Lipids are macronutrients composed of carbon, hydrogen and oxygen. They constitute the human body's main energy reserve and play a fundamental role in cell structure, hormone regulation and the absorption of certain vitamins. Lipids come in different forms:
Saturated fatty acids: Mainly found in animal products (butter, cheese, fatty meats) and certain tropical oils (coconut oil, palm oil), they are solid at room temperature and tend to be more resistant to oxidation.
Unsaturated fatty acids: They fall into two categories:
Monounsaturated: Found in olive oil, avocados and nuts, they are beneficial for cardiovascular health.
Polyunsaturated: These include omega-3 (fatty fish, flaxseed, walnuts) and omega-6 (vegetable oils, seeds). These fatty acids are essential, as the body cannot synthesize them.
Trans fatty acids: Found in certain processed foods and partially hydrogenated oils, they are associated with an increased risk of cardiovascular disease.
Triglycerides: the main form of lipid storage in the body, made up of three fatty acids attached to a glycerol molecule.
Phospholipids and sterols: Play a key role in the structure of cell membranes and the production of hormones (e.g. cholesterol).
Lipids are found in a wide variety of foods:
Vegetable oils: olive oil, rapeseed oil, sunflower oil.
Oleaginous fruits: almonds, walnuts, hazelnuts.
Oily fish: Salmon, mackerel, sardines, rich in omega-3.
Dairy products: Butter, cheese, whole milk.
Meat and eggs: Fatty meats, egg yolks.
Processed foods: Industrial products containing trans fats (cookies, pastries, ready-made meals).
Lipids are more complex to digest than carbohydrates, as they are insoluble in water and require specific enzymes and bile salts to be absorbed.
Emulsification in the small intestine: Bile, produced by the liver and stored in the gall bladder, solubilizes lipids by forming micelles.
Action of pancreatic lipases: These enzymes break down triglycerides into free fatty acids and monoglycerides.
Absorption in the intestine: Fatty acids are absorbed by intestinal cells and reformed into triglycerides.
Transport in the blood: Triglycerides are incorporated into lipoproteins (chylomicrons) and transported to tissues.
Once absorbed, lipids have several metabolic functions:
Energy production: fatty acids are oxidized in mitochondria via β-oxidation, producing ATP.
Storage in adipose tissue: Excess lipids are stored as triglycerides in adipocytes for later use.
Synthesis of cell membranes and bioactive molecules: Cholesterol is used in the production of steroid hormones (cortisol, testosterone, estrogen) and cell membranes.
Lipids perform a number of essential functions:
Source of energy: 1 gram of lipid provides around 9 kcal, more than double that of carbohydrates and proteins.
Building cell membranes: Phospholipids and cholesterol ensure membrane structure and fluidity.
Hormone synthesis: Lipids are involved in the production of steroid hormones and eicosanoids (regulators of inflammation).
Absorption of fat-soluble vitamins: Vitamins A, D, E and K require the presence of lipids to be absorbed.
Regulation of inflammation and cardiovascular health: Omega-3s have anti-inflammatory and heart-protective properties.
Thermal insulation and organ protection: Adipose tissue helps regulate body temperature and protects vital organs from shock.
Lipid consumption, whether from animal or plant sources, varies significantly across the world due to dietary habits, food availability, and socio-economic factors. It is essential to differentiate between lipid sources to understand their nutritional and health impacts.
According to FAO food balance reports, the availability of dietary lipids has steadily increased since 1961:
From 49g per person per day in 1961 to 68g in 1990 globally.
In developed countries, availability increased from 93g to 128g.
In developing countries, it doubled from 28g to 49g over the same period.
This increase reflects a nutritional transition marked by urbanization and dietary changes.
North America has the highest lipid consumption in the world, reaching 169g per person per day.
This high intake is often linked to processed foods and animal fats.
However, studies have shown that reducing dietary fat intake, as seen in the U.S. (from 42% of energy intake in the 1970s to 34% in 2000), did not necessarily decrease obesity rates.
On the contrary, obesity increased, suggesting that sedentary lifestyles and higher carbohydrate consumption play a key role.
Lipid consumption varies across European countries but remains generally high.
Countries such as Ireland, Denmark, Luxembourg, and Belgium have lipid availability exceeding 170g per person per day.
This intake is largely due to animal fats and dairy products.
Growing awareness of health risks associated with excessive saturated fat consumption has led to dietary recommendations promoting unsaturated fats.
Lipid consumption in Asia is generally lower than in Western countries, although it is increasing.
This rise is particularly notable in rapidly developing countries like China, where urbanization and Western dietary influences have led to higher animal fat consumption.
This dietary shift is associated with an increase in non-communicable diseases, such as cardiovascular diseases and diabetes.
Africa has the lowest lipid consumption worldwide, with notable regional differences.
In Central Africa, average consumption is 43g per person per day.
This low intake is often due to limited fat availability and traditional carbohydrate-rich diets.
Urbanization and greater access to processed foods are gradually increasing fat consumption, particularly from plant-based sources.
Lipid consumption in Arab countries varies depending on culinary traditions and economic development.
In North Africa, diets are rich in vegetable oils, particularly olive oil.
In the Gulf countries, animal fat consumption is higher due to high meat intake.
This dietary diversity results in varied lipid consumption trends across the Arab world.
Lipids are more than just an energy reserve—they play a vital role in cellular function, hormone regulation, and overall body protection.
A balanced diet that prioritizes unsaturated fat sources while limiting excessive trans and saturated fats is essential for maintaining long-term health.
Lipids are much more than just an energy reserve: they play an essential role in cell function, hormone regulation and body protection. A balanced diet that favors unsaturated lipids and limits excess trans fats and saturated fats is fundamental to long-term health.
