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What are lipids? – Structure, Types, Origin, Role and FAQ’s

Jul 9, 2022

What are lipids?

You might have seen oil or butter floating on water. It doesn’t dissolve in water and does not even mix with it. If you have seen this in real life, then you will be able to understand the topic – what are lipids? 

A topic in biochemistry and biology, lipids are macromolecules insoluble in water. However, they are soluble in nonpolar solvents made with hydrocarbons. They store a lot of energy. They are sometimes used as a synonym for ‘fats’. However, fats are a subgroup of a type of lipids. Some of the examples are vitamins A, D, E, and K, waxes, fats, oils, hormones, and cell membranes that are not made up of proteins. 


After understanding what is a lipid, it’s time to understand its types, where they come from and what is its role. 

Types of lipids 

They are present in three types:

  • Phospholipids: They make up the outermost layer of cells in humans and animals. Phospholipids create a thick-coated protective layer around the cells to maintain them. In the autoimmune disorder, also called antiphospholipid syndrome, proteins on lipids are attacked, resulting in the damage of the protective layer. 
  • Sterols: They are a type of hormone belonging to the subset of steroids. You might have heard the term – cholesterol. It is the primary sterol that makes up the body. Plant sterols are beneficial to the body and are found in various foods, such as soya, sunflower oil, etc., to produce a fit body. Several hormones and Vitamin D are produced because of cholesterol. Sterols also produce bile salts working on fats so cells can absorb them. High-density cholesterol is good for health as it absorbs and brings it back to the liver. On the other hand, low-density cholesterol is bad for health that accumulates in the body, blocking arteries and increasing the risk of heart failure.
  • Triglycerides: They are the fats and oils commonly found in every food. These are the major constituents of both saturated and unsaturated parts. Omega fatty acids are a type of triglyceride essential for the body because of their nutritional properties. They are proven to reduce blood pressure, bad triglyceride levels and inflammation. Food items rich in omega fatty acids are tuna and salmon. Including them in your diet can reduce the risk of a heart attack and prevent clotting inside the body.

If you have been consuming canned food items, then after learning about what is a lipid, you must stop it right away. Canned food items contain trans fats, which are artificially hydrogenated to get the desired texture of food items. Consuming these foods can increase bad cholesterol in the body. Hence, try to avoid these for a good and healthy body.

Origin of lipids

What are lipids – this phrase is easy to grasp. Easier is to learn about where they come from. Carbohydrates break down to release energy in the human body. Excess carbs are converted into triglycerides. The synthesis of fatty acids does it from acetyl-CoA by the phenomenon called lipogenesis. That takes place in the endoplasmic reticulum. 


In multicellular organisms, like animals and fungi, these processes are handled by a single multi-functional protein. On the other hand, bacteria utilise multiple separate enzymes to do so. Various unsaturated fatty acids cannot be synthesised by mammalian cells. Therefore, it becomes necessary to consume omega-3 fatty acids as a part of the diet. 

Do you know?


Acetyl-CoA is responsible for producing multiple isoprenoids by getting involved in the mevalonate pathway. These isoprenoids include crucial lipids such as steroid hormones and cholesterol. 

Role of lipids 

They are made up of a reduced form of hydrocarbons. When hydrocarbons metabolise, they get oxidised to release ample amounts of energy. That way, they become an enormous source of energy storage. The major responsible for this are triglycerides found in fat cells. They are an ester that is created from three fatty acids and glycerol. 


This play a crucial role in the human body, from structural components of cell membranes to storing energy. Not only in the living organism but they are also used in the world of cosmetics, food industries and nanotechnology. 


After exploring what is a lipid, it is significant to witness its importance and usage in daily life. Though they make up the body and are needed by the cells to perform regular functions, heavy intake of lipids can harm life. Too many lipids in the body can cause heart-related issues and increase the risk of liver failure. Low-density lipoprotein can clog the arteries, leading to a heart stroke or attack. If you have heard the term ‘bad cholesterol, then you should know that they are a form of lipids, particularly saturated lipids.


They consume more cholesterol and diminish the number of receptors to remove low-density cholesterol from the human blood. Therefore, being aware and consuming them carefully should be done if you want a healthy and long life. 

Frequently Asked Questions on Lipids

1. What are the types of lipids?

A.They are of three types – sterols, phospholipids and triglycerides. Sterols do not contain any fatty acids. They possess ring-shaped structures, like a chicken wire mesh. They are interlinked; thus, they produce complex molecules. The best example of sterol is cholesterol. It is present in abundance in the body. Next are phospholipids. They are found in both plants and animals.


They are synthesised in the human body, so there is no need to consume them. Phospholipids have only two fatty acid molecules that are attached to glycerol. The third one is bonded to the phosphate group. Last and most important is triglyceride. The main and major form of lipids is triglycerides. They make up more than 95% of the diet because they are found in most fatty foods. 

2. What food contains lipids?

A. Two kinds of food contain lipids – good and bad. Good food contains lipids, which are healthy for the human body. In contrast, bad food is what you should avoid living a healthy life. Good foods that contain avocados, seeds, nuts, plant-based oils, eggs, and many more. Bad foods that contain fatty fish, meat, full-fat dairy, and more. You should not completely avoid consuming bad lipid food items. You can control the diet and amount of intake. Having proper food with good lipids is a must. If you have been consuming a bad lipid diet, it’s time to cut down now. 

3. Are lipids good for health?

A. They offer large amounts of storage for energy. You don’t have to consume large amounts of meat or dairy products to meet the minimum requirement of lipids daily. Fats add flavour to foods and help in preparing drooling dishes. It also satisfies hunger and gives fullness to the stomach. They also add texture to the food, making them appealing to others.

In the human body, they control temperature, keeping it constant. If you know what are lipids, then you must know that they are a key to brain structure and function. They help nerves to send signals to the brain. Moreover, they provide warmth in the cold season as the blanket layer of subcutaneous fat covers the body and keeps it warm under extremely cold temperatures. 

4. What are lipids made up of?

A. Fatty acids are nothing but long chains of hydrocarbons. In chemical terms, they contain an even number of carbon atoms, usually 12 to 24 carbons long. They are found abundantly in the cell membrane. The main framework comprises a glycerol backbone, a phosphate group and two fatty acid tails. The phosphate group is hydrophilic in nature, and the two fatty acid tails are hydrophobic.

The hydrophilic part faces outward compared to the hydrophobic part, which faces inward. This way, the cell membranes manage the entry and exit of the cell. Most of them are made up of a similar structure that gives special arrangements. 

 5. Why are lipids important? 

A. They form a major part of the human body. They are present in diverse groups that have different functions. From the smallest structure, cholesterol and phospholipids are the primary membranes that distinguish a cell from its environment. Steroid hormones, made from lipid-derived constituents, make important chemical messengers, including estrogen and testosterone.

To understand their significance of them at the micro and medium level, it is important to learn what are lipids, what they do and how they perform. At the biggest level, triglycerides come into the picture. They are stored in adipose tissues, providing thermal insulation to the body. 

6. How are lipids used in industries? 

They have been used in industries for ages. If you are aware of what are lipids, then you might know that plant-based lipids are used in industries to produce hydrocarbon-like aromatic compounds, such as waxes, terpenes, carotenoids, and sterols. They are produced with the help of glycerophospholipids and triacylglycerides. They are the most widely used compounds in domestic crops, such as soybean, canola, and corn.

With the help of crystallisation and other separation methods, they are separated so they can be used in coatings, paintings, printing inks, leather processing, solvents, surfactants, cosmetics/pharmaceuticals, pesticide/herbicides, fuels, polymers, and lubricants. In the future, lipids-based products will be expected to replace petroleum-based products like fuels and plastics.



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