Glucose – a form of carbohydrate, is the main chemical form from which all macronutrients are synthesized. Essentially our body is designed to "run" on glucose.
From before we are born, we are attracted to the taste of carbohydrates – principally their sweetness as it is the main taste acquired in the womb.
Different Kinds of Carbs
Carbohydrates can be divided into two types: simple (monosaccharides) and complex (disaccharides, oligosaccharides, and polysaccharides).
- Monosaccharides – glucose, dextrose, and fructose (e.g. the sugar found in fruit)
- Disaccharides – saccharose/sucrose (table sugar), lactose (milk sugar), maltose (malt sugar)
- Oligosaccharides – found in onions, peas, lentils, cabbage
- Polysaccharides – starchy (potatoes, pasta, rice) and non-starchy (peas, beans, cauliflower, nuts, seeds)
How Do Carbs Work?
Your cells run on glucose, so each and every type of carbohydrate is broken all the way down to glucose before it can be used. Eating glucose itself would immediately raise blood sugar levels while more complex carbs have a slower release (the more complex, the slower).
When glucose levels drop we feel hungry and potentially fatigued, headachy, nervous or lacking in concentration. Complex carbohydrates help maintain a healthy level of blood glucose and the prolonged effect of satiety (not feeling hungry).
The only forms of carbohydrate that cannot be broken down into glucose are indigestible fiber. These are a natural constituent in numerous foods like fruit, vegetables, whole grains, lentils, beans, nuts, and seeds.
Carbs In Children's Diets
Children need plenty of carbs to keep up with the demand for their growing bodies and active lives. For the first 4-6 months of age, this is typically provided by the lactose present in breastmilk or formula. Once they start eating solids, the main source of carbohydrates should be grains, legumes, and vegetables.
Carbs should make up 40% of total daily calorie intake for children under 1 year and 45-60% over 1 year. Added sugars should ideally be kept to a minimum.
Fiber is a type of complex carbohydrate that is resistant to being broken down and absorbed in the small intestine. It arrives in the colon undigested where it may be fermented by the bacteria found there.
There are 2 types of fiber: (1) soluble and insoluble. Soluble fiber (psyllium, pectin, beta-glucan) is found in oats, legumes and some fruit and vegetables. It absorbs water and acts as some kind of gel in the digestive system helping to relieve constipation. Insoluble fiber (cellulose, lignin) can be found in whole grains, bran, fruits and vegetables. It stimulates the colon and kind of a laxative effect.
In general, eating a healthy, well-balanced diet is sufficient to ensure you are getting enough fiber in your diet. The table below breaks it down in more detail, but day-to-day just make sure you eat enough fruit, vegetables, and grains (whole grains!).
|Age (years)||oz / day|
|1 - 3||0.35|
|4 - 6||0.50|
|7 - 10||0.55|
|11 - 14||0.65|
|15 - 17||0.75|
- Gallagher ML. The Nutrients and Their Metabolism. In: Mahan LK, Escott-Stump, S. Krause’s Food & Nutrition Therapy. International Edition, 12e. 2008. pg. 39-143.
- Englyst KN, Liu S, Englyst HN. Nutritional characterization and measurement of dietary carbohydrates. Eur J Clin Nutr 2007;61:19-39.
- Cummings JH, Stephen AM. Carbohydrate terminology and classification. Eur J Clin Nutr 2007;61 Suppl 1:S5-18.
- World Health Organisation. Guideline: sugars intake for adult and children. (World Health Organization, 2015).