According to a recent sample, one child's pizza was found to contain almost three times as much salt as that found in another brand of pizza, while some brands of standard baked beans contain only two-thirds the salt of others.
Reductions have been made by some manufacturers since these surveys were conducted, the FSA pointed out, but said that levels still needed to substantially decrease across the full range of processed foods in order to reach the Agency's target of reducing salt consumption to 6 grams a day by 2010.
"The Agency is working closely with industry to secure further commitments to salt reduction," it said in a statement.
Scientific research has linked high levels of salt in the diet to high blood pressure, which increases the risk of heart disease and stroke. High blood pressure is a cause, or a contributing factor, in over 170,000 deaths each year in England alone, the FSA said.
The recommended level of salt intake for adults is 6g a day and proportionally lower for children. On average, adults are currently consuming about 9.5g a day.
Sir John Krebs, chairman of the Food Standards Agency, said that the real cause for concern with the salt content of products such as pizzas or baked beans was that these foods increasingly formed the core of many UK households' diets - quick, simple and easy-to-prepare foods for adults and children alike.
"Foods such as baked beans, spaghetti and pizza are products which families rely on," he said. "Some 75 per cent of our daily salt intake comes from salt hidden in products such as these, and not from salt that we add ourselves. The fact that the salt in one can of baked beans, or a pizza, can vary so dramatically indicates that manufacturers can reduce the amount of salt they add to these products. The Food Standards Agency wants to see more substantial reductions in salt in food products."
The FSA tested 98 fresh, frozen and take-away pizzas as part of the survey, assessing the nutrient content via laboratory analysis once the samples had been cooked according to the manufacturers' instructions.
For a standard children's cheese and tomato pizza, the Iceland and Sainsbury retail chains were found to be the worst offender, with a 95 g portion of their own label kids pizza containing 28 per cent of the recommended maximum salt intake for a 7-10 year old (5g per day). Sainsbury has subsequently altered the formulation of its product to reduce the salt content.
Even some of the 'best' performers had relatively high salt levels: Tesco's kids pizza had 20 per cent of the maximum recommended level, although Waitrose's version had a much more acceptable 10 per cent.
But children seem to fare better than their parents: the maximum intake of salt recommended for adults is 6g day, and according to the FSA a 200g portion (i.e. half a standard pizza size) of Dr Oetker Crisp Fine Base Speciale pizza provides a whopping 73 per cent of that intake in one go - some 4.4 g of salt.
Tesco, whose kids pizzas were among the best in terms of salt content, is another chief offender when it comes to adult portions, with its Stonebaked Pepperoni pizza containing 4.1 g or 68 per cent of the maximum recommended intake. Yet the same company also produces two of the best performances, with its Ham and Pineapple and Barbecue Chicken pizzas contributing 50 per cent and 40 per cent of the recommended intake respectively.
Take-away pizza also seems to be slightly better than their retail equivalents, at least according to the FSA's data. The worst offender was the Pizza Hut Thin Base Margherita Pizza, which contained around 50 per cent of the daily salt intake level, while the best performer was Dominos Thin Base Original Cheese and Tomato Pizza with 40 per cent. As for baked beans and tinned pasta, some 115 products were surveyed, with samples divided into categories by product type as well as healthy eating brands and children's brands. The salt, sugar and fat content of the products were taken from the labels of the products.
Children again seem to far much better than their parents, with the worst offender (Safeway Kids Spaghetti Letters and HP Character range of Children's Pasta Shapes) containing 24 per cent of the 5g/day recommended maximum salt intake and the best (Sainsbury's Blue Parrot Café Range, whose pizza was one of the worst performers, and Asda Kids Super Saucy Spaghetti Letters) both containing just 10 per cent. HP said it had reformulated its product to reduce the salt content, while Asda's product is no longer available, the FSA said.
Heinz, the company most widely associated with baked beans, is also one of the better performers when it comes to salt content (half a tin contains 35 per cent of 6g/day recommended intake), according to the FSA's survey, along with own labels from the Co-op and Waitrose. But the own labels from Morrisons, Budgens and Somerfield were all found to contain more than 50 per cent of the maximum intake level, making them the worst offenders.
Heinz has in fact informed the FSA that it has reformulated its baked beans recipe since the survey was carried out, reducing the salt content even further.
As for standard spaghetti in tomato sauce, the last 'staple' of the British diet tested by the FSA, half a tin of Asda's own label spaghetti loops were found to contain a whopping 62 per cent of the maximum intake level, on a par with the Co-op, whose baked beans were among the best available.
At the other end of the scale, Heinz was again the best performer, with its spaghetti and spaghetti hoops containing 35 and 27 per cent of the maximum salt intake respectively (and again the company has reformulated since the survey was carried out to reduce the content further).
Other 'good' performers in this category were HP, Somerfield, Sainsbury and Crosse & Blackwell.
One key finding of the survey is that there is very little consistency among own labels in particular when it comes to salt content. Sainsbury's Blue Parrot range, for example, has some of the highest and lowest salt contents, while Tesco's pizzas vary dramatically as well. While the Co-op's baked beans are among the best, its tinned spaghetti was one of the worst.
Trust in a brand name or retailer to consistently provide the same level of quality and nutrition is a vital part of consumers' shopping habits, and the FSA's study suggests that there is still a long way to go before any of the major players (with the possible exception of Heinz) are likely to show any level of consistency when it comes to salt content.