One of my wife's pet peeves is when students in her cooking classes are so concerned about the amount of salt that she uses for seasoning meat and fish. We like fully-seasoned food. And, occasionally, we are reminded of the "dangers" of sodium by such students or others who "are only trying to help." But, I suspect that we actually consume less sodium than most. One thing that probably shocks people is the fact that we use a salt, Diamond Crystal Kosher (DCK), which looks larger than "normal" table salt. Two teaspoons of DCK has about the same amount (weight) of salt/sodium as table salt---DCK appears twice as large as an equivalent amount of table salt. I bet another reason for the surprise is that we season food from scratch. We rarely use prepared foods. And high-calorie foods like meat and fish requires a good bit of salt to make it taste good. Of course, if you buy prepared foods, this salt has already been added, so you never see the shocking act of adding the proper amount of salt.
But, what is a proper amount of sodium? The USDA tries to determine appropriate sodium levels as a function of "serving size", but I think this is ridiculous. Depending on the food, one might consume many servings of one type of food, but few of another. It seems to me that the closest thing we have to a constant in food is calories. People naturally balance the amount of calories they eat, probably due to fullness/hunger instincts. Different people eat different rates of calories, but each individual keeps a fairly constant calorie intake. They might over/under-eat over short periods (a day or two), but quickly return to their normal rate. So, I think the best way to define appropriate sodium intake is via calories. The USDA says the typical diet is 2000 calories/day and recommends no more than 2 grams of sodium/day. In studying various nutritional labels, this rate of 1 milligram of sodium per calorie seems quite reasonable. Even foods we might think are high sodium, like potato chips, are fine. 100 grams of potato chips might look like a lot of sodium---388 mg. But, that is for 559 calories, or a rate of .69 mg sodium per calorie. You'll get full eating potato chips before eating too much sodium.
When my wife and I eat steak, we'll typically cook over 1 pound of meat. Here is the nutritional information for rib eye steak, a cut we often eat when we eat steak (which is not that often). Note that 1 pound of this raw beef has 1243 calories, but only 254 mg of sodium. So, based on the 1 mg/calorie rule, it requires another 1000 mg of sodium. That's a lot of salt, especially considering that salt is only approximately 39% sodium---6 grams of salt (one teaspoon) has 2.3 grams of sodium. Note that salt is NaCl (sodium chloride); the atomic weight of Na is appx. 39% of the weight of Na and Cl. So, that pound of rib eye steak needs approximately 1 teaspoon of DCK salt. This looks like a lot to someone who mostly eats prepared foods. But, in fact, even the USDA wouldn't complain.
If you turn the lens on deli meats, you might be surprised for a good reason. We're visiting family and this morning, we had Oscar Mayer Deli Fresh Honey Smoked Turkey Breast. I was curious of the sodium content, so I took a look at the nutritional label. 470 mg of sodium per 50 calories, or 9.4 mg sodium per calorie. Egad! If you eat 2000 calories of this deli meat, you'll consume 18.8 grams of sodium. Apparently, this is normal for conventional deli meat. Of course, "all natural" deli meat might be different. Recall that 2 pounds of steak has almost 2500 calories, yet only requires 2500 milligrams of sodium to taste good. Of course, Oscar Mayer proudly advertises the fact that it is 98% fat free and low calorie (per serving). But, servings are silly and our obsession with "fat free" is ridiculous. Our bodies need a reasonable amount of fat and humans seem to get fat much more easily on a high-carb, low-fat diet than one which includes a reasonable amount of fat.
My deli meat sodium discovery makes me realize just how important it is to avoid prepared foods. I've known that recommendation to be important, but I didn't realize that prepared foods can have 9-10 times the reasonable level of salt (1 mg/calorie). When we prepare our own food, we are careful to add just enough salt to enhance flavor. We would never come close to adding the amount of salt that is found in conventional deli meat! Yet, when we eat prepared foods, whether in grocery stores or in restaurants, we don't see the amount of salt that goes into the food and hence aren't as careful. So, I think the advice we are given to be careful of our sodium intake is a bit silly---we see most of the salt that goes into your food and hence are naturally careful. I believe those that need to be careful are people who rely on prepared and restaurant food for the majority of their calorie intake.