Omega-3: who fish oil actually helps
The same molecule behaves differently at a low dose in healthy people and at a high dose in patients with raised triglycerides.
Arguments about omega-3 usually break down over two details: the dose, and the baseline risk of the people studied. The same compound gives different results in different scenarios.
Prevention in healthy adults
In VITAL, 1 g of omega-3 a day did not reduce major cardiovascular events across the whole group. ASCEND and several meta-analyses point the same way: in people without elevated risk, the effect is small or absent.
High doses in high-risk patients
REDUCE-IT is a different story. Four grams a day of icosapent ethyl, in patients with raised triglycerides and high cardiovascular risk, did reduce events. That is a prescription product at a prescribed dose in a selected population — not supermarket capsules taken for general wellbeing.
Judging quality
- Read the EPA and DHA amounts, not the weight of the capsule. They are separate lines on the label.
- Rancid oil smells like paint. Good oil has a mild, neutral marine smell.
- If you take anticoagulants, discuss high doses with your doctor — clotting can be affected.
The short version
Eating fish twice a week is a cheap, well-studied strategy. Capsules make sense when fish is absent from your diet, or when a doctor has prescribed a specific dose for a specific reason.
Sources
- Manson JE et al. Marine n−3 Fatty Acids and Prevention of Cardiovascular Disease and Cancer (VITAL). N Engl J Med, 2019.
- Bhatt DL et al. Cardiovascular Risk Reduction with Icosapent Ethyl (REDUCE-IT). N Engl J Med, 2019.
- ASCEND Study Collaborative Group. Effects of n−3 Fatty Acid Supplements in Diabetes Mellitus. N Engl J Med, 2018.