Lipids in food

What role for lipids?

In nutrition, there is 2 kind of lipids : Triglycerides (TG) and phospholipids (PL) which share the fact that they are made of oily acids (OA).

The physical and nutritional properties of lipids will depend on the nature of the OAs that form them. There is 3 sorts of OAs:

• SF or Saturated Fats (0 double links)
• MUFAs or Monounsaturated Fatty Acids (1 double link)
• PUFAs or Polyunsaturated Fatty Acids (several double links)

Regarding the PUFAs

There are 2 families : ω3 et ω6. There is absolutely no metabolic transformation or functional substitution from one to the other family.

SC PUFAs Short Chain Polyunsaturated Fatty Acids

Among the PUFAs, we call Essential Fatty Acids the 2 precursors:

• Linoleic acid (C18:2): ω6 PUFA precursor
• α–linoleic acid (C18:3): ω3 PUFA precursor

Food has to bring those Essential Fatty Acids because our body cannot synthesise them. During most of our life (except for babies and the elderly), the synthesis of the several Fatty acids is possible thanks to an enzyme, the Δ6 desaturase. However, there is a competition between the 2 precursors as they use the same enzyme for their synthesis, which lead us to the need of a balance: Linoleic acid/ α–linoleic acid = 5

Those two fatty acids are found in vegetal oils :

• Linoleic acid : Sunflower, corn, nut…
• α–linoleic acid : Canola, soy, nut..

LC PUFA Long Chain Polyunsaturated Fatty Acids

LC PUFA (more than 18 carbon atoms fatty acids) also have special value.

• ω6 family: Arachidonic acid (C20:4) (Animals, meat, milk, egg)
• ω3 family : EPA (eicosapentaenoic acid, C20:5) and DHA (docosahexaenoic aci, C22:6) (Marine animals and related oils)

General role of lipids in food

• Important energy provider even when small in quantity, very useful for long distance trails like ultra, some biking races or different kind of raids…
• Thermoregulation purposes : fundamental principle when temperatures are low or hostiles (air or water; e.g. Norseman, UTBM or Saintélyon…)
• Role of metabolic stock (under the form of triglycerides in the adipose tissue), heat insulator (interesting for swimmers whose thermal neutrality is around 32-33°C in a 25°C water….), protection against chocks (rugby men appreciate…) .

Role of SF saturated Fatty Acids:

These SF have an important role into the supply of energy. The excess of Saturated fatty acids is one of the closest factor associated with coronary mortality.

They raise significantly the platelet aggregability and help in the production of the atheromatous plaque, which increase the cardiovascular risk. We consequently have to limit our consumption of SF regarding frequency and quantity, without exclusion! Every nutrient is vital to human beings! Our « occidental » society is in excess regarding this factor which implies reduction without exclusion is best compromise to enjoy food without deeply endangering our health!

Important resources of SF are mostly concentrated in animal fats : fat charcuterie (rillettes, sausages, …), cheeses, fat pieces of meat (fat rib eye steak, rib steak…), butter, sour cream… and vegetable oil (coconut oil, copra, palm…

Note: 2 saturated fats that are hypocholesterolemic : lauric acid and myristic acid. The butyric acid (C4:0) comes from the deterioration of fibers inside our colon. This one is interesting as it inhibits the proliferation of tumor cells. Some Long chain fatty acids play an important role is the structure of some nervous cells such as myelin.

Role of monounsatated fatty acids (MUFAs): Omega 9 series or Ω9

They participate in the supply of energy and have a hypocholesterolemic role.

Associated with a moderate physical activity, they participate in the prevention of athérosclerosis and some other cardiovascular complications by increasing our « good » cholesterol and lowering the « bad » (LDL).

Food sources for MUFA are olive, colza, hazelnut, avocado and almond oils. Our alimentation, strongly based on olive oil, is correct among the French population! The Mediterranean model influenced olive oil establishment in our alimentation.

Role of Polyunsaturated fatty acids (PUFAs):

Omega 3 ou Ω3

• Role in the building of nervous tissue and retina
• Long Chained PUFAs like EPA (eicosapentaenoic) and DHA (docosahexanoic acid):
  • Triglyceride lowering effect
  • Decrease of the insulin resistance : Diabetes and obesity prevention
  • Prevention of degenerative diseases of the brain (Alzheimer…)
  • Decrease of the inflammatory response regarding chronic pathologies (polyarthritis, sinus infection…), but also tendinitis, muscular traumas…
  • Special interest for the athlete as a primary and secondary preventive action: In fact, the inflammation is either « adaptive » (forcing the adaptive mechanism to better the next day) or « negative » (when it’s too strong and present, usually leading the total stop of the effort, and resting for several days or weeks…). All of this is difficult to manage when sporting season is on its way… Modulating the inflammation through the intake of Long Chain and prophylactic omega 3 is essential to manage the season. This is the only complement to take if complements have to be taken ;D
• Alimentary sources:
  • Short Chained PUFAs (alpha-linoleic acid): Oils of colza, soy, nuts, flaxseeds, purslane, lamb’s lettuce, animal sector (chickens, cows) fed with flaxseeds, from which comes an increased omega 3 nutritional value of eggs and milk.
  • Long Chained PUFAs: fat fishes from cold seas and their oils (mackerel, herring, pilchard…)

Omega 6 serie or Ω6

• Reproductive role : A deficiency provokes a degeneration of testicles and difficulty to procreate from women.
• Epidermis role: Epidermis cells differentiation, skin protection (healing), skin integrity maintenance.
• Platelet function role : avoiding platelets to gather and therefore to form a thrombus.
• Immune function and inflammatory reaction role: Too weak or too high supplies are immunosuppressive.
• Hypocholesterolemic effect: protection against the myocardium infarctus and involvement in lipemia regulation (fatty acids rate circulating in our blood).
• Food sources:
  • Short Chained PUFAs (linoleic acid): grape seed oil, sunflower oil, wheat germs, corn.
  • Long Chained PUFAs (arachidonic acid) : egg, meat.
• Personal remark: We usually eat too much omega 6, so no worries about its supply…

Omega 3 and 6 Series

• Growth role : Cell multiplication
• Mediators synthesis (prostaglandin, leukotriene) which act like hormones
• Role in the expression of genes by modulation: inhibition or activation. Through this « game », Omega 3 activate some coding genes’ translation for enzymes acting in the lipolysis (triglyceride catabolism)

Omega 3 play a role in weight loss, or at least, in the regulation of body composition. This is a positive factor for the acquisition of a health weight for the athlete pursuing sportive performances. Omega 3 allow us to « lose or gain positive weight » depending our body mass index (BMI)is respectively or abnormally raising or lowering.

A sentence summing up the dietary care of athlete is : « Your alimentary plans are loaded in quantity… I eat a bit of everything for a change… I don’t gain weight, or I gain muscular weight for a better feeling… I don’t feel tired, I’ve got more energy and recovering is easier and faster… I don’t hurt myself so often… I have a better efficiency! ». In other words, sport season is optimised! 😀

A tip I can give you : « The biggest mistake is to think through the body scale which, especially regarding stamina activities, is more a downfall than an advantage. I can say that to you as I can see it every day : if you don’t eat or eat very small quantities, thinking it might light you up, allowing you to run faster and to minimise energy spending, this is mostly wrong! At the end, your muscular supports (or fibres) are less numerous, your glycogen and lipid stocks are lower which will unavoidably lead you to an early stop of the effort or some related pathologies : tendinitis, micro fractures, mental weakness, less pleasure to the effort… 😀 »

Sportingly,

Nicolas AUBINEAU
Sports Dietitian Nutritionist