Food is any material food consumed to give nutrition to an organism. Food is generally of plant, animal, or fungus origin, and comprises necessary nutrients, including proteins, carbohydrates, vitamins, or iron. It is used as the primary source of nourishment by the body, and the energy it provides is used in metabolism. The major function of food is to supply energy to the body so that it can function properly. It provides people with the substances they need to live, think, and work.

A typical diet is normally composed of carbohydrates, protein, fat, vitamins and minerals. The first five classes of macronutrients constitute the majority of what people consume. Other foods are included as specialties or may be counted as supplements to a traditional diet. The six major groups of macronutrients are simple carbohydrates, simple sugars, starches, fatty acids, non-starchy vegetables, and fruits. The term glycemic index (GI) is sometimes used to describe the carbohydrates/sugar glycemic load (GR) in foods.

The United States Department of Agriculture (USDA) defines food as a “frequently consumed food that provides at least some of the nutrients necessary for normal bodily functions.” To meet the GI requirements, foods must meet certain minimum criteria. Foods meeting the minimum criteria are said to be “balanced” or “nutritional”, as defined by the USDA. Foods that are not nutritionally balanced are considered to be “low-nutrient”.

Carbohydrates are the main source of calories in foods. They are also the most frequently used source of energy in the US. Simple carbohydrates are those that are made up of two or more sugars. Examples of complex carbohydrates are those that contain three to nine sugar molecules. Some examples of frequently consumed complex carbohydrates are potatoes, pasta, rice, oatmeal, and cereal.

Nutrients are the main sources of nutrients in foods. Most plant food sources of nutrients are water-soluble, which means they are soluble in water and non-water soluble, which mean they are insoluble in water. Water-soluble fibers are found in fruits and vegetables, beans, nuts, and seeds. Non-water-soluble fiber sources are nuts, whole grains, legumes, grains, and whole soybeans.

The purpose of this study session was two fold. The first part focused on identifying main sources of nutrients in foods. The second part focused on determining the amount of each nutrient required for normal daily consumption. The sources of these nutrients are listed in Table 1. Based on the food source data, the nutrient estimates for the average individual were calculated.