What Dr Rhonda Patrick says about fish oil — and why she checks IFOS

Fish oil is one of the top supplements in the UK. It is also one where tests often find products that do not match the label. Dr Rhonda Patrick is a science researcher. Her FoundMyFitness podcast has covered omega-3s in depth. When fans ask how to pick a brand, she keeps making the same point. Do not trust the front of the bottle. Look up the batch on IFOS.

The recurring concern: oxidation

Patrick’s clearest message is about oxidation. She thinks it gets too little notice. And it matters more than most people know. Long-chain omega-3s (EPA and DHA) are very unsaturated fats. That makes them prone to going rancid. Oxidised omega-3s lose their power. They also form by-products that do not act like the fat you wanted. Heat, light, and shelf time all push the oxidation markers up.

On her own plan, Patrick avoids products with a total oxidation (Totox) value above 10. That is well below the GOED trade limit of 26. Oxidation is also why she dropped krill oil. She found the products on sale were often low-dose. They also went rancid easily.

What she does personally

• Form. She takes fish oil in its natural triglyceride form. She says the body takes it into cell membranes better than the ethyl-ester form. That cheaper form shows up in many concentrated products.
• Dose. In recent updates she has said she takes about 2 g of EPA + DHA per day. That is down from a past 4 g/day plan. She splits it across the day.
• Target. She frames the goal as the Omega-3 Index. That is the share of EPA + DHA in red blood cell membranes. She points to roughly 8% as a good target for most people. She cites data linking an 8%+ index to lower all-cause death than a 4% index.
• Vegetarian option. When fish oil is not a fit, she suggests algae-derived omega-3. Fish get EPA and DHA from algae in the first place. And the ALA → EPA → DHA conversion in humans is poor.

Why she points to IFOS specifically

When asked how she vets a brand, Patrick names one programme: International Fish Oil Standards (IFOS). The reason is simple. IFOS shares the real numbers, per batch. It is not just a pass/fail badge. For each certified lot you can read the measured EPA and DHA against the label claim. You can also read the peroxide value, the anisidine value, the combined Totox score, and the levels of mercury, lead, arsenic, cadmium, PCBs, and dioxins.

That is what makes the IFOS report a real check, not a logo. A brand can lose stars on one batch. The front of the pack stays the same. If you only look at the bottle, you will not see it.

What IFOS catches that a label does not

• Under-dosing against label claim. Surveys have found omega-3 products where the real EPA + DHA content falls short of the box. IFOS measures and shares the assayed amount for each batch.
• Oxidation already in the bottle. Peroxide and anisidine values are not on consumer labels. But they are the numbers Patrick means when she talks about freshness. IFOS reports them directly.
• Heavy metals and lasting contaminants. Marine oils build up contaminants from the sea. IFOS tests every certified batch against limits for mercury, lead, arsenic, cadmium, PCBs, and dioxins.

Practical takeaway

Patrick’s point is about quality, not a brand. The trade will sell fish oil whether or not it is fresh, dosed right, or low in contaminants. Batch-level testing is the only way to tell. IFOS is the certification built for the job. Its results are out in the open. If you spend money on omega-3s, look up the lot first. That turns the buy from a leap of faith into a check you can do.

A few things are worth noting. Star ratings change between batches. A brand with a 5-star history can make a 4-star lot. So the check is per-batch, not once. IFOS does not screen for sport banned substances. Athletes who compete should look for fish oils that also carry Informed Sport or NSF Certified for Sport. And certification confirms what is in the bottle. It does not promise any health outcome.

You can browse all IFOS-certified fish oils on Certwell, or read the longer reference on how IFOS testing works.