Form matters alongside freshness: triglyceride (rTG) products absorb better than ethyl esters taken casually, though a fatty meal largely closes the gap. Krill's absorption advantage is real but modest, and priced beyond its evidence. For pregnancy, freshness certification stops being a preference and becomes the requirement.
SOURCE LIBRARY · Imported evidence summary · Clinical review pending
The capsule is a variable too
Buying a product that is what it says
Fish oil goes rancid. In independent surveys, up to 39% of retail products exceeded freshness limits and content averaged as low as 68% of the label. Oxidized oil is degraded oil - five checks fix most of it.
1
Third-party tested
IFOS 5-star or USP Verified seals check freshness, content, and contaminants against published limits - the only functional substitute for prescription-grade oversight.
2
Unflavored softgels
In the latest US survey, 68% of flavored products failed the freshness limit versus 13% of unflavored. Skip gummies and flavored liquids.
3
Dose by EPA+DHA, not “fish oil”
A 1,000 mg fish-oil capsule may hold only 300 mg of the active molecules. The label's EPA+DHA line is the number that counts.
4
Fresh and protected
Recent manufacture date, opaque bottle, antioxidants like mixed tocopherols. Refrigerate liquids after opening; use before expiry.
5
Trust your nose
A fishy or paint-like smell means advanced rancidity - fresh oil is nearly odorless. Bite one capsule from a new bottle.
Key evidence
- [27]Albert BB, et al. Fish oil supplements in New Zealand are highly oxidised and do not meet label content of n-3 PUFA. Sci Rep. 2015;5:7928.
- [29]Griscom PV. Omega-3 Fatty Acids Are Not One Intervention: A Moderator-Matrix Review. 2026. Literature searched through July 2026. Umbrella source for this guide; claims without a numbered primary citation are synthesized there.