The general definition of a superfood is: a food with high nutrient or phytochemical content that may confer health benefits with minimal negative traits. A negative trait can be anything with significant amounts of undesirable substances (toxins, food additives, contaminants, bad fats, etc.) accompanying the beneficial substances.
The terms are not in common use by dietitians or doctors. The term is first believed to appear circa 1915. The Macmillan Dictionary defines "superfood" as "a food that is considered to be very good for your health and that may even help some medical conditions". The Oxford Dictionary definition states a superfood is “a nutrient-rich food considered to be especially beneficial for health and well-being".
The European Food Information Council stated that it was impractical for consumers to have a diet based only on presumed superfoods when nutrients are provided readily from a diet containing diverse foods, especially fruits and vegetables.
Though there is no legal or medical definition, superfoods are nutrient powerhouses that pack large doses of antioxidants, polyphenols, vitamins, and minerals. Consuming them may reduce the risk of chronic disease, prolong life, and improve overall health.