The main difference monounsaturated and polyunsaturated fatty acids is that the monounsaturated fatty acids contain only one double bond in the hydrocarbon chain, whereas polyunsaturated fatty acids contain more than one double bond in the hydrocarbon chain. Furthermore, monounsaturated fatty acids lower the LDL-cholesterol and total cholesterol and increase the production of HDL cholesterol, while polyunsaturated fatty acids reduce the serum cholesterol levels and the production of both LDL and HDL cholesterol.
Monounsaturated and polyunsaturated fatty acids are the two types of unsaturated fatty acids with double bonds in the fatty acid chain.
Key Areas Covered
1. What is Monounsaturated Fatty Acid
– Definition, Structure, Importance
2. What is Polyunsaturated Fatty Acid
– Definition, Structure, Importance
3. What are the Similarities Between Monounsaturated and Polyunsaturated Fatty Acids
– Outline of Common Features
4. What is the Difference Between Monounsaturated and Polyunsaturated Fatty Acids
– Comparison of Key Differences
Key Terms
Double Bonds, Essential Fatty Acids, HDL, LDL, Monounsaturated Fatty Acids, Polyunsaturated Fatty Acids, Unsaturated Fatty Acids
What is Monounsaturated Fatty Acid
Monounsaturated fatty acids (MUFAs) are one of the two types of unsaturated fatty acids with a single, double bond in the hydrocarbon chain. However, all other bonds of the hydrocarbon chain are single bonds. Generally, they occur in vegetable oils, including olive, sesame, and canola oil, peanut butter, nuts, such as peanuts and cashews, avocados, olives, sesame seeds, and healthy spreads labelled “high oleic”.
Figure 1: Oleic Acid
Furthermore, the most common monounsaturated fatty acids are palmitoleic acid (16:1 n−7), cis-vaccenic acid (18:1 n−7), and oleic acid (18:1 n−9). Here, the palmitoleic acid contains hydrocarbon chains with 16 carbons. Also, its double bond occurs nine carbons away from the carboxylic group. On the other hand, cis-vaccenic acid contains 18 carbons in the hydrocarbon chain. Oleic acid also contains 18 carbons in its hydrocarbon chain. The double bond of the latter two monounsaturated fatty acids also occurs nine carbons away from the carboxylic group.
What are Polyunsaturated Fatty Acids
Polyunsaturated fatty acids (PUFAs) are the second group of unsaturated fatty acids with more than one double bonds. Along with monounsaturated fatty acids, these fatty acids help to lower bad cholesterol or LDL in the blood. Generally, polyunsaturated fatty acids occur in nuts, seeds, fish, seed oils, and oysters.
Figure 2: Linoleic Acid
Moreover, the two main important types of polyunsaturated fatty acids are the omega-3 (α-linoleic acid) and omega-6 (linoleic acid) fatty acids. Their importance is due to our body’s inability to synthesize them through regular metabolic reactions. The main sources of linoleic acid are nuts and fatty seeds like poppy, sesame, hemp, and flaxseed, while the main sources of α-linoleic acid are walnuts, seeds like chia, hemp, and flaxseed, and vegetable oils.
Similarities Between Monounsaturated and Polyunsaturated Fatty Acids
- Both are unsaturated fatty acids having double bonds in the hydrocarbon chain.
- Furthermore, both are long-chain hydrocarbons, having a carboxylic group at one end and an alkyl group at the other end.
- Also, they are liquid at room temperature and are solidified when chilled.
- Moreover, both are types of trans fat and are considered healthy fats.
- They improve blood cholesterol levels by decreasing LDL levels.
- Besides, they help to decrease the risk of heart disease and type 2 diabetes.
Difference Between Monounsaturated and Polyunsaturated Fatty Acids
Definition
Monounsaturated fatty acids refer to the fatty acids that have one double bond in the fatty acid chain with all of the remainder carbon atoms being single-bonded. In contrast, polyunsaturated fatty acids refer to the fatty acids with constituent hydrocarbon chains, possessing two or more carbon-carbon double bonds.
Number of Double Bonds
The number of double bonds is the main difference between monounsaturated and polyunsaturated fatty acids. Monounsaturated fatty acids contain a single, double bond in the hydrocarbon chain while polyunsaturated fatty acids contain more than one double bonds in the hydrocarbon chain.
Found in
Monounsaturated fatty acids occur in olive, sesame, and canola oils while polyunsaturated fatty acids occur in sunflower seed oil, safflower, and corn oils.
Melting Point
Moreover, while monounsaturated fatty acids have a higher melting point, polyunsaturated fatty acids have a lower melting point.
Importance
Besides, the monounsaturated fatty acids lower the LDL cholesterol and total cholesterol and increase the production of HDL cholesterol while polyunsaturated fatty acids reduce the serum cholesterol levels and the production of both LDL and HDL cholesterol. Thus, this is the functional difference between monounsaturated and polyunsaturated fatty acids.
Examples
Palmitoleic acid, oleic acid, and cis-vaccenic acid are examples of monounsaturated fatty acids while omega-3 fatty acids and omega-6 fatty acids are examples of polyunsaturated fatty acids.
Conclusion
Monounsaturated fatty acids are the unsaturated fatty acids with a single, double bond in the hydrocarbon chain. On the other hand, polyunsaturated fatty acids are the unsaturated fatty acids with more than one double bond in the hydrocarbon chain. Both types of fatty acids are important for improving cholesterol levels in the blood by lowering LDL cholesterol levels. Therefore, both are beneficial for lowering the risk of heart disease and type 2 diabetes. However, the main difference between monounsaturated and polyunsaturated fatty acids is the number of double bonds in the hydrocarbon chain.
References:
1. D’Souza, Gillian. “Saturated vs. Unsaturated Fats: Which Is Better for You?” Medical News Today, MediLexicon International, Available Here.
Image Courtesy:
1. “Oleic-acid-skeletal” (Public Domain) via Commons Wikimedia
2. “Linoleic acid” By Edgar181 – Own work (Public Domain) via Commons Wikimedia
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