“The Mediterranean diet extends lifespan”

PREDIMED randomly assigned 7,447 adults aged 55 to 80 who were at high risk of heart disease but had none yet, to one of three groups: a Mediterranean diet with free extra-virgin olive oil, the same diet with free mixed nuts, or a comparison group advised to cut down on fat [1].

After a median of 4.8 years, a major cardiovascular event - a heart attack, a stroke, or death from heart disease - occurred in 3.8% of the olive-oil group and 3.4% of the nut group, against 4.4% of the low-fat group. That works out at roughly 30% fewer events on either Mediterranean diet [1].

The trial's history is worth knowing. Its first report, in 2013, was withdrawn after the authors found that some participants had not been properly randomly assigned - household members enrolled together, and randomisation lists used inconsistently at some of the eleven sites - and the figures above come from the corrected 2018 re-analysis [1].

The harder question is whether the diet lengthens life. The Cochrane review assessed 30 randomised trials covering 12,461 people; judging PREDIMED, the largest of them, it found little or no effect on the total death rate, alongside a fall in strokes from about 24 to about 14 per 1,000 people [2].

The evidence that the diet extends lifespan comes instead from observational studies, which record what people already choose to eat rather than assigning them a diet. Across 29 of them following 1.68 million people, each 2-point rise on a standard Mediterranean-diet adherence score was linked to a 10% lower chance of dying from any cause, and the link grew steadily the closer people stuck to the diet [3].

The authors of that pooled analysis rate their own evidence as low quality, and confounding is the reason: people who eat this way also tend to smoke less, move more and be better off, and no observational study fully separates the diet from the life around it [3].

On mechanism, the Cochrane review found small falls in blood pressure and in cholesterol on a Mediterranean-style diet, which fits the pattern of olive oil, vegetables, legumes, fish and nuts displacing red meat and ultra-processed food [2].

The practical read: this is one of the best-evidenced ways to eat for your heart, and the clearest single result is fewer strokes. Added years are plausible given how consistent the observational data are, but no trial has shown them.

The diet itself is not pizza and pasta: daily vegetables, legumes, olive oil and fruit, weekly fish, and red meat kept to a minimum.