1. Active fatty acids per day
Find the separate EPA and DHA amounts. “1,000 mg fish oil” does not automatically mean 1,000 mg EPA+DHA.
Check how many capsules or millilitres make up the stated serving.
2. Source, form and quality
Fish, krill and algae oils can suit different dietary needs. Do not reduce the comparison to one phrase such as triglyceride or ethyl ester; dose, purity, freshness and tolerability all matter.
Look for clear data on purity, oxidation, traceability and sustainability.
3. Usability and real cost
Taste, capsule size, storage and serving affect whether a product is practical for you over time.
Calculate cost per daily serving and check any subscription or loyalty terms before checkout.
Fish oil or algal oil?
Diet, allergy, taste, preferred format and the actual EPA–DHA profile can all shape the choice. Algal oil provides DHA directly and some products also contain EPA; products should not be assumed to have the same composition.
For fish oil, look for species, origin and traceability. For algal oil, check the algal source, actual EPA and DHA, and carrier oils. In both categories, the specific label matters more than the category name.
Concentration, chemical form and absorption
Triglyceride, re-esterified triglyceride, ethyl ester and phospholipid describe how fatty acids are carried. Absorption can also be influenced by the meal, dose and formulation, so the name of one form is not a complete quality verdict.
Compare daily EPA+DHA, usability and independent quality information first. Chemical form can then be an additional consideration, especially when tolerability or how the product is taken differs.
Freshness, oxidation and storage
Polyunsaturated fats are susceptible to oxidation. Peroxide value reflects part of primary oxidation, anisidine value part of secondary oxidation, and TOTOX combines the two. These are laboratory quality measures, not home diagnostic tests.
Look for batch-linked or regular quality documentation, intact packaging, and clear expiry and storage instructions. After opening, follow the label, protect the product from heat and light, and do not use it when the pack is damaged or the product is clearly unusual.
- batch and expiry information
- purity and oxidation testing
- protection from light, heat and air
- storage period after opening
Price, subscriptions and true daily cost
Divide pack price by the number of daily servings, then note the EPA+DHA provided per day. Similarly priced bottles can differ greatly in concentration, serving count and the number of capsules required.
For subscriptions, check minimum term, delivery frequency, cancellation, automatic renewal and the one-off purchase price. A discount is not useful when the quantity or contract does not fit the intended use.