Often when people talk about carbohydrates the obvious choices come to mind such as bread, cereals and pasta. However, there are a few different types of carbohydrates available in our foods – and they are not created equally. In fact, the variety and quantity of carbohydrates that we consume can have an impact on our overall health.
Carbohydrates are found primarily in plant foods and are one of the three necessary macronutrients needed by our bodies to function, along with protein and fat. Dairy products are the only animal foods that contain carbohydrates in the form of lactose. Carbohydrates are crucial as they provide the majority of calories needed for our daily activities.
They are classified according to their chemical structure into three types: simple sugars, starches – otherwise known as complex carbohydrates – and dietary fibre.
Simple carbohydrates are one or two units of sugar bound together that are easily and quickly digested. They can be found in foods that are unrefined such as fruits or milk, but are most often found in highly processed foods that tend to be void or lower in nutritional value. Examples include: white sugar, fructose, maltose, sucrose, honey, molasses, soft drinks and candies.
When eaten these sugars are quickly digested and absorbed into the bloodstream where they can rapidly increase the blood sugar levels. However, if they are eaten unprocessed and in a natural state such as in a piece of fruit that contains fibre and vitamins, the blood sugar level rises at a more gradual pace.
Complex carbohydrates are long-chained glucose units that contain hundreds to thousands of sugar molecules linked together. They provide vitamins and minerals that are needed to sustain health and, like simple carbohydrates, are often paired with fibre as well.
It takes time for your body to break the bonds between the molecules and to digest the starches, meaning blood sugar levels rise at a much slower rate. Starches are found in varying levels in foods such as: green and starchy vegetables, whole grains, legumes, beans and some fruits.
Dietary fibre is another form of complex carbohydrate but unlike the simple or complex starches, our bodies do not have the ability to break the bonds between the sugar molecules and so it passes through our system offering very few calories (if any). However, it does provide a food source for some of the beneficial bacteria in our intestines.
Dietary fibre is found in varying amounts in plant food and consists of two varieties – soluble and insoluble.
Soluble fibre attracts water and forms a gel like substance that slows digestion. This process helps to balance blood sugar and to carry out excess cholesterol and hormones. It can be found in foods such as beans, lentils, oats, barley and apples.
Insoluble fibre has the ability to increase the bulk of stool; act as a brush to sweep the intestines; and to promote regularity. Foods that contain insoluble fibre include wheat bran, whole grains, seeds and the skins of fruit and vegetables.
Ultimately, both simple and complex carbohydrates end up in the blood stream as glucose, which is the body’s main source of energy. However, what differentiates the two digestible forms of carbohydrates is the rate at which they are broken down and converted into glucose (per serving). This is referred to as the glycemic load. The faster that sugar is absorbed into the bloodstream the higher the overall load.
And the glycemic loads can vary quite a bit. For example, all simple sugars and most refined starches (white breads and pastas) are broken down rapidly and therefore have a high glycemic load. When consumed in excess these carbohydrates can disturb blood sugar levels and lead to health problems including diabetes.
Conversely, most complex carbohydrates tend to have a low to medium glycemic load due to their vitamin, minerals and higher fibre content. These “good” carbohydrates eaten in moderation with protein and fat are an important part of a healthy diet.
Sheila Ream, CNP is a certified nutritionist in the Beach. Reach her at firstname.lastname@example.org