Fatty Acids – An Overview

Fatty acids are part oflipid class, with variations found in nature, food, organisms, microorganisms, and are a significant element of the cell membranes. They have important biological, structural, and operational functions, and also, they are very important fuel and storage houses of energy for many cells.

Fatty acids are the building blocks of fats(lipids) in our bodies. The fats we consume in our food, break down by our body, during digestion, and are converted into essential fatty acids, which could subsequently be absorbed by our bloodstream.

Definition of fatty acids

Fatty acids are carboxylic acids with hydrocarbon chains (–CH2–CH2–CH2–) and represented by a chemical formula R-COOH, where R means hydrocarbon chain.

Nature of Fatty acids

The fatty acids are amphipathic in character, i.e. each has hydrophilic (water loving) COOH and hydrophobic (water hating) hydrocarbon chain groups in the arrangement.

(Amphipathic: Molecules having both hydrophilic and hydrophobic ends.)

Fatty acids usually are not present in their standalone form, but instead exist as three chief types of esters: triglycerides (glycerol and three fatty acids), phospholipids (fatty acids with a phosphate group and -OH group), and cholesteryl esters.

General structure of fatty acids

Fatty acids are comprised of chemical groups which produce polar “heads” and non-polar “tails” The polar heads are either hydrophilic, or soluble in water, whereas the nonpolar tails are hydrophobic, or insoluble in water.

Molecules of fatty acids spontaneously form aggregate structures like lipid bilayers in cell membranes, making use of their hydrophilic ends oriented toward the water along with their hydrophobic ends protected from the water.

Classification of fatty acids

Fatty Acids are classified into four major categories:

1. Straight chain
2. Branched chain
3. Substituted fatty acids
4. Cyclic fatty acids

Straight-chain Fatty Acids

Fatty acids, where the carbons are organized linearly.

These are subclassified into 2 categories:

1. Saturated fatty acids
2. Unsaturated fatty acids.
3. Saturated fatty acids

No dual bond is present in the hydrocarbon series of Fatty Acids

Further categorized as

1. Even carbon acids carry an even number of carbons
2. Odd carbon acids carry an odd number of carbons
3. Unsaturated fatty acids

contain double bonds in their hydrocarbon chains.

further simplified as

1. Monoenoic or monounsaturated fatty acid

fatty acids that carry a single double bond in the molecule, image

1. Polyenoic or polyunsaturated fatty acid

have two (Dienoic), three (Trienoic), or four double bonds (Tetraenoic).

Branched Chain Fatty Acids

Chains of fatty acids have branches. These are less abundant in nature.

example: Isovaleric acid

Substituted Fatty Acids

In substituted fatty acids one or more hydrogen atoms have been replaced by another group.

example: Cerebronic acid and oxynervonic acids of brain glycolipids

 

Cyclic Fatty Acids

Fatty acids bearing cyclic groups are called cyclic. Present in some bacteria and seed lipids.

example: hydnocarpic acid of chaulmoogra seed.

Numbering of Fatty-acid Carbon Atoms

Most commonly occurring fatty acids possess a straight chain of carbon atoms, with a carboxyl group (–COOH) at one end, and a R group (–CH3) at the opposite end. Carbon atoms2 and 3 are usually known as α along with βrespectively. The counting generally begins at the −COOH end.

Essential fatty acids

Essential fatty acids, which are needed for optimal health of human and can’t be synthesized by the human body and needs to be supplied from the diet are called essential fatty acids.

They are polyunsaturated fatty acids, namely linoleic acid, and linolenic acid. Arachidonic acid can be synthesized from linoleic acid. Therefore, in deficiency of linoleic acid, arachidonic acid also becomes essential fatty acids. Humans lack the enzymes to introduce double bonds at carbon atoms beyond C9 in the fatty acid chain. Hence, humans cannot synthesize linoleic acid and linolenic acid having double bonds beyond C9. Therefore, linoleic and linolenic are crucial fatty acids.

Functions of Essential Fatty Acids (EFA)

Synthesis of Eicosanoids

Linoleic acid and linolenic acid supplied by the diet are the precursors for the synthesis of a variety of other unsaturated fatty acids. Arachidonic acid, a fatty acid derived from linoleic acid is an essential precursor of eicosanoids, which include:

• Prostaglandins
• Thromboxane
• Prostacyclin
• Leukotrienes.

(Eicosanoids are indicating molecules made from Arachidonic acid. Their primary role is mounting or preventing inflammation, allergies symptoms, fever along with other immune reactions.)

Maintenance of Structural Integrity

Essential fatty acids are needed for tissue and membrane structure and function. These essential fatty acids are vital elements of phospholipids in the cell membrane and assist to maintain the structural integrity of membranes.

Development of Retina and Brain

Docosahexaenoic acid which is synthesized from linolenic acid is particularly needed for the development of the brain and retina during the neonatal period (a newborn infant under 28 days of age).

Important functions of fatty acids

1. They function as foundations of phospholipids and glycolipids.
2. Fatty acid derivatives function like hormones, e.g. Prostaglandins.
3. Essential fatty acids out of the diet may influence people’s health conditions. They aren’t just helpful for disease determination but are also exceptionally helpful in establishing a diagnosis of disease.
4. Fatty acids have higher consequences on health and play an essential role in cardiovascular disease prevention.
5. Fatty acids are fuel (energy resources) for many cells and also store energy.

FAQs related to Fatty Acids

1. What are fatty acids?
   • Fatty acids are carboxylic acids with hydrocarbon chains and are a significant component of lipids. They play crucial roles in biological, structural, and operational functions, serving as a major energy source for cells.
2. How are fatty acids related to fats in our bodies?
   • Fatty acids are the building blocks of fats (lipids) in our bodies. The fats we consume in our diet are broken down during digestion and converted into essential fatty acids, which can be absorbed into the bloodstream.
3. What is the general structure of fatty acids?
   • Fatty acids have a carboxylic acid group (COOH) and a hydrocarbon chain (–CH2–CH2–CH2–). They are amphipathic molecules, meaning they have both hydrophilic (water-loving) and hydrophobic (water-hating) regions.
4. How are fatty acids classified?
   • Fatty acids are classified into four major categories: straight chain, branched chain, substituted fatty acids, and cyclic fatty acids. Straight-chain fatty acids further categorize into saturated and unsaturated fatty acids.
5. What is the difference between saturated and unsaturated fatty acids?
   • Saturated fatty acids have no double bonds in their hydrocarbon chains, while unsaturated fatty acids contain double bonds. Unsaturated fatty acids are further classified into monoenoic (monounsaturated) and polyenoic (polyunsaturated) based on the number of double bonds.
6. What are essential fatty acids, and why are they important?
   • Essential fatty acids, such as linoleic acid and linolenic acid, are crucial for optimal human health. They cannot be synthesized by the body and must be obtained from the diet. They play roles in the synthesis of eicosanoids, maintenance of structural integrity, and the development of the brain and retina.
7. What are the functions of essential fatty acids (EFA)?
   • Essential fatty acids serve various functions, including the synthesis of eicosanoids (prostaglandins, thromboxane, prostacyclin, leukotrienes), maintenance of structural integrity in tissues and membranes, and the development of the brain and retina during the neonatal period.
8. How do fatty acids impact health?
   • Fatty acids function as the foundation of phospholipids and glycolipids, act as precursors for hormone-like molecules (e.g., prostaglandins), and have significant consequences on cardiovascular health. They serve as both fuel and energy storage for many cells in the body.

Summary

Fatty acids, essential components of lipids, contribute to the structural and functional aspects of cell membranes. They are categorized into straight-chain, branched-chain, substituted, and cyclic types, with straight-chain fatty acids further classified into saturated and unsaturated varieties.

The essential fatty acids, linoleic acid, and linolenic acid, play crucial roles in health, serving as precursors for eicosanoids and contributing to the structural integrity of tissues, particularly in the development of the brain and retina during the neonatal period. The text also highlights the amphipathic nature of fatty acids and their existence in various ester forms.

Additionally, the summary outlines the impact of essential fatty acids on health, including their role as foundations for phospholipids, their function in hormone synthesis (e.g., prostaglandins), and their significance in cardiovascular health.

The comprehensive understanding of fatty acids presented in the text underscores their importance as both energy sources and storage for cells, shedding light on their diverse functions in maintaining overall well-being.