FIsh oil and immune system

[Guest guest]

I found this article while looking for information on omega 3 use and

immune system. I think this is something all should take note of. We

all need to examine the good and bad of anything we undertake.

Sept. 20, 2001

>>

> MU RESEARCHER CAUTIONS AGAINST HIGH DOSES OF FISH OIL SUPPLEMENTS

> Large Amounts Might Compromise Disease Resistance

>

> COLUMBIA, Mo. -- Known as a cholesterol reducer and a protective

agent

> for the heart, Omega-3 fatty acids -- also known as fish oils --

have

> received much attention from scientists in the past two decades.

> However, for all their benefits, a University of Missouri-Columbia

> researcher recommends that those with weakened immune systems

should

> avoid large doses of fish oil.

>

> " When the benefits of fish oil were first recognized, they were

> thought to be a 'magic bullet,' " said Fritsche, associate

> professor of animal and nutritional sciences. " However, the

influence

> Omega-3 fatty acids have on immune cell function indicates that

under

> some circumstances, disease resistance is impaired. "

>

> Fritsche has studied Omega-3 fatty acids since 1982. Interest in

the

> oils began after researchers discovered that Greenland Eskimos had

a

> low incidence of death caused by cardiovascular diseases, despite

the

> fact that their diet of marine fish was high in fat and

cholesterol.

> Soon after this finding, other health benefits started to be

> uncovered.

>

> " Among the benefits researchers found was that, in large amounts,

> Omega-3s had an anti-inflammatory effect, " he said. " While this in

> itself can be beneficial to those suffering from inflammatory

diseases

> such as arthritis, our research indicates that those with weakened

> immune systems, such as the elderly, could be at risk if they are

> taking large amounts of fish oil for therapeutic reasons. "

>

> Fritsche explained that inflammation plays a key role in the body's

> defense against infection. It acts like an alarm, notifying the

immune

> system that an infectious agent, such as bacteria, has been

detected.

> In addition, inflammation is designed to help slow the spread of

the

> infection through the body.

>

> In his research, Fritsche studied how mice responded to bacterial

> infection after being fed diets containing varied levels of two

> specific Omega-3 fatty acids. He found that mice fed diets

containing

> fish oils responded slower to infection and were more likely to die

> from the infection than mice fed diets containing no fish oil.

>

> " It appears fish oil causes a decrease in the production of a

molecule

> that helps to shape the immune response, but we don't know what the

> long-term consequences are to the immune system, " he said. " Our

goal

> now is to determine why and how this impairment of the immune

system

> occurs. If we can figure out the mechanisms behind it, we might be

> able to prevent it. "

>

> -30-

>

Fish Oil Feeding Delays Influenza Virus Clearance and Impairs

Production of Interferon- and Virus-Specific Immunoglobulin A in the

Lungs of Mice1,2

M. Byleveld*3, Gerald T. Pang, L. Clancy and C. K.

*

* Discipline of Nutrition and Dietetics and Discipline of Immunology

and Microbiology, University of Newcastle, NSW, 2308, Australia

3To whom correspondence should be addressed.

Ingestion of fish oil can suppress the inflammatory response to

injury and may impair host resistance to infection. To investigate

the effect of a diet containing fish oil on immunity to viral

infection, 148 BALB/c mice were fed diets containing 3 g/100 g of

sunflower oil with either 17 g/100 g of fish oil or beef tallow for

14 d before intranasal challenge with live influenza virus. At d 1

and d 5 after infection, the mice fed fish oil had higher lung viral

load and lower body weight (P < 0.05). In addition to the greater

viral load and weight loss at d 5 after infection, the fish oil group

consumed less food (P < 0.05) while the beef tallow group was

clearing the virus, had regained their preinfection weights and was

returning to their preinfection food consumption. The fish oil group

had impaired production of lung interferon- (IFN-), serum

immunoglobulin (Ig) G and lung IgA-specific antibodies (all P < 0.05)

although lung IFN-/ß and the relative proportions of bronchial lymph

node CD4+ and CD8+ T lymphocytes did not differ between groups after

infection. The present study demonstrates a delay in virus clearance

in mice fed fish oil associated with reduced IFN- and antibody

production and a greater weight loss and suppression of appetite

following influenza virus infection. However, differences observed

during the course of infection did not affect the ultimate outcome as

both groups cleared the virus and returned to preinfection food

consumption and body weight by d 7.

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© 2002 The American Society for Nutritional Sciences J. Nutr.

132:3566-3576, December 2002

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Critical Review

(n-3) Fatty Acids and Infectious Disease Resistance

Michele and L. Fritsche1

Departments of Nutritional Sciences, Animal Sciences, and Molecular

Microbiology and Immunology, University of Missouri, Columbia, MO

65211

1To whom correspondence should be addressed. Email:

FritscheK@....

ABSTRACT

TOP

ABSTRACT

INTRODUCTION

Infectious disease resistance

(n-3) PUFA and the...

(n-3) PUFA and host...

(n-3) PUFA and gram-negative...

(n-3) PUFA and gram-positive...

(n-3) PUFA and bacteria...

(n-3) PUFA and viral...

(n-3) PUFA and parasitic...

Conclusions

LITERATURE CITED

The current view of the manner in which (n-3) polyunsaturated fatty

acids (PUFA) affect the immune system is centered on their ability to

alter cytokine production and secondarily to diminish eicosanoid

biosynthesis. The purpose of this article is to review the evidence

that (n-3) PUFA affect host infectious disease resistance. Although

there have been a few human clinical trials involving (n-3) PUFA and

human infectious disease, the data are equivocal and the study

designs confounded by the simultaneous inclusion of other

immunonutrients (i.e., arginine and nucleotides) with the (n-3) PUFA.

Thus, this review focuses on animal feeding trials that include an in

vivo challenge of the host with a live infectious agent. Host

survival and pathogen clearance are the most common end points

measured in these studies. The data suggest that (n-3) PUFA can both

improve and impair host resistance to a number of pathogens. However,

the data are still quite limited in breadth and depth. For those

pathogens for which data exist, the number of published studies in

general does not exceed two or three. Emphasis is placed on defining

important microbiological and immunological differences in various

host-pathogen interactions that might help explain the incongruity in

the findings published to date. The authors believe that direct

examination of (n-3) PUFA on human infectious disease resistance is

warranted.

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