Another look at spinach

The world's highest profile spinach endorser, Popeye

Popeye was not so wrong when he liked to eat spinach before a fight

The leafy green vegetable really can boost your muscle power.

It was thought the iron content of spinach accounted for its status as a superfood.

But researchers at the Karolinska Institute in Sweden have found that the inorganic nitrate it contains is the secret of its strength-giving property.

They gave a small dose of nitrate, equivalent to that found in a plate of spinach, to exercising volunteers and found it reduced their need for oxygen.

Their improved muscle performance was due to increased efficiency of the mitochondria that power cells, the researchers wrote in Cell Metabolism.

They suggest their finding could offer one explanation for the health benefit of eating fruit and vegetables, the mechanism of which still remains unclear.

Great efforts have been made to isolate the key ingredients of a healthy diet, with limited success.

Nitrates could be one of those key ingredients.

They interact with bacteria in the mouth to produce nitric oxide, a physiologically important molecule with a key role in lowering blood pressure.

Jeremy Laurance