Nutrients Health Article

Nutrients

An important aspect of nutrition is the daily intake of nutrients. Nutrients consist of various chemical substances in the food that makes up each person's diet. Many nutrients are essential for life, and an adequate amount of nutrients in the diet is necessary for providing energy, building and maintaining

body organs, and for various metabolic processes. People depend on nutrients in their diet because the human body is not able to produce many of these nutrients—or it cannot produce them in adequate amounts.

Nutrients are essential to the human diet if they meet two characteristics. First, omitting the nutrient from the diet leads to a nutritional deficiency and a decline in some aspect of health. Second, if the omitted nutrient is put back into the diet, the symptoms of nutritional deficiency will decline and the individual will return to normal, barring any permanent damage caused by its absence.

There are six major classes of nutrients found in food: carbohydrates, proteins, lipids (fats and oils), vitamins (both fat-soluble and water-soluble), minerals, and water. These six nutrients can be further categorized into three basic functional groups.

Carbohydrates

Carbohydrates are the major source of energy for the body. They are composed mostly of the elements carbon (C), hydrogen (H), and oxygen (O). Through the bonding of these elements, carbohydrates provide energy for the body in the form of kilocalories (kcal), with an average of 4 kcal per gram (kcal/g) of carbohydrates (a kcal is equivalent to a calorie on a nutritional label of a packaged food).

Carbohydrates come in a variety of sizes. The smallest carbohydrates are the simple sugars, also known as monosaccharides and disaccharides, meaning that they are made up of one or two sugar molecules. The best known simple sugar is table sugar, which is also known as sucrose, a disaccharide. Other simple sugars include the monosaccharides glucose and fructose, which are found in fruits, and the disaccharides, which include sucrose, lactose (found in milk), and maltose (in beer and malt liquors). The larger carbohydrates are made up of these smaller simple sugars and are known as polysaccharides (many sugar molecules) or complex carbohydrates. These are usually made up of many linked glucose molecules, though, unlike simple sugars, they do not have a sweet taste. Examples of foods high in complex carbohydrates include potatoes, beans, and vegetables. Another type of complex carbohydrate is dietary fiber. However, although fiber is a complex carbohydrate made up of linked sugar molecules, the body cannot break apart the sugar linkages and, unlike other complex carbohydrates, it passes through the body with minimal changes.

Although carbohydrates are not considered to be an essential nutrient, the body depends on them as its primary energy source. The body utilizes most carbohydrates to generate glucose, which serves as the basic functional molecule of energy within the cells of the human body (glucose is broken down to ultimately produce adenosine triphosphate, or ATP, the fundamental unit of energy). When the supply of carbohydrates is too low to adequately supply all the energy needs of the body, amino acids from proteins are converted to glucose. However, the typical American individual consumes more than adequate amounts of carbohydrates to prevent this utilization of protein.