Nigella Lawson's tempting creations may look easy to recreate as she whips them up on screen - but more than five million adults cannot understand the recipes.

A survey has found that the chef's verbose style makes it harder for adults with poor literacy skills to follow the instructions.

Delia Smithwas also difficult to understand among adults who have the literacy level of an 11-year-old, representing 16 per cent of the adult working population.

According to the study, both chefs use long sentences, too many adjectives, extra commentary and personal observations.

The survey, carried out by the Government's Get On campaign, looked at a variety of recipes from Smith, Lawson, Nigel Slater, Jamie Oliver and Gordon Ramsay.

It found that Slater was the easiest chef to follow, with all his recipes reaching the entry level three standard, or that expected of an 11-year-old.

Male chefs generally use less chat and a more direct approach, according to the research.

Ramsay said: "I'd hate to think there might be people who aren't giving cooking and new recipes a go because they are worried about the reading, writing or maths side of things.

"Brushing up on their literacy could make them a better chef, as well as improving their life."

The campaign is aimed at helping those with poor skills and offers tips such as how to convert weights and measurements.

Skills minister David Lammy said: "No one needs be deprived of enjoying Delia Smith's bubble and squeak or Nigella's chocolate fudge cake."

The Evening Standard's literary editor David Sexton said: "I thought Nigella's first book, How To Eat, was a classic, not only for its recipes but for its qualities as a memoir, explaining just what food had meant to her in her life and how it fitted into the way she lived. It was, in its eccentric way, very well written.

"Now that Nigella's a great big TV star, the strain shows in her prose. It's incredibly self-proclamatory nearly all I, I, I. It's because she's not really writing a recipe book at all, so much as selling her personality and supposed lifestyle.

"Then when she does give practical advice to others it often seems quite odd, suddenly dropping into the second person - 'whether you add cream or not is entirely up to you.' It sounds de haut en bas. But that's Nigella and that's the daft cookery culture we now have."

For more information about the campaign, call 0800 100 900 or visit www.dfes.gov.uk/get-on