Unsaturated Fats: Monounsaturated and Polyunsaturated

Nutrition

What are unsaturated fats?

Unsaturated fat is a type of fat or fatty acid that is healthy and is, therefore, referred to as healthy fat. It is a form of lipid, which is a chemical insoluble in water but soluble in some organic solvents such as alcohol, ether, and chloroform.

Along with carbohydrates and proteins, lipids are the main components of plant and animal cells. Cholesterol and triglycerides are examples of lipids.

Unsaturated fats come mainly from plant foods. They stay liquid at room temperature unlike saturated fats, which stay solid. These are good or healthy fats, which have health benefits for your body.

Characteristics

  • Unsaturated fats are lipids, which are almost always plant-based. However, certain natural unsaturated fats are present in meat, which also contains saturated fats.
  • Unlike saturated fats, which are in the solid-state at room temperature, unsaturated fats stay in a liquid state at room temperature and hence are available as oils such as vegetable oils.
  • The shelf life of unsaturated fats is only a few days because they spoil or turn rancid early, unlike saturated fats. However, antioxidants help in protecting this rancidity.
  • Due to their instability, these fats are chemically hydrogenated to increase their shelf life. This hydrogenated unsaturated fat is called Trans fat.
  • Unsaturated fats are called good fats because they have certain health benefits when consumed.
  • They may be monounsaturated fats or polyunsaturated fats depending on their chemical structure.

Plant sources 

Unsaturated Fats are derived from plants such as:

  • Olive
  • Corn
  • Cottonseed
  • Peanut
  • Safflower
  • Sunflower
  • Soya bean

How much unsaturated fat should you consume daily?

According to the U. S. Food and Drug Association, about 30% of your calorie intake can be in the form of unsaturated fats. That is, if you consume 2000 calories per day, you can take about 67 grams of unsaturated fats daily.

If you’re having a 2,000-calorie diet, your total fat (all fats) intake should account for 400 to 700 calories, which is 20 to 35 percent.

Of this, the goal is to get 50 to 65 percent from unsaturated fat sources. Therefore, of the 2,000-calorie diet, 200 to 450 calories should come from unsaturated fat.

Chemical structure

The chemical structure of unsaturated fatty acid contains one or more double bonds in the fatty acid chain.

Unsaturated fat has at least one double bond within its fatty acid chain. If it contains one double bond, it is monounsaturated, and if it contains more than one double bond, it is polyunsaturated fat.

Where the double bonds exist, the hydrogen atom is eliminated.

Why do unsaturated fats spoil?

As in saturated fats, unsaturated fats also have a chain of carbon atoms with hydrogen atoms attached. However, certain carbon atoms have a double bond between them. And, where there is a double bond, the hydrogen atom is eliminated.

That double-bonded carbon atom is thus unattached and becomes vulnerable to oxidation (called peroxidation) by the oxygen of the atmosphere. This oxidation causes unsaturated fats to spoil or become rancid. The shelf life of the unsaturated is, therefore, only a few days.

List of unsaturated fats

Examples of these good fats include:

  • Palmitoleic acid
  • Oleic acid
  • Linoleic acid
  • Myristoleic acid
  • Arachidonic acid

Types of unsaturated fats

Unsaturated fats are classified according to their chemical structure into:

  1. Monounsaturated fats
  2. Polyunsaturated fats

Where there is only one carbon atom with a double bond, it becomes monounsaturated fat.
When there is more than one carbon atom with a double bond, it is called polyunsaturated fat as shown above.

1. Monounsaturated fats

These fats are also called MUFA – Monounsaturated fatty acids. As explained above, they have only one double bond between the carbon atoms.

Examples 

  • Palmitoleic acid
  • Oleic acid.

Natural sources 

  • Whole milk products
  • Red meat
  • Fruits like olives and avocado
  • Nuts
  • Oils such as  Tea seed oil, Olive oil, Canola Oil, Grape seed oil, Macadamia oil, Groundnut or peanut oil, Sesame oil, Corn oil, Safflower oil, Sunflower oil, Camellia
  • Whole Grain wheat cereal
  • Oatmeal

Benefits and advantages 

Disadvantages 

  • These fats are more vulnerable to rancidity than saturated fats.
  • They are known to increase insulin resistance (which makes insulin less effective).

2. Polyunsaturated Fats

Polyunsaturated fatty acids have more than one double bond between the carbon atoms in their molecular structure. That is, there are more than one carbon atoms, which does not have a hydrogen atom attached to them.

Omega-3 fatty acids and Omega-6 fatty acids are two polyunsaturated essential fatty acids, which are not manufactured by the body and have to be obtained from dietary sources.

Food sources 

  • Whole Grain Wheat
  • Bananas
  • Sunflower seeds
  • Hemp seeds
  • Peanut butter
  • Margarine
  • Fish especially wild salmon and fish oil
  • Nuts
  • Leafy green vegetables
  • Algae
  • Krill

Benefits and advantages 

  • Omega-3 fatty acids are known to reduce the risk of a heart attack.
  • Omega-6 fatty acids reduce the risk of heart disease.
  • Omega-3 fatty acids inhibit the growth of a prostate tumor.
  • High levels of Omega-3 fatty acids are associated with a reduced risk of breast cancer.
  • Polyunsaturated fat intake reduces the risk of sclerosis.

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