People adhering to vegan diets have significantly lower Omega-3 Index values compared to those on lacto-ovo vegetarian, pescatarian, and non-vegetarian eating patterns, according to research involving members of the Adventist Health Study cohort.

The peer-reviewed study published in Prostaglandins, Leukotrienes and Essential Fatty Acids (PLEFA) sheds new light on how diet patterns influence long-chain omega-3 levels (EPA and DHA) across different groups.

Findings

The study measured both dietary intake and red blood cell levels (i.e., Omega-3 Index) of omega-3 polyunsaturated fatty acids (PUFAs), including EPA and DHA, among vegan, lacto-ovo vegetarian, pesco-vegetarian, and non-vegetarian participants.

Vegans had the lowest Omega-3 Index among all groups. Vegetarians also had EPA and DHA intake levels well below recommended targets. “For these groups, the most reasonable way to raise these levels is to consume algae-derived EPA+DHA supplements,” the authors concluded.

In comparison, pescatarians and non-vegetarians achieved notably higher Omega-3 Index values, consistent with consumption of fish or marine-derived omega-3s.

The results underscore that diet alone may be insufficient for certain populations — especially strict plant-based eaters — to reach optimal Omega-3 Index levels without supplementation or fortified foods.

The study supports the notion that omega-3 status is strongly influenced by dietary source, and that baseline differences by diet group should be accounted for in both nutritional research and personalized health strategies.

“As more people move toward plant-based eating, it’s critical to understand the nutritional gaps that can come with that shift,” said Dr. Bill Harris, president of the Fatty Acid Research Institute (FARI) and co-author of the study. “This study provides clear evidence that omega-3 status is one of those gaps — and it’s one we can easily fix through awareness, testing, and smart supplementation.”

Implications

This research adds to the dialogue around plant-based nutrition and omega-3s. While vegan diets offer many health benefits, results from the current study suggest that without use of algae-based EPA/DHA supplements or fortified foods, some individuals may fall short of beneficial levels of long-chain omega-3s.

In turn, suboptimal Omega-3 Index values have been associated in other studies with increased risk for cardiovascular, cognitive, and inflammatory conditions.

Given the growing global interest in plant-based diets, this work prompts a reevaluation of dietary recommendations, educational messaging, and supplement strategies to ensure that those avoiding animal-sourced foods can still maintain robust omega-3 status, researchers said.