Oméga-3:
faits - thérapeutique et posologie
Maladie
de Crohn: quantité selon les valeurs de référence
DACH
Les journaux spécialisés ont consacré
aux oméga-3 les articles suivants. La liste de ces publications
a été établie en avril 2003 et n'aspire nullement
à l'exhaustivité. Source: MEDLINE.
Ces données servent de référence pour les
médecins et les thérapeutes, de sorte à déterminer
la dose thérapeutique dans le cadre de la maladie de
Crohn.
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Therapeutic
efficacy of N-3 polyunsaturated fatty acid in experimental Crohn's
disease.
Shoda R: Division of Gastroenterology,
International Medical Center of Japan, Tokyo, Japan; Matsueda K,
Yamato S, Umeda N
J Gastroenterol 1995 Nov 30 Suppl 8:98-101
Abstract
We investigated the therapeutic efficacy of n-3 polyunsaturated
fatty acids (PUFAs) on trinitro-benzene sulfonic acid (TNBS)-induced
colitis in the rats, which condition is considered an experimental
Crohn's disease (CD). In rats with TNBS-induced colitis, feeding
with an elemental diet (ED) plus 2% n-3 PUEA-rich perilla oil
significantly suppressed plasma leukotriene (LT) B4 and ulcer
index compared to that in rats fed with ED plus 2% n-6 PUFA-rich
safflower oil (34.2 +/- 12.3 s 63.8 +/- 13.2 pg/ml and 8.8 +/-
12.1 vs 66.4 +/- 33.1, P < 0.01, respectively). Moreover, the
plasma LTB4 and the ulcer index were significantly correlated
(P < 0.05). Feeding with ED plus 2% alpha-linolenic acid (A-LA)-rich
vegetable oil significantly reduced plasma LTB4 and colonic weight
compared to that in rats fed with ED plus 2% eicosapentaenoic
acid (EPA)/docosahexaenonic acid (DHA)-rich fish oil in this model
(61.6 +/- 10.5 vs 85.0 +/- 20.9 pg/ml and 0.83 +/- 0.13 vs 0.96
+/- 0.08g, P < 0.05, respectively). This study suggested that
dietary fat manipulation with perilla oil can reduce colonic damage
and that this is correlated with the suppression of plasma LTB4.
The therapeutic efficacy of A-LA in controlling intestinal
inflammation in experimental CD may be superior to that of EPA
and DHA.
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n-3
fatty acids and the immune system in autoimmunity.
Ergas D: Department of Internal Medicine
B, Kaplan Medical Center, Rehovot, Israel; Eilat E, Mendlovic S,
Sthoeger ZM
Isr Med Assoc J 2002 Jan 4:34-8
Abstract
In short-term studies, both in animals and in humans, fish
oil seems to exert anti-inflammatory effects. However, these effects
may vanish during long-term treatment. There is a possibility
that in autoimmune diseases, supplementation of dietary n-3 fatty
acids might lead to a decrease in the number of autoreactive T
cells via apoptosis, as demonstrated in (NZBXNZW) F1 lupus mice
[40]. Thus, the "fade away" effect might be due to regrowth of
pathogenic autoreactive cells. In animal models of autoimmune
diseases, diets high in n-3 fatty acids from fish oil increase
survival and reduce disease severity in spontaneous autoantibody-mediated
disease, while n-6 linoleic acid-rich diets appear to increase
disease severity. The situation in human disease is probably more
complex. Some of the discrepancy between studies can be attributed
to methodologic problems. The effect of fish oil is dose, time
and disease-dependent. Since the anti-inflammatory effects depend
on the balance between n-3 and n-6 fatty acids, the relative proportion
of EPA and DHA and possibly co-treatment with dietary vitamin
E, the dose/effect ratio may vary between individuals. Furthermore,
some animal studies demonstrating efficacy used very high doses
that may be incompatible with human consumption. It seems that
fish oil is only mildly effective in acute inflammation. In those
chronic inflammatory disorders where it was found to be effective,
several weeks are necessary to exhibit results. Yet, this
mild anti-inflammatory effect, possibly through downregulation
of pro-inflammatory cytokine production, leads to striking therapeutic
improvement in critically ill patients.
Fish oil supplementation seems advantageous especially in acute
and chronic disorders where inappropriate activation of the immune
system occurs. Fish oil has only a mild effect on active
inflammation of diseases such as rheumatoid arthritis, SLE and
Crohn's disease, but it could prevent relapse (in some of the
studies). In diseases where the inflammation is mild, such as
IgA nephropathy, fish oil may slow or even prevent disease progression.
The above could explain the observation in some populations of
a decreased incidence of inflammatory and autoimmune diseases
[3], since the constant consumption of n-3 fatty acids could suppress
any autoreactive (or hyper-reactive) T cells. However, if there
is already an existing disease, increased consumption might not
be beneficial over a long period. Therefore,
the use of n-3 fatty acids can be recommended to the general healthy
population, not only to prevent atherosclerosis but possibly also
to reduce the risk of autoimmunity.
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Essential
fatty acids in health and chronic disease.
Simopoulos AP: Center for Genetics,
Nutrition and Health, Washington, DC
Am J Clin Nutr 1999 Sep 70:560S-569S
Abstract
Human beings evolved consuming a diet that contained about
equal amounts of n-3 and n-6 essential fatty acids. Over the
past 100-150 y there has been an enormous increase in the consumption
of n-6 fatty acids due to the increased intake of vegetable oils
from corn, sunflower seeds, safflower seeds, cottonseed, and soybeans.
Today, in Western diets, the ratio of n-6 to n-3 fatty acids
ranges from approximately 20-30:1 instead of the traditional range
of 1-2:1. Studies indicate that a high intake of n-6 fatty
acids shifts the physiologic state to one that is prothrombotic
and proaggregatory, characterized by increases in blood viscosity,
vasospasm, and vasoconstriction and decreases in bleeding time.
n-3 Fatty acids, however, have antiinflammatory, antithrombotic,
antiarrhythmic, hypolipidemic, and vasodilatory properties. These
beneficial effects of n-3 fatty acids have been shown in the secondary
prevention of coronary heart disease, hypertension, type 2 diabetes,
and, in some patients with renal disease, rheumatoid arthritis,
ulcerative colitis, Crohn disease, and chronic obstructive pulmonary
disease. Most of the studies were carried out with fish oils [eicosapentaenoic
acid (EPA) and docosahexaenoic acid (DHA)]. However, alpha-linolenic
acid, found in green leafy vegetables, flaxseed, rapeseed, and
walnuts, desaturates and elongates in the human body to EPA and
DHA and by itself may have beneficial effects in health and in
the control of chronic diseases.
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