The main types of nutrients are carbohydrates, fats, proteins, vitamins and minerals. The body needs them to maintain healthy cells and proper metabolism.
Carbohydrates are compounds that are usually produced by plants. As the name suggests, they are composed of carbon (carbo-), hydrogen (hydration) and oxygen (-atos). The simplest carbohydrates are sugars. Complex carbohydrates are large molecules of linked sugar groups. The body depends on sugar glucose, which breaks down from carbohydrates, for its primary energy needs and brain function. Table sugar, maple syrup, maize, wheat and rice are examples of carbohydrate-rich foods.
Fats are also composed of carbon, hydrogen and oxygen and are made of two-component molecules: glycerol and fatty acid. From both animal and vegetable sources, fats are highly concentrated sources of energy and are necessary for the absorption of vitamins A, D, E and K. Peanut oil, butter, egg yolk and lard are some examples of fats.
Proteins are long and complex chains of amino acids, which are the basis of all living cells. Proteins contain carbon, hydrogen, oxygen, nitrogen and other elements. They supply nitrogen and amino acids for every cell type, substance and activity in the body. Muscles, bones, cartilage, skin, blood, and tissue cells are made from proteins, as are enzymes, which promote chemical reactions in the body, and antibodies, which fight infections. Cell growth, repair and replenishment also require protein. Egg whites, soybeans, fish, beef and chicken are some protein-rich foods.
However, most foods are combinations of nutrients, even in their natural state. For example, beef is made up of fat and protein, and milk is a combination of protein, fat and carbohydrates. Foods such as bread or tuna salad, made from a variety of ingredients, contain many different nutrients.
ORGANIC AND INORGANIC
Vitamins are organic substances (carbon containers) known as coenzymes, compounds that work with enzymes to help regulate chemical reactions in the body. Most vitamins are present only in foods and food supplements. One of the vitamins the body produces is vitamin D.
Minerals are found in organic elements – those that do not contain carbon – that are needed in tiny amounts for the body’s nutritional balance. Two examples of inorganic elements are iron and zinc.
Water is another vital substance; it accounts for two-thirds of body weight. Water performs a variety of functions, helping to carry nutrients and oxygen throughout the body, and helping both digestion and waste disposal of the system, people need six to eight glasses of water each day. Juices, soups, fruits and vegetables are good sources of fluids. The same cannot be said of coffee, tea, cola drinks and alcohol, which dehydrate the body. The equivalent of three or four glasses of water usually comes from the food consumed each day.