What Experts Are Saying About Unsaturated and Saturated Fatty Acids
Fats are considered to be the ‘baddie’ of all the nutrients related to obesity, heart disease and cancer. However, being the most energy dense of the macro-nutrients, it does play a vital role in making sure that we meet our daily energy needs and enables the absorption of fat-soluble vitamins and carotenoids.
Fatty acids are the building blocks from which lipids are made. Fatty acids found in foods and fats stored in the body are in the form of triacylglycerols, a glycerol molecule backbone to which three different fatty acids are attached.
Fatty acids are made up of a backbone of carbon atoms with a methyl group (CH3), and a carboxyl group (COOH). Hydrogen atoms are joined to the string of carbon atoms, forming a hydrocarbon chain. They vary in chain length from 2 to 80 carbons, but are typically present in food as 14, 16, 18, 20 and 22 carbon atom chains.
In this post, we are interested in knowing the differences between unsaturated and saturated fatty acids.
What are Unsaturated and Saturated Fatty Acids?
Unsaturated fatty acids may contain one or more double or triple bonds and can be separated into monounsaturated, polyunsaturated, and acetylenic fatty acid.
Most unsaturated fatty acids have the cis orientation but trans fatty acids are also present. More than 100 naturally occurring monounsaturated fatty acids have been identified, but most of these are very rare compounds.
It is important to know that carbon chain length influences the characteristics of fatty acids, as does the presence or absence of double bonds between carbon atoms:
- If there is only one double bond present in an unsaturated fatty acid, it is said to be a monounsaturated fatty acid.
- If there is more than one double bond present, the fatty acid is said to be a polyunsaturated fatty acid.
Double bonds in unsaturated fatty acids can be arranged in one of two ways; cis or trans configurations. The cis-form are predominantly found in foods.
Examples of monounsaturated fatty acids with cis-configuration include:
Examples of polyunsaturated fatty acids:
There are many sources of unsaturated fatty acids you can get in a diet, they include:
The flesh of white fish and seafood typically contain very low amounts of fat. The fat that is present tends to be long chain omega-3 PUFAs. The flesh of oily fish is a rich source of fatty acids than white fish. Oil-rich fish include sardines, salmon, pilchards, mackerel, herring and trout, whether canned, fresh or frozen.
On the other hand, saturated fatty acids also have the same functional groups with no double bonds in their hydrocarbon chain.
The lengthy chain ranges from C6 to C20, saturation depends on the number of carbon atoms in a chain length and they can either be in liquid or solid form.
Common examples of saturated fatty acids:
Saturated fatty acids sources:
- Poultry skin
The fatty acid composition of meat is dependent on whether or not the species is a ruminant. In cows, about 90% of the dietary unsaturated fatty acids are hydrogenated to SFAs in the rumen during digestion.
Why We Need Unsaturated and Saturated Fatty Acids
Studies have investigated the influence of unsaturated fatty acids on ischaemic and haemorrhagic stroke. The studies showed that MUFA, a class of unsaturated fatty acids in serum, plasma or red blood cells of ischaemic stroke cases are linked to a reduced risk. Whereas omega-6 PUFA also showed that, higher intake of linolenic acid was related to a reduced risk of ischaemic stroke.
On the contrary, not all saturated fatty acids are bad, however, it is widely considered that some may have little impact on serum cholesterol levels, such as lauric, myristic and palmitic acids adversely affect LDL cholesterol. Stearic acid is deemed neutral.
It has been suggested that SFAs between C12 to C18 are not harmful and may explain the lower effect of dairy products on blood cholesterol.
The benefit of SFAs reduction and substitution with PUFAs helps lower bad cholesterol, prevents coronary risks and heart diseases.
The American Heart Association and American College of Cardiology Guideline on Lifestyle Management to reduce cardiovascular risk reports strong evidence for reducing SFA intake to lower LDL cholesterol. Similarly, The National Lipid Association Expert Panel strongly recommends a diet low in SFA. Despite this strong evidence to limit SFA in a diet, current intake in the USA is 10.7% of energy.
The Differences Between Unsaturated Fatty Acids and Saturated Fatty Acids
Both unsaturated and saturated fatty acids play a key role in our health and it is always important to know the differences before considering them in a diet.
Differences between unsaturated fatty acids and saturated fatty acids:
- Unsaturated fatty acids have one or two double bonds in their molecular chain. SFAs have single bonds.
- Unsaturated fatty acids have lower boiling and melting points. SFAs are higher.
- Unsaturated fatty acids cannot be synthesized, meaning they are essential. SFAs are produced in animals and is considered non-essential.
- Unsaturated fatty acids are easily oxidized. SFAs are stable to oxidation and they do not turn rancid.
- Unsaturated fatty acids are less harmful and does not cause any heart problems, e.g. oleic acid. SFAs such as stearic acid at higher concentrations is not good for the heart.
I hope this article helped you know the differences between unsaturated fatty acids and saturated fatty acids.