Main Difference – Carbohydrates vs Lipids
Macronutrients are the nutrients required in large amounts in the diet. They can be divided into three categories. They are carbohydrates, proteins and lipids. A carbohydrate consists of carbon (C), hydrogen (H), and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water). Carbohydrates are further divided into three groups including monosaccharides, disaccharides, and polysaccharides. Both monosaccharides and disaccharides are water soluble whereas polysaccharides are not soluble in water. In contrast, lipids are a diverse group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E, and K), monoglycerides, diglycerides, triglycerides, phospholipids, and others. All these compounds are not soluble in water. This is the main difference between carbohydrates and lipids. Both carbohydrates and lipids act as the main fuels and energy storage compounds of the human body. The biochemical metabolism of carbohydrates and lipids are closely interconnected, but these macronutrients have different purposes. In this article, let’s discuss the difference between carbohydrates and lipids in terms of their intended uses as well as chemical and physical properties.
What are Carbohydrates
A carbohydrate is a macronutrient consisting of carbon (C), hydrogen (H) and oxygen (O) atoms. Similar to a water molecule, it has a hydrogen–oxygen atom ratio of 2:1 and its empirical formula is Cm(H2O)n. Carbohydrates are also known as hydrates of carbon, and it mainly exists as polyhydroxy aldehydes and ketones. The glycemic index (GI) and glycemic load concepts have been developed to characterize carbohydrate-rich food behavior during human digestion to identify the speed and extent of their effect on blood glucose levels.
What are Lipids
Lipids are macronutrient mainly consisting of carbon (C), hydrogen (H) and oxygen (O) atoms. It is a hydrophobic or small amphiphilic molecule that is not soluble in water. Biological lipids are from two distinct types of biochemical subunits known as ketoacyl and isoprene groups.
Difference Between Carbohydrates and Lipids
The differences between carbohydrates and lipids can be divided into following categories. They are;
Categories and Examples
Carbohydrates: Carbohydrates are categorized into following subgroups;
- Monosaccharides – glucose, fructose, galactose, xylose
- Disaccharides – sucrose, lactose, maltose, trehalose
- Polyols – sorbitol, mannitol
- Oligosaccharides – maltodextrins, raffinose, stachyose, fructo-oligosaccharides
- Polysaccharides – amylose, cellulose, amylopectin, modified starches, hemicellulose, pectins, hydrocolloids
Lipid: Lipids are categorized into following subgroups;
- Fatty acids – arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid
- Glycerophospholipids – phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine
- Sphingolipids – sphingomyelins, cerebrosides, and gangliosides.
- Sterol lipids – testosterone and androsterone
- Prenol lipids – quinones and hydroquinones
- Polyketides – erythromycins, tetracyclines, avermectins
Carbohydrates: 4 calories of energy per gram of energy is generated in the human cells when metabolizing the carbohydrates.
Lipid: 9 calories of energy per gram of energy is generated in the human cells when metabolizing the lipids. Lipids provide more than twice the number of calories compared to carbohydrates.
Carbohydrates: Majority of carbohydrates groups (except polysaccharides) are soluble in water, and they are hydrophilic in nature
Lipid: Lipids are not soluble in water because they are hydrophobic in nature
Digestion and Absorption
Carbohydrates: Digestive enzymes from saliva, pancreas and small intestine act directly on sugars and starches in the foods and break down carbohydrates into simple sugars known as monosaccharides, which are absorbed into the bloodstream for distribution to organs and tissues. Cells absorb the simple sugar with the assistance of the hormone insulin.
Lipid: Lipid has a complex digestive process. The gallbladder releases the bile acid into small intestine after food ingestion and bile contributes to breaking down large lipid globules into microscopic droplets, which are consequently digested by enzymes from the pancreas. Then the lining cells of small intestine absorb the digested fat particles and transported by carrier proteins.
Major Digestive Enzyme
Carbohydrates: The major digestive enzyme is α-amylase.
Lipid: The major digestive enzyme is Lipase.
Primary Functions in the Living Organisms
Carbohydrates: Primary functions of dietary carbohydrates are as follows;
- Providing energy for body organs and tissues
- Creating structural components in animals and plants (e.g. cellulose in plants and chitin in arthropods)
- Synthesis of coenzymes (e.g. ribose in ATP, FAD, and NAD) and the backbone of the genetic molecule known as RNA
- Function in immune system, fertilization, preventing pathogenesis and blood clotting
- Synthesize of carbohydrates from carbon dioxide and water by photosynthesis in plants
Lipid: Primary functions of dietary lipids are as follows;
- Storing energy in the cells
- Facilitating the absorption and distribution of fat-soluble vitamins
- Providing structural stability for cells and cushioning vital organs like kidney, liver,
- Cell signaling mechanisms
- Synthesis of reproduction hormones
Primary functions in industry
Carbohydrates: Primary functions of carbohydrates are as follows;
- The complex carbohydrate starch used as the main ingredient in bakery products, noodles, and pasta production
- Starch is used as a thickening agent in sauces
- Simple carbohydrates, such as sugar used in beverages, candy, jams, and desserts production
Lipid: Primary functions of lipids are as follows;
- Used for cosmetic production
- Wax production
- Used as a lubricant in many industrial applications
- Used for emulsion production
- Cooking oil and spreads production
Natural Food Sources
- Wheat, maize, rice, barley contains starch (polysaccharides)
- Fruits contain fructose and dietary fiber
- Milk contains lactose
- Nuts such as peanuts, cashew nuts, almonds, walnut
- Fruits such as avocado
- Seeds such as sunflower, flax, rapeseed seeds
- legumes (soy)
- Fish and sea foods
- Excess consumption of refined sugars is associated with increased risk of metabolic syndrome, type II diabetes, cancers, cardiovascular diseases and obesity
- Consumption of dietary fiber such as cellulose, hemicellulose, pectins, hydrocolloids can reduce the risk of colon cancers, constipation, type II diabetes, and obesity
- High amount of saturated fats consumption may increase LDL cholesterol and risk of heart disease, and increase risk of type II diabetes and obesity
- Unsaturated fats are associated with various health benefits including the reduction of the risk of cancer development, prevention of cardiovascular disease, platelet aggregation, and hypertension. They have anti-inflammatory properties and lower markers of inflammation in the blood. However, some unsaturated fats have both pro-inflammatory and anti-inflammatory properties.
In conclusion, carbohydrates and lipids are primarily essential macronutrients, and they offer important nutrients to the daily diet. Carbohydrates are considered as a ready source of fuel to cells, whereas lipids can store energy in fat tissue for future use. However, excess consumption of these macronutrients may associate with detrimental health effects.
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