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Facing the Fats series graphic

To recap, triglycerides are what we typically call fats or oils which consist of 3 fatty acids fused to a glycerol backbone.

The basic structure of a dietary fat which is called a triglyceride or triacylglycerol. It is comprised of 3 fatty acid chains and one glycerol backbone.
R here represents the variable fatty acid chains. Source

Fats can come from animal or plant sources, providing and assisting with the absorption of fat-soluble vitamins such as Vitamin A, D, E and K, along with essential fatty acids (EFAs). As we stated in part 1, the structure of fat has a big role in its function and you’ve probably heard lots about unsaturated vs saturated fats, trans fats or even weird abbreviations like MUFA, PUFA, EPA and DHA. So, what are these?

What are monounsaturated fats?

If you recall, saturated fats which come from animal sources, have as many hydrogens as possible surrounding the carbon atoms and can fit closely together like strands of wool closely packed to make a solid sweater. So typically, saturated fats are solid at room temperature, while unsaturated fats have fewer hydrogen atoms bonded to the carbon chain, forming kinks in the structure and enabling these lipids to be liquid at room temperature. Many unsaturated fats are available from plant sources.

Avocados are good sources of unsaturated fatty acids, typically monounsaturated fats.
Avocados provide unsaturated fatty acids, typically monounsaturates. Source

Most research has shown that unsaturated fats have a beneficial effect on heart health and improve blood cholesterol levels. The abbreviation MUFA stands for monounsaturated fatty acids, such as oleic acid and palmitoleic acid. A dive deeper into the chemistry of these molecules show that unsaturated fatty acids contain double bonds between the carbon atoms (which restrict how many hydrogen atoms they can bond to). The position or configuration of the hydrogens around this double bond is important to predict the activity of the triglyceride. Naturally, the cis – configuration, where the hydrogens are on the same side, is more regularly seen, while the trans – configuration where the hydrogens are on different sides is less common.

The structure of unsaturated fatty acid chains. cis-configurations lead to large kinks in the chain, making the fatty acid more liquid at room temperature. While trans- configurations are less kinked and can pack closely to be solid at room temperature.
Check out that kink in cis oleic acid! These kinks in the fatty acid chain will enable the fats to be liquid at room temperature than saturates. Source

Good sources of monounsaturated fats include:

  • Avocado
  • Olive
  • Nuts e.g. Almonds, Cashews, Peanuts, Hazelnuts, Pecans
  • Peanut butter
  • Vegetable oils e.g. Olive oil, Corn oil, Canola or Rapeseed oil, Safflower oil Sesame seed oil, Soybean oil
Almonds also provide monounsaturated fat.
Almonds are a great source of unsaturated fats. Keep portions small (a handful a day) as these are packed with calories. Source

What about those dreaded trans fats?

While trans fats are unsaturated fats, because of the position of the hydrogens on their double bond, they can pack pretty tightly together and can act similarly to saturated fats. Naturally, ruminants such as cows and sheep produce a small amount of trans fats, but we should be more concerned about the higher amounts which are present in some processed foods.

As we have moved away from using saturated fats like butter and ghee to improve cardiovascular health, the manufacturing industry strived to find ways to make unsaturated fats easier to use in multiple applications (hello, baking!) and easier to transport (because we all know what a mess oil could be). Can you imagine baking a puff pastry with oil instead of butter or margarine? And let’s not even get started on the taste of lard. But if not for the earlier solid fats, we would not have been able to advance to current food technology.

Margarine or fat spreads can contain trans-fats, though advances to research and food technology has prevented this,and food policy often bans or limits the amount of trans-fats in such products.
Margarine or Spread is probably one of the first things you think of when you hear trans-fats. Frying oils can also produce trans fats and so, fried foods should be reduced. Source

Unfortunately, the earlier processes of hydrogenation of vegetable oils, such as partial hydrogenation produced trans fats. Many studies show evidence that these are detrimental to cardiovascular health by negatively affecting blood cholesterol levels, whereby increasing low-density lipoproteins (LDLs) and reducing high-density lipoproteins (HDLs), similarly to saturated fats. HDLs have a more positive effect on lowering cholesterol and improving heart health, so we want to ensure they are plentiful! 

Given the detrimental effects, food policy in many countries dictates that manufacturers must avoid the production of trans fats. And so, they use newer processes such as complete hydrogenation, interesterification and fractionation of oils which bypasses the production of trans fats to produce more useful solid fats.

Although delicious, doughnuts can have small amounts of trans fats from the shortening in their dough and the frying process. Though in more recent times, better alternatives have been used. But along with the high sugar content of this food, it maybe better to just have one at a time. Source

Although we have made these advances, some foods may still contain a small quantity of trans fats and we must still be mindful of the amount we consume. Eating amounts of less than 2% of your daily energy intake (less than 5g) can be ok.

Similarly, because of the effect of saturated fats on heart health, we should reduce our consumption to less than 10% of energy daily (roughly 22g of saturated fat). The best way to know how much you’re getting per serving is to check the nutrition label.

UK traffic light food label showing the Energy, Total Fat, Saturated Fat, Sugar and Salt content in a serving of a grilled burger.
The UK traffic light front of pack labelling give a quick glance at the nutritional content of your food. Source
US Nutrition fact label  highlighting trans fat content of a food.
Typical US food label. Highlighted is the trans fats in this food. Source

We’ll talk about how we can reduce our unhealthy fat intake and increase our healthy fat in the next two posts. What was your biggest misconception about fats? Have you ever used lard for cooking or frying? What’s your go-to fat/oil for cooking?

Post Author: Christina

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