Nutritional C15:0 Deficiencies: A New At-Home Test to Assess and Optimize Your C15:0 Levels (and Your Health)

A new nutritional deficiency syndrome has been discovered, and it’s called Cellular Fragility Syndrome. As the name implies, people with Cellular Fragility Syndrome have more fragile cells, resulting in accelerated aging that can impair our long-term metabolic, heart, and liver health. Caused by low C15:0 levels, this is the first deficiency syndrome to be discovered in 75 years, and it may affect as many as 1 in 3 people globally.

Importantly, a new at-home test available from Genova Diagnostics, called the Fatty15 C15:0 Test, has been developed to help you assess your baseline C15:0 and develop a personalized plan to replenish, maintain and optimize your levels.

So, let’s take a deeper dive into this new test, how to interpret your results, and how you can use them to improve your long-term health, including reversing a C15:0 nutritional deficiency. 

Great. Wait, what is C15:0?

C15:0 (aka pentadecanoic acid) is the first essential fatty acid to be discovered in almost 100 years. C15:0 is a naturally-occurring odd-chain saturated fatty acid, with trace levels found in dairy fat, as well as some types of fish and plants. 

As an essential fatty acid, C15:0 is critical for our bodies as it actively repairs, restores and revitalizes our long-term health at the cellular level by:*

• Strengthening our cell membranes (and us) against age-related breakdown
• Repairing mitochondrial function, which keeps our body’s energy-producers going
• Naturally activating receptors (including PPARs and AMPK) that regulate our metabolism, immunity, mood, sleep and appetite
• Naturally inhibiting damaging pathways (including mTOR and JAK-STAT) as a means to support longevity

All in, C15:0 provides 36+ cellular benefits to support our long-term health.

What is Cellular Fragility Syndrome (aka, nutritional C15:0 Deficiency Syndrome)?

C15:0 is a strong, stable fatty acid that keeps our cell membranes strong (and our cells healthy). If our cell membranes have low levels of C15:0, our cells become fragile and cause a newform of cell death, called ferroptosis. 

As a result, nutritional C15:0 deficiencies can speed up aging and compromise our metabolic, heart, and liver health. This syndrome is called Cellular Fragility Syndrome. Studies support that Cellular Fragility Syndrome may be impacting as many as 1 in 3 people globally.

So, tell me more about the new at-home C15:0 test.

You can determine your C15:0 levels using either a test at your doctor’s office or with a new at-home test. 

The Fatty15 C15:0 Test, offered by Genova Diagnostics, measures C15:0 levels in your red blood cell membranes, which is ideal for assessing your cell strength and susceptibility to Cellular Fragility Syndrome. This test reports your C15:0 results as both a percentage (%) of total fatty acids, as well as the actual amount (in µg/ml).

How do I interpret my C15:0 test results?

The best place to start is with your reported percentage of C15:0 (% of all fatty acids) in your red blood cell membranes. Based on extensive peer-reviewed studies, the following guide can help interpret your C15:0 levels: 

• Low Zone: under 0.20%. Low C15:0 levels can cause weakened cell membranes and Cellular Fragility Syndrome. Numerous studies have shown that people with low C15:0 levels are more likely to have impacted metabolic, heart, and liver health.
• Healthy Zone: 0.20% - 0.4%. Most people have C15:0 levels in this range, which can protect against Cellular Fragility Syndrome and support metabolic, heart, and liver health.
• Optimal Zone: 0.40% - 0.64%. People living in the Longevity Blue Zone of Sardinia have average C15:0 levels of 0.64%. Another extensive study showed that C15:0 levels > 0.4% are associated with the most protected heart health.

I’m in. How much C15:0 do I need in my diet to not be deficient? And how much do I need to reach those optimal levels?

Most people have a baseline of around 0.2% C15:0, which is *technically* ok, but not really great when you consider that Sardinians living to 100 are closer to 0.64%. So ideally, we should all be aspiring to be somewhere in the Optimal Zone of 0.40% - 0.64%. 

So how can you increase your C15:0 levels? Here’s a good rule of thumb: 

For every 100 mg of C15:0 daily, most people can raise their levels by around 0.1%, which means we need to add 100-200mg of C15:0 per day to our diets to stay in the “Healthy Zone”. 

However, people who have a C15:0 deficiency (< 0.2%) may need higher amounts of daily C15:0. That amount will depend on your baseline C15:0 levels.

Now that I know how much daily C15:0 I need in my diet, any recommendations?

While simply eating more dairy doesn’t translate to the metabolic, liver, and heart-health benefits of C15:0, the Longevity Blue Zone Sardinian diet provides some important clues on how to achieve optimal C15:0 levels, good heart health, and supported longevity. 

The Sardinian diet is low in meat (which is typically eaten only once a week) and high in dairy (primarily cheese, which is part of their daily diet). Importantly, Longevity Blue Zone Sardinians make their own cheese from local goats and sheep that graze on mountainous grass. Not only have studies shown that grass-fed animals produce higher-C15:0 milkfat, but that mountainous grass-fed animals produce the highest-C15:0 milkfat. 

Longevity Blue Zone Sardinians typically eat locally made pecorino cheese, which has double the C15:0 levels of butter from cows in the U.S. They also eat an aged goat cheese that has a higher amount of free fatty acids - which translates to more bioavailable C15:0. 

Ah, now we know how Longevity Blue Zone Sardinians achieve C15:0 levels that are 3x higher than the rest of us.

Why can’t I just eat more of any food that contains C15:0?

While there are foods that contain C15:0, there is a balance between getting enough good C15:0 versus adding too many proinflammatory even-chain saturated fatty acids. Here are the top limitations of many food-based sources of C15:0:

• Milk fat contains only 1% C15:0, and has more than 40% proinflammatory fatty acids (such as C16:0 and C18:0). Higher levels of C16:0 and C18:0 have been repeatedly associated with poorer metabolic, heart, and liver health.
• This unfavorable ratio of bad-fats-to-good-fast is present in just about all foods that contain C15:0.
• Some studies have shown that high fat diets may actually limit absorption of food-based C15:0.
• The amount of C15:0 in dairy fat is dependent on what animals are fed. Grass-fed animals produce milk that has more C15:0 compared to animals fed corn.

These limitations are why experts have concluded that eating more dairy products does not holistically and reliably improve our health. And why these experts have concluded that individual beneficial ingredients in milk (ahem, C15:0) can perform better when they are isolated and pure.

Fatty15 to the rescue.

Fatty15 is a pure, science-backed, bioavailable, and tiny vegan-friendly C15:0 supplement. This award winning ingredient was developed by doctors and scientists to supplement our diet and help us maintain healthy C15:0 levels.

Numerous studies have demonstrated broad health benefits of the pure C15:0 ingredient in fatty15, including optimal metabolic, heart, liver, and LDL cholesterol health. To boot, more than half of fatty15 customers report feeling better within 2 weeks, including deeper sleep, calmer mood, and improved joint comfort.

Each capsule contains 100mg of C15:0, which allows you to tailor a C15:0 supplement regimen to your specific needs (aka 1 or 2 capsules a day). As a reminder, most people need an added 100-200 mg of C15:0 per day to maintain “Healthy Zone” C15:0 levels.

How does fatty15 support longevity?

Extending healthspan and longevity by strengthening cell membranes isn’t a new idea. In fact, A.J. Hulbert’s Cell Membrane Pacemaker Theory of Aging shows that nature has used this trick for millions of years. 

In his studies, Hulbert demonstrated that long-lived mammals (like humans and elephants) have cell membranes with the sturdiest fatty acids. These strong cell membranes result in lower lipid peroxidation and longer lives. 

A recent paper introduced the Cellular Stability Hypothesis, which states that cell membrane strength dictates not only a species’ longevity, but the longevity of individuals within a species - including humans.

Pure C15:0 (aka fatty15) has many more longevity-enhancing activities, including:*

• 36+ cellular benefits, which was better than three leading longevity-enhancing molecules: rapamycin, metformin, and acarbose.
• Targeting six out of 12 hallmarks of aging, including cellular senescence, inflammaging, mitochondrial dysfunction, gut dysbiosis, impaired cellular signaling, and epigenetic alterations
• AMPK activation and mTOR inhibition, both of which support longevity 
• Raising LPE C15 levels, which has been associated with slower biological aging rates
• Improved growth of a healthy gut microbe, Bifidobacterium adolescentis, which has been shown to increase longevity in multiple species

As shared earlier, people who live in the Sardinian Longevity Blue Zone are healthier longer and are more likely to live 100+ years. Sardinia has the world’s largest percentage of men who live to at least 100, which has been attributed to their good heart health. Studies found that this long-lived population has high C15:0 levels: a whopping 0.64%. As a reminder, the rest of the world has an average C15:0 level of only 0.2%. 

How often should I test my C15:0 levels?

Start by assessing your baseline C15:0 levels. Depending  on your results, you can implement a new routine designed to raise and maintain “Healthy Zone” C15:0 levels. After starting and staying on a new dietary or supplementation routine, we recommend retesting your C15:0 levels in 3 months to 6 months.

So, how do I know that raising fatty15 raises C15:0 levels and fixes Cellular Fragility Syndrome?

Well, science. A recently published paper shows how the pure C15:0 ingredient in fatty15 reverses all core components of ferroptosis and Cellular Fragility Syndrome. This includes studies demonstrating how fatty15 directly:

• Raises C15:0 blood levels
• Strengthens red blood cell membranes by 80%, and stabilizes them against premature breakdown
• Lowers lipid peroxidation & iron deposition in the liver
• Lowers reactive oxygen species (ROS) levels by 45%
• Repairs mitochondria

That’s like, 5 for 5. This also explains why studies have repeatedly shown that people with higher C15:0 levels have better long-term metabolic, heart, and liver health.

Go, C15:0. So long Cellular Fragility, hello Cellular Stability.

Order the test:

Genova Diagnostics At-Home Fatty15 C15:0 Test

Read the study:

Venn-Watson, S. The Cellular Stability Hypothesis: Evidence of Ferroptosis & Accelerated Aging-Associated Diseases as Newly Identified Nutritional Pentadecanoic Acid (C15:0) Deficiency Syndrome. Metabolites 14 (2024): 355.