Dietary advice can be complicated. Good quality sources can have conflicting information, pitting one recommendation against another. And that holds true for even the best, science-based guidelines out there, including the current government recommendations -- the USDA's 2010 Dietary Guidelines for Americans, known as DGAs.
When the new guidelines came out, it was clear that we all had a lot of work to do in overhauling our diets: the DGAs recommended eating fewer calories overall, with more fresh produce and whole grains and less added sugar, saturated fat and salt. The recommendations were developed by a panel of experts and were nutritionally sound, but were they possible to follow in the real world?
In a perfect world, we could follow each guideline simultaneously, but actual implementation into our over-scheduled, unpredictable lives is another matter entirely. Public health researchers often refer to this phenomenon as the "real world use" principle -- the unfortunately large divide between what could be and what will be, when we factor in the imperfect nature of human behavior.
A couple of researchers from the University of Washington in Seattle decided to look into what this schism could mean for the government's recommendations on dietary salt. The DGAs include a hard-line maximum on daily sodium intake: 1,500 mg for Americans over age 50, black Americans of any age and those who already suffer from hypertension or cardiovascular disease; 2,300 mg for everyone else. Meanwhile, Americans typically eat between 2,395 and 4,476 mgs of dietary salt daily.
Obviously our diets need to change, but can they change that much? The researchers, Matthieu Maillot and Adam Drewnowski of the Nutritional Sciences Program and Center for Public Health Nutrition, School of Public Health, created models of six 'ideal' diets customized to age and sex and compared those to 'real world' diets that were created using information from the CDC's National Health and Nutrition Examination Survey (NHANES). They tracked how much salt a person would eat if they met requirements for 27 other nutrients -- things like fat, protein, fiber, potassium and calcium -- and, conversely, how many other nutrient requirements could be met while also reducing sodium to the recommended 1,500 mg per day. They found that when the diets were adequate in all other nutrients and met the DGA salt recommendation, the food didn't suit the typical American palate, as determined by the NHANES responses. Explained the researchers:
The idealized "lowest sodium" patterns were created by re-placing existing food choices with unsalted foods. For example, unsalted french fries and potato chips were sub-stituted for salted versions, cooked fresh meats were sub-stituted for processed meats, and unsalted cucumbers were substituted for olives. ...
At that point, the amounts of meats, poultry and fish, eggs, and grains had to be sharply reduced, whereas the amounts of fruit, beans, nuts, and seeds were greatly increased. Vegetables remained in the model because of their very low energy density and because vegetables are among the most nutrient-dense foods.
For young men, the difference was most profound: the diet of a 20- to 30-year-old American man became virtually unrecognizable with "sharp deviations from existing food patterns" under 2,000 mg of sodium, according to the research. "Compliance with the 2010 sodium guidelines will require large deviations from current eating behaviors and/or a profound modification of the U.S. food supply," concluded Maillot and Drewnowski. In other words: if we want to meet all of our nutritional goals, we've got to start choosing very different foods.