Takeaway pizzas from chains and fast-food restaurants typically contain up to two and a half times more salt than the equivalent from supermarkets, research from health groups reveals.
Campaigners said consumers were being let down by the absence of clear labelling and information about high levels of salt – which is a major health risk – in takeaway foods.
Half of all the takeaway pizzas surveyed contained the entire maximum daily recommendation of salt – six grams (o.2 oz).
The survey by Consensus Action on Salt and Health and the Association of London Environmental Health Managers is released at the start of the annual Salt Awareness Week.
It analysed 199 margherita and pepperoni fresh and frozen pizzas from takeaways, pizza chains and supermarkets across the UK. They found that takeaway pizzas were found to contain up to two and a half times more salt than the average supermarket pizza (2.73g of salt per 100g compared with 1.08g salt/100g).
A pepperoni pizza from the Adam & Eve restaurant in Mill Hill, London, contained 10.57g of salt. At 2.73g of salt per 100g, it means the food is saltier than Atlantic seawater, which is 2.5g of salt per 100g. The restaurant said it has now changed its recipe to make its pizza less salty.
The Department of Health's target for salt content in pizza by the end of 2012 is a maximum of 1.25g of salt per 100g. But less than a fifth (16%) of the takeaway pizzas tested met this target compared with three-quarters (72%) of supermarket pizzas.
Prof Graham MacGregor, chairman of Cash and professor of Cardiovascular Medicine at the Wolfson Institute of Preventive Medicine at Barts and the London School of Medicine said: "The government is not taking enough action to reduce the amount of salt in the takeaway sector. Salt puts up our blood pressure – the highest risk factor for stroke. Reducing our intake would save thousands of people suffering and dying from a stroke."
In supermarkets, more than eight in 10 pizzas (85%) provided some form of front of pack nutrition information. A Pizza Express supermarket pizza had almost half the salt of the takeaway equivalent and less than one in five supermarket pizzas are high in salt although two in three are high in saturated fat.
The saltiest supermarket pizza was Tesco's Full-on-flavour Simply Pepperoni thin stone-baked pizza which had 1.8g (4.77g per 265g pizza). Tesco said: "We have been cutting levels of salt across our ranges since 2005 and continually look at how we can improve products further. We are in the process of reducing salt in this particular pizza and in just a few weeks it will have 10% less salt."