Of all the main nutrients we consume daily, fats are likely to be the most controversial. There is considerable confusion surrounding the different types of fats and how they are used, stored and disposed of within the body. The low fat movement was an extensive and orchestrated campaign to remove fats from our diet after it was thought to be associated with ill-health back in the 20th century. Fast forward to now, and we are realising that the fats, similar to the other macronutrients, carbohydrates and proteins, are not as simple as 'good' or 'bad'.

The most commonly talked about fats are saturated and unsaturated fats. The saturated/unsaturated prefix basically describes the chemical or molecular make up. Unsaturated fats can be monounsaturated or polyunsaturated fats. Fats also differ from source to source – for example, coconut oil has a very different chemical structure to butter or other animal fats. This is why it is important not to always lump fats into their saturated or unsaturated category as even within that category, they differ.

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GOOD OR BAD? Bridie Kersten says the medical community is coming to a better understanding of fats in our diet. PICTURE: Via Unsplash

 

"[W]henever the structure of fats or oils is compromised, it is more likely to affect our health. We have also learned recently that our body is very well able to regulate our cholesterol and safely digest and use saturated fats but in the presence of inflammation, oxidisation and glucose (sugar), these fat structures can become changed/damaged."

Polyunsaturated fats are either Omega-3 fatty acids or Omega-6 fatty acids. We cannot synthesise these within our body, so they must be obtained from the diet, giving them the classification of essential fatty acids. The Omega-3 and Omega-6 fatty acids are both required but in different quantities. We easily get Omega-6 fatty acids from our diet from foods such as red meat, chicken and seed oils. We are less likely to have enough Omega-3 fatty acids which are found in fish, nuts and seeds.

The unsaturated family of fats (Omega-3, Omega-6, and so on) help to regulate blood cholesterol levels, inflammation, blood clotting and blood pressure.

These so-called 'good' fats help to provide energy for our body’s functions, store energy for times of need (although, as we know, this system of energy storage is sometimes too effective), facilitate the absorption and use of fat soluble vitamins (vitamins A, D, E and K). They are also required for the production of hormones, the development of many parts of the body such as the eyes and help to regulate the immune system. This is just some of what fats do within the body – they are involved in countless processes.

To digest fats, we need to dissolve them, because, as we know, fats (or oils) do not easily dissolve. Therefore, the liver makes a product called bile which dissolves the fats so they can be absorbed and used. When bile has been made but is waiting to be used, it is stored in a small gland-like organ called the gallbladder. There is a complicated conversation that happens between the digestive system and the brain to decide when to make bile, store bile or release stored bile. An interruption of this conversation can lead to conditions such as poor fat absorption and gallstones.

Trans fats (generally considered to be 'bad' fats) are created when a fat that would normally be liquid at room temperature is hydrogenated, making it a solid at room temperature. The introduction of trans fats has changed the food manufacturing industry as it is cheaper than its alternative - butter - but still makes flaky pastry and crispy fried foods. The only problem is that the chemical change required to make it a trans fat is not well received within the body and it greatly increases the risk of many health problems such as heart disease and type 2 diabetes. They affect the way that our body uses and recycles cholesterol, leading to an imbalance between the various types of cholesterol. And while these types of cholesterol are not necessarily dangerous on their own, when they become disrupted or oxidised (damaged), they can become more dangerous to our health.

In fact, whenever the structure of fats or oils is compromised, it is more likely to affect our health. We have also learned recently that our body is very well able to regulate our cholesterol and safely digest and use saturated fats but in the presence of inflammation, oxidisation and glucose (sugar), these fat structures can become changed/damaged. This new, damaged fat acts differently within the body and can lead to a range of health problems, including heart disease and metabolic disorders such as obesity and type 2 diabetes. This is one of the main reasons that we are now, as a medical community, moving on from the low fat movement and instead, encouraging a balanced diet with a variety of fats from the saturated and unsaturated categories and also plenty of wholegrains, fruits, vegetables and protein in an effort to keep a healthy balance within the body also. We continue to advocate the avoidance of trans fats, however.

This information is a general overview of the different fats in our body and a brief look at how they are digested and what might make them a “good” or a “bad” fat and does not cover all of the important points to consider when adding or removing fats from your lifestyle so please do your research and consult your health care practitioner before making changes to your eating habits.

Bridie Kersten is a registered nutritionist with an advanced diploma in nutrition and a Bachelor of Health Science (biochemistry and nutritional medicine).