The Fat Files

Fat refers to the nutrient group known as ‘lipids’. Lipids supply more energy per gram than both protein and carbohydrates and is therefore relied on heavily for fuel. Fat also insulates the body which keeps us warm.

Lipids have some siblings; triglycerides (fats and oils), phospholipids and sterols.

Let’s get down to the nitty gritty…

A triglyceride has a particular structure which is important to its function.

It is made up of one molecule of glycerol and three fatty acid chains (chemically speaking, the chains are made up predominantly of carbon atoms with hydrogen attached). These fatty acid chains can be from 4 to 24 carbons long. Fatty acids that are 18 carbons long are the most common in food.

Anyway...

You would have heard the term ‘saturated’ and ‘unsaturated’ fat. Fatty acids that are unsaturated are either mono-unsaturated or poly-unsaturated. Poly-unsaturated fatty acids are your omega-3 and 6.

Phospholipids

Due to the chemical structure of phospholipids, they are commonly used by the food industry as emulsifiers. They can be found naturally in foods such as eggs, liver and soybeans. Phospholipids have important roles in the body. They make up part of our cells called the cell membrane, where lipids are able to move in and out. They also allow some fat-soluble substances such as certain vitamins and hormones to pass through.

Sterols

A lot of our body compounds are made up of sterol, including sex hormones, bile acids, vitamin D and of course the most famous, cholesterol.

Cholesterol gets a lot of bad press however, it is an integral compound in the body which is synthesised from the liver and used for many different things in the body.

There is good cholesterol (HDL (high-density lipoprotein)) and bad cholesterol (LDL (low- density lipoprotein)). Cholesterol (LDL) can be harmful in the body when it builds up on the artery walls and forms deposits. This can lead to a disease called atherosclerosis, which can cause heart attacks and strokes.

Lipids and Health

So what’s bad fat?

When cholesterol is elevated in the blood it can cause cardiovascular disease. What is important to know is that food high in cholesterol does not raise cholesterol levels in the blood as much as saturated fats does.

Saturated fats mainly come from animal sources such as whole milk, butter, cheese and fatty cuts of meat. They can also be derived from coconut and palm.

Trans fats can also raise LDL cholesterol and lower the good stuff, HDL cholesterol. Trans fats are usually found in deep fried foods, cakes, pastry’s, chips etc. (the delicious food).

What’s good fat?

Unsaturated fats (mono and poly) have the most benefits in the body.

Some examples of mono-unsaturated fats include:

• Olive oil

• Peanut oil

• Avocados

• Nuts

• Seeds

• Meats

• Eggs

Examples of poly-unsaturated fats (omega 3 & 6)

• Vegetable oils

• Walnuts, almonds

• Fatty fish (salmon, mackerel, tuna)

• Soybeans

There are many health benefits of omega 3 and 6, including reducing blood pressure, preventing blood clots, protecting against irregular heartbeats, and improving immunity and brain function.

Whitney, E., Rady Rolfes, S., Crowe, T., Cameron-Smith, D., Wals, A. (2011). Understanding nutrition: Australia and New Zealand edition. Melbourne: Cengage Learning, pp. 146-154