and total fermented dairy (rs = 0.24).[10]
  • In a four-week crossover feeding trial of 124 healthy adults, plasma 15:0 was 0.26% of total fatty acids after a dairy phase and 0.22% after a control phase.[11]
  • In a randomized dairy-feeding trial of 62 adults, plasma phospholipid C15:0 and C17:0 were not associated with dairy fat intake after adjusting for liver fat.[12]
  • In 16 healthy adults in a double-blind crossover trial, inulin fiber raised plasma pentadecanoic acid by about 17% over 7 days, so blood levels are not purely a dairy marker.[13]
  • In two small human studies, one of 21 participants on a fiber supplement and one of 19 inpatients on high versus low fiber diets, fiber did not raise circulating odd-chain fatty acids.[14]
  • In male Sprague-Dawley rats, a ~30% increase in dietary total fat resulted in a ~35% decrease in circulating C15:0.[15]
  • In 28 healthy men, a 19-day dairy exclusion lowered dairy-associated metabolites, including pentadecanoic acid.[16]

Heart and Metabolic Cohorts

In large cohorts, higher blood C15:0 tends to travel with lower diabetes risk and, less consistently, with better blood pressure. These are associations, and several well-run studies found nothing or found the opposite. Our C15 and metabolic health page gives context, and the CARDIA and ARIC explainer walks through the newest cohort analysis.

  • In 3,196 CARDIA adults, each standard deviation higher plasma C15:0 was linked to 1.47 mm Hg lower systolic blood pressure (95% CI 0.96 to 1.99 lower) and a hazard ratio of 0.86 (95% CI 0.78 to 0.95) for 10-year incident hypertension.[2]
  • In 3,889 White ARIC participants, each standard deviation higher C15:0 was linked to 2.69 mm Hg lower systolic pressure.[2]
  • Plasma C15:0 was not associated with incident cardiovascular disease in either CARDIA (3,196 adults) or ARIC (3,889 adults).[2]
  • Mendelian randomization found no evidence for a causal effect of C15:0 on systolic pressure, diastolic pressure, resting heart rate or hypertension.[2]
  • In 8,185 adults in the China Kadoorie Biobank followed for about 5 years, people in the top third of red blood cell 15:0 had an adjusted hazard ratio of 0.72 (95% CI 0.59 to 0.89) for ischemic heart disease versus the bottom third.[17]
  • In 4,775 US adults in NHANES 2011 to 2014, higher blood C15:0 was linked to lower odds of hypertension (odds ratio 0.78, 95% CI 0.66 to 0.93) in a one-time cross-sectional analysis.[18]
  • In the same NHANES analysis, the relationship weakened above 1.5 parts per thousand of total fatty acids (odds ratio 0.89, 95% CI 0.74 to 1.07, P = 0.2158).[18]
  • In 4,150 Swedish adults, higher serum 15:0 was linked to lower cardiovascular disease risk (hazard ratio 0.75 per interquintile range, 95% CI 0.61 to 0.93), while all-cause mortality risk was lowest around the median level.[19]
  • In two large US cohorts, plasma 15:0 was not significantly associated with total stroke (pooled hazard ratio 0.85, 95% CI 0.54 to 1.33, highest versus lowest quartile).[20]
  • A pooled analysis of 18 prospective cohorts, as summarized in a narrative review, found 12% lower cardiovascular disease risk in the highest versus lowest quintile of circulating C15:0.[21]
  • The same review notes null findings for C15:0 and heart disease in UK Biobank and the Danish Diet, Cancer and Health Study.[21]
  • In EPIC-InterAct, with 12,403 incident type 2 diabetes cases and a 16,154-person subcohort, higher plasma phospholipid 15:0 was linked to lower type 2 diabetes risk (hazard ratio 0.79 per standard deviation, 95% CI 0.73 to 0.85).[22]
  • In 63,682 adults across 16 prospective cohorts, higher circulating 15:0 was linked to lower type 2 diabetes risk (hazard ratio 0.80, 95% CI 0.73 to 0.87, per 10th to 90th percentile range).[23]
  • A meta-analysis of prospective studies found a risk ratio of 0.86 (95% CI 0.76 to 0.98) per standard deviation of C15:0 for type 2 diabetes, with heterogeneity of I2 = 72.9%, meaning study results varied considerably.[24]
  • An umbrella review of 1,226,322 participants found a risk ratio of 0.82 (95% CI 0.73 to 0.92) for type 2 diabetes with higher C15:0, and graded the evidence suggestive (class III), not strong or convincing.[1]
  • A meta-analysis adding 33 prospective studies and 112,193 participants found a pooled relative risk of 0.74 (0.68 to 0.80) for diabetes per 10th to 90th percentile range of 15:0.[17]
  • In 37,421 Dutch adults with 893 incident type 2 diabetes cases, dietary pentadecylic acid on its own showed no significant association with type 2 diabetes.[25]
  • In men in the EPIC-Potsdam cohort (820 incident type 2 diabetes cases and a subcohort of 1,248), lysophosphatidylcholine(C15:0) was linked to higher type 2 diabetes risk (hazard ratio 1.96, 95% CI 1.06 to 3.63).[26]
  • In the TRIGR birth cohort of 244 children with islet autoimmunity and 488 matched controls, higher serum 15:0 was linked to higher odds of islet autoimmunity (odds ratio 3.41, 95% CI 1.70 to 6.85).[27]
  • A Mendelian randomization study using genetic data from 7,824 people and muscle data from 461,089 participants linked genetically higher 15:0 to lower appendicular lean mass (beta 0.250 lower, 95% CI 0.140 to 0.361 lower).[28]
  • In 607 mother-infant pairs, C15:0 in red blood cells was found at higher levels in small-for-gestational-age infants than in appropriate-size infants, in both mothers and newborns.[29]

The Supplement Trials

Very little randomized human data exists on C15:0 supplements, and what exists is small and in specific groups. The details are in our explainer on the supplement trial.

  • A randomized, double-blind trial gave 200 mg of C15:0 or placebo daily for 12 weeks to 30 young adults with overweight or obesity, 20 on C15:0 and 10 on placebo.[3]
  • In that trial, blood C15:0 rose 1.88 µg/mL more than placebo (P = 0.003).[3]
  • Individual changes in blood C15:0 in the supplement group ranged from a drop of 1.21 to a rise of 5.31 µg/mL.[3]
  • Apart from a mean drop of 11 U/L in the liver enzyme GGT relative to placebo, the trial found no other significant changes in any secondary outcome.[3]
  • Only 10 of the 20 people on C15:0 ended the trial above the authors’ blood-level threshold of 5 µg/mL; this grouping was exploratory and made after the fact.[3]
  • In that exploratory comparison, the median change in ALT was a drop of 29 U/L above the threshold, a rise of 6 U/L below it and no change (0 U/L) on placebo.[3]
  • Those above the threshold also took more of their capsules, with adherence of 95.0% versus 84.3%, so adherence may explain part of the difference.[3]
  • In the TANGO trial of 88 Chinese women with NAFLD, liver fat fell by 33% with diet plus pentadecanoic acid, 30% with diet alone and 10% in controls.[30]
  • In that trial, C15:0 supplementation reduced LDL cholesterol further and increased the abundance of Bifidobacterium adolescentis, but most other improvements occurred in both diet groups.[30]

Cell and Animal Work

Lab and animal studies are where most mechanism claims originate. They show what is possible in a dish or an animal, not what happens in people. Our cell study explainer shows why.

  • In 12 primary human cell systems, C15:0 was non-cytotoxic at all concentrations and had activities involving 36 biomarkers across 10 systems, while EPA was cytotoxic to four cell systems at 50 µM.[5]
  • In the same cell screen at 17 µM, C15:0 shared 12 activities with EPA and had 28 additional clinically relevant activities.[5]
  • In a separate cell-based comparison, C15:0 at 17 µM shared 24 activities with rapamycin across 10 cell systems.[31]
  • In a screen of 94 human cancer cell lines, C15:0 slowed growth in only 13 (13.8%), most of them non-Hodgkin B-cell lymphomas.[32]
  • In a cell-free enzyme screen, C15:0 inhibited FAAH with an IC50 of 2.5 µM and MAO-B with an IC50 of 19.4 µM.[33]
  • In a mouse model, pentadecanoic acid supplementation reduced atherosclerotic plaque burden by around 50%.[34]
  • In Wistar rats with chemically induced liver fibrosis, oral pentadecanoic acid at 10, 20 and 40 mg/kg daily for 9 weeks reduced liver enzymes and fibrosis markers.[35]
  • In 5/6-nephrectomized mice given a branded odd-chain triglyceride for 8 weeks, the rise in kidney markers BUN and creatinine was attenuated, and survival did not differ.[36]
  • In pregnant and lactating mice fed 1% C15:0, the diet caused mild insulin resistance, and offspring grew faster.[37]
  • In high-fat-fed mice for 20 weeks, neither milk fat nor C17:0 supplementation improved liver fat or insulin resistance.[38]

Safety and Regulation

Safety data for C15:0 are thin, and regulatory status is often described more strongly than the public record supports. Company statements below are the company’s own claims. For more, see Is C15 an essential fatty acid?.

  • No significant adverse events occurred in the randomized trial of 30 young adults over 12 weeks.[3]
  • In a rat toxicology study, an odd-chain algal oil showed a no observable adverse effect level of 150,000 ppm, or 15% of the diet.[39]
  • FDA’s Substances Added to Food inventory lists pentadecanoic acid only as a flavoring agent or adjuvant.[40]
  • FDA’s entry cites FEMA number 4334 and FEMA GRAS publication number 23, a reference to an industry trade association’s own panel assessment and not an FDA decision.[40]
  • Trade press reports that the company’s FA15 GRAS determination approves food use at up to 245 mg per day; this is the company’s claim, and the article does not say who made the determination.[41]
  • The company’s FAQ says safety studies have been completed for up to 250 mg a day; this is the company’s claim.[42]
  • The company’s FAQ says it received GRAS status by the FDA, whereas FDA’s own food-substance entry shows only a flavoring listing.[42][40]
  • The company’s FAQ reports side effects such as constipation, diarrhea or headache in less than 0.1% of customers; this is unverified company reporting and not trial data.[42]
  • The cached copy we hold of FDA’s GRAS Notice Inventory is a stale landing page that does not itself show any FDA notice for pentadecanoic acid, so we could not confirm a GRAS notice from it.[43]

What Is Still Unknown

The honest list of open questions is long. These statements come from the researchers and reviewers themselves, plus one company statement about its own trials.

  • A review notes that serum odd-chain fatty acid evidence for dairy fat intake is mostly observational, with a lack of well-controlled dose-response intervention studies.[8]
  • A review of lab and animal work says prospective clinical outcomes are still lacking and that dosing and long-term safety need to be clarified.[44]
  • The authors of the supplement trial say its secondary findings of possible metabolic benefits are preliminary and need a larger setting.[3]
  • They also list the small sample, the 12-week duration and a single dosage regimen as reasons their findings are preliminary.[3]
  • The authors of the CARDIA and ARIC analysis say the collective evidence is not consistent with a causal cardiovascular benefit of C15:0.[2]
  • A review concludes that the literature on pentadecanoic acid and blood pressure is inconsistent.[45]
  • An independent mini-review says pentadecanoic acid might be described as essential, yet further investigations are needed.[46]
  • The company’s FAQ states that clinical trials of its own ingredient are in development; this is the company’s statement.[42]

How to Cite This Page

Cite as: Pentadecanoic Acid (C15:0) Statistics: Key Research Numbers in 2026. C15 Hub. https://c15hub.com/c15-pentadecanoic-acid-statistics/. Accessed Month Year (add the month and year you read it). Please cite the original studies in the References list below for any figure you reuse, since each number here belongs to the paper it came from.

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This page is for information only and is not medical advice.

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Frequently Asked Questions

Is C15:0 proven to prevent disease?

No. Higher blood C15:0 is linked to lower diabetes risk in several pooled analyses, but the umbrella review graded that evidence suggestive (class III), and a Mendelian randomization analysis found no evidence of a causal effect on blood pressure.[1][2]

How many randomized trials of C15:0 supplements exist?

Among the studies summarized on this page, one randomized trial tested pure C15:0 capsules alone, in 30 young adults, and one trial tested C15:0 supplementation alongside diets in 88 Chinese women with NAFLD.[3][30]

What is a normal blood level of C15:0?

No reference range is established in these sources. One preprint of 4,069 US adults reported an average serum level of 23.33 µmol/L, and a study of 826 healthy young Canadians reported a mean of 17.8 µmol/L for plasma total-lipid 15:0, but they used different samples and units.[6][7]

References

  1. Lipid biomarkers for the prediction of type 2 diabetes risk, an umbrella review and updated meta-analyses of prospective observational studies. Frontiers in endocrinology, 2026
  2. Plasma pentadecanoic acid is modestly related to cardiovascular health in CARDIA and ARIC cohorts: observational associations without evidence of causality. Frontiers in Nutrition, 2026
  3. Pentadecanoic Acid Supplementation in Young Adults with Overweight and Obesity: A Randomized Controlled Trial. The Journal of nutrition, 2024
  4. Fatty acids as biomarkers of total dairy and dairy fat intakes: a systematic review and meta-analysis. Nutrition Reviews, 2018
  5. 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, 2022
  6. Serum Levels of Pentadecanoic Acids and Heptadecanoic Acids Negatively Correlate with Kidney Stone Prevalence: Evidence from NHANES 2011-2014. Research Square, 2024
  7. Comprehensive Profiling of Plasma Fatty Acid Concentrations in Young Healthy Canadian Adults. PLoS ONE, 2015
  8. Can individual fatty acids be used as functional biomarkers of dairy fat consumption in relation to cardiometabolic health? A narrative review. The British journal of nutrition, 2022
  9. GC-MS Based Metabolomics and NMR Spectroscopy Investigation of Food Intake Biomarkers for Milk and Cheese in Serum of Healthy Humans. Metabolites, 2018
  10. Evaluating the Robustness of Biomarkers of Dairy Food Intake in a Free-Living Population Using Single- and Multi-Marker Approaches. Metabolites, 2021
  11. Recommended dairy product intake modulates circulating fatty acid profile in healthy adults: a multi-centre cross-over study. British Journal Of Nutrition, 2015
  12. Assessing the validity of plasma phospholipid fatty acids as biomarkers of dairy fat intake using data from a randomized controlled intervention trial. The American journal of clinical nutrition, 2022
  13. Odd-chain fatty acids as a biomarker for dietary fiber intake: a novel pathway for endogenous production from propionate. The American journal of clinical nutrition, 2017
  14. Odd Chain Fatty Acids Are Not Robust Biomarkers for Dietary Intake of Fiber. Molecular nutrition & food research, 2021
  15. The Dietary Total-Fat Content Affects the In Vivo Circulating C15:0 and C17:0 Fatty Acid Levels Independently. Nutrients, 2018
  16. Microbiota and Metabolite Modifications after Dietary Exclusion of Dairy Products and Reduced Consumption of Fermented Food in Young and Older Men. Nutrients, 2021
  17. Erythrocyte odd-chain fatty acids and the risk of cardiometabolic diseases: a prospective study and updated meta-analysis. European Journal of Preventive Cardiology, 2025
  18. Associations between serum pentadecanoic acid (C15:0) and heptadecanoic acid (C17:0) levels and hypertension: a cross-sectional analysis of NHANES data. Lipids in health and disease, 2025
  19. Biomarkers of dairy fat intake, incident cardiovascular disease, and all-cause mortality: A cohort study, systematic review, and meta-analysis. PLoS medicine, 2021
  20. Circulating biomarkers of dairy fat and risk of incident stroke in U.S. men and women in 2 large prospective cohorts. The American journal of clinical nutrition, 2014
  21. Pentadecanoic acid (C15:0) and cardiovascular disease: A narrative review. World journal of cardiology, 2025
  22. 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, 2014
  23. Fatty acid biomarkers of dairy fat consumption and incidence of type 2 diabetes: A pooled analysis of prospective cohort studies. PLoS medicine, 2018
  24. Circulating Saturated Fatty Acids and Incident Type 2 Diabetes: A Systematic Review and Meta-Analysis. Nutrients, 2019
  25. Intake of dietary saturated fatty acids and risk of type 2 diabetes in the European Prospective Investigation into Cancer and Nutrition-Netherlands cohort: associations by types, sources of fatty acids and substitution by macronutrients. European journal of nutrition, 2019
  26. Association of the odd-chain fatty acid content in lipid groups with type 2 diabetes risk: A targeted analysis of lipidomics data in the EPIC-Potsdam cohort. Clinical Nutrition, 2021
  27. Serum fatty acids and risk of developing islet autoimmunity: A nested case-control study within the TRIGR birth cohort. Pediatric diabetes, 2021
  28. The causal relationship of human blood metabolites with the components of Sarcopenia: a two-sample Mendelian randomization analysis. BMC geriatrics, 2024
  29. Association between Maternal and Foetal Erythrocyte Fatty Acid Profiles and Birth Weight. Nutrients, 2018
  30. Effect of an Asian-adapted Mediterranean diet and pentadecanoic acid on fatty liver disease: the TANGO randomized controlled trial. The American journal of clinical nutrition, 2024
  31. Pentadecanoic Acid (C15:0), an Essential Fatty Acid, Shares Clinically Relevant Cell-Based Activities with Leading Longevity-Enhancing Compounds. Nutrients, 2023
  32. Pentadecanoic Acid (C15:0) at Naturally Occurring Circulating Concentrations Has Selective Anticancer Activities Including Targeting B-Cell Lymphomas with CCND3 Oncogenic Alterations. Nutrients, 2025
  33. Aging-Associated Amyloid-β Plaques and Neuroinflammation in Bottlenose Dolphins (Tursiops truncatus) and Novel Cognitive Health-Supporting Roles of Pentadecanoic Acid (C15:0). International journal of molecular sciences, 2025
  34. A gut microbial odd-chain fatty acid alleviates atherosclerosis in mice. Nature, 2026
  35. Pentadecanoic acid attenuates thioacetamide-induced liver fibrosis by modulating oxidative stress, inflammation, and ferroptosis pathways in rat. Naunyn-Schmiedeberg's archives of pharmacology, 2025
  36. Renal function-improving action of Pentadecyl®, a multifunctional triglyceride from Aurantiochytrium limacinum, in a mouse model of chronic kidney disease. Experimental and therapeutic medicine, 2026
  37. Pentadecanoic acid (C15:0, PA) induces mild maternal glucose intolerance and promotes the growth of the offspring partly through up-regulating liver PPARα and MAPK signaling pathways. Food & function, 2024
  38. Heptadecanoic Acid Is Not a Key Mediator in the Prevention of Diet-Induced Hepatic Steatosis and Insulin Resistance in Mice. Nutrients, 2023
  39. Safety evaluation of odd-chain fatty acid algal oil. Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association, 2021
  40. Substances Added to Food: pentadecanoic acid. U.S. Food and Drug Administration, 2026
  41. Recently discovered fatty acid ingredient, FA15, gets GRAS nod for food use. Nutritional Outlook, 2026
  42. Fatty15 FAQs. Fatty15 (Seraphina Therapeutics), 2026
  43. GRAS Notice Inventory. U.S. Food and Drug Administration, 2026
  44. Molecular and cellular mechanisms of pentadecanoic acid. World journal of biological chemistry, 2025
  45. Association Between Circulating Fatty Acids and Blood Pressure: A Review. Current nutrition reports, 2025
  46. New insights on pentadecanoic acid with special focus on its controversial essentiality: A mini-review. Biochimie, 2024

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease. Content is for informational purposes only and is not medical advice; consult a qualified healthcare provider before starting any supplement. As an Amazon Associate we earn from qualifying purchases.

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