In this context, “vegetable” is a culinary term without a precise, widely-agreed-upon definition. While some definitions label all plant foods as vegetables,[1][2] others are more specific, excluding fruit, seeds, and nuts.[1][3] The most commonly-used definitions include potatoes.
Although potatoes are commonly considered vegetables, nutritionally they are more similar to starchy staple foods like bread, rice, and oats than to other foods we commonly call “vegetables”, like tomatoes, lettuce, and carrots. Most of the foods we call “vegetables” are low-calorie plant foods that have a high vitamin, mineral, and fiber content per calorie. For this reason, potatoes have sometimes been categorized differently than other vegetables in dietary guidelines[4] and scientific studies of diet-disease relationships.[5]