What Are Carbohydrates?

Carbohydrates are the primary source of energy for the cells in the body, especially the nervous system and red blood cells.  The brain alone uses a minimum of approximately 100 grams (400 calories) of carbohydrates daily.  Anyone who has gone on a low carbohydrate diet and experienced “brain fog,” knows that the brain does not like to be without carbohydrates for energy.  While the body can utilize fats for energy, and protein in cases of starvation, it prefers carbohydrates.  The simplest forms of carbohydrates are sugars.  The more complex forms are starches.

Simple SugarsLet’s start with the simple sugars.  The simplest monosaccharides (mono- means one, saccharide mean sugar) are glucose, fructose and galactose.  Glucose is the form of energy that the body uses.  When you have blood drawn, they measure blood glucose levels.  Fructose is the sugar found in fruits.  Galactose isn’t normally found in foods by itself – it’s usually combined with another sugar molecule to make another form of sugar.  The disaccharides (di- means two) includes sucrose, lactose and maltose.  Sucrose is common table sugar.  Lactose is the sugar found in milk and milk products.  Maltose is composed of two glucose molecules linked together.  When you think of “malt” liquor, this brewing process uses maltose.  As you can see by now, any compound that ends in -ose is a sugar.

Complex CarbohydratesLarge complex sugars are called polysaccharides.  They are also referred to as complex carbohydrates.  Polysaccharides can be digestible or indigestible.  The digestible polysaccharides include starches.  Starches can be found in potatoes, beans, breads, pasta, rice and other starchy foods.  Starch is the storage form of energy used by plants.  In humans, our storage form of energy from carbohydrates is glycogen, which contain long, branching chains of glucose.  We store approximately 400 grams (1,200 calories) of glycogen in our muscles and liver.  This storage form is important to provide the body energy for when we sleep, have extended periods between meals, or exercise heavily.

Important for humans are the plant polysaccharides that are mostly indigestible.  We call this dietary fiber, and it’s an important part of any healthy diet.  Humans do not have the ability to break down plant fiber, so this ends up becoming the bulk of stool.  Fiber is pretty easy to see in some foods like celery.  The strings you see in celery?  That’s the fiber.

So, where do we find carbohydrates?  Fruits, vegetables and grains.  Meats and seafood alone do not contain carbohydrates.  Meat dishes can contain carbohydrates if some sort of sauce is added, but the meat by itself does not have sugars.  I mentioned earlier that the sugar lactose is found in milk.  Milk is unique in that it contains protein, carbohydrates and fat.  If you think about it, that makes sense.  Milk is the primary food source for newborns.  So, it makes sense that every nutrient that a baby would need would be found in milk.

Like protein, 1 gram of carbohydrate equals 4 calories of energy.  When protein breaks down, it can break down into the individual amino acids, which can be reused to form another protein molecule.  However, carbohydrates are used for energy.  Glucose can be used immediately or be stored for later energy use in the form of glycogen.  When glucose or glycogen is broken down, the end result is energy, carbon dioxide and water.  There’s nothing left to reuse.  That is why the majority of calories from our diets should contain carbohydrates from fruits, vegetables and grains.

So, how much carbohydrates do we need in a day?  MyPlate has separate recommendations for fruits, vegetables and grains.  For fruits, the recommendations are:

Daily recommendation for fruits*
Children 2-3 years old                                                1 cup
4-8 years old                                                                1 to 1 ½ cups

Girls 9-13 years old                                                     1 ½ cups
14-18 years old                                                            1 ½ cups

Boys 9-13 years old                                                     1 ½ cups
14-18 years old                                                            2 cups

Women 19-30 years old                                             2 cups
31-50 years old                                                           1 ½ cups
51+ years old                                                               1 ½ cups

Men 19-30 years old                                                  2 cups
31-50 years old                                                          2 cups
51+ years old                                                              2 cups

*These amounts are appropriate for individuals who get less than 30 minutes per day of moderate physical activity, beyond normal daily activities. Those who are more physically active may be able to consume more while staying within calorie needs.

According to the USDA, a cup of fruit is defined as, “In general, 1 cup of fruit or 100% fruit juice, or ½ cup of dried fruit can be considered as 1 cup from the Fruit Group.”

For vegetables, the daily recommendations are:

Daily recommendation for vegetables*
Children 2-3 years old                                              1 cup
4-8 years old                                                              1½ cups

Girls 9-13 years old                                                   2 cups
14-18 years old                                                          2½ cups

Boys 9-13 years old                                                   2½ cups
14-18 years old                                                          3 cups

Women 19-30 years old                                           2½ cups
31-50 years old                                                         2½ cups
51+ years old                                                             2 cups

Men 19-30 years old                                                3 cups
31-50 years old                                                        3 cups
51+ years old                                                            2½ cups

* These amounts are appropriate for individuals who get less than 30 minutes per day of moderate physical activity, beyond normal daily activities. Those who are more physically active may be able to consume more while staying within calorie needs.

According to the USDA, one cup of vegetables is defined as, “In general, 1 cup of raw or cooked vegetables or vegetable juice, or 2 cups of raw leafy greens can be considered as 1 cup from the Vegetable Group.”

The daily recommendations for grains are:

 

Daily
recommendation*

Daily minimum amount
of whole grains

Children 2-3 years old 3 ounce equivalents 1 ½ ounce equivalents
4-8 years old 5 ounce equivalents 2 ½ ounce equivalents
Girls 9-13 years old 5 ounce equivalents 3 ounce equivalents
14-18 years old 6 ounce equivalents 3 ounce equivalents
Boys 9-13 years old 6 ounce equivalents 3 ounce equivalents
14-18 years old 8 ounce equivalents 4 ounce equivalents
Women 19-30 years old 6 ounce equivalents 3 ounce equivalents
31-50 years old 6 ounce equivalents 3 ounce equivalents
51+ years old 5 ounce equivalents 3 ounce equivalents
Men 19-30 years old 8 ounce equivalents 4 ounce equivalents
31-50 years old 7 ounce equivalents 3 ½ ounce equivalents
51+ years old 6 ounce equivalents 3 ounce equivalents

* These amounts are appropriate for individuals who get less than 30 minutes per day of moderate physical activity, beyond normal daily activities. Those who are more physically active may be able to consume more while staying within calorie needs.

According to the USDA, an ounce equivalent is defined as, “In general, 1 slice of bread, 1 cup of ready-to-eat cereal, or ½ cup of cooked rice, cooked pasta, or cooked cereal can be considered as 1 ounce equivalent from the Grains Group.”  Notice that there is a separate recommendation for whole grains.   The USDA recommends that half of your grain intake should come from whole grains.

So, that’s it for today on carbohydrates.  We covered a lot of material and I know that a lot of this was rather dry.  Unfortunately, we all need to know the basics before we get into the fun stuff.  We’ll talk more about carbohydrates on Wednesday and this will be more interesting material.

Until then, remember that… there are no excuses when it comes to your health!

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3 thoughts on “What Are Carbohydrates?

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