Fish oil and cold-pressed oils provide good fatty acids, but they have a weak spot: they “go rancid easily” when exposed to air, heat and light · Rancid (oxidized) oil doesn’t just smell bad — its nutritional value drops and it may form undesirable compounds · How to choose and store it so you get a good product · This article sums it all up
oxidize easily
of freshness
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Polyunsaturated fatty acids (such as omega-3s) have many double bonds, so they react easily with oxygen and go “rancid” (rancidity/oxidation) · Rancid oil smells fishy and sour, tastes acrid, and has lower nutritional value
1 Why freshness matters
- Lower value — oxidized omega-3s provide less benefit
- Undesirable compounds — rancidity forms peroxides and aldehydes
- Easy to spot — strong fishy burps or foul-smelling capsules = a warning sign
2 Oil quality indicators
| Value | What it tells you |
|---|---|
| Peroxide Value (PV) | Primary oxidation level |
| Anisidine (AV) | Secondary oxidation |
| TOTOX | Overall freshness value (the lower, the fresher) |
| Heavy metals | Purity (mercury, lead) |
💡 Did you know? BLB P uses 9 cold-pressed oils — cold pressing helps preserve the value of the fatty acids and lowers the risk of heat damage · Thai FDA 26-1-10867-5-0050 · Halal · A dietary supplement, not a medicine
3 How to choose and store it
- Check the production/expiry date and choose a brand with quality control
- Store in a cool, dark place — some types should be refrigerated after opening
- Close the lid tightly to reduce air exposure
- If the smell changes or turns rancid — don’t keep taking it
References
- Albert BB, et al. Fish oil supplements: oxidation and quality. Sci Rep.
- Jackowski SA, et al. Oxidation levels of commercial fish oils. J Nutr Sci.
- GOED Voluntary Monograph — Oxidation limits.
💡 Looking for a helper? Read next: Which omega-3 brand is best — choose wisely 👉