A new essential nutrient discovered by a dolphin vet holds promise for healing the brain, heart, liver and more. Celeste McGovern investigates fatty acid C15:0
When epidemiologist and veterinarian Dr Stephanie Venn-Watson joined a US Navy program in 2001, she couldn’t imagine that her assignment to help the military’s trained dolphins live longer, healthier lives would lead her to challenge decades of nutritional public health dogma. Nor had she any idea her work could lead to the rediscovery of a long-overlooked nutrient—one that’s revolutionizing our understanding of aging, disease and metabolic health in humans.
For decades, the US Navy has trained these remarkably intelligent mammals to find underwater mines, recover equipment and rescue lost divers. Housed in San Diego Bay, navy dolphins lead enviable lives. They’re free to swim, play and socialize daily in the open ocean and voluntarily return to their naval base each evening, where they receive a steady diet of fresh fish.
It’s a lifestyle with health benefits: Compared to their cousins in the wild who typically live 20–30 years, navy bottlenose dolphins often live into their 40s and 50s—about the equivalent of 80 years for a human.
As Venn-Watson’s team began to study these long-lived dolphins, they noticed a curious pattern: Some aged gracefully, while others developed diseases like those in aging people.
“Older dolphins age a heck of a lot like older people,” Venn-Watson says. “They develop high cholesterol, chronic inflammation, arthritis—even changes in the brain consistent with Alzheimer’s disease.”
The obvious question was why. Compared to the graceful agers, “they were in the same population, getting the same care and the same fish, so what made the difference?” asked Venn-Watson.
In 2015, her team applied a relatively new field of research—metabolomics, the study of thousands of small molecules that fuel life—to blood samples from the navy dolphins and identified about 100 compounds linked to healthier aging. One alone stood out.
Initially the scientists assumed the healthiest dolphins owed their resilience to omega-3 fatty acids, long celebrated as the “good fats” in fish, their dietary staple. “But it wasn’t omega-3s,” says Venn-Watson. “It was C15:0—a saturated fat!”
The molecule C15:0 (pronounced C-15), also known as pentadecanoic acid, has been known about for decades, but it’s been mostly neglected. Its crucial role in fighting chronic disease was a shocker.
It wasn’t enough to show that C15:0 correlated with better health. The question was whether it could cause it.
To find out, Venn-Watson’s team conducted a series of experiments in dolphins and in laboratory models of human disease. They discovered C15:0 drives health and bodily repair in multiple ways: It strengthens cell membranes, repairs mitochondria and improves their energy production, and activates metabolic receptors that regulate inflammation, mood and metabolism.
In models of type 2 diabetes and fatty liver disease, the compound lowered glucose, cholesterol and inflammation while correcting anemia, improving liver function and reducing tissue scarring.
“It wasn’t just associated with better health,” says Venn-Watson. “It was actually driving it. When we gave dolphins that were less healthy a diet higher in fish-based C15:0, they got better.”
Their blood markers normalized. Their red blood cells strengthened. And their metabolic function stabilized.
The team bundled their findings into a landmark 2020 paper. Their conclusion: C15:0 meets the criteria for an essential fatty acid—a nutrient the human body cannot make on its own and must obtain through diet.1
That made C15:0 the first essential fatty acid discovered since omega-3 and omega-6—over 90 years ago. “It’s basically the discovery of a new vitamin,” Venn-Watson told the audience at a scientific talk.
The paper triggered a surge of research. Within 18 months, over two dozen studies confirmed the findings: Higher C15:0 levels correlated with healthier aging, better metabolic profiles and lower disease risk. Several independent teams now agree that C15:0 is essential for maintaining baseline health.2
The findings are stunning for more than their therapeutic potential; C15:0 is a saturated fat, the kind demonized by public health for decades. These fats have been cast as the main target of the war on fats, the villains behind heart disease.
“Choose skim milk,” “Avoid butter” and “Margarine is heart-healthy” all became mantras of 1970s public health experts. They consistently promoted a low-fat diet, and things haven’t changed much.
“The USDA Dietary Guidelines for Americans (2020–25) mentions limiting dietary saturated fats 161 times in a 164-page document,” says Venn-Watson. “Similarly, the American Heart Association recommends no more than 5 to 6 percent of daily calories come from saturated fats.”
The same is true in the UK, where HEART UK claims, “Reducing saturated fat lowers the risk of cardiovascular disease” and the National Health Service says, “It’s best to reduce your overall fat intake and swap saturated fats for unsaturated fats.”
These organizations recommend only low-fat, fat-free and soy milk. High-fat butter, sour cream and cream cheese (which happen to be major sources of C15:0) are frowned upon.
The result? For the past four decades, our diets have been drained of C15:0-rich whole-fat dairy and butter, replaced with watery low-fat and no-fat milk products, artificial vegetable oil spreads and dairy substitutes.
In the US, during the 20 years after the low-fat revamp of nutritional advice, the average person cut more than three-quarters of their daily intake of whole-fat milk, dropping it from 283 to 65 g per day.3
The recommendations, criticized for their flawed science at the time and since, were designed to target heart attacks in middle-aged men, but they came with dire consequences. “We as a population haven’t really gotten healthier,” Venn-Watson points out. “We’ve gotten sicker. Type 2 diabetes, heart disease and fatty liver disease have all gone up—especially among younger people.”
One 18-year longitudinal study of more than 25,000 children found those who drank whole-fat milk had a lower risk of obesity than children who drank 1 percent fat or “skim” milk.4 And multiple studies have demonstrated associations between higher dietary intake of full-fat dairy and reduced risk of type 2 diabetes and cardiovascular disease.5
While there are plenty of potential culprits in the current epidemic of metabolic diseases afflicting people at younger ages, the rise of disease with reduced-fat diets is undeniable.
By happenstance, the diet of the navy dolphins abruptly changed, too. In the 1990s, the population of fish they were routinely fed, called euchalon, suddenly crashed.
When euchalon went on the list of endangered species, it went off the navy dolphin menu and was replaced with capelin, a relatively low-fat fish with negligible C15:0. Dolphins with lower C15:0 started to develop metabolic syndrome (insulin resistance), anemia and fatty liver disease—conditions that were all corrected decades later when the problem was recognized and the diet was replaced with a high-C15:0 fish.6
In humans, as in dolphins, low levels of C15:0 began to show up as a common denominator in several metabolic disorders.
“We now know that there are ‘good’ and ‘bad’ dietary saturated fats,” Venn-Watson explains. “Odd-chain saturated fatty acids (especially C15:0) are anti-inflammatory, have many health benefits and have been repeatedly associated with a lower risk of type 2 diabetes and cardiovascular disease in studies. Conversely, even-chain saturated fatty acids (like C16:0) have the opposite effects in these same studies.”
The trouble is, public health has lumped them all together in one big glob as “unhealthy” saturated fats, and now “there is mounting evidence that our decreased dietary intake of C15:0 over the past fifty years has resulted in a nutritional C15:0 deficiency syndrome,” says Venn-Watson.
A mounting body of scientific evidence—more than 100 peer-reviewed papers in recent years—points to C15:0 as critical to delaying aging-related breakdown.
The link between C15:0 and fatty liver disease (see below) emerged almost by accident. In 2008, the navy veterinarians noticed a handful of dolphins, though apparently healthy, occasionally had slightly elevated liver enzymes.
They weren’t drinking alcohol. Parasites were ruled out, then viral and bacterial infections. No toxins could explain the problem either.
One term popped up in about a third of the pathology reports, however: hemosiderosis. In these cases, pathologists could see tiny, dark dots of iron buildup in the dolphins’ livers. A closer look showed they weren’t in healthy cells but in inflammatory liver cells called Kupffer cells.
“Lo and behold, there’s a distinct condition in humans that involves iron-filled Kupffer cells. It’s called dysmetabolic iron overload syndrome (DIOS),” says Venn-Watson.
It starts with fragile blood cells that are filtered into the Kupffer cells, which take the iron for recycling. When too many red blood cells are dying, the iron accumulates. In humans, DIOS is linked to disturbed metabolism, insulin resistance and nonalcoholic fatty liver disease.
The most promising pharmaceutical treatment for fatty liver disease, resmetirom, was introduced in 2024, but it’s reported to resolve only about 30 percent of cases. That’s why Venn-Watson says a “tsunami” of liver disease is about to crash down on humanity—and why her team was excited about the dolphin fatty liver disease, which included DIOS and metabolic syndrome.
They discovered over the next few years that dolphins with lower C15:0 had more fragile red blood cells, which resulted in anemia as they aged. Feeding dolphins a diet higher in C15:0 raised its levels in their red blood cell membranes, strengthening the cells and completely eliminating anemia.
Supplementing pure C15:0 in this model of metabolic syndrome successfully lowered glucose, cholesterol and inflammation. And in a model of anemia + DIOS + fatty liver disease + metabolic syndrome, it lowered triglycerides and inflammation. It also alleviated anemia, liver iron overload and the progression of liver disease across multiple species.
The implications were profound: Declining dietary C15:0 intake may be a root cause of today’s explosion of metabolic diseases.
Around the time Venn-Watson’s papers were gaining attention, she received an email from Dr Jeffrey Schwimmer, a pediatric gastroenterologist at Rady Children’s Hospital in San Diego and a leading expert on fatty liver disease in children. He thought the dolphins’ fatty liver disease was unlikely to be the same as what he saw in his pediatric patients, but he wanted to look at her research.
She sent him a set of preserved dolphin liver slides, and both scientists were astonished to find the disease looked identical. What’s more, the same biological chain of events seemed to be underlying it in both humans and dolphins: nutritional C15:0 deficiency, fragile red blood cells, anemia, liver iron overload, then fatty liver disease and metabolic syndrome.
Schwimmer’s group went on to demonstrate that fatty liver was related to a C15:0 deficiency in 237 children with the condition; the higher the C15:0, the lower the liver fat. It also showed that the greater their full-fat dairy consumption, the lower their liver fat.7 It was the first time fatty liver disease had been linked to C15:0 in children, though a number of studies have linked the two in adults.
In an early trial, Schwimmer’s group recruited 30 overweight and obese individuals aged 18–22 and gave them 200 mg of either encapsulated pure C15:0 powder or rice flour (the placebo) every day for three months.
Blood levels of C15:0 rose in the patients taking the supplement without any side effects, and among those who reached the minimum adequate circulating levels of 5 mcg/mL or more, there were also measurable improvements in liver enzyme and iron levels, signaling improved liver health.8
Venn-Watson guesses that further improvements and clinical changes would have been seen with supplementing C15:0 beyond 12 weeks.
In 2025, researchers in India reconfirmed what Schwimmer had found: that C15:0 supplementation effectively lowered liver enzymes (improved liver function), lowered liver inflammation and oxidative stress, and stopped harmful liver iron overload. They used a rat model that mimicked a newly described nutritional C15:0 deficiency syndrome, called cellular fragility syndrome.9
This, and a good deal of other new research, is helping to solidify the hypothesis that a C15:0 deficiency is the primary driver of iron-dependent cell death (called ferroptosis), which leads to iron overload in cells.
Ferroptosis was discovered by Columbia researchers in 2012, and today there are more than 66,000 studies on PubMed about it. More are being added every day since it underlies most age-related chronic diseases that take us out in the end, including heart disease, cancer, type 2 diabetes and fatty liver disease.
“Ferroptosis is emerging as the calling card of nutritional C15:0 deficiency and cellular fragility syndrome, the first nutritional deficiency to be found in 75 years,” says Venn-Watson.10
In relation to cancer, C15:0 is turning out to be a critical player. In large population studies, people with higher levels of C15:0 in their bloodstream tend to have a lower risk of colorectal cancer.11
Meanwhile, studies of breast tissue have found healthy tissue contains more C15:0 than cancerous tissue, suggesting the body may lose the protective fatty acid as cancer develops.12 Researchers think this may be because C15:0 helps keep cells calm and stable.
It reduces chronic inflammation, supports the cell’s outer membrane, and helps the cell’s protein-making machinery run smoothly. When those systems break down, cells can become stressed and more prone to turning cancerous.
Similar associations of high C15:0 and low cancer risk have been found with liver, pharyngolaryngeal (throat and voice box) and bladder cancer.13
Venn-Watson published a study in 2025 after testing various concentrations of C15:0 against 94 human cancer cell lines. She found C15:0 slowed tumor growth most effectively in a subset of B cell lymphomas (a type of blood cancer) and in breast, liver and lung cancer lines. However, it had “broad anticancer activities,” which suggests that optimizing C15:0 levels may be a way to prevent or treat cancer.14
Other research is just beginning to question the potential role of C15:0 in another tsunami disease: Alzheimer’s. A recent study of 19 navy bottlenose dolphins found they also develop the same age-related brain changes seen in Alzheimer’s disease.
Scientists found signature amyloid-beta plaques and signs of inflammation and microglial activation concentrated in the hippocampus, the brain’s memory center. The pattern mirrors what happens in aging human brains, strengthening dolphins’ role as a natural model for studying cognitive decline.
The same research uncovered something even more compelling: C15:0 naturally blocked two enzymes involved in neuroinflammation and dopamine breakdown, which are already major drug targets for Alzheimer’s and Parkinson’s therapies. This means C15:0 may be protective and essential to healthy brain aging.15
These findings align with those of a growing number of research teams worldwide who are exploring C15:0’s role in human health and questioning the wisdom of the entrenched low-fat dietary guidelines. Our blanket avoidance of unprocessed natural fats may be starving our cells of critical nutrients.
The discovery of C15:0 suggests that balance—not elimination—is key. By restoring the right fats, we may be able to rebuild the cellular stability our bodies have been missing.
According to the cellular stability hypothesis, human longevity depends on how stable the fatty acids that make up cell membranes are. Since C15:0 plays a big role in this stability, it may have a direct role in longevity.
This means circulating C15:0 levels that are 0.2 percent or less of total fatty acids may represent a deficiency state (nutritional C15:0 deficiency syndrome or cellular fragility syndrome), increasing the risk of ferroptosis, diabetes, cardiovascular disease and fatty liver disease.
In contrast, Venn-Watson argues, levels greater than 0.4 percent and perhaps as high as 0.64 percent are likely optimal for long-term health.16
The good news: restoring C15:0 levels doesn’t require radical change. Adults likely need 100–200 mg per day, roughly the amount obtained from 2 cups of whole milk before the low-fat era. But reaching that amount today can be difficult without supplementation or a moderate return to whole-fat dairy (see below for the pros and cons of dairy and other food sources of C15:0).
To help, Venn-Watson and her husband, navy physician Dr Eric Venn-Watson, developed a pure, vegan-friendly C15:0 supplement. “Our bodies don’t make enough of it,” she explains. “So we have to get enough from our diet to stay healthy, especially as we age.”
Their company now collaborates with global health experts to revisit dietary guidelines and challenge the stigma surrounding fat. As she says, “Let’s neutralize the term. There are good and bad fats—and some, like C15:0, are essential for life.”
The implications are huge: healthier aging, stronger immunity, and improved liver and metabolic function, all through a molecule once hidden in plain sight.
What began as a mission to help the US Navy’s beloved dolphins live happy, healthy lives may just help dissipate a global tsunami of metabolic disease in humans.
“It shows that when we combine compassion with innovation to improve life for other species, we can improve life for all,” Venn-Watson says, adding what has become her team’s motto: “Save the dolphins, save the world.”
One of the strongest signals for C15:0’s role in human longevity comes from the well-studied longevity hotspot on the Italian island of Sardinia—a so-called Blue Zone—where a small collection of isolated mountain villagers routinely live to age 100 and beyond. Sardinia had 606 centenarians in 2024, which is about 10 times the concentration of 100-year-olds in the rest of Europe.
The longevity of Sardinians is attributed to their laid-back lifestyle—unchanged for centuries—and their traditional diet, which happens to be high in C15:0-rich grassfed meat and whole dairy, especially in aged cheeses made from grassfed sheep and goat milk, like pecorino.
Contrary to the claims of vegan Dan Buettner, who popularized the idea of Blue Zones, their tradition focuses on raising sheep and pigs, and they often mention lamb and spit-roasted suckling pig as common foods in interviews.
Sardinians also eat homemade whole-grain bread, beans (chickpeas, fava beans, lentils), fresh vegetables and fruit, and bottarga, a salted fish roe. They forage for wild herbs, mushrooms and fruits and drink their famous flavonoid-rich Cannonau red wine—every day but never in excess. Some also reportedly use mastic oil, which is super high in C15:0.
A study comparing people aged 65–70 and over 80 in the Sardinian high-longevity zone to those in a low-longevity zone on the same island found striking differences in C15:0 levels. Blue Zone Sardinians under age 70 had the highest record of C15:0 in their blood: 0.64 percent of total fatty acids, compared to C15:0 values in the populations of other Western countries, which hover around 0.2 percent or lower.
Even Blue Zone Sardinians over age 80 had an average C15:0 of 0.42 percent, compared to just 0.29 percent of those in the low-longevity zone of Sardinia.1 It sounds like the even the low-longevity Sardinians are better off than most of us.
Though it’s important to note that Sardinians likely live longer due to a combination of factors, examining their diet seems to imply higher C15:0 is linked to longevity. Plus, it’s probably a good idea to enjoy a good glass of red wine and some pecorino cheese.
Grassfed dairy products—including cheese, milk and butter—are the most practical dietary way to boost C15:0 levels. Other contributors include certain fatty fish, like anchovies, sardines, herring and salmon.
As well, bacteria in the gut use inulin from dietary fiber to produce small amounts of C15:0. One study showed people who eat very high amounts of fiber-based inulin (30 g daily) had up to 17 percent higher C15:0 levels.1
The trouble with butter
Butter contains roughly 1 percent C15:0, which is modest but meaningful for those aiming to increase this beneficial fatty acid. However, butter also contains about 40 percent even-chain saturated fats, such as palmitic acid (C16:0), which are pro-inflammatory and linked to increased cardiovascular disease risk and type 2 diabetes.
“This could help explain why hundreds of studies with dairy fat, including butter intake, have had mixed results,” says C15:0 researcher Stephanie Venn-Watson.
Moderation is key. Choosing high-quality butter from grassfed cows can slightly increase C15:0 intake while minimizing exposure to inflammatory saturated fats. “I personally use a high-quality butter from grassfed cows, in moderation,” says Venn-Watson.
Aged cheeses
For those looking to maximize benefits, pairing butter with other grassfed dairy products and C15:0-supportive foods is a good idea. In Sardinia, Italy, where people routinely live to see their 100th birthday, pecorino cheese made from local sheep’s milk has very high C15:0 content and is a staple in the diet. Many aged cheeses in general have higher C15:0 content if you can’t find pecorino.
Once scientists saw C15:0 helping stressed cells recover from heart disease, metabolic dysfunction, cancer and cognitive problems, the next question came pretty naturally: If it can help our insides age more gracefully, what might it do for the skin?
In a recent randomized, placebo-controlled clinical study, 49 women aged 35–59 with dry, sagging skin took a daily capsule of a Japanese Aurantiochytrium (single-celled marine organism) oil product enriched in C15:0 for 12 weeks. Researchers tracked changes in skin firmness, collagen levels, moisture and barrier function.
By the end of the study, the women taking the C15:0 supplement showed gradual but noticeable improvements: greater skin elasticity and hydration, denser collagen and less moisture loss from the skin surface. In contrast, those in the placebo group saw little improvement, and some saw their skin moisture and elasticity decline.1
Fatty liver disease is getting more attention as a swelling global public health epidemic. First identified in just 20 nonalcoholic patients with inflamed livers at the Mayo Clinic in Minnesota in the 1980s, it has now ballooned to affect one in three people globally, including one in 10 children.
It may begin with negligible symptoms, but it can cause fatigue, pain in the upper right abdomen and general malaise. It’s the fastest-growing cause of liver cancer and the leading cause of liver transplantation.
When it progresses, damage from liver cirrhosis becomes more visible as a swollen belly and legs, itchy skin, red palms, and yellow skin (jaundice). It’s associated with a high risk of heart disease death and an overall higher risk of dying.
Epidemiologist and veterinarian Dr Stephanie Venn-Watson and her husband, US Navy physician Dr Eric Venn-Watson, have developed a pure, vegan-friendly C15:0 supplement called Fatty15. It appears to be the only C15:0 supplement available in the US and UK right now.
Finland-based supplement company VitaMondo offers a C15:0 powder with worldwide shipping, although it’s currently not shipping to the US.
Here are the details for both options.
Fatty15
C15:0 Fatty Acid Supplement, $119.95/£103.99 for a one-time 90-day starter kit (90 capsules)
US: fatty15.com; UK: healf.com
Supplied in a refillable glass bottle, Fatty15 contains 100 mg pentadecanoic acid per capsule with nothing else added besides the vegetable cellulose capsule. It’s manufactured in the USA under the highest cGMP (current Good Manufacturing Practices) conditions, and every batch is tested to confirm a purity of 98 percent or higher.
VitaMondo
Premium Pentadecanoic Acid 98% (C15:0), £32.88 for 1.8 oz (50 g)
vitamondo.eu
This powdered form of C15:0 has been lab-tested to confirm it’s at least 98 percent pure and free of heavy metals and other contaminants. It’s also vegan, non-GMO and available in three size options. Each package comes with a small measuring spoon, and the suggested dosage is 200–500 mg daily. Mix it with some fat-containing food for best absorption.
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