Volume 12, Numéro 1, Janvier-Février 2005
|Page(s)||5 - 15|
|Publié en ligne||15 janvier 2005|
Synergie et acides gras – XXIe siècle : une ère nouvelle pour les lipides
Conférence présentée le 3 décembre 2004, à la 16e journée de nutrition et thérapeutique. Université Victor Segalen – Bordeaux 2
24, Quai du 4 Septembre, 92100
The various disciplins of Science reveal a complex, consistent, and flexible world of lipids, which moreover allows for most of the biological world resilience. Marketing of Science, Commercial and Political marketing, have wanted to simplify this complex world at the most, reaching the limits of binary reduction of black and white, of Opposition and Exclusion. The Communication Mediatory Mask has ceased fulfilling its social function of interpreter, transmitter of truth. It became reducer, letting appearance to be confused with reality, disinformer by fact. Thus, the way to cognitive dissociation and repeated inconsistencies, was fully mapped out. Children of the century, researchers became heavily contaminated, and scientists were accused of inconsistancy. In the food and agri-business field, as well as in the pharmaceutical field, the sanction has been, is or will be severe (animal flours and new variants of prion disease, coxiBs or anti-Cox2). The real scientific discourse is actually very consistant, provided no acquisition, no question, neither from past nor for present time, is ignored, provided one’s accepts its complexity. Several ignored questions or problems about to be solved or renewed, are raised :- Tendency to take a part for the whole, the concept of flux speed, of endogenous synthesis speed, concept of the influence of a different man made environment – Excess of exogenous or endogenous oleic acid, danger of cholesterol oleate, but requirement for a little amount of endogenous oleic acid - Phytosterols and 25-OH vitamin D- Requirement for a saturated fatty acids minimal amount. -Confusion between Vaccenic acid :-C18 :1n-7trans, natural parent of Rumenic acid, and Elaidic acid (C18 :1n-9trans) product of industrial hydrogenation. Furthermore new and old data on the confusion between alphalinolenic acid (in general) and alpha-linolenic in sn-2 position, the only one to be indispensable, are emerging together with the consequences of this confusion. It is logical to acknowledge Rapeseed oil as the best source of alpha-linolenic acid in sn-2 position bioavailable. It is more than questionnable for Soybean oil. The knowledge explosion last quarter of the 20 th century has made the Opposition- Eclusion of the P/S ratio completely obsolete. The 21 st century is opening up with three themes which are as completely different as consistent this time, Competition, Balance, Synergy. Competition can take place between five unsaturated fatty acids families : Palmitoleic, Oleic, Vaccenic n-7trans, Linoleic, Alpha-Linolenic, using common enzymatic systems of selective esterification, elongation, desaturation, deacylation-reacylation, and for the upper derivatives of LA and ALA using numerous oxygenases. Competition can also take place intra-family, e.g. The homeostatic Thromboxane (n-6 family) and Prostacycline (n-6 family) balance in the cardiovascular field, which thus makes the exclusive interest for the phospholipids LC n-6, n-3 (resident drugs) somewhat insufficient. Moreover when LCn-3 inhibit COX2 which syntethise Prostacycline, Lauric acid is an inducter. The concept of Balance is fundamental, the low fat /high carbohydrate diet following, the advice of the P/S « vulgate » transforming 36 %of the protective A phenotype into the dangerous B phenotype (small LDLs), doubling the vascular risk. Thus the principle of precaution creates an artificial risk in 36 % of the population to improve 10 % of the same population! The concept of Synergy is the third theme of the 21 st century. It became indispensable with the discovery of cotranscriptionnally myristoylated proteins or peptides which play a major rôle at the phospholipidic membranes. In vitro myristic acid increases delta-6 desaturase activity, a key step in unsaturated fatty acid métabolism. In vivo in human, the presence in the diet of myristic acid in sn-2 position, and alpha-linolenic in sn-2 position, at a precise range, is correlated with a rise of DHA in cholesterol esters and in phospholipids. Similarly LCAT activity is synergistically increased in humans by 153 % by the same combination of alpha-linolenic and myristic acid both at the sn-2 position. Opposition-exclusion are the marks of the 20 th century. Competition, balance, synergy are the bases of a new era for lipids in the 21 st century.
Key words: alpha-linolenique in sn-2 position / myristique in sn-2 position / myristoylated proteins / LCAT / anti-Cox2 / phenotype A and B
© John Libbey Eurotext 2005
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