Nutrient density

Nutrient density is a ratio: the vitamins and minerals a food provides, divided by the energy it provides. A food is dense when it delivers a meaningful share of a nutrient without taking much of the day's calories to do it.

It is a way of ranking foods, not a claim about health outcomes. Two foods can differ sharply in density and both belong in the same week of eating.

Take two foods supplying the same amount of a nutrient. The one that does it in fewer calories leaves more of the day free for everything else you need, which is the whole practical argument.

Organ meats, shellfish and egg yolks tend to rank high on this measure because they concentrate several nutrients at once. Density also explains why a food can be worth eating weekly rather than daily, since the portion needed is small.

Density rankings come from food composition databases such as USDA FoodData Central. Those are laboratory measurements of what foods contain, not trials of what eating them does.

There is also no single agreed formula. Different scoring systems weight different nutrients, so two published rankings of the same foods can disagree, and any list is a reflection of the choices behind it.

Pick one meal a week and build it around a food that ranks high. That is a smaller change than restructuring a whole diet and it is the one most people actually keep.

Density is a tie-breaker rather than a rule. It is most useful when you are already choosing between two foods and want a reason to prefer one.