Carbs: A-Z of Nutrients
How much do you need daily?
Carbohydrates should be the body’s main source of energy in a healthy balanced diet, but not all carbohydrates are the same (more on this below). There are three different types of carbohydrates found in food – sugar, starch and fibre. The government published new guidelines in July 2015 recommending that adults should aim for a fibre intake of 30 grams a day.
Visit the A-Z of Nutrients to read about recommended daily doses.
Are we getting enough?
On average, we consume much less fibre than the recommended amount. In 2018, the UK National Diet and Nutrition Survey found that the average intake in adults is 19 grams per day, well below the recommended 30 grams per day.
Why do we need it?
Carbohydrates are essential for good health as they provide us with glucose, which is the main source of energy for the human body and all its cells. They are present in food in the form of sugar (simple carbohydrates), starch and fibre (complex carbohydrates). Fibre is the only type of carbohydrate that cannot be converted to glucose and used as an energy source but it has other important functions.
When people talk about blood sugar levels, it always means the amount of glucose in the blood. As carbohydrates get digested, they release glucose into the bloodstream. Some foods release it faster and some slower. Based on this, a measurement of glucose-release speed has been devised called the ‘glycaemic index’ (GI). Foods that release glucose quickly have a high GI, foods that release it slowly have a low GI and there’s a whole range of foods with a medium GI.
A carbohydrate is a molecule containing carbon, oxygen and hydrogen. Depending on how many of these molecules are bound together, their different types and number, carbohydrates can be either simple or complex. Both simple and complex carbohydrates can be a part of a healthy diet.
Simple carbohydrates (sugars):
- single sugar molecules (monosaccharides) – eg glucose and fructose
- two sugar molecules linked together (disaccharides) – eg table sugar (sucrose, consisting of glucose and fructose) and milk sugar (lactose, consisting of glucose and galactose)
These carbohydrates are digested quickly and we should watch our intake – with the exception of fruit and vegetables. Fruit and vegetables naturally contain fructose, a simple sugar. But if fruit and vegetables are eaten fresh and whole they also supply a wealth of complex carbohydrates along with many other nutrients which slow down the speed of sugar absorption. Fruit and vegetables are among the healthiest foods so there’s no need to limit their intake. They are best eaten raw, lightly cooked or blended in a smoothie (avoid canned). See our wallchart comparing smoothies and fresh juice here.
Beware of fruit juices – unless they are freshly made, they undergo a pasteurisation process which destroys most of the goodness of the fruit and the result can be little more than just sweet water.
Complex carbohydrates (polysaccharides):
consist of many sugar molecules linked together in complex structures. Complex carbohydrates usually mean starch and fibre. The difference is that we can digest starch very well – your body breaks it down to single glucose molecules – whilst we cannot digest fibre.
In terms of starch, it’s naturally a part of many foods (wholegrains, pulses, root vegetables, pumpkins, courgettes etc) which belong in a healthy diet. These foods contain starch along with many other nutrients and your body digests them slower. On the other hand, refined starches used as a binding ingredient in foods such as biscuits, processed snack foods and sweets are extracted from their natural source – a process that strips off all the other nutrients – and are not very healthy because your body can digest them faster which may result in high blood sugar levels.
If you have too much sugar in your blood at any given moment (more than your body’s cells can take up), your body will immediately try to restore the balance by removing some of the sugar and storing it as fat.
The healthiest sources of carbohydrates:
Unprocessed or minimally processed foods such as wholegrains, fruit and vegetables, pulses (lentils, beans, peas) – these release their energy gradually, promote good health by providing vitamins, minerals, fibre, antioxidants and many important phytonutrients.
Unhealthy sources of carbohydrates:
Processed or refined foods such as white bread, pastry, sugary and savoury processed snacks, cakes, sweets, fizzy and sugary drinks (including hot drinks with flavoured syrups) and other processed commercial foods – these contain easily digested carbohydrates that turn to sugar fast and may contribute to weight gain, heart disease, diabetes and some types of cancer. See additional information at the end of this section for more on sugars and sweeteners.
Continue reading about carbohydrates on Viva! website.