Fats: which ones, why and where?

Fats, fatty acids, lipids… Whatever their name, they are macronutrients provided by our diet and are essential for the proper functioning of the body, just like proteins and carbohydrates.

WHAT ARE THEY? HOW TO CHOOSE THEM?

We often hear about good and bad fats, but it’s not that simple. There are indeed several forms, of varying benefit to the body:

To be encouraged: 

• Polyunsaturated fatty acids, the famous omegas 3 and 6, are so-called essential fatty acids because your body cannot synthesize them. Your diet must therefore provide them, with an omega 6/omega 3 ratio of 5/1.¹ This means that you must consume 5 times more omega 6 than omega 3.
• Monounsaturated fatty acids, mainly represented by Omega 9s. They are found in olive oil or oilseeds such as almonds or nuts.

To be limited: 

• Saturated fatty acids, which should not be consumed excessively, are mainly found in animal fats (butter, cream, lard, etc.) and certain vegetable oils (palm oil).
• Trans (or hydrogenated) fatty acids, which should be limited because of their harmful effects on your health. Refer to the list of ingredients to detect them.

The recommendation is for 20% of daily fat intakes to be taken as monounsaturated fatty acids, a minimum of 5% as polyunsaturated fatty acids and a maximum of 12% as saturated fatty acids out of your total energy intake.²

Cholesterol is also a useful lipid for the body. Present in many tissues, mainly in the brain, liver and spinal cord, it is a constituent of cell membranes and is involved in the production of certain hormones. We often hear about “good” and “bad” cholesterol. In reality, this means cholesterol transporters: the “good” ones will have the mission of recovering surpluses in order to eliminate them, while the “bad” ones will distribute the cholesterol around the body.

WHY ARE THEY ESSENTIAL?

Lipids are involved in many essential functions: 

• They are part of the constitution of our cells and thus contribute to their proper functioning.³
• They play a crucial role in the transport of certain proteins, hormones and fat-soluble vitamins (A, D, E, E, K) in the blood.⁴
• They contribute to the synthesis of certain hormones such as sex hormones.⁵
• They also store energy, especially in fat tissue.⁵
• This is why it is important not to avoid them at all costs, as they are not all equal.

WHERE CAN I FIND THEM IN MY DIET?

There are visible fats, which are used as they are, such as butter, oil and cream. Not all fats are suitable for cooking. When they start smoking it means that the maximum temperature has been exceeded. They can lose their nutritional benefits with heat and harmful compounds can form. For example, walnut oil and rapeseed oil cannot tolerate excessive heat. 

And then there are “hidden” fats in food: fatty fish such as salmon, mackerel or sardines are good sources of omega 3, while delicatessen, cheese (especially hard cheese), pastries, ready-made meals or pie pastry may contain saturated fatty acids or even trans saturated fatty acids. Prefer shortcrust pastry, as it generally contains the lowest fat. As for meats, depending on the type and cut, they may also be high in fat, especially in saturated fatty acids. Vary sources and prefer white meats, which are generally less fatty.

1. AFSA, Acides gras de la famille oméga 3 et system cardiovasculaire

2. CERIN, Les dernières recommandations en lipides, 2013

3. Abdul et al., The role of lipids in retroviral replication, chapitre 10, Retrovirus-Cell interactions, p353-399, 2018

4. Nozomu Kono, Intracellular transport of fat-soluble vitamins A and E, Traffic, volume 16, issue1, 2014

5. ANSES, Les lipides, 2019