Legumes — lentils, beans, chickpeas, peas — are the rare food that counts as both a protein source and a vegetable, combining plant protein with fibre and minerals at low cost.
USDA FoodData Central lists cooked lentils at roughly 9 g of protein and 8 g of fibre per 100 g, alongside folate, iron, potassium and magnesium — four nutrients public-health surveys repeatedly find under-consumed. The Dietary Guidelines for Americans give beans, peas and lentils their own subgroup within vegetables, recommend them across all its healthy eating patterns, and count them toward either the vegetable or the protein-food target. The Academy of Nutrition and Dietetics vegetarian position paper lists legumes among the foods that make well-planned plant-based diets nutritionally adequate.