Which long-chain omega-3 fatty acids may be limited in vegan diets?

• A. ALA and DHA
• B. EPA and DHA
• C. EPA and ALA
• D. DHA only

Answer: (B)

Long-chain omega-3s, EPA and DHA, come mainly from marine sources or algae. In vegan diets, these direct sources are avoided, so the diet relies on ALA from plant foods like flax, chia, and walnuts. The body can convert ALA to EPA and then to DHA, but this conversion is inefficient and can be very limited in practice. Because of that limited conversion, vegans may have lower levels of EPA and DHA unless they use algae-based supplements or fortified foods. That’s why EPA and DHA are the long-chain omega-3s that may be limited in vegan diets. DHA-only would miss that EPA can also be lacking, and ALA is not a long-chain fatty acid, so it doesn’t address the question of the long-chain forms.