Does taking omega-3 help you stay healthy for longer?

Omega-3 reliably lowers your triglycerides (a fat found in the blood) by around 15%. That is its strongest effect. But lower triglycerides do not automatically mean you will live longer.

Many studies combined, with nearly 144,000 participants, found no difference in the chance of dying early. For death caused by a heart condition there was a small benefit. For strokes there was no benefit. People who took fish oil in a large group of more than 427,000 people followed for years had lower death rates, but this was not an experiment. People who take supplements often live in other healthier ways too, so you cannot conclude from this that the fish oil was the cause.

In people who already have heart disease there are signs of a modest benefit. The American Heart Association concludes, on the basis of large studies, that omega-3 offers the most to that group. If you want to try it as a healthy person to support your heart, buy a fish oil capsule that lists EPA and DHA on the label, around 1 gram per day, and keep that up for at least 12 months. Discuss it with your doctor.

When it comes to biological ageing, the results are mixed. An analysis of 777 older adults found that after three years of omega-3 (1 gram of EPA+DHA per day) there was a small slowing on DNA-methylation measurements: a difference of a few months. That was not a pre-planned measurement and what it means for real-world health is unknown. Another large study of 1,031 participants found no effect on telomere length after four years. The evidence for slowing biological ageing is therefore too early and too contradictory to rely on; if you still want to try it, choose a fish oil capsule that lists EPA+DHA on the label and take 1 gram per day for at least 3 years. On the label, look at the combined EPA+DHA figure, not the total weight of the capsule: those two numbers often differ considerably.