Nutrition and Wellness

Part I

Proper nutrition means that one’s diet supplies all the essential nutrients to carry out normal tissue growth, repair, and maintenance. It also implies that the diet will provide enough substrates to produce the energy necessary for work, physical activity, and relaxation.

Diet and nutrition often play a crucial role in the development and progression of chronic diseases. A diet high in saturated fat, trans fat, and cholesterol increases the risk for atherosclerosis and coronary heart disease. In sodium-sensitive individuals, high salt intake has been linked to high blood pressure.

The Essential Nutrients

The essential nutrients the human body requires are

…

• Carbohydrates• Fats• Proteins• Vitamins • Minerals• Water

Carbohydrates, fats, proteins, and water are termed macronutrients because people need to take in proportionately large amounts daily.

Nutritionists refer to vitamins and minerals as micronutrients because the body requires them in relatively small amounts.

Depending on the amount of nutrients and calories they contain, foods can be classified as high nutrient density or low-nutrient density.

Foods with high-nutrient density contain a low or moderate amount of calories but are packed with nutrients.

Foods that are high in calories but contain few nutrients are of low-nutrient density and commonly are called “junk food.”

Carbohydrates

• Carbohydrates are the major source of calories the body uses to provide energy for work, cell maintenance, and heat.

• The major sources of carbohydrates are breads, cereals, fruits, vegetables, and milk and other dairy products.

Carbohydrates are classified as simple carbohydrates and complex carbohydrates.

Simple Carbohydrates

Simple carbohydrates (such as candy, soda, and cakes), commonly denoted as sugars, have little nutritive value. These carbohydrates are divided into two groups:

• Monosaccharides (glucose, fructose, and galactose)

• Disaccharides (sucrose, lactose, and maltose)

Simple carbohydrates often take the place of more nutritive foods in the diet.

Complex Carbohydrates

Complex carbohydrates are formed when simple carbohydrate molecules are linked together. Three types of complex carbohydrates are:

• Starches• Dextrins• Glycogen

Starches are commonly found in seeds, corn, nuts, grains, roots, potatoes, and legumes.

Dextrins are formed from the breakdown of large starch molecules exposed to dry heat, such as when bread is baked or cold cereals are manufactured.

Glycogen is the animal polysaccharide synthesized from glucose and found in only small amounts in meats. Glycogen constitutes the body’s reservoir of glucose. Many hundreds to thousands of glucose molecules are linked to be stored as glycogen in the liver and muscles. When a surge of energy is needed, enzymes in the muscle and the liver break down glycogen and thus make glucose readily available for energy transformation.

Complex carbohydrates provide many valuable nutrients and also are an excellent source of fiber (also called roughage).

Fiber• Fiber is a form of

complex carbohydrate.

• A high-fiber diet gives a person a feeling of fullness without added calories.

• Dietary fiber is present mainly in plant leaves, skins, roots, and seeds.

• Processing and refining foods removes almost all of the natural fiber.

• Fiber is important in the diet because it decreases the risk for cardiovascular disease and cancer.

• Increased fiber intake also may lower the risk for coronary heart disease because saturated fats often take the place of fiber in the diet, thus increasing the formation of cholesterol.

Health disorders that have been tied to low intake of fiber are constipation, diverticulitis, hemorrhoids, gallbladder disease, and obesity.

Fibers are typically classified according to their solubility in water.

• Soluble• Insoluble

Soluble fiber dissolves in water and forms a gel-like substance that encloses food particles. This property allows soluble fiber to bind and excrete fats from the body. Soluble fiber has been shown to decrease blood cholesterol and blood sugar levels. Soluble fiber is found primarily in oats, fruits, barley, and legumes.

Insoluble fiber is not easily dissolved in water, and the body cannot digest it. This fiber is important because it binds water, resulting in a softer and bulkier stool that increases peristalsis (involuntary muscle contractions of intestinal walls), forcing the stool onward, and allows food residues to pass through the intestinal tract more quickly.

Fats

• Fats, or lipids, are the most concentrated source of energy. Each gram of fat supplies 9 calories to the body. Fats, also part of the cell structure, are used as stored energy and as an insulator to preserve body heat. They absorb shock, supply essential fatty acids, and carry the fat-soluble vitamins A, D, E, and K.

• The main sources of dietary fat are milk and other dairy products, and meats and alternatives.

• Fats are classified into simple, compound, and derived fats.

Simple Fats

• Simple fats consist of a glyceride molecule linked to one, two, or three units of fatty acids. According to the number of fatty acids attached, simple fats are divided into monoglycerides (one fatty acid), diglycerides (two fatty acids), and triglycerides (three fatty acids).

Compound Fats

Compound fats are a combination of simple fats and other chemicals. Examples are phospholipids, glucolipids, and lipoproteins.

Derived Fats

Derived fats combine simple and compound fats. Sterols are an example. Although sterols contain no fatty acids, they are considered lipids because they do not dissolve in water. The most often mentioned sterol is cholesterol, which is found in many foods and is manufactured from saturated fats in the body.

Proteins

• Proteins are used to build and repair tissues, including muscles, blood, internal organs, skin, hair, nails, and bones.

• Proteins can also be used as a source of energy, but only if not enough carbohydrates are available.

• Proteins are composed of amino acids, containing nitrogen, carbon, hydrogen, and oxygen.

• The primary sources of protein are meats, meat alternates, milk, and other dairy products.

Vitamins

• Vitamins function as antioxidants and as coenzymes (primarily the B complex), which regulate the work of enzymes.

• The body cannot manufacture vitamins; they can be obtained only through a well-balanced diet.

MineralsMinerals serve several important

functions. They are constituents of all cells, especially those in hard parts of the body (bones, nails, teeth); are crucial in maintaining water balance and the acid-base balance; are essential components of respiratory pigments, enzymes, and enzyme systems; and regulate muscular and nervous tissue excitability.

Water

Water, the most important nutrient, is involved in almost every vital body process. Water is used in digesting and absorbing food, in the circulatory process, in removing waste products, in building and rebuilding cells, and in transporting other nutrients.

• Water is contained in almost all foods, but primarily in liquid foods, fruits, and vegetables.

• For decades the recommendation was to consume at least eight cups of water per day.

The Institute of Medicine of the National Academy of Sciences (NAS) has indicated that people are getting enough water from the liquids (milk, juices, sodas, coffee) and the moisture content of solid foods.

To be continued…

Credits

• Fitness and Wellness (Pages 119-142) Cengage Textbook