Understanding Carbohydrates
What are carbohydrates?
All carbohydrates are made up from sugars. There are a number of different types of sugars but in the body all carbohydrate metabolism converts sugar to glucose, our body's preferred energy source. Glucose is the main sugar present in many foods but some contain different sugars, such as fructose in fruit, lactose in milk, as well as others. Most sugars are digested and absorbed and converted to glucose, some cannot be digested, and are called fiber.
There are 3 basic types of carbohydrates:
1. Simple Carbohydrates - also called sugars
Sugars occur naturally in foods. Sugars are also added to foods in many forms. All added sugars, including honey and molasses, contribute primarily energy and taste and have no other significant nutritional advantages. Sugars are made up of simple molecules that are quickly and easily digested into the bloodstream. The sudden surge of energy they produce can be very upsetting for our system. These carbohydrates should be eaten only in small quantities.
Foods high in simple carbohydrates:
Table sugar, syrups, preserves, jelly, ordinary sodas/ soft drinks, sweets, candies and cakes.
Food ingredients high in simple carbohydrates:
Dextrose, fructose, glucose, lactose, maltose, sucrose, fruit juice concentrate, molasses, glucose syrup, honey.
2. Complex carbohydrates - also known as starch
These are made up of 'complex' molecules, so it takes longer for our body to digest them. The slow absorption of sugars provides us with a steady supply of energy and limits the amount of sugar converted into fat and stored. We stay full for longer and our system is not upset.
We should eat about 60% of our calories in the form of complex carbohydrates.
Foods high in complex carbohydrates:
Wholemeal bread, potatoes, pasta, rice (esp. brown), fruits, vegetables, beans and legumes.
Food ingredients high in complex carbohydrates:
Bran, wheatgerm, barley, maize, buckwheat, cornmeal and oatmeal.
3. Very complex carbohydrates - also known as fiber
This type of carbohydrate is a component of plants SO complex that is largely undigested. Nevertheless, it provides bulk, which keeps us feeling full and it has significant health benefits. It helps lower cholesterol, reduces the risk of diabetes and helps combat certain cancers. Dietary fibre, especially from whole grains and legumes, plays a useful role in regulating bowel function, more specifically in the prevention of constipation. There are two types of fibre, soluble and insoluble, that combine together in varying proportions in most fibre-containing foods to form the total fibre content of food. We should eat 25-30 grams of fiber per day.
Foods high in fibre:
Whole grains, bran of wheat and oats, vegetables, fruit and legumes, such as dried beans, peas and lentils.
Why are carbohydrates important?
Carbohydrates are the body's primary source of fuel. The energy can be released quickly and easily to fulfill immediate requirement within cells.
The Nutrition Recommendations for Canadians state that "The Canadian diet should provide 55% of energy as carbohydrate from a variety of sources." Eating patterns that are high in complex carbohydrate and fibre are associated with a lower incidence of heart disease and certain types of cancer. When the Nutrition Recommendations were released, data from 1986 showed that Canadians got approximately 48% of a day's energy from carbohydrate.
The goal to get more of a day's energy from carbohydrate is not to increase overall energy intake but rather to change the source of energy. When a person reduces fat intake there is a significant reduction in energy intake since fat provides twice the energy of either protein or carbohydrate. As fat intake is reduced, the energy should be compensated for by an increase in carbohydrate intake.
Sources:
http://www.anphealthcenter.com/lowfatdiet.html
http://www.weightlossforall.com/carbohydrates.htm
http://www.hc-sc.gc.ca/hpfb-dgpsa/onpp-bppn/food_guide_background_5_e.html