A diversified food supply is contingent on underlying biodiversity in the locality where one lives or at a distance from it, if trade routes are established. Indigenous people generally settled at the water's edge so that aquatic foods made up part of their diversified diet, with the rest of the diversity dependent on how much they hunted and gathered, on herded animals, engagement in subsistence agriculture, the ability to process and preserve food and/or food commodities traded. The rapid urbanization of much of the world's population distances people from the origin of their food, the understanding of the required commodities in the human diet (e.g., aquatic food, plant foods, lean animal foods, what animals are fed, basics of freshness). At the same time, adequacy of food intake may be more reliably achieved when the food supply can continue irrespective of season, climate or distant conflict. Urban gardens partly rectify this discord between urbanization and a genuinely varied diet, replaced by purported variety where the same basic commodity is presented in many different forms (e.g., wheat grains such as bread, breakfast cereal of various kinds, pasta and baked goods). However, diversified processing may 'dilute out' health adverse techniques. The health benefits of a diversified diet relate in part to the environmental integrity, which the required biodiversity provides, in part to minimizing adverse factors, which may exceed acceptable thresholds in a narrow diet, and to the need for the wide spectrum of food components, macronutrients, micronutrients and phytochemicals, which Homo sapiens' physiology requires. Whilst most food diversity is attributable to plant sources, animal sources often provide significant nutritional security (e.g., fish and eggs for vitamin D, fish for n-3 fatty acids, lean meat for iron and zinc and in readily assimilable forms). Food diversity assumes greater importance with aging populations as their physical activity usually (if not necessarily) declines and the required food component diversity of the diet increases correspondingly. There are ways in which the required food diversity (probably 20-30 biologically different distinct foods over the course of a week) can be reduced. This is by the inclusion of more food component dense foods--like fish, lean meat, eggs, seeds and nuts. Not only does food diversity have relevance in a public health and food policy sense, but also in individual counseling in clinical practice. Assessment of a patient's food variety can be rapid and semi-quantitative, encouraging small and consequential changes in diet. When ethnicity is taken into account, in the clinical setting, this process can be even more rewarding for the practitioner and patient.