How To Reach The Sardinian C15:0 Longevity Zone

November 2, 2025

Welcome to Issue 155 of Science Says! Our weekly newsletter where you’ll learn the latest healthy aging and C15:0 research news that our team of doctors, scientists, and experts are most excited about—without having to go search for it.

Eric and Steph
Co-Founders, Doctors, Nerds

What Dr. Stephanie Venn-Watson, our co-founder and author of The Longevity Nutrient and over 80 peer-reviewed scientific publications, is reading.

Healthy Aging

Impacts of Diets on C15:0 Levels

A new set of studies, bundled into one paper, took a look at population C15:0 levels in Asia, where dairy fat (our primary source of food-based C15:0) is not a prominent part of the diet. The two questions to be answered:

What food sources, other than dairy fat, positively influence C15:0 levels?
Do higher C15:0 levels predict better long-term heart and metabolic health in Asian populations, similar to what has been repeatedly reported in the U.S. and Europe?

Let’s dive into what these studies by Sun et al. showed, and how we can optimize our diets, including how to achieve Sardinian Longevity Zone C15:0 levels.

I’m in. What did these studies show?

Well, a few things.

First, Sun et al. looked at associations between red blood cell membrane C15:0 levels, dietary patterns, and health outcomes among 10,933 people from 10 different geographic regions in Asia (average participant age of 58 years old). This prospective cohort study followed participants for approximately 5 years. In this study, Sun et al. found that people with higher C15:0 levels had better long-term heart health.
Second, they conducted a meta-analysis of population cohort studies with C15:0 and health outcomes, which included their Asian cohort, as well as 33 other population studies (three Asian, 15 American, 14 European, and one Australian). In this meta-analysis including 112,193 participants with a median follow-up range of 3 to 20 years, higher C15:0 was associated with better long-term metabolic health. Further, there were differences in the strength of C15:0 associative benefits on cardiovascular health, based on region and gender.
Third, in the Asian-specific study, higher C15:0 levels were correlated with higher consumption of dairy products (> 200 g/day), fish (> 150 g/day), and wheat (aka fiber). Interestingly, people who ate more red meat had lower C15:0 levels. This finding actually aligns with a large European cohort study, where Forouhi et al. also showed that the more red meat in your diet, the lower your C15:0 levels.

A closer look at regional C15:0 levels.

When we put together population C15:0 levels reported across large regional studies, we gain a better understanding of where different parts of the world rank. Below, you can see that Chinese populations have lower C15:0 levels (median of 0.05% C15:0 among total fatty acids) compared to the U.S. and Europe (median of 0.2%). Meanwhile, Sardinians living in the High Longevity Zone have the highest C15:0 levels (average of 0.4% to 0.6%).

Importantly, whether in Asia, U.S., or Europe, higher C15:0 levels are repeatedly correlated with better long-term metabolic and/or cardiovascular health.

What’s up with Sardinia?

Sardinia is particularly interesting because it has both Low and High Longevity Zones. When comparing these two zones in Sardinia, Manca et al. showed that people living in the High Longevity Zone had average C15:0 levels of 0.4 to 0.6%, which was 2 to 3 times higher than those in the Low Longevity Zone. This is because Sardinians in the High Longevity Zone have essentially replaced their meat with cheese. Further, their cheese is from local sheep and goats feeding on high-altitude grass, which results in high-C15:0 containing cheese… including pecorino.

Got it. Not to be selfish, but what does this all mean to me?

Combined, these studies support the following, which can help optimize our own C15:0 levels:

There’s a benefit to raising one’s C15:0 levels. No matter your baseline, achieving higher C15:0 levels appears to be beneficial to long-term health, though specific benefits (aka metabolic, cardiovascular, etc) may differ based on region and gender. Beyond association, we have extensively covered how C15:0 (especially at levels > 0.2%) directly supports long-term health, and a selected list of peer-reviewed studies are provided below.
Increasing dairy fat reliably increases C15:0 levels, with a caveat. No matter the region, higher dairy fat is the strongest dietary driver of higher C15:0 levels. As Arghavani et al. showed in their cross-over clinical trial, however, increasing dairy fat intake also increases proinflammatory C16:0 levels, which were correlated with increased blood pressure.
Fish and fiber can provide further C15:0 leverage. In regions where there is lower dairy fat intake, C15:0 levels can be increased with higher intake of dietary fish and whole grains (aka fiber). The average C15:0 levels achieved with fish and fiber alone, however, are lower than what studies support as healthy C15:0 levels (> 0.2%).
Don’t count on red meat to raise your C15:0 levels. Large population studies in Europe and Asia have shown that eating red meat, despite containing C15:0, is associated with lower C15:0 levels. This may be consistent with mouse mouse studies from Jenkins et al. and Ampong et al, showing that mice fed a high fat diet also had lower C15:0 levels compared to mice fed a baseline diet. The hypothesis is that too-high amounts of other dietary fats compete with dietary C15:0, resulting in lower dietary C15:0 absorption.

So, the dietary equation of [some amounts of high-quality dairy (aka from grass-fed cows) + fatty fish (like salmon, anchovies or herring) + fiber – red meat] can help support healthy C15:0 levels.

A true role for supplementation.

Robust studies are supporting C15:0’s health benefits, including:

Understanding how C15:0 works (AMPK, AKT, and PPAR activator and mTOR, JAK-STAT and Nk-FB inhibitor)
Demonstrated efficacy in relevant models (including supported metabolic, cardiovascular, liver, red blood cell, gut, and immune health)
Prospective cohort studies
Randomized controlled clinical trials

As we reviewed last week, clinical trials have shown that every 100 mg of pure C15:0 supplementation raises our C15:0 levels, on average, by an additional 10 uM (or approximately 0.1%). This supports that there is a true role for supplementing diets with C15:0 to reliably tap into C15:0’s health benefits, regardless of where we live and what we eat.

Enjoy your extra fall-back hour, and have a fantastic week, everyone!