Wholesome food is undiseased, uncontaminated, unadulterated. Plants and animals that furnish human food need health themselves. For this they require themselves proper and plentiful food, fresh air, uncontaminated water, cleanliness of surroundings, protection from weather blights of cold or drought or violence, and intelligent care as they are produced, transported, marketed, prepared, served.

Plants poorly nourished make inferior food; diseased plants make dangerous food. Poorly cared-for grain foods cause disease instead of furthering health. Quality of soils and science-methods of production are garden problems, but only as these are known and used to grow well plants can humanity be fed with wholesome vegetables. The part of the plant used for food and the way it is used determine somewhat the care needed in growing and keeping it.

Animals poorly fed and living under unsanitary conditions are not healthy, therefore cannot provide wholesome human food. Food-inspection is expected to regulate the condition of meats marketed. Not only diseased parts, but any part of an animal that is in any way diseased is unsafe for food. All meat eaten must be from undiseased animals and must not be stored for a long time.

Freezing and thawing change foods undesirably. Substances unfavorable to human life may be left in foods in which bacteria have grown, even after the bacteria are themselves destroyed. Some germs only delay their development at low temperatures. Natural ferments change foods in un-propitious ways not readily revealed to the senses. Hence the necessity of scientific examination of foods that are transported or stored and of legal regulation to procure a wholesome food-supply for humanity.