This seems like a good idea to me. People are far too unaware of what is in the food they are consuming and I certainly don't see any harm in increasing awareness. It is then up to individuals to decide whether they wish to follow the advice.
You could argue that these items should be made healthier, rather than warnings being applied, but it is not always possible to match the convenience and flavour of these long life products without these additives.
As long as consumers are aware of what is in their food, it is up to them whether they want to continue using these types of sauces or find a healthier option - to me the problem is when people just don't know what they are eating.
The company behind Dolmio and Uncle Ben's sauces has defended its "bold" advice that some products should only be consumed once a week due to high salt, sugar or fat content. Mars Food said it would distinguish between "everyday" and "occasional" items on packaging and on its website. It said the move was "right" as some foods were higher in salt, sugar or fat to give an authentic taste. Some experts welcomed the move, while others said it did not go far enough. Once a week, or "occasional", items include Dolmio lasagne sauces, pesto, and carbonara and macaroni oven kits, and Uncle Ben's oriental sauces.