About carbohydrates
Carbohydrates are also called saccharides, which can be divided into four groups:
- Monosaccharides
- Disaccharides
- Oligosaccharides
- Polysaccharides
Monosaccharides and disaccharides are sugars, which are the smallest carbohydrates. Even though they are called sugars, only some have a sweet taste.
Nutritionists often refer to carbohydrates as either simple or complex. However, it is important to keep in mind that the exact distinction between these groups can be ambiguous.
Simple carbohydrates
1. Monosaccharides
Monosaccharides are the simplest form of sugar and the most basic units of carbohydrates. Examples of monosaccharides are glucose and fructose (fruit sugar). Monosaccharides, especially glucose, are the major fuel sources for metabolism, providing us with energy. They are also the building blocks of all the other saccharides.
Fun fact: Besides fruit, fructose can also be found in semen. It is produced by the seminal vesicles, and it serves as the energy source that allows sperm to ‘swim’. Men would be infertile without it.
2. Disaccharides
Disaccharides are sugars which are formed when two monosaccharides are joined together. Three common examples are sucrose, which is regular table sugar (cane or beet sugar), lactose (milk sugar), and maltose (malt sugar).
Saccharides are linked together through condensation reactions, and they are broken up through a process called hydrolysis. These are chemical processes that describe removing a water molecule (condensation) or adding a water molecule (hydrolysis).
Complex carbohydrates
3. Oligosaccharides
Oligosaccharides are polymers, which means they consist of a chain of multiple (typically three to ten) monosaccharides. They can have many functions in our body, for example in our cells or in our immune systems.
4. Polysaccharides
Polysaccharides are the most abundant carbohydrate found in food. They are macromolecules, meaning they are long chains of many repeating monosaccharides. Examples include starch, glycogen and cellulose. Their function is usually either structure- or storage-related.
Structure-related:
Cellulose has a structure-related function by providing strength to the cell walls of plants. It is also one of the main components of dietary fibre. Even though this is hard to digest for humans, it has other health benefits, such as enhancing digestion of other nutrients.
Fun fact: Cellulose is the most abundant carbohydrate in nature, and paper and cotton are nearly pure cellulose.
Storage-related:
Starch is used for energy storage in plants, and glycogen is used for energy in animals. When glucose is not immediately needed for energy, it can be converted into these more space-efficient polysaccharides for storage. Later they can be broken down again into glucose for energy. Glycogen is mainly stored in the cells of your liver (5–6%) and your muscles (1–2%). The uterus also stores glycogen during pregnancy to nourish the embryo.
Nutrition
Processed or refined plant-based foods, including sweets, cookies, candy, honey, soft drinks, breads, fruit products, pastas and cereals are relatively high in carbohydrates. Unprocessed plant-based foods, including beans, rice, and fruits are typically low in carbohydrates. Animal-based foods generally have the lowest carbohydrate levels, although milk does contain a high proportion of lactose.
Carbohydrates provide approximately 4 kilocalories of energy per gram (3.87 for simple sugars, and 3.57 to 4.12 for complex carbohydrates). Adults should get 55–75% of their total energy from carbohydrates. Preferably 45–65% should be from whole-grain carbohydrates, and only 10% directly from sugars (simple carbohydrates).
Low-carb diets are not healthy because you are missing out on the health advantages of carbohydrates, such as the intake of dietary fibre. Disadvantages of low-carb diets might include halitosis, headache and constipation. More disadvantages are currently still being researched, such as possible increased risks of osteoporosis and cancer. The only reason these diets work is because you are restricting calorie intake, which you can do in many (much healthier) ways. The ketogenic diet is an extreme form of a low-carb diet. It was developed as a medical diet for treating epilepsy, for which it is still effective. However, through celebrity endorsement it has now become a weight loss diet which carries serious health risks.
In the long term, effective weight loss or maintenance depends on calorie restriction, not the ratio of macronutrients in a diet.
Although low-carb diets do not prevent you from getting type 2 diabetes, they can be useful in managing the disease if you have it (this does not apply to type 1 diabetes). However, it is still recommended for people with diabetes to adopt a generally healthy diet, rather than a diet focused on carbohydrates or other macronutrients.