Carbohydrates and Fibre

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Carbohydrates are macronutrients. The others being proteins and fats. The main role of carbohydrates (carbs) in our bodies is to make glucose which is the fuel that gives us energy and keeps everything going. Carbs also provide more than 60 percent of the amount of energy required by the body. This energy is mostly used for normal body functions such as heartbeat, digestion, breathing and body movement.

All carbohydrates are formed from sugar molecules. Although most body cells use a combination of fat and carbohydrates, the brain is only able to use carbohydrates. So, this could explain one of the reasons why people on low carbohydrate diets may struggle to cope.

Carbohydrates are commonly divided into two groups:

1) Simple carbohydrates (sugars) e.g. fruits, jams, sweets soda and packaged cereals.
2) Complex carbohydrates (starches), e.g. bread, potato and pasta.

There is another form of complex carbohydrate, which is fibre. This is the indigestible part of starch which is found in vegetables, fruits and grains.

  1. Simple carbohydrates are simple sugars which have a chemical structure of one or two sugars. Simple carbohydrates are digested by the body quickly, because of this simple chemical structure. Therefore it is advised that their consumption be in small quantities, or not at all in the case of diabetics. Monosaccharides are those types of simple carbohydrates which consist of only one sugar e.g. fructose and glucose. Disaccharides consist of two linked monosaccharides and examples include lactose, maltose and sucrose.
  2. Complex Carbohydrates refer to the linkage of anywhere between ten and many thousands of simple sugar molecules. These sugars are mostly rich in fibre, vitamins and minerals. They take longer to digest, they don’t raise the blood sugar levels as quickly as simple carbohydrates, and they contribute significantly to energy production. Starch is the most common complex carbohydrate.

While carbohydrates are commonly classed into either simple or complex carbohydrates, they can also be categorised as refined or unrefined carbohydrates.

Refined carbohydrates (simple) are ones where they have been altered from their original form. Properties may have been removed and manufactured elements added such as colourings and preservatives. These are still a good source of energy, but with being refined they have had vital elements removed such as dietary fibre, vitamins and minerals. Because they have a high GI, they also produce a faster insulin response, raising blood sugar levels. Examples of refined carbohydrates include:-

• White bread, white rice and pasta made from white flour
• Cakes, biscuits and pastries
• Crisps, sugar, honey
• Fruit juice concentrates

Unrefined carbohydrates (complex) are ones where they have been altered little from their original form; they are still mainly in their natural state. These are a good source of energy, and they are a good source of dietary fibre, vitamins and minerals. They have a lower GI; they give a slower sustained insulin response, and are generally better for our health. Examples of unrefined carbohydrates include:-

• Wholemeal bread, whole grain rice, and whole grain products
• Fresh, frozen and tinned vegetables
• Sweet potatoes
• Pulses (e.g. lentils, beans, peas, soybeans )

There are two main types of fibre, insoluble and soluble and there are many different versions of each type, all of which have slightly different beneficial effects. It is recommended to get as much variety of fibre as possible in our daily intake by eating a wide variety of foods.

Insoluble Fibre

Insoluble fibres hold water in the digestive tract thus increasing bulk. This “bulk” helps the removal of waste from the body and thus aids in the prevention of illnesses such as Constipation, Haemorrhoids and Diverticulitis.

Where do you get Insoluble Fibre from? It is normally found in the outer protective layer of plants and also in unrefined wheat, oats, pulses, rice, wholegrain bread and many fruits and vegetable skins.

Soluble fibre

Soluble fibre contains gums and pectin. This type of fibre helps to lower cholesterol levels and controls blood sugar. It can be found in all fruit and vegetables.

Where are the best sources of soluble fibre? The best sources are said to be apples, prunes, barley, citrus, vegetables, oats, pears and strawberries.

The current recommended intake of fibre is 18g per day. With the average person in the Western world only taking in around 12g per day, we should look to ensure we consume enough fibre. It is worth noting that because fibres slow the entry of carbohydrates / glucose into the blood stream and provide increased bulk to our food, without increasing calories, they are a good weight management source. But too much fibre can have the negative effect of increasing the rate at which food goes through the gut resulting in the decrease of absorption of essential nutrients. Therefore stick to the recommended intake, and only aim for a 5g increase over a three to five day period, and keep drinking plenty of water for it to be effective.

Summary

Unfortunately carbs have become a dirty word in recent times especially due to the popularity of low-carb diets such as the Atkins or Dukan diets. What people should know is that carbohydrates are such a broad category, and as per above information, not all carbs are bad.

Carbs are important to our health because in a healthy balanced diet, they are the body’s main source of energy, High fibre and slow release carbs (low GI) help regulate sugar levels in the blood.

As per previous reference in The Food Groups, to the eatwell plate, we should look to make sure our diets are made up of a third of starchy foods. Those starchy food should be preferably wholegrain varieties, low GI, which as emphasised above provide a wider range of nutrients (such as vitamins and minerals), fibre to help keep our bowels healthy and can help us to feel fuller for longer reducing the temptation to overeat.

Next to The Glycaemic Index