Soba noodle labels list as much as 900mg sodium per serving—which has limited our use of it. But when we boiled five brands of soba, they lost an average of 80% of their sodium, down to about 80mg per serving. The FDA only requires labels to list the nutritional properties of foods as packaged. Food makers may voluntarily present "as prepared" information, but that's an extra step, and calculation, for them. Most foods used in cooking are rarely consumed as packaged—like soba noodles.
Bottom line: Always consider the ingredients added and methods used in preparing foods.