If you spend your lunch hour chomping your way through salad in the hope of a health boost, you may not be getting the goodness you want – unless you choose your leaves carefully.
Food scientist Steve Rothwell (www.stevesleaves.co.uk), who has a PhD in the health benefits of watercress, explains that the most beneficial salads contain baby leaves – young plants that have not grown to full maturity.
'Leaves in general are nutritious because they contain a range of vitamins, minerals and phytochemicals (natural plant compounds) including carotenoids that help plants catch light and convert it to energy,' he says.
Beta carotene is a source of Vitamin A, for healthy skin and vision, and the carotenoids lutein and zeaxanthin are important for eye health. But it's the leaves exposed to light that contain the highest amounts of these beneficial compounds.
'If you take an adult iceberg lettuce, for instance, the outer leaves are exposed to light,' says Rothwell. 'But these are often discarded in favour of the pale, tender – yet less nutritious – inner leaves. Juvenile plants usually consist of a few loosely gathered leaves which all get exposed to the sun. This is why baby plants are better for you.