The premise behind most "superfoods" lists — that there exists a small set of foods so nutritionally exceptional that daily consumption of them can substitute for an otherwise poor diet — is one of the more durable pieces of nutritional mythology in circulation. The foods on these lists are not harmful; they are genuinely nutritious. The problem is the framing that elevates them above the broader principle they are meant to illustrate.

The foods that appear most consistently on nutritionists' lists of items worth incorporating into daily eating share characteristics rather than specific identities. They tend to be nutrient-dense relative to their caloric content. They tend to contain significant fiber. They tend to have anti-inflammatory properties. They tend to be whole foods rather than processed ones. The specific items — blueberries, spinach, salmon, walnuts, legumes — are interchangeable with other foods that share the same characteristics.

Spinach, for instance, is on virtually every list. It is a genuinely excellent food — high in iron, folate, vitamin K, and antioxidants, with minimal calories and significant fiber. But kale, Swiss chard, collard greens, and a dozen other dark leafy greens share most of these properties. The person who eats kale daily because spinach is unavailable has not failed to eat a superfood; she has eaten a different superfood.

The most durable nutritional advice is the least specific: eat a variety of vegetables and fruits, emphasizing dark-colored ones; include whole grains rather than refined ones; consume protein from diverse sources including legumes; minimize added sugar, refined starches, and processed foods; drink water. This advice is not exciting enough to generate list-based content, but it contains everything the "5 foods to eat every day" article is actually trying to communicate.