Introduction
Carbohydrates, along with fats and protein, provide 100% energy to all cells in the body and are the fastest when it comes to supplying energy. [1,4] It is usually in the form of either starch or sugars in plant based foods.
The amount of energy in 1 gram differs though 4 calories in 1 g of carbohydrates and proteins, and 9 calories in a gram of fats.
It is classified into oligosaccharides, polysaccharides (starch form), monosaccharides, disaccharides (sugar form) and sugar alcohols based on the number of sugar units. [1]
The different naturally occurring sugar forms include glucose, galactose, fructose, sucrose, lactose, maltose, and trehalose [1].
Added sugars and syrups are different from naturally occurring sugars in foods and include white sugar, brown sugar, raw sugar, corn syrup, maple syrup etc. It is usually found in processed foods like soft drinks, cakes, cookies, pies, fruit, fruit punch, dairy desserts, and candy.
However, most carbohydrates occur as starches in food and are found abundantly in certain vegetables, grains, legumes etc.
Two metrics have been developed in order to rank dietary carbohydrates food sources based on their impact on the blood sugar levels in the body:- Glycemic Index (GI) and Glycemic Load (GL). [1,3] Usually, processed foods tend to have a high GI and GL.
Also, the brain is the only true carbohydrate-dependent organ and the minimum carbohydrate requirements are determined by the brain’s requirement for glucose. [2]
- The two digestible carbohydrates, starches and sugars, are broken down into their most elementary form, glucose, along the gastrointestinal tract and is used for energy. [3,6]
- The blood sugar levels rise as carbohydrates are consumed-, signalling the pancreas to secrete insulin. [2,6]
- Insulin, in turn, signals the body’s cells to absorb the glucose for energy or for storage. [6]
- The factors that influence GI are the carbohydrate type and physical determinants of the rate of digestion.
- Also, a low carbohydrate diet, at an intake of less than 50 g for a prolonged period, leads to the production of ketosis, however, an intake of 50 to 100 g per day is sufficient to avoid ketosis. [2,3]
- Storage capacity is approximately around 500 – 1000 g in adults of which 300 to 400g can be stored in the muscles [3,5].
- Also, daily carbohydrate intake corresponds to about 50–100% of the carbohydrate stores in the body compared with about 1% for protein and fat. [5]
- This means that excess carbohydrate intake cannot be the basis of weight gain because of the limited storage capacity, possibly. [5]
- Furthermore, compared to protein, carbohydrate conversion to fats occurs only under extreme conditions. [5]
- Glycogen is present in the muscles and liver for storage, and utilisation of blood glucose levels. [2]
- The undigested carbohydrates reach the colon and are eliminated in stools.
- Dietary fibre is one of the carbohydrates which humans cannot digest and is the most commonly excreted type of carbohydrate. [3]
Body Functions
Recommended Daily Intake
Deficiency Symptoms
Carbohydrate Food Sources
Excessive Intake/ Toxicity Side Effects
Carbohydrate Interaction With Other Nutrients
Nutrient Profiles For Food Groups
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