Both DHA and EPA can technically be converted from ALA, but the conversion rates from ALA to DHA or EPA are extremely low, ranging from undetectable to around 10%.

Non-fish eaters may have an increased conversion efficiency, however, so it is possible that vegetarians and vegans may convert more EPA and DHA from ALA than the rest of the population. Still, what small amount of science exists on the subject is relatively young, so if you eat a plant-based diet, you should pay extra consideration to your omega-3 intake.

The latest research on Omega-3s focuses on heart rate variability (HRV) as a gauge of overall cardiovascular health.

HRV is the change in the time interval between heartbeats. If the time between your heartbeats changes very little, you would have a lower HRV; whereas, if the time between beats varies considerably—say, in response to changing levels of stress—you would have a higher HRV.

In general, it’s a good thing to have higher variability, because it indicates a greater ability to respond to stress. In other words, your heart is able to react to a new circumstance—exercise, rest, stress, etc.—and continue to function properly. On the other hand, people with low HRV are more likely to experience sudden, unexpected cardiac death.

How does all this relate to Omega-3s? Unfortunately, people with low Omega-3 levels are more likely to have low HRV.

There is evidence that vegans may have lower levels of circulating Omega-3s than other segments of the population.

The Omega-3 index is a measure of the concentration of EPA and DHA in the blood. Greater than 8% has been identified as optimal for cardiac protection. In a recent study on HRV, when 23 vegans were compared to 24 omnivores (all volunteers), the vegan cohort had significantly lower levels of EPA and DHA than omnivores. The vegans had a mean Omega-3 index of 2.7% compared with 5.4% in omnivores.

Although both groups were below optimal, the vegans had significantly lower levels of Omega-3s. That is a concern, and not just because of HRV. Omega-3s have a role in reducing inflammation and decreasing our risk of heart disease, cancer, arthritis and cognitive decline. And these lower levels of Omega-3s did in fact correlate with lower HRV: the vegans studied had lower HRV during the waking hours, compared with omnivores, although no difference during sleep.

Admittedly, this was a small study. And the impact of low levels of Omega-3s, and reduced HRV, on cardiovascular risk is complex and requires further research. It does, however, point to a possible mechanism by which those following a vegan diet can further reduce inflammation and cardiovascular risk.