What is omega-3, and how do DHA and EPA differ?

Omega-3 is not a single substance. It is a family of fatty acids, and they come from different places.

How many kinds are there?

Three come up most often.

ALA comes from plants such as flaxseed, chia and walnuts. The body can convert ALA into EPA and DHA, but only to a limited extent.

EPA and DHA come from oily sea fish and certain algae. These two are the most studied.

What is the recognised statement?

Annex 2 of Thai Ministry of Public Health Notification No. 447 (B.E. 2566) states that docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) contribute to the normal function of the heart.

The notification also sets conditions: a food carrying this statement must contain at least 40 mg of DHA and EPA combined per serving, and the label must state that 250 mg of DHA and EPA should be taken per day.

That 250 mg a day figure is a label statement the notification requires, not a recommended intake.

How do DHA and EPA differ?

They differ in the number of carbons and double bonds in the molecule. Products vary in their EPA to DHA ratio depending on the raw material and the process used.

Where do they come from in food?

Oily sea fish such as salmon, mackerel, sardines and tuna. From plants, flaxseed, chia and walnuts supply ALA.

Short-bodied mackerel is an easy and inexpensive source in Thailand.

How do you read a fish oil label?

Look at three things. First, the actual EPA and DHA amounts rather than the total weight of fish oil — labels usually read fish oil 1,000 mg (provides EPA 180 mg, DHA 120 mg).

Second, the number of capsules per serving.

Third, the form of the oil, such as rTG or ethyl ester, which differ in how they are processed and in concentration.

What should you watch out for?

If you take anticoagulant medication or have surgery scheduled, speak to a doctor before supplementing. Check the allergen information on the label before taking it.

Dietary supplements are not intended to prevent, treat or cure any disease.