CARBOHYDRATES - What they are and what they do

Carbohydrates are one of three macronutrients – the other two being proteins and fats – that provide the body with building blocks and energy for all bodily functions. Carbohydrates ultimately break down into glucose, commonly referred to as blood sugar. The main function of carbohydrates is to provide energy, especially for the brain, in the form of glucose (the brain’s preferred energy source). Carbohydrates include sugars, starches and other indigestible substances such as fibre. 

Carbohydrates are broken down into two broad groups: simple carbohydrates and complex carbohydrates. From a chemical perspective, simple carbohydrates include sugars, and complex carbohydrates include starches and fibres. From a practical perspective, another way to distinguish between simple and complex carbohydrates is to ask yourself whether or not the food is in its natural form (the form that nature provided it in).  If the answer is ‘yes’, then consider it a complex carbohydrate. 

Examples of complex carbohydrates are vegetables, fruits, legumes and whole grains. Note that many grain products, such as pastas, breads, rice, crackers, cakes and cookies are often made with refined grains as opposed to whole grains. Refined grains have had the vitamin- and mineral-rich bran and germ removed during processing, leaving only the starchy middle of the grain. These refined grain products are then ‘enriched’ with some, but not all, of the nutrients that were lost in processing.

Most canned or bottled juices are also simple carbohydrates. They can be high in sugar (especially fruit juices - even if no sugar is added) and they lack the fibre one would get by eating the fresh fruit or vegetable. In addition, certain vitamins are easily damaged during processing.

Complex carbohydrates are the healthiest source of carbohydrates as they help to prevent blood sugar fluctuations. The fibre content promotes satiety and slows digestion, allowing the body to absorb glucose at a rate that won’t spike insulin and blood sugar levels. Simple carbohydrates cause a rapid spike in blood sugar and while this gives a short ‘energy high’, a crash soon follows.

The amount of carbohydrate that needs to be consumed to meet the average daily minimum amount of glucose used by the brain is 130 grams (4.58 oz); however, daily carbohydrate consumption is typically higher than this in order to meet the energy needs of not just the brain, but the rest of the body. In general, it is recommended that 45% to 65% of dietary calories come from carbohydrates - with the majority coming from complex carbohydrates. Note that 1 gram (0.035 oz) of carbohydrates provides 4 calories.

An excess of simple carbohydrates in our meals and snacks creates a whole host of health issues and promotes weight gain as the excess glucose from carbohydrate metabolism will be stored as fat. An excess of simple carbohydrates puts stress on the pancreas, compromising its ability to secrete both insulin and digestive enzymes. It will most likely also lead to a deficiency in fibre and essential nutrients and will rob the body of many minerals, including calcium and magnesium. 

For these reasons, it is important to ensure carbohydrate consumption is primarily in the form of complex carbohydrates such as vegetables, fruits and whole grains. Strive for 5 to 10 servings of fruits and vegetables, and 2 to 3 servings of whole grains/whole grain products daily.


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