Quel sont les bon gras pour la santé?

Bonjour à tous.

Voici les recherches scientifiques dont j’ai parlé.

Bonne écoute et bonne lecture.

httpv://www.youtube.com/watch?v=_a_qc_imYx8&feature=player_embedded

Un acide gras saturé est un acide gras ayant des atomes de carbone totalement saturés en hydrogène (voir figure). Chaque carbone porte le maximum d’hydrogènes possible. On ne peut pas ajouter d’hydrogène à la molécule ; elle est saturée.

Toutes les liaisons entre les carbones sont simples (pas de liaisons doubles carbone-carbone). Les acides gras saturés se trouvent notamment dans les graisses animales (lait, fromage, beurre, viande, lard, etc.) mais aussi dans l’huile de coco et de palme (voir tableau). Ils ont tendance à être solide à température ambiante.

Un acide gras insaturé est un acide gras qui comporte une ou plusieurs double liaisons carbone-carbone.
On parle d’acide gras mono-insaturé lorsqu’il n’y a qu’une seule double liaison et d’acide gras poly-insaturé lorsqu’il y en a plusieurs. Les acides gras poly-insaturés sont notamment d’origine végétale. a plupart des huiles végétales sont riches en acides gras insaturés, notamment les huiles de colza, de maïs et d’olive. Les exceptions sont les huiles de palme et de coco qui sont saturées. Les corps gras riches en acides gras insaturés ont tendance à rester à l’état liquide à température ambiante


Recherche 1

Mitochondrion. 2010 Aug 4.
Dietary fatty acids and oxidative stress in the heart mitochondria.
Lemieux H, Bulteau AL, Friguet B, Tardif JC, Blier PU.
Laboratoire de Biologie Intégrative, Université du Québec, Rimouski (Québec), Canada.
Abstract
Our study compared the effects of different oils on oxidative stress in rat heart mitochondria, as well as on plasma parameters used as risk factors for cardiovascular disease. The rats were fed for 16weeks with coconut, olive, or fish oil diet (saturated, monounsaturated, or polyunsaturated fatty acids, respectively).The cardiac mitochondria from rats fed with coconut oil showed the lowest concentration of oxidized proteins and peroxidized lipids. The fish oil diet lead to the highest oxidative stress in cardiac mitochondria, an effect that could be partly prevented by the antioxidant probucol. Total and LDL cholesterols decreased in plasma of rats fed fish oil, compared to olive and coconut oils fed rats.A diet enriched in saturated fatty acids offers strong advantages for the protection against oxidative stress in heart mitochondria.

Recherche 2

Lipids. 2009 Jul;44(7):593-601. Epub 2009 May 13.
Effects of dietary coconut oil on the biochemical and anthropometric profiles of women presenting abdominal obesity.
Assunção ML, Ferreira HS, dos Santos AF, Cabral CR Jr, Florêncio TM.
Faculdade de Nutrição, Universidade Federal de Alagoas, Maceió, AL 57072-970, Brazil.
Abstract
The effects of dietary supplementation with coconut oil on the biochemical and anthropometric profiles of women presenting waist circumferences (WC) >88 cm (abdominal obesity) were investigated. The randomised, double-blind, clinical trial involved 40 women aged 20-40 years. Groups received daily dietary supplements comprising 30 mL of either soy bean oil (group S; n = 20) or coconut oil (group C; n = 20) over a 12-week period, during which all subjects were instructed to follow a balanced hypocaloric diet and to walk for 50 min per day. Data were collected 1 week before (T1) and 1 week after (T2) dietary intervention. Energy intake and amount of carbohydrate ingested by both groups diminished over the trial, whereas the consumption of protein and fibre increased and lipid ingestion remained unchanged. At T1 there were no differences in biochemical or anthropometric characteristics between the groups, whereas at T2 group C presented a higher level of HDL (48.7 +/- 2.4 vs. 45.00 +/- 5.6; P = 0.01) and a lower LDL:HDL ratio (2.41 +/- 0.8 vs. 3.1 +/- 0.8; P = 0.04). Reductions in BMI were observed in both groups at T2 (P < 0.05), but only group C exhibited a reduction in WC (P = 0.005). Group S presented an increase (P < 0.05) in total cholesterol, LDL and LDL:HDL ratio, whilst HDL diminished (P = 0.03). Such alterations were not observed in group C. It appears that dietetic supplementation with coconut oil does not cause dyslipidemia and seems to promote a reduction in abdominal obesity.

Recherche 3

Am J Clin Nutr. 2003 Sep;78(3):370-5.
Effect of different forms of dietary hydrogenated fats on LDL particle size.
Mauger JF, Lichtenstein AH, Ausman LM, Jalbert SM, Jauhiainen M, Ehnholm C, Lamarche B.
Institute on Nutraceuticals and Functional Foods, Laval University, Quebec, Canada.
Abstract
BACKGROUND: Dietary trans fatty acids (FAs), which are formed during the process of hydrogenating vegetable oil, are known to increase plasma LDL-cholesterol concentrations. However, their effect on LDL particle size has yet to be investigated.
OBJECTIVE: We investigated the effect of trans FA consumption on the electrophoretic characteristics of LDL particles.
DESIGN: Eighteen women and 18 men each consumed 5 experimental diets in random order for 35-d periods. Fat represented 30% of total energy intake in each diet, with two-thirds of the fat in the form of semiliquid margarine (0.6 g trans FAs/100 g fat), soft margarine (9.4 g trans FAs/100 g fat), shortening (13.6 g trans FAs/100 g fat), stick margarine (26.1 g trans FAs/100 g fat), or butter, which was low in trans FAs (2.6 g trans FAs/100 g fat) but rich in saturated fat. LDL particle size and distribution were characterized by nondenaturing, 2-16% polyacrylamide gradient gel electrophoresis.
RESULTS: Relative to the LDL particle size observed after consumption of the butter-enriched diet, LDL particle size decreased significantly and in a dose-dependent fashion with increasing amounts of dietary trans FAs (P < 0.001). Cholesterol concentrations in large (> 260 A) and medium-sized (255-260 A) LDL particles also increased proportionately to the amount of trans FAs in the diet.
CONCLUSION: Consumption of dietary trans FAs is associated with a deleterious increase in small, dense LDL, which further reinforces the importance of promoting diets low in trans FAs to favorably affect the lipoprotein profile.

LE « LIPID HYPOTHESIS »

Recherche: Harvard School of Public Health
“Types of Dietary Fat and Risk of Coronary Heart Disease: A Critical Review”
(Frank B. Hu, et al., Journal of the American College of Nutrition, Vol. 20, 1, 5-19 (2001))
Cet article résume bien les fondations en ruine du ‘’Lipid Hypothesis’’:
Seulement deux recherches ont démontré “une association significative positive entre la quantité de gras saturé ingéré et le risque d’une maladie coronarienne”; plusieurs autres recherches n’ont pu trouver une simple association.
De plus, seulement une recherche a réussi à démontrer ‘’une association significative inverse entre l’ingestion des gras polyinsaturés et les maladies coronariennes.’’
Traduction : La quantité de gras saturé présente dans une diète n’a probablement aucune incidence sur le risque de se retrouver avec une maladie du cœur, et les preuves supportant l’augmentation de la quantité des gras polyinsaturés en réduisant les risques sont presque inexistantes.
Pour ce qui est des dangers du cholestérol, l’article démontre « une association positive faible et non significative entre le cholestérol ingéré et les maladies coronariennes. »

L’huile de coco

Les gras insaturés en excès

Favorise le bon fonctionnement de la glande thyroïde
Accélère le métabolisme
Favorise la respiration cellulaire car elle ne s’oxyde pas dans le corps à haute température
Puissants antioxydant
Anti-inflammatoire
Renforce le système immunitaire
Protège contre le cancer
Stabilise les taux de cholestérol

Affectent la glande thyroïde
Affectent la respiration cellulaire
Les graines des plantes bloquent les enzymes digestives (défense naturelle)
S’oxydent facilement à la chaleur favorisant ainsi la prolifération des radicaux libres dans l’organisme (s’attaque à l’ADN)
Affaiblissent le système immunitaire et causent : le vieillissement, l’inflammation, les caillots de sang, les problèmes de foie, le cancer, augmente les chances de diabète.

***Exemples tirés de William Woylan. Tout droits réservés.