C15:0 Science Round-Up Series: Population Studies

Healthy Aging

A Preponderance of Evidence Across Populations

It’s back to school time, so we thought, what better time to do a Round-Up Series on what makes C15:0, well, so science-backed? In this series, we will cover the following six key topics on C15:0:

• Mechanisms of Action: How C15:0 works
• Optimal Effective Levels & Daily Intake: C15:0 bioavailability and amounts needed to achieve active levels
• Cell-Based Efficacy: What C15:0 does at the cellular level
• In Vivo Efficacy: What C15:0 does at the whole-body level
• Epidemiological Studies: People who have higher levels of C15:0 have healthier __________ (we’ll fill in the blanks)
• Clinical Trials: Randomized controlled clinical trials with C15:0

What makes the science behind C15:0 so robust is its consistency across all six topics above – including 100+ studies across numerous independent research teams throughout the world. We’ll also share how C15:0 study outcomes – from its mechanisms of action to clinical trials – are intricately interlinked.

Last week, we covered seven peer-reviewed publications on controlled clinical trials, which support C15:0’s role in promoting our liver, red blood cell, vascular, skin, and mood health. This week, we summarize the evidence of similar C15:0 health benefits when we look across populations.

Tens of thousands of people tracked for decades. 

There are a slew of studies where people’s C15:0 levels and their health have been tracked over time. These are also called prospective cohort studies. And there have been so many of these studies, that there are now meta-analyses (aka studies of studies) that lead to the following conclusions:

People with higher C15:0 levels have better long-term health, especially:

• Heart health
• Metabolic health

Additionally, studies have shown that people with higher C15:0 levels also have better:

• Liver health
• Red blood cell health
• Mood health

… and even a younger biological age. Below are highlighted findings in each of these areas.

Let’s get to the heart of C15:0.

In their meta-analysis including 14 prospective cohort studies following 26,772 people, Li et al. found that people with higher C15:0 levels are 17% more likely to keep their long-term heart health.

This aligns with the Arghavani et al. crossover clinical trial we shared last week, where raised dietary and circulating C15:0 levels were linked to improved vascular function.

Similarly, other population-based studies have shown that higher C15:0 levels are linked to:

• Lower cholesterol, triglyceride, and liver enzyme levels, as shown by Zheng et al. (see below).
• Healthy blood pressure, shown by Chen et al. and Huang et al. in both adults and children.

Importantly, these studies showed the opposite was for even-chain saturated fatty acids, like C16:0 and C18:0, where higher levels were consistently associated with poorer biomarkers of heart health (see below).

Higher C15:0 = healthier metabolism.

In their meta-analysis including 22 prospective cohort studies following 166,745 people, Li et al. showed that people with higher C15:0 levels are 24% more likely to keep their long-term metabolic health.  Specifically, related to healthy glucose metabolism.

This massive study-of-studies showed that for every 50% increase in the percentage of circulating C15:0, long-term metabolic health was protected by 8%.

Translation: If a person has a C15:0 level of 0.2% and increases it to 0.4% of total fatty acids, that person’s odds of protecting their long-term metabolic health would go up 16%. Not bad for a single nutrient. Again, these studies showed the opposite was for C16:0, where higher C16:0 levels were consistently associated with poorer metabolic health.

Higher C15:0 = better health on many fronts, including a younger biological age.

In addition to meta-analyses on heart and metabolic health, population-based studies have shown that people with higher C15:0 have better long-term:

• Liver health, including studies with adults and children from Kratz et al. and Sawh et al., respectively.
• Red blood cell health, including stronger cells and lower oxidative stress in a study by Sobeleva et al.
• Mood health, where both Brydges et al. showed that people with higher C15:0 had calmer moods.

Given all the above, it is not surprising that Liu et al. found that people with higher C15:0 in their lipids had a younger biological age than their chronological age, using both gold standard measurements (aka AgeAccelPheno and Age AccelGrim). And yet again, while higher levels of C15:0 were associated with a younger biological age, higher C16:0 was associated with an older biological age (see below).