Nutrient-dense foods are foods that are high in nutrients such as vitamins, minerals, lean protein, healthy fats, and complex carbohydrates, and are relatively low in calories. These foods are the healthiest to consume, as they provide the most benefits to our bodies.
The United States Department of Agriculture states that, “the most nutritious or nutrient-dense foods include vegetables, fruits, whole grains, seafood, eggs, beans and peas, unsalted nuts and seeds, fat-free and low-fat dairy products, and lean meats and poultry- all with little or no saturated fat, sodium, and added sugars.”
Some examples of nutrient-dense foods that you can add to your grocery list for a healthier diet are: sweet potatoes, salmon, kale, quinoa, seaweed, garlic, blueberries, dark chocolate, liver, eggs, sardines, avocadoes, spinach, almonds, oysters, mushrooms, red cabbage, chick peas, and goji berries.
Source: https://www.choosemyplate.gov/nutrition-nutrient-density
https://www.healthline.com/nutrition/11-most-nutrient-dense-foods-on-the-planet#section2 ff