The place of fats in our diet

At the request of the European Commission, the European Food Safety Authority, EFSA, based on the most recent knowledge available, has formulated opinions on fat intakes and started an updating process nutritional reference values ​​(NRV).

These nutritional reference values ​​indicate optimal nutrient intakes as part of a balanced diet , which when integrated into an overall healthy lifestyle contribute to good health.

The EFSA has therefore decided to set fat intakes in a reference interval of between 20% and 35% of daily energy intake.

Based on observations of dietary intake, staying within this range, no nutritional deficiencies or adverse effects on blood lipids or body weight were observed. It has also been highlighted that total fat intakes above 35% may be compatible with both good health and normal body weight, depending on the type of foods consumed and the level of physical activity.

1 - Introduction

The intake of saturated fatty acids and trans fatty acids (the consumption of which should be avoided) should be as low as possible within the framework of an appropriate nutritional intake. No specific values ​​are recommended for intakes of mono and polyunsaturated fatty acids, but the EFSA recommends that they replace saturated fatty acids as much as possible.

Long-chain omega-3 acids , found in fatty fish, are particularly beneficial for cardiovascular health; also their daily intake was set at 250 mg per day , which corresponds to a daily intake of only 20 grams of salmon.

But what are these lipids and what recommendations for athletes?

Weight is related to performance. Lipids or fats are directly responsible for the accumulation of fat mass and the increase in weight because they alone are stored. Also, maintaining optimal adiposity is the objective of every athlete and for some a priority if we think of bodybuilders in pre-competition. However, we cannot do without lipids and not consuming enough of them leads to serious counterproductive deficiencies for the athlete. Lipids are a large family made up on one side of fatty acids, on the other by a group including steroids, fat-soluble vitamins and other terpenes.

Some values:

Fats are not homogeneous and it is important to choose foods throughout the day in order to maintain a good balance in fatty acid intake .

During the day, between 25 and 33% fat per day: hidden in foods and intake: oil, butter, etc.

And a report on total daily energy: AGS < 8% MUFA: 20% and PUFA: 4%

Example for a 2000 Kcal ration: 73g (33%) including AGS < 18g; MUFA: 45g; PUFA: 9g

2 - What are lipids used for?

- Energetic : they help provide the energy necessary for the functioning of our cells. Remember that one g of fat provides 9 calories. For a 70 kg man with a body fat of 15% this represents a reserve of 94,500 Kcal!

- Insulating and protective : by forming subcutaneous fat they protect us from the cold and absorb blows during physical shocks.

- Structural ; they participate in the development of the membranes of our cells to which they give solidity, plasticity, conductivity, thus improving exchanges: brains, nervous, blood, muscular systems, etc.

- Metabolic : they constitute, from cholesterol, bile salts which allow us to manage the absorption and digestion of fats. Cholesterol is also a precursor of hormones and maintains our balance by regulating our metabolism: testosterone, progesterone, estrogens, cortisol, aldosterone.

- Transporters : carry fat-soluble vitamins A, D, EK, carotene, etc.

- Palatability : fats give the taste and modify the consistency of dishes improving their flavors: smoothness, finesse, etc.

- Satiety : these molecules are recognized in the brain and serve to regulate appetite

3 - Where are they found?...

We consider :

Hidden fats contained in the natural foods we consume

The visible fats we add to our dishes to improve their flavor

- 1% Starchy foods a little, bread depending on composition

- 2 to 5% Yogurts, Swiss biscuits, milk... Except skimmed

- <10% Cooked roast pork hams, defatted dry hams, tripe….

- 10% Meat, fish, eggs

- 10-20% Pâtés and head cheeses, cured hams, andouille sausages, andouille sausages

- 15 to 35% Creams

- 20 to 75% Cheeses

- 20-30% Smoked breasts, terrines, mortadella, cervelas….

- 30-40% Black pudding, fresh sausage, dry sausages, mousses, pâtés and rillettes….

- 40 to 60% Margarines

- 80% Butter

- 100% Oils

4 - What are they?

Dietary fats are 95% made up of triglycerides (or triacylglycerols): a trident-shaped combination (without the handle) of a glycerol (a trialcohol) and three fatty acid molecules which may be similar or different.

During digestion, thanks to lipases (mainly pancreatic) , the two fatty acids arranged at the ends are released by modifying their conformation.

The remaining monoglyceride crosses the intestinal barrier and will be esterified again to form a new triglyceride which will incorporate the chylomicrons to reach the lymphatic system. The lifespan of chylomicrons is limited: thanks to lipoprotein lipase, part of the triglycerides will be transferred into the adipose tissue while waiting to be reinjected in the event of an energy need.

The fatty acid composition of adipose tissue triglycerides varies depending on the nature of dietary fatty acids. Two are more particularly represented: 45% for oleic acid, monounsaturated, and 30% for palmitic acid, saturated. The remainder is made up of various other fatty acids, knowing that those with a long chain (more than 20 carbons and very desaturated (4 to 5 double bonds) are poorly represented in adipose tissue. On the other hand, the latter are very present in membrane phospholipids. such as arachidonic acid C20:4 ω 9 and eicosapentaenoic acid (EPA) C20:5 ω 3) of which animal products are a good source.

The latter needs its precursor to be present and if our body is capable of transforming a large number of fatty acid chains, certain so-called essential cannot be synthesized due to lack of enzymes and must therefore be present in our diet. : this is the case for linoleic and alpha linolenic acid , otherwise called ω 6 and ω 3, which we will talk about again.

During their release and after transformation by hepatic enzymes (elongases, desaturases) the fatty acids are incorporated into cellular structures and participate in physicochemical cohesion by forming phospholipids: the plasticity and fluidity of the membranes depend on the nature of the fatty acids. which will enter into its composition: saturated or desaturated. At this level and inside cells, they participate in numerous metabolic regulations: enzymatic syntheses, production of prostaglandins, functioning of hormonal receptors which are composed of proteins embedded in the phospholipid bilayer, role in intercellular adhesion.

Lipids are part of the composition of the central part of plasma lipoproteins which, depending on their nature, are more or less rich in triglycerides or esterified cholesterol. They act as a vector to transport fat-soluble substances such as vitamin E and this function is also carried out in dietary fats. The absorption of the four major fat-soluble vitamins (A, D, E and K) is associated with lipid intake.