Learn what fish oil, krill oil and plant-based omega-3 sources provide, and how to compare the amounts on a label.
By Evolution Supplements · Updated 28 October 2026
What are omega-3 fatty acids?
Omega-3s are a family of fats found in foods and supplements. The main names you will see are ALA, EPA and DHA. Understanding these helps you compare fish oil, krill oil and plant-based options.
Omega-3 fatty acids form part of cell membranes and have roles in normal body function. Their presence in a product tells you which fats it supplies; the actual amounts and your wider diet are important too.
ALA, EPA and DHA: what is the difference?
Name
Full name
Common sources
ALA
Alpha-linolenic acid
Flaxseed, chia seeds, walnuts and their oils.
EPA
Eicosapentaenoic acid
Fish, fish oil, krill oil and some algae-derived oils.
DHA
Docosahexaenoic acid
Fish, fish oil, krill oil and algae-derived oils.
ALA is an essential fat that must come from the diet. The body can convert some ALA into EPA and DHA, but this conversion is limited. That is why plant sources of ALA and direct sources of EPA or DHA should not be treated as identical on a label.
Fish oil, krill oil and algal oil explained
Fish oil
Fish oil provides EPA and DHA in amounts that vary between formulas. A concentrated softgel may provide a different EPA/DHA amount from another capsule with a similar total oil weight.
Krill oil
Krill are small marine crustaceans. Krill oil supplies EPA and DHA, with a proportion of its fats associated with phospholipids, molecules that also form part of cell membranes. It naturally contains the red pigment astaxanthin.
Its composition differs from conventional fish oil. That difference alone does not prove that every krill product produces better health outcomes. Compare the declared EPA and DHA, serving size and source rather than relying on the oil name.
Algal oil and other plant sources
Algal oil comes from algae and can provide DHA, and sometimes EPA, in a format suitable for plant-based diets when the complete product is vegan. Flaxseed oil instead mainly supplies ALA. Read the active-fat declaration and capsule shell ingredients.
Cod liver oil
Cod liver oil can supply vitamins A and D as well as omega-3s. These additional nutrients matter if you already take a multivitamin. NHS advice is to avoid fish liver oil supplements during pregnancy because of their vitamin A content.
How to read an omega-3 label
Total fish oil is not the same as EPA plus DHA. A label may show several figures: oil weight, total omega-3, individual EPA and DHA, and the number of capsules needed for the serving.
Find the labelled serving size.
Read EPA and DHA separately.
Add EPA and DHA if comparing their combined amount.
Check whether the figures apply per softgel or per daily serving.
Review the source, allergens and any added nutrients.
For a clearly hypothetical example, a serving containing 1,000mg oil might provide 300mg EPA and 200mg DHA. Its combined EPA/DHA amount is 500mg, rather than 1,000mg.
Advanced Omega-3 supplies 750mg combined EPA and DHA per softgel, in a 90-softgel bottle. The directions specify one daily with food. It contains fish oil and a bovine-gelatin shell.
PER4M Krill Oil's two-softgel serving supplies 1,000mg krill oil, including 400mg phospholipids and 200 micrograms astaxanthin. Its 120-softgel bottle provides 60 labelled servings. Krill is a crustacean allergen, and the product contains gelatin.
These figures explain the different compositions and serving formats. Check the current packaging before use.
Omega-3 benefits and everyday nutrition
EPA and DHA contribute to normal heart function, with the beneficial effect obtained from a daily intake of 250mg combined EPA and DHA. DHA contributes to the maintenance of normal brain function and vision at 250mg DHA daily. These are distinct amounts for distinct nutritional functions.
Those functions should not be turned into promises to treat heart disease, improve memory in everyone or accelerate gym recovery. Medical use of high-dose omega-3 preparations is a separate subject from choosing a daily food supplement.
NHS advice is to eat at least two portions of fish weekly, including one oily-fish portion. Individual guidance differs in pregnancy and for some other groups. A supplement can add specific fats, but does not provide everything that a varied meal does.
Choosing an omega-3 formula
Start with the source you want, then compare EPA/DHA per daily serving, capsule count and suitability. Take the product as directed, usually with food where specified, and account for any overlapping oils or vitamins.
Ask a pharmacist or clinician about suitability if taking anticoagulant or antiplatelet medicines, managing a medical condition or preparing for surgery. Higher doses are not automatically a better everyday choice.
Omega-3 FAQs
Does 1,000mg fish oil mean 1,000mg omega-3?
No. Find the total omega-3, EPA and DHA declarations. The oil also contains other fats.
Is krill oil fish oil?
They are different marine sources. Krill are crustaceans, so check the allergen declaration and the active-fat amounts.
Are all omega-3 capsules vegan?
No. Fish and krill are animal-derived, and capsule shells may contain gelatin. Check the complete formulation of an algae-based alternative.
Should I take omega-3 before or after training?
Follow the label and choose a consistent daily routine. There is no established need to time an everyday omega-3 supplement around a workout.
Explore Fish Oil & Omega-3
Compare the current product labels, serving directions and availability in our range.
General information for adults. Follow the selected product's label and check allergens. Seek qualified advice about suitability if pregnant, breastfeeding, taking medication or managing a medical condition. Supplements should complement a varied, balanced diet and healthy lifestyle.
