From Web MD.com
Reduce Salt in Your Diet
Skip the shaker and you may still get way too much sodium. Here’s why.
Sodium acts as a flavor enhancer, and many canned, frozen, and other processed foods are full of it, says Havas. Plus, many chefs cook with processed foods and then add more salt. “A typical fast-food meal can contain up to 5,000 mg of sodium — more than double the daily recommended limit,” adds Edward J. Roccella, Ph.D., of the National Heart,Lung, and Blood Institute. Asian food is a big offender, thanks to MSG (a sodium-rich food additive) and soy sauce. Another culprit: pizza. Cheese is high in salt, and meat toppings, such as Canadian bacon and sausage, often contain high-sodium preservatives called sodium nitrites. When you order, ask for half the cheese and more veggie toppings. And no matter where you’re dining, ask your waiter about low-sodium options.
Dietary Guidelines (.pdf)