Well Being: C15:0 or Pentadecanoic Acid

As many of you know, Jill and I take a lot of supplements. One of the rationales behind this is that as we age, our gut becomes less able to absorb nutrients. Hence, many people, as they age, become deficient in micronutrients.

With that in mind, combine that with the fact that for the last thirty years, the US government and big pharma have been at war with saturated fat. Particularly dairy fat. Due to government and pharma ad intervention, the average American has significantly reduced their intake of full-fat dairy and cheese.

A new supplement has come to my attention that has some very unique clinical benefits. C15:0, also known as pentadecanoic acid, is an odd-chain saturated fatty acid found primarily in trace amounts in dairy fat, ruminant meat (particularly grass-fed meat), some fish, and certain plants (ref, ref). Its chemical structure consists of a 15-carbon saturated chain, making it structurally distinct from the more common even-chain saturated fatty acids.

Recent research has proposed that C15:0 may be an essential fatty acid—meaning it is a nutrient needed by the body for maintaining baseline health but not readily produced endogenously, so it must be obtained through diet or supplementation (ref, ref, ref). Higher circulating levels of C15:0 have been associated in epidemiological studies with lower risks of cardiometabolic diseases (like type 2 diabetes and heart disease) and improved health outcomes (ref, ref, ref). Experimental studies have identified anti-inflammatory, antifibrotic, and metabolic benefits in cell and animal models (ref, ref).

Primary dietary sources of C15:0 are whole-fat dairy products such as milk, butter, cheese, and ruminant meat.

Typical C15:0 Content in Foods (Approximate Values)

• Full-fat dairy (per 100g of fat): About 1% is C15:0, translating to 50–130 mg per serving depending on the dairy product23.

  • Cheese (1 oz/28g): 50–130 mg

  • Butter/heavy cream (1 tbsp/14g): 50–60 mg

  • Full-fat yogurt (3/4 cup/170g): 70–100 mg

  • Ruminant meats per 1 oz: 17.5–32.5 mg of C15:0

  • Fish per 1 oz: 2.5–16.25 mg of C15:0

As a supplement, C15:0 is marketed for supporting metabolic, heart, liver, and immune health, but while clinical and cell studies are promising, population-wide long-term effect data and regulatory designation as "essential" are still under scientific review.

How the Dolphin Connection Led to the discovery C15:0:

• Dr. Stephanie Venn-Watson, a veterinary epidemiologist, worked with the U.S. Navy’s marine mammal program in San Diego, which cares for bottlenose dolphins who, like humans, can live several decades and develop many of the same age-related diseases such as high cholesterol, fatty liver disease, and prediabetes.

• Venn-Watson’s team observed that while some older dolphins developed these conditions over time, others stayed remarkably healthy. This led to a search for the factors that might predict healthy aging in dolphins.

• Profiling hundreds of blood molecules, her team examined dolphins’ serum and their fish-based diets. Out of approximately 465 molecules, one was notable: healthier dolphins, particularly older ones, consistently showed higher blood levels of a rare fatty acid, C15:0 (pentadecanoic acid).

• The researchers adjusted the dolphins’ diets, increasing fatty fish that are naturally higher in C15:0. The result? The dolphins’ insulin, glucose, and cholesterol levels improved, and signs of chronic inflammation were reduced (ref).

• C15:0 had not been previously recognized as an “essential” fatty acid—the last such discovery was omega-3 in 1929. Further studies revealed both dolphins and humans with higher C15:0 levels tend to have reduced risk of diabetes, heart disease, and fatty liver, along with signs of healthier cellular aging (ref).

• The team studied C15:0 in animal and cell models, discovering that supplementation can strengthen cell membranes, decrease inflammation, and support mitochondria.

• Noticing similar health benefits in dolphins and humans, Venn-Watson co-founded Seraphina Therapeutics and introduced Fatty15, the first pure, vegan C15:0 supplement, under an exclusive patent license from the U.S. Navy.

In summary:
Fatty15 exists because of a decade-long quest to improve dolphin health. The discovery that C15:0—scarce in many modern diets—was the top predictor of healthy aging in dolphins opened the door to human studies and, ultimately, to Fatty15 as a supplement. This “dolphin-to-human” story highlights how animal health research can unexpectedly spark innovation in human longevity science.

• A randomized, double-blind, placebo-controlled trial in young adults with overweight or obesity (n=30) studied 200 mg C15:0 daily for 12 weeks. Compared to placebo, those taking C15:0 had a significantly greater increase in circulating C15:0 levels (1.88 μg/mL difference) (ref). Among those reaching higher C15:0 blood levels, there were notable decreases in liver enzymes (ALT and AST, markers of improved liver function) and an increase in hemoglobin (suggesting improved red blood cell health).

• Clinical trial registry and review confirm C15:0 trials have focused primarily on biomarker changes, liver health, red blood cell metrics, safety, and physiological markers in populations at risk of metabolic issues (ref, ref).

• So far, weight, glucose, and cholesterol changes have not been consistently observed in short-term (3 month) trials in humans, and these endpoints remain the subject of ongoing and future studies (ref).

• Animal and cell studies also show evidence of anti-inflammatory, anti-fibrotic, and metabolic benefits for C15:0, but robust long-term outcome data in humans are still being developed (ref).

Summary:

C15:0 (including Fatty15) has undergone peer-reviewed, placebo-controlled human trials showing it can safely raise C15:0 levels and may improve liver and red blood cell health. Broader clinical outcome research is ongoing to further define its effects on metabolic disease, aging, and other health risks (ref).

All that said, the team and Venn-Watson co-founded Seraphina, a supplement company to develop and sell Pentadecanoic Acid as a supplement in the U.S. and globally. Fatty15 has an exclusive license from the U.S. Navy to commercialize C15:0 (pentadecanoic acid) as a dietary supplement.

Fatty15 has 100 mg per serving (capsule). This is a very pure, known concentration. However, going back to the foods that naturally have C15:0, there are other options. One ounce of cheese has 50–130 mg and 3/4 cups of yogurt has 70-100 mg.

Remember, dairy fat contains significantly more C15:0 (pentadecanoic acid) than most other food sources. C15:0 is recognized as a dietary biomarker of dairy fat intake and is present in its highest concentrations in full-fat dairy products like whole milk, butter, cream, and certain cheeses.

One interesting fact is that sheep and goats milk contains much higher levels of C15:0 than other cheeses.

Pecorino Sardo and other traditional Sardinian sheep’s milk cheeses are some of the richest sources. Grass-fed pecorino contains up to 1.4% of total fats as C15:0, surpassing cow’s milk butter at 0.8%. According to one source, just half an ounce of grass-fed pecorino can deliver approximately 200mg of C15:0, equal to or more than the daily amount found in the supplements (which have 100 mg per capsule).

Cheeses from grass-fed cows, sheep, or goats consistently contain higher levels of C15:0 than those from grain-fed animals.

A case study demonstrating the potential benefits of increased C15:0 levels is the high-altitude sheep and goat herders in Sardinia, a famous blue zone with the highest concentration of male centenarians. Up to 25% of their calories come from dairy, particularly pecorino cheese and a soft goat cheese aged 30 days, both of which are high in C15:0. Cell membrane C15:0 concentrations in Sardinians can be up to 0.6%.

Cheese Type - C15:0 per 1 oz (28g) serving

• Pecorino (grass-fed, sheep) ~200 mg

• Cheddar (cow, full-fat) 80–110 mg

• Parmesan 80–110 mg

• Emmental/Swiss 70–90 mg

• Gorgonzola 90–110 mg

• Gruyère (Alpage) — (high)

C15:0 in Food Chart

On the broader point regarding full-fat dairy and metabolic health:

• A comprehensive meta-analysis of prospective cohorts and biomarker studies (up to 20 years of follow-up) found that higher circulating levels of dairy fatty acids (15:0 and 17:0, present in full-fat dairy) are linked to a reduced risk of type 2 diabetes (ref).

• Several population and cohort studies, such as the PURE study with over 147,000 participants across 21 countries, a Swedish prospective study on heart disease (ref), and various systematic reviews, indicate that high intake of full-fat dairy is either neutral or linked to lower risks of cardiovascular disease, type 2 diabetes, and obesity risk. (ref)

Following government recommendations to reduce saturated fat, the dietary intake of whole milk dropped fourfold from 1.2 cups per day to about 1/4 cup per day. Unfortunately, this led to a significant reduction in C15:0, ultimately having the opposite effect of what was intended and may have led to more obesity, type 2 diabetes, and Nonalcoholic Fatty Liver Disease.

Some believe that C15:0 deficiency is contributing to a concerning trend: younger people are increasingly being diagnosed with diseases once thought exclusive to older individuals. Conditions such as diabetes, high blood pressure, and fatty liver, which were once rare among the young, are now becoming alarmingly prevalent.

An 18-year longitudinal study found that children fed whole-fat milk had lower incidence rates of obesity. Other studies have shown associations between higher dietary full-fat dairy and lower rates of type 2 diabetes and heart disease.

Current research suggests a recommended daily intake of C15:0 (pentadecanoic acid) of approximately 100–300 mg to achieve and maintain levels associated with beneficial health effects. This proposed range is based on epidemiological and interventional studies linking this intake to improved cardiometabolic, liver, and cellular health, and on pharmacokinetic data suggesting 200 mg per day is needed to achieve desired blood concentrations (ref).

Not everyone can find grass-fed or sheep’s milk cheese, plus many people have allergies to dairy or don’t like to eat that much of it. Additionally, the amount of C15:0 varies in food. Also, during travel, eating well isn’t always an option.

So, eating a diet rich C15:0 and even considering Fatty15 supplementation is worth considering.

Certainly, switching out low or no fat dairy or dairy substitutes is an easy change to make.

Eating more whole foods and grass-fed meats makes us healthier.

Be healthy, be happy and live a longer life - isn’t that what we all strive for?

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