Running is one of the most popular physical activities – and for good reason.¹ Not only does it help you achieve the recommended levels of physical activity in less time than other exercise methods, it doesn’t require a gym membership, specialized training, or expensive gear. All you need is a pair of sneakers, and you’re on the road to better health—right? Well, not so fast (no pun intended). 

According to a recent study, running may decrease your omega-3 levels and increase your chances of omega-3 imbalance. Given the importance of omega-3 status for cardiovascular, cellular, and immune health, should runners be concerned?

Keep reading to learn more about the health benefits of running, along with some important considerations concerning physical exertion, omega-3 levels, and heart health. 

The inspiring health benefits of running

Based on several studies, runners tend to have: 

• A lower risk of developing type 2 diabetes²
• Greater reductions in body fat compared to those who practice other types of exercise⁴
• A better chance of battling obesity-related genes if present⁴
• Higher levels of the good cholesterol (HDL) and lower amounts of the artery-clogging bad cholesterol (LDL)^5,6
• Lower triglyceride levels and resting heart rate⁷
• Fewer problems with low-moods and healthier brains^8,9
• A reduced risk of cardiovascular disease and death – although, ironically enough, the risk of having a cardiac event increases during running¹⁰

After considering all of the benefits of running, many of you may be inclined to start a running regimen. Great! But before you cinch your laces, we would like you to consider the importance of evaluating your omega-3 status as part of your running regimen.

Can Running Contribute to Omega-3 Deficiency?

In a new study looking at the relationship between the number of miles run weekly and omega-3 status in recreational runners, researchers found that runners who logged the most miles had the lowest omega-3 index and the highest AA/EPA ratio—two reliable predictors of cardiovascular health.¹¹

The average omega-3 index of runners in this trial was 3.37% (well below the target range of 8%-11%), and the average AA/EPA ratio was 18.4–which is markedly higher than what’s considered optimal for heart health.^12,13 Based on these results, the researchers concluded that running may deplete omega-3 levels and negatively contribute to changes in the omega-3 index and AA/EPA ratio, but that more research is needed to establish causality. 

Importantly, low omega-3 index scores and high AA/EPA ratios are linked to several adverse health conditions.^14,15 Cardiac events have been associated with low omega-3 status – and interestingly, elite and recreational athletes have an increased risk of sudden death from cardiac events.^16,17 If future trials confirm that running depletes omega-3s, achieving optimal omega-3 status may increase exercise safety.

To read about the doses of omega-3 that are supportive for most healthy adults, please refer to our article on omega-3 dosage.

Why might runners require more omega-3s?

Great question. One reason that runners might require more omega-3s than non-runners is because vigorous physical exercise increases muscle insulin sensitivity, which changes the concentration of omega-3s in our muscle’s membranes.¹⁸ Support for this idea comes from muscle biopsy studies, which suggest that during exercise, muscle membranes accumulate DHA as part of an adaptative response.¹⁹

When DHA accumulates in the muscle-membranes (as a result of exercise), it displaces the proinflammatory arachidonic acid – causing it to move out of the muscles and into the blood. As a result, higher arachidonic acid levels in the blood and reduced omega-3 availability may negatively impact the cardiovascular and central nervous systems.^20,21

To be clear, we’re not implying that running depletes omega-3s in a way that damages the cardiovascular and nervous systems. Rather, we think it’s important to acknowledge that if a person’s omega-3 levels are low before starting a running regimen, running could worsen the problem, and there could be consequences. This will become increasingly important if future trials confirm that running depletes omega-3s. For now, realize that only observational trials have shown this to be true.

Could low omega-3 status affect heart function in runners? 

As mentioned earlier, elite and recreational athletes have an increased risk of sudden death following a cardiac event – also known as the ‘exercise paradox’. One of the cardiovascular risk markers related to the heart’s electrical rhythm is heart rate variability.^22,23

What is heart rate variability?

The human heart rate has a degree of irregularities between each heartbeat – this is known as heart rate variability (HRV). Although it may seem counterintuitive, an unhealthy or low HRV means that your heart rate has a predictable rhythmic beat like a metronome, while a higher, healthier HRV has an off-beat tempo – sort of like someone learning to play the drums.

How does exercise affect heart rate variability?

Research shows that as the intensity or duration of exercise increases, an individual’s heart rate variability decreases.²⁴ And as heart rate variability decreases, the risk of cardiac events increase – which may explain why sudden death following a cardiac event is the leading medical cause of death in athletes. So again, as exercise intensity increases, heart variability decreases, and risk of cardiac events increase. Gulp. ²⁵

How does omega-3 status influence heart rate variability?

The omega-3 index is highly correlated to the levels of EPA and DHA in the heart tissues, which is why achieving a target index of about 10% is so important for heart health.²⁶ Omega-3s are known to influence the heart’s electrical rhythm, and indeed, several studies suggest that low omega-3 status can negatively affect heart rate variability.

For example, research finds that:

• Supplementation with omega-3s can increase heart rate variability²⁷
• Individuals with a higher AA/EPA ratio are more likely to die from causes related to heart rate variability²⁸
• A higher AA/EPA ratio has been linked to higher rates of heart rhythm issues in patients who’ve suffered a major cardiac event²⁸
• Infants fed diets low in DHA had higher pulses and lower heart rate variability²⁹
• In elderly populations, higher DHA is linked to fewer problems with the heart’s electrical system³⁰
• Individuals with optimal DHA levels after cardiac surgery were less likely to experience dangerous changes in heart rhythm³¹

Conclusion

The idea that exercise depletes omega-3 stores is not new, and in fact, many serious athletes supplement with omega-3s for this reason.³² Although athletes are certainly a minority, vigorous exercise has the potential to deplete omega-3 levels in everyone—and those who participate in vigorous physical activity multiple times a week could very well be depleting their omega-3 stores. 

Importantly, running isn’t the only type of activity classified as ‘vigorous’. Swimming laps, speed-walking, playing tennis (singles), jumping rope, hiking up steep trails, and aerobic dancing are all examples of other vigorous activities capable of altering one’s omega-3 status.

Taking into account the established health benefits of omega-3s, and the new evidence suggesting that vigorous exercise can deplete omega-3 levels, it is recommended that individuals who partake in vigorous exercise multiple times per week talk to their doctor about how their activity level may be affecting their omega-3 status and whether supplementation is advisable.