Friday, March 5, 2010

What are Carbohydrates

What are carbohydrates? In our culture, carbohydrates are considered malign nutrients. They are, however, nutritional powerhouses, and our bodies have many mechanisms for coping with having inadequate amounts of them. They are central to our human physiology. First and foremost, carbohydrate is the exclusive fuel of your brain and the first choice for exercising muscle.

Let’s review a little of the history of our food supply. Back in the early 1900’s, we ate a lot of carbohydrate, about 500 grams per day. A slice of bread is 15 grams of carbohydrate, so, you may note that 500 grams is a lot! I'm sure that back then people were more physically active. Whole grains dominated the carbohydrate supply. It was from whole wheat bread, brown rice and whole oats that those carbohydrates came.

There was a steady decline of whole grains until the early 1960’s. They were essentially disappearing from the American dinner plate. Why was that the case? We began refining carbohydrates. “Refining” means to take away outer bran layer. This began in the 1940’s.

In the 1960’s, we started to see total carbohydrate consumption to rise again. Instead of whole grain, however, we began to eat highly processed sweetened foods. Since the early 1900’s the consumption of sweeteners has increased substantially.

This shift in the American food landscape has been associated with the development of some chronic diseases, most notably type 2 diabetes. Is it the carbohydrate or is it the form of it?

What are Carbohydrates? Simple and Complex Ones

Let’s get to some carbohydrate basics. What are carbohydrates? Carbohydrates are made up of three elements: carbon, hydrogen and oxygen. Carbohydrates in foods exist in multiple forms, from the most simple to the more complex. How they are categorized depends on how many glucose or sugar units are contained within it.

What are the simple carbohydrates? These are termed simple sugars or monosaccharides. On your food label they are going to be listed sugars. The most important monosaccharides in human nutrition are glucose, lactose and fructose. Most monosaccharides don’t exist in simple form in food. It’s the disaccharides that are found in food, they are: sucrose (table sugar), maltose (malt sugar) and lactose (milk sugar).

If you look at a carton of milk it would tell you that each serving of milk has 12 grams of sugar. That is not sugar added by the manufacturer, but the sugar of the milk itself: lactose. These disaccharides are two monosaccharides stuck together.

Complex Carbohydrates

Complex carbohydrates are known as Polysaccharides. Poly means many (20 or more sugar units stuck together). Given the length of the compound, it takes longer physiologically to break those molecules down into their component parts. The carbohydrates that go to your blood have to be in a monosaccharide form. The digestion of that long complex carbohydrate takes a longer time.

Breads, cereals and fruits are mostly complex carbohydrates. Mono and disaccharides are also found in these foods in less amounts. The carbohydrate content of a slice of white bread and a slice of whole grain bread are actually the same. The content is the same, but they behave differently. Keep in mind also that not all the nutrients that are lost in the refining of that grain are replaced. The two that stand out are fiber and magnesium. We can look at big public health surveys that suggest that more magnesium in your diet, the less type 2 diabetes you have.

What are the functions of carbohydrates? The primary function of carbohydrate is to serve as an energy source. It is the high-octane fuel that your body prefers for your brain. It has 4 calories a gram. Fat is also a valuable supply of energy, but carbohydrate is needed to burn that fat completely. In the absence of carbohydrate, breakdown of fat is incomplete and so-called ketone bodies are formed. Ketones are like the waste products of an inefficient car engine. They cause nausea, stomachache and other awful things.

An often forgotten role of carbohydrate it’s protein sparing. Carbohydrates spare protein so it can do its own unique function. Carbohydrates protect or bodyguard protein. It protects it so it can build and repair tissue. When there is inadequate energy in the form of carbohydrate, some protein would be broken down to satisfy the energy need for basal metabolic rate.

Why is protein broken down and not fat? Because protein can serve as a source of carbohydrate. Protein can be sent to the liver and turned into carbohydrate if your intake is too low. I’m really serious when I say that your body needs carbohydrates for optimal functioning. In the absence of them, your body has a default plan: to send that valuable lean mass to the liver to turn it into carbohydrate.

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