Which diet is best supported by evidence for a long, healthy life?

For cardiovascular health, the Mediterranean dietary pattern is the best-supported diet you can adopt today. In the largest randomised trial (PREDIMED, conducted in people with elevated cardiac risk), there were approximately 30% fewer serious cardiovascular events. That study had a methodological problem, was re-analysed, and reached similar conclusions, so the result stands on reasonably firm ground. The core of the pattern: plenty of vegetables, legumes, fish, olive oil and nuts, with little red meat and processed products. No exact protocol is needed; the direction is what matters.

For brain health it is more honest to say that the evidence disappoints. Observational studies suggested an association, but the only genuine controlled trial (the MIND study, conducted over three years in older adults) found no measurable benefit for cognition compared with an equally calorie-restricted diet. It is possible that three years is too short, or that the effect occurs mainly when you start earlier in life, but that has not yet been demonstrated. If you follow the Mediterranean pattern for your heart, you are therefore probably also doing the wisest thing we currently know for your brain, but that is a side benefit, not a proven primary goal.

The most concrete first step: make olive oil your default fat, eat at least one serving of legumes or fish every day, and replace snacks with a handful of unsalted nuts. Those are the components that were most consistently represented in the studies.