C15 Supplements EXPOSED

Watch this on YouTube.

What is C15?

Pentadecanoic acid, better known as C15, is a saturated fatty acid made up of 15 carbon atoms. You’ll find it naturally in small amounts in foods like full-fat dairy and certain fish. Recently, C15 has become a hot topic in the wellness world, with supplement brands and media outlets touting it as a revolutionary nutrient for health and longevity.

So, what’s all the buzz about?

Back in 2023, The Washington Post highlighted growing interest in C15, citing researchers who believed it might help improve immune function and support heart health. Some even hinted at potential anti-aging properties. Riding that wave, a supplement company called Seraphina Therapeutics launched Fatty15, a capsule containing purified C15. They boldly claim it’s “the first essential fatty acid discovered in nearly 100 years.”

But here’s the catch: According to established nutritional science, there are only two essential fatty acids for human health—alpha-linolenic acid (an omega-3) and linoleic acid (an omega-6). Both have 18-carbon chains, and C15 isn’t considered essential by any medical authority.

Seraphina also introduced the term “Cellular Fragility Syndrome,” a phrase you won’t find in any medical textbooks or peer-reviewed studies. It seems to be unique to the company’s marketing language and isn’t recognized by the broader scientific community.

If you search for Fatty15 online, you’ll see some eyebrow-raising claims. One listing on Amazon boasts that it can “strengthen cells by 80%” and “improve mitochondrial function by 45%,” promising “3X more cellular benefit” than fish oil. However, there’s no publicly available evidence backing those exact figures. It’s not clear where these numbers come from—or if they’re rooted in peer-reviewed science at all.

A lot of the enthusiasm around C15 traces back to Dr. Stephanie K. Venn-Watson, a veterinarian who studied dolphin health. While her findings have sparked interest, her research has focused mainly on dolphins, not humans. It’s also worth noting that she co-founded Seraphina Therapeutics, the company selling Fatty15, which raises questions about potential conflicts of interest.

Human Benefits of C15

Despite the hype, robust clinical data on C15 in humans is limited. A few small randomized trials and observational studies have been conducted, but the results are modest at best.

In one 12-week study, healthy overweight adults who took C15 daily showed small shifts in liver enzyme levels—but there were no changes in weight, cholesterol, or blood sugar. Another trial involving overweight women with fatty liver disease found that adding C15 to a weight-loss diet slightly improved cholesterol, but again, didn’t impact weight or blood sugar.

So, while there may be some minor metabolic benefits, especially for individuals with fatty liver disease, C15 doesn’t appear to offer broad health improvements for the general population.

Does C15 Promote Longevity?

Not really. While one Swedish study did find that people with higher blood levels of C15 had a lower risk of heart disease, their overall mortality rate was the same as those with lower levels. Another observational study came to a similar conclusion—no difference in lifespan.

Bottom line? The idea that C15 is a life-extending, age-reversing miracle nutrient just isn’t supported by science. Right now, the most generous interpretation of the data is that C15 might offer slight metabolic benefits to certain individuals—but it’s a far cry from the transformative health solution some supplement companies would like you to believe.

C15 vs Omega-3

C15 supplements like Fatty15 are often hyped as a superior alternative to omega-3 fish oils, but let’s take a closer look at the facts. Right now, there are no human clinical trials that directly compare C15 to fish oil. And when we zoom out to look at the broader research, omega-3 fatty acids—especially EPA and DHA found in fish oil—have a much stronger and longer-established record of health benefits than C15.

Let’s start with cholesterol. The few small trials on C15 have shown only mild, inconsistent effects on cholesterol levels. On the other hand, fish oil has been studied far more extensively. A meta-analysis of 90 randomized controlled trials—covering over 70,000 people—found that fish oil reliably improves lipid profiles, including lowering triglycerides and supporting heart health.

The story is similar when it comes to fatty liver disease. Only one of the C15 studies showed slight improvements for people with fatty liver. Meanwhile, multiple clinical trials have confirmed that fish oil helps reduce liver fat and lower liver enzymes, making it a more consistent and effective option.

And when we talk about longevity—something many supplement companies love to promise—C15 just doesn’t have the data to support any real claims. Fish oil, by contrast, has been linked to reduced mortality in a variety of populations. People with heart failure who take fish oil appear to live longer. Research has also shown that higher fish or omega-3 intake is associated with lower risk of death from cancer and chronic kidney disease. The evidence is clear: omega-3s deliver more measurable benefits across a range of health conditions.

So, if you’re wondering which supplement packs the bigger punch for your health, the science is overwhelmingly in favor of omega-3s. Whether you’re looking to improve your cholesterol, reduce liver fat, or support longevity, fish oil has the track record. C15? Not so much.

Should You Take C15?

Now, to be fair, some observational studies have found that people with higher blood levels of C15 tend to have better metabolic health. But that doesn’t necessarily mean that C15 is causing those benefits. More likely, it reflects a diet that includes healthier food choices—especially full-fat dairy products like yogurt, milk, and cheese.

In fact, full-fat dairy has long been recognized as part of a balanced, health-supporting diet. Studies show that when people eat more dairy—especially within the framework of a Mediterranean-style diet—they tend to have lower risks for cardiovascular disease. Dairy intake has also been associated with a lower chance of developing fatty liver. And fermented dairy products like yogurt have been linked to a reduced risk of death from certain types of cancer.

So, instead of chasing results with isolated C15 supplements, you might get better outcomes by simply eating more high-quality, full-fat dairy. That approach delivers not just C15, but also calcium, protein, probiotics, and vitamins like K2—nutrients that work together to support your health. C15 on its own is just one piece of the puzzle. It’s like trying to build a house with only nails—you need the full framework to make it work.

In the end, adding more full-fat and fermented dairy to your diet is a smarter, more cost-effective, and evidence-backed move than relying on a pricey capsule. Unless you’re a bottlenose dolphin, the benefits of taking C15 alone are likely to be limited at best.

Top alternatives to C15

• Fish oil (EPA) – 1 to 4 caps / day

Learn more about

• The Best Proteins and Fats for Losing Belly Fat
• CLA for Weight Loss
• Coconut Oil and MCTs For Weight Loss
• Is Cheese Good For Weight Loss?
• Is Milk Good For Weight Loss?
• Supplement reviews

See also

• 
  C15 Supplements EXPOSED
  Pentadecanoic acid (C15) is not well-studied, and there’s no evidence showing they’re more effective than fish oil or beneficial for aging.
• 
  Real Health Benefits of Black Seed
  Black seed has some proven benefits, particularly for asthma and diabetes management, though many exaggerated claims still surround its use.
• 
  Kratom: Benefits and Risks
  Kratom is not a safe treatment for pain or other health conditions due to limited research, safety concerns, and potential of addiction.
• 
  The Truth About Vitamin Patches
  Vitamin patches don’t work well since most nutrients can’t pass through the skin. The main exceptions are Vitamin D and caffeine.
• 
  CoQ10: Benefits and Myths
  CoQ10 supports heart health, some muscle conditions, and PCOS, but doesn’t help with fertility, athletic performance, or weight loss.