CARBOHYRATES

 Carbohydrates are the main energy source for the human body.  Chemically carbohydrates are organic molecules in which carbon, hydrogen and oxygen bond together. We break down carbohydrates in the body during the process of metabolism to release energy.  Carbohydrates can be thought of as hydrates of carbon, hence the name.

 There are two types of carbohydrates (carbs), the simple sugars and those carbohydrates that are made of long chains of sugars – the complex carbohydrates. 

All carbohydrates are made up of units of sugar (also called saccharide units).  Carbohydrates that contain only one sugar unit (monosaccharides) or two sugar units (disaccharides) are referred to as simple sugars. They are broken down quickly in the body to release energy.  Two of the most common monosaccharides are glucose and fructose. Both have the same chemical formula, however, they have different structures. 

Examples of simple sugar from foods include:

Fructose (found in fruits)

Galactose (found in milk products)

 

Double sugars include:

Lactose (found in dairy)

Maltose (found in certain vegetables and in beer)

Sucrose (table sugar)

Honey

 

Complex carbohydrates are long chains of simple sugar units bonded together and are referred to as polysaccharides. 

 Complex carbohydrates, often referred to as “starchy” foods and include:

Legumes

Starchy vegetables

Whole-grain breads and cereals.

When the body eats carbs, the body breaks them down into simple sugars which are absorbed into the blood stream.  As the sugar level rises in your body, the pancreas releases a hormone called insulin.  Insulin is needed to move sugar from the blood into the cells where the sugar can be used as a source of energy.

Once absorbed into the bloodstream, the human body distributes glucose to the areas where it is needed for energy or stores it as glycogen for energy. (This process is done fairly quickly within a couple hours after eating. Thus when the diet consists only of simple sugars, one is likely to feel hungry again soon.) If one consumes more glucose than is needed for immediate energy the excess glucose is bonded together to form glycogen molecules.  The body stores the glycogen in the liver and muscle tissue as an “instant” source of energy. When the body has stored all the glycogen that it can, any remainder will be stored as fat. Glycogen is the source of energy most often used for exercise.  It is needed for short, intense bouts of exercise from sprinting to weight lifting because it is immediately accessible.  Glycogen supplies energy during the first few minutes of any sport.

 Complex carbohydrates or polysaccharides have three or more sugars and include starches and fiber.

 When humans eat starch, an enzyme in saliva and in the intestines, amylase, breaks the bonds between the repeating glucose units, thus allowing the sugar to be absorbed into the bloodstream.  Fiber makes it more difficult for the digestive enzymes to break down the starches into glucose. This digestion process takes longer than the metabolism of simple sugars and thus one does not feel hungry as soon. Complex carbohydrates also gives one energy over a longer period of time.  Examples of complex carbohydrates are starchy vegetables, whole grain rice, breads and cereals and legumes such as beans, lentils ad dried peas. 

 Fiber is found in complex carbohydrates – legumes, and whole grain breads and cereals.

Whole grains have a tough, fibrous outer layer called bran that protects the inside of the  kernel.  The interior contains the starchy endosperm. Its job is to protect stored energy for the germ, the seed’s reproductive kernel, which nestles inside the endosperm.  The germ is rich in vitamins, minerals and unsaturated oils.   The invention of the industrial roller mills in the late 19^th century  changed what we got from the grains.  Milling strips away the bran and germ, making the grain easier to chew, easier to digest and easier to keep without refrigeration.  Processing also pulverizes the endosperm, turning it from a small, solid nugget into millions of minuscule particles.   Refining wheat creates fluffy flour that makes light, airy breads and pastries.  But there is a nutritional price to be paid.  The process strips away more than half of wheat’s B vitamins, 90% of the vitamin E, and virtually all of the fiber.  (Enriching the flour does add back some of the vitamins.)

 Fiber is present in all plants that are eaten for food, including fruits, vegetables, grains and legumes.  Fiber is categorized as: soluble – dissolves in water and insoluble that does not dissolve in water.

The more calories you eat each day, the more fiber you need.  Current recommendations suggest that adults consume at least 20 grams of dietary fiber per day and some teens and men may require 30-35 grams per day.

 Another important polysaccharide is cellulose or plant fiber and cannot be digested by humans. It passes through the digestive track without being absorbed into the body and is essential in the diet because it helps exercise the digestive track and keep it clean and healthy. 

 In recent years there has been much discussion about carbohydrates as science gains knowledge about these complex substances.  There are claims that fiber lowers cholesterol, that it helps the body’s natural anticoagulants and helps prevent formation of small blood clots, etc. For all this I will leave it up to scientific research to prove or disprove these claims.  I do know that carbohydrates have received unwarranted attacks in recent years as being “bad”.  I do not think of any wholesome food as being bad or harmful. It is true that some individuals may have a physical disorder and must avoid some foods. It is also true that some individuals eat more of a type of food than they should. However common sense and good nutrition knowledge can allow us to enjoy a variety of delicious foods. Relating to carbohydrates, carbohydrates have a definite function in our human diet and I believe, should be incorporated as recommended.

 The primary function of carbohydrates is to provide energy for the body, including and especially (to be discussed in a future post) for the brain and the nervous system.  An enzyme, amylase, helps break down carbohydrates into glucose (blood sugar) which is used for energy by the body.  Foods in the carbohydrate category contain vitamins and minerals essential to life and the best way to get these essential nutrients is from eating these foods.

 Carbohydrates fill numerous roles such as the transport and storage of energy  (glycogen),  and (to be discussed in future posts) as components of coenzymes (ATP, FAD, and NAD) and the backbone of genetic molecules (RNA and DNA).  Saccarides  and their derivatives include many other important biomolecules that are important in the immune system, fertilization, pathogenesis, blood clotting and development

Tags: carbohydrates, carbs, complex carbohydrates, fiber, polysaccharides, simple sarbohydrates, starch, sugar | Posted in Nutrition