Is Nutrition Really the Key to Good Health?

Having recently returned from Madrid, I confess that I saw little evidence of the Mediterranean diet being consumed there (apart, that is, from the red wine): though, of course, Madrid is in the middle of the peninsula, far from the Mediterranean. Perhaps things are different on the coast. Nevertheless, at over 80 years, Spain has one of the highest life expectancies in the world.

Is this because of the much-vaunted Mediterranean diet? Spanish research recently reported in the New England Journal of Medicine provides some – but not very much - support for the healthiness of that diet.

The researchers divided 7000 people aged between 55 and 80 at risk of heart attack or stroke because they smoked or had type 2 diabetes into three dietary groups. One group (the control) was given dietary advice concerning what they should eat; the two other two groups were cajoled by intensive training sessions into eating a Mediterranean diet, supplemented respectively by extra olive oil or nuts, supplied to them free of charge.

They were then followed up for nearly five years, to find which group suffered from the most (or the least) heart attacks and strokes. The authors, of whom  there were 18, concluded:

Among persons at high cardiovascular risk, a Mediterranean diet supplemented with extra-virgin olive oil or nuts reduced the incidence of major cardiovascular events.

The authors found that the diets reduced the risk of the subjects suffering a heart attack or stroke by about 30 percent. Put another way, 3 cardiovascular events were prevented by the diet per thousand patient years. You could put it yet another way, though the authors chose not to do so: 100 people would have to have stuck to the diet for 10 years for three of them to avoid a stroke or a heart attack. This result was statistically significant, which is to say that it was unlikely to have come about by chance alone, but was it significant in any other way?