Flaxseed oil, chia seeds, hemp seeds and walnuts are often praised for being rich in plant-based omega-3s. These foods provide alpha-linolenic acid (ALA), an essential omega-3 fatty acid—essential means that the body can’t make it and must obtain it from food. But ALA is only part of the omega-3 story.

To really understand what we’re getting from these foods—and what we might be missing—it helps to break down the differences between ALA, EPA and DHA.

What are ALA, EPA and DHA?

Omega-3s are a family of polyunsaturated fats with anti-inflammatory and cell-supportive roles throughout the body. The three most commonly discussed omega-3s are:

  • ALA (alpha-linolenic acid) – found in plants like flax, chia, hemp and walnuts
  • EPA (eicosapentaenoic acid) – found in oily fish and algae
  • DHA (docosahexaenoic acid) – also found in oily fish and algae

ALA is found in plant foods and plays a valuable role in health, but the critical omega-3s the body uses most actively—EPA and DHA—must either come from the diet or be converted from ALA. DHA, in particular, plays a structural role in the brain and retina, where it is highly concentrated in cell membranes.

Can the body convert ALA to EPA and DHA?

Technically, yes—but the conversion is limited. Most studies suggest that less than 5–10% of ALA becomes EPA, and less than 1–5% becomes DHA. Several factors can influence this conversion, including genetics, overall diet, age, sex and levels of competing fatty acids like omega-6.

For those relying solely on plant-based sources of ALA, this limited conversion is not likely to be enough to meet optimal levels—especially when it comes to supporting brain, eye, heart and inflammatory health, where DHA and EPA are most active.

While humans can convert small amounts of ALA into EPA and DHA, oily fish obtain these critical fats by eating algae and smaller marine organisms that already contain them.

What are the best sources of EPA and DHA?

  • Oily fish (such as salmon, mackerel, anchovies, sardines and herring)—easily remembered by the acronym SMASH
  • Algal oil supplements (a plant-based, sustainable source of EPA and DHA)
  • Fish oil supplements, which are rich in both EPA and DHA and are well-studied for cardiovascular, cognitive and inflammatory support

For vegetarians and vegans, algal oil is the most direct and reliable source of DHA and EPA—bypassing the inefficient conversion from ALA and providing active omega-3s in forms the body can immediately use. While not everyone may need high-dose supplementation, an optimal omega-3 index is important for everyone. Individuals with low dietary intake or specific health goals—such as cognitive or cardiovascular support—may benefit from targeted supplementation.

What about the omega-3 index?

Emerging research suggests that the omega-3 index—a measure of EPA and DHA levels in red blood cell membranes—may be a more accurate and clinically meaningful marker of omega-3 status than the traditional omega-6 to omega-3 ratio. An index of 8% or higher is generally associated with better cardiovascular outcomes, while levels below 4% have been linked to increased risk.

For individuals who don’t consume fish regularly, omega-3 index values are often suboptimal—highlighting the potential benefit of including preformed EPA and DHA through diet or supplementation.

The bottom line

ALA has its own benefits, but it isn’t a reliable way to meet the body’s needs for EPA and DHA—especially for those on plant-based diets. If you’re choosing to avoid fish, consider algal oil as a clean and effective way to get active omega-3s.

If you’re wondering whether your omega-3 intake is sufficient—or would like help finding the right form for your needs—feel free to speak with one of our qualified team members in store. For more personalised advice, you’re welcome to book a consultation at www.viveclinic.com.au.

Article written by
Peter Christinson
BHSc (Nutritional and Dietetic Medicine)
Retail and Clinic Manager