Carbohydrates - Their Impact On Health

Comments · 607 Views

In food science and in many informal contexts, the term "carbohydrate" often means any food that is particularly rich in the complex carbohydrate starch (such as cereals, bread and pasta) or simple carbohydrates, such as sugar (found in candy, jams, and desserts).



Examples of foods high in carbohydrates. Pasta (above) and cake.

In food science and in many informal contexts, the term "carbohydrate" often means any food that is particularly rich in the complex carbohydrate starch (such as cereals, bread and pasta) or simple carbohydrates, such as sugar (found in candy, jams, and desserts).

In biochemistry, a carbohydrate is a biological molecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water); in other words, with the empirical formula Cm(H2O)n (where m could be different from n). This formula holds true for monosaccharides. Some exceptions exist; for example, deoxyribose, a sugar component of DNA, has the empirical formula C5H10O4. Carbohydrates are technically hydrates of carbon; structurally it is more accurate to view them as polyhydroxy aldehydes and ketones.

Carbohydrates are one of the main types of nutrients. They are the most important source of energy for the body. Carbohydrates are called simple or complex, depending on their chemical structure. Simple carbohydrates include sugars found naturally in foods such as fruits, vegetables, milk, and milk products. They also include sugars added during food processing and refining. Complex carbohydrates include whole grain breads and cereals, starchy vegetables and legumes. Many of the complex carbohydrates are good sources of fiber.

Carbohydrates are found in a wide variety of foods. The important sources are cereals (wheat, maize, rice etc.), potatoes, sugarcane, fruits, table sugar (sucrose), bread, milk, etc. Starch and sugar are the important carbohydrates in our diet. Starch is abundant in potatoes, maize, rice and other cereals. Sugar appears in our diet mainly as sucrose (table sugar), which is added to drinks and many prepared foods such as jam, biscuits and cakes, and glucose and fructose which occur naturally in many fruits and some vegetables.


Simple carbohydrates e.g. sugar. Complex carbohydrates e.g. starch.

Types Of Carbohydrates

Monosaccharides, also called simple sugars, are the most basic units of carbohydrates. They are fundamental units of carbohydrates and cannot be further hydrolyzed to simpler compounds. They are the simplest form of sugar and are usually colorless, water-soluble, and crystalline solids. Examples of monosaccharides include glucose, fructose, and galactose. Monosaccharides have a sweet taste, fructose being the sweetest and galactose the least sweet.

A disaccharide (also called a double sugar) is the sugar formed when two monosaccharides (simple sugars) are joined by glycosidic linkage. Like monosaccharides, disaccharides are soluble in water. Three common examples are sucrose, lactose, and maltose.


An oligosaccharide is a saccharide polymer containing a small number (typically two to ten) of simple sugars (monosaccharides). Oligosaccharides can have many functions including cell recognition and cell binding. For example, glycolipids have an important role in the immune response.

Polysaccharides are polymeric carbohydrate molecules composed of long chains of monosaccharide units bound together by glycosidic linkages and on hydrolysis give the constituent monosaccharides or oligosaccharides. They range in structure from linear to highly-branched. Examples include storage polysaccharides such as starch and glycogen, and structural polysaccharides such as cellulose and chitin.

Main Function

Energy Foods

Functions Of Carbohydrates

Carbohydrates are one of the major food groups needed for the body to function properly and stay healthy. The primary function of carbohydrates is to act as a fuel source for the body’s energy needs. All types of carbohydrates, whether monosaccharides, disaccharides, oligosaccharides, or polysaccharides, are turned into sugar before they are used by the body for energy. The only exception is fiber which has no nutritional value but rather acts as an aid in the digestion of food.

Carbohydrates perform numerous other roles in living organisms. Polysaccharides serve for the storage of energy (e.g. starch and glycogen) and as structural components (e.g. cellulose in plants). The 5-carbon monosaccharide ribose is an important component of coenzymes (e.g. ATP, FAD and NAD) and the backbone of the genetic molecule known as RNA. The related deoxyribose is a component of DNA. Saccharides and their derivatives include many other important biomolecules that play key roles in the immune system, fertilization, preventing pathogenesis, blood clotting, and development.

Another function of carbohydrates is to prevent the breakdown of proteins for energy. By consuming sufficient amounts of carbohydrates in your diet, you ensure that your body can meet its energy needs, but if your intake of carbohydrates is too low, or you are using them up too quickly, such as during intense exercise, then your body is forced to break down proteins for energy. Protein is kind of like the backup generator when the primary energy source goes out. It's great that the body has this backup system in place, but when proteins are used up for energy, they are no longer available to do their life-sustaining jobs, like helping with muscle contractions and maintaining body tissues.





Carbohydrates are widespread in our food. Exceptions are meat and fish, which have no carbohydrate, but rather pure fats. Plant foods are our primary source of carbohydrate, and some, such as grains, are the most concentrated.

Carbohydrate consumed in food yields 3.87 calories of energy per gram for simple sugars, and 3.57 to 4.12 calories per gram for complex carbohydrate in most other foods. Relatively high levels of carbohydrate are associated with processed foods or refined foods made from plants, including sweets, cookies and candy, table sugar, honey, soft drinks, breads and crackers, jams and fruit products, pastas and breakfast cereals. Lower amounts of carbohydrate are usually associated with unrefined foods, including beans, tubers, rice, and unrefined fruit. Animal-based foods generally have the lowest carbohydrate levels, although milk does contain a high proportion of lactose.

The best source of carbohydrates are unprocessed whole foods, like fresh fruit, 100% juice, whole grains, foods made with whole grains, and many vegetables. These foods also contain fiber, vitamins, minerals and antioxidants. Foods made with refined grains have fewer of these nutrients. Foods loaded with added sugars have few nutrients and can add excess calories.

Foods that are a source of carbohydrates include:
Rice, Barley, Wheat, Couscous, Oats, Rye, Buckwheat, Pasta, Noodles, Cornmeal, Flour, Tortillas, Bulgur, Cereals, Fruit, Dried fruit: dates, raisins, etc., Potatoes, Legumes: white beans, black beans, kidney beans, pinto beans, garbanzo beans, lentils, Quinoa, Sweet potatoes, Winter squash, like butternut and acorn, Carrots and carrot juice, Bread, Bagels, Fruit juice, Sugar, Honey, Agave syrup, Corn syrup, Molasses, Milk, Nuts and nut butters

While vegetables are primarily carbohydrate, most aren’t concentrated carbohydrate, because they have high water content.

Foods made with high carbohydrate ingredients like flour and sugar will typically also be high carbohydrate. Products like muffins, pancakes, cakes and doughnuts, candy, snack foods, crackers, and cookies are high carbohydrate. Beverages sweetened with sugar, honey, agave and corn syrup are also high carbohydrate.

inadequate carbohydrate intake can lead to significant health problems including; low energy, foggy brain, dizziness, and fainting.


Carbohydrates are a common source of energy in living organisms; however, no carbohydrate is an essential nutrient in humans. Humans are able to obtain all of their energy requirement from protein and fats, though the potential for some negative health effects of extreme carbohydrate restriction remains.

If you have ever gone on a low-carb diet and felt like your brain was foggy for a few days, then you experienced just how important carbohydrates are to proper brain function. Our bodies could not function properly without carbohydrates, the brain especially, relies almost entirely on the carbohydrate glucose for its energy needs. If your intake of carbohydrates is inadequate, your body will draw on glycogen stores to give the brain fuel. Once the stores fail, the body begins to break down muscle tissue to make glucose.

In the case of dietary fiber – indigestible carbohydrates which are not a source of energy – inadequate intake can lead to significant health problems. Dietary fiber has many health benefits. It can reduce your risk of heart disease, diabetes and some cancers, and also help weight control. Fiber is also important for digestive health - insoluble fiber bulks up stools and makes waste move through the digestive tract more quickly, which is better for the gut and can help to prevent constipation. Soluble fiber may also help this process by making the stools softer and easier to pass. Some types of fiber can be fermented by gut bacteria, producing substances that appear to be good for gut health. Providing ‘food’ for gut bacteria can also help increase the number of healthy bacteria in the gut.

Soluble fibers such as beta-glucans and pectins, can help reduce blood cholesterol, so eating plenty of foods like oats, fruit, root vegetables and pulses is a good idea, particularly if you know you have a high cholesterol level or other risk factors for heart disease.

Following a diet consisting of very low amounts of daily carbohydrate for several days will usually result in higher levels of blood ketone bodies than an isocaloric diet with similar protein content. This relatively high level of ketone bodies is commonly known as ketosis and is very often confused with the potentially fatal condition often seen in type 1 diabetics known as diabetic ketoacidosis. Somebody suffering ketoacidosis will have much higher levels of blood ketone bodies along with high blood sugar, dehydration and electrolyte imbalance.



Dental caries.


The body uses carbohydrates as its main source of energy. Consuming too many carbohydrates or too much of the wrong type of carbohydrates leads to health problems.

Obesity: Diets containing large amounts of carbohydrates are associated with obesity due to increased caloric intake. Obesity increases the risk of many physical and mental conditions. Health consequences fall into two broad categories: those attributable to the effects of increased fat mass (such as osteoarthritis, obstructive sleep apnea, and social stigmatization) and those due to the increased number of fat cells (diabetes, cancer, cardiovascular disease, non-alcoholic fatty liver disease). Increases in body fat alter the body's response to insulin, potentially leading to insulin resistance. Increased fat also creates a pro-inflammatory state, and a pro-thrombotic state.

Type 2 Diabetes: Consuming too many carbs, especially those with a high glycemic load, can increase your risk of several disorders, including Type 2 diabetes. After you consume a carbohydrate-containing meal and your blood sugar increases, your pancreas releases insulin, which helps convert glucose into a storage compound in your liver, muscles and other tissues. This eventually lowers your blood sugar. Type 2 diabetes develops when your body stops making insulin or you become insensitive to it. According to the Linus Pauling Institute, consuming too many carbs that cause a quick rise in blood glucose puts a high demand on your pancreas for insulin and significantly increases the likelihood of developing Type 2 diabetes.

Cardiovascular Disease: A diet containing too many carbohydrates can raise your blood level of triglycerides, a type of unhealthy fat that travels in your blood. It can also lower your blood levels of high-density lipoprotein, often referred to as good cholesterol, according to the Linus Pauling Institute. High triglyceride levels along with relatively low levels of high-density lipoprotein can significantly raise your risk of heart disease. A high-carbohydrate diet can also have negative effects on your blood vessels. A clinical study published in the "Journal of the American College of Cardiology" showed that, when healthy subjects consumed a high-carbohydrate meal, especially one containing foods with high glycemic loads, their arteries became rapidly enlarged. The researchers concluded that, over time, this effect could damage artery walls and lead to atherosclerosis and other vascular disorders.

Denture caries: Diets with large amounts of carbohydrates in the form of simple sugars can cause denture caries. There is "convincing evidence from human intervention studies, epidemiological studies, animal studies and experimental studies, for an association between the amount and frequency of free sugars intake and dental caries" while other sugars (complex carbohydrate) consumption is normally associated with a lower rate of dental caries. Also, studies have shown that the consumption of sugar and starch have different impacts on oral health with the ingestion of starchy foods and fresh fruit being associated with low levels of dental caries.

Amounts of free sugar intake recommended to be less 10% of total carbohydrate intake by WHO.


Humans typically cannot metabolize all types of carbohydrate to yield energy e.g. fiber. Even though these complex carbohydrates are not very digestible, they represent an important dietary element for humans, called dietary fiber. Fiber enhances digestion, among other benefits.

Based on the effects on risk of heart disease and obesity in otherwise healthy middle-aged adults, the Institute of Medicine recommends that adults get between 45–65% of total dietary energy from whole-grain carbohydrates. The Food and Agriculture Organization and World Health Organization jointly recommend that national dietary guidelines set a goal of 55–75% of total energy to be derived from carbohydrates, but only 10% directly from sugars (the term for simple carbohydrates; monosaccharides and disaccharides).

Nutritionists often refer to carbohydrates as either simple or complex. However, the exact distinction between these groups can be ambiguous. The term complex carbohydrate was first used in the U.S. Senate Select Committee on Nutrition and Human Needs publication Dietary Goals for the United States (1977) where it was intended to distinguish sugars from other carbohydrates (which were perceived to be nutritionally superior). However, the report put "fruit, vegetables and whole-grains" in the complex carbohydrate column, despite the fact that these may contain sugars as well as polysaccharides. This confusion persists as today some nutritionists use the term complex carbohydrate to refer to any sort of digestible saccharide present in a whole food, where fiber, vitamins, and minerals are also found (as opposed to processed carbohydrates, which provide energy but few other nutrients). The standard usage, however, is to classify carbohydrates chemically: simple if they are sugars (monosaccharides and disaccharides) and complex if they are polysaccharides (or oligosaccharides).

In any case, the simple vs. complex chemical distinction has little value for determining the nutritional quality of carbohydrates. Some simple carbohydrates (e.g. fructose) raise blood glucose slowly, while some complex carbohydrates (starches) especially if processed, raise blood sugar rapidly. The speed of digestion is determined by a variety of factors including which other nutrients are consumed with the carbohydrate, how the food is prepared, individual differences in metabolism, and the chemistry of the carbohydrate.

Read more