The most nutrient-dense foods – and one of the primary components of a paleo diet – are vegetables. Try eating more of the healthiest: kale, seaweed, spinach, and arugula. The second most nutrient-dense food is meat from wild or grass-fed animals, like fish, cattle, buffalo, and boar. Animal meat is high in B vitamins, omega-3s, amino acids, and other nutrients essential to good health.