The Influence of Fat on Immune Function

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Posted: Sat Apr 03, 2004 8:07 pm Post subject: The Influence of Fat on Immune

Function

 

The influence of fat on the immune function has

only recently come under serious study. It is known that

polyunsaturated fatty acids, particularly linoleic acid, are

required for optimal functioning of the immune system.

 

High level of fats, impact negatively on the immune system and

decrease its ability to cope with cancer tumours, allergies,

infections by microbial organisms and both thymic-dependent and

thymic-independent antigens.

Immune responses can thus be enhanced or depressed,depending on the

concentration of dietary lipids.

It has been found that high-fat diets consistently depress

resistance to malaria and tuberculosis in rats, and respiratory

infections in chickens, but the same seems to be true for humans.

Lower respiratory tract infections in infants, for example, are

significantly more common in obese infants than in non-obese

infants, and in one third of obese infants, adolescents and adults

studied there was impairment of cell-mediated immune responses.[ii]

The mechanism whereby fats interfere with the

body's ability to combat the growth of cancerous tumours has also

been investigated.

A subpopulation of T-lymphocytes, known as natural killer cells,

specifically react to destroy tumour cells before they can

proliferate.

Recently it has been found that diets high in polyunsaturates,

particularly those rich in n-6 fatty acids

(e.g. linolenic acid),

impact negatively on the ability of these killer cells to seek out

and destroy cancer cells.

Three types of blood cells are associated with the

immune response and secrete substances that effect B- and T-cell

activity in many ways.

Examples of lymphokines are interferon and interluekon 1, of which interferon

stimulates T-cell proliferation and interleukon 1 stimulates a broad range of

cells, including the

natural killer cells, neutrophils, and B- and T-lymphocytes.

T-cells do not produce antibodies which combine with antigens,

rendering them inactive and enabling phagocytes to engulf the

invaders.

These substances, including prostaglandin, which are produced from the essential

fatty acids, linolenic and linoleic acid.

Those prostaglandins that have a relaxing, anti-flammatory

and anti-clotting effect are generally formed from alpha-linolenic

acid whilst those with the opposite effect are manufactured from

linoleic acid and arachidonic acid (AA).

More than one hundred different prostaglandins have been identified, and they

promote or inhibit basic bodily functions such as fever, blood clotting,

vasodilation

and constriction, stress, allergy responses, membrane permeability,

eye pressure, inflammation, steroid production, appetite, fat

metabolism and the functioning of the immune system.[iv]

When prostaglandins occur in a balanced relationship they tend to relax

arteries and reduce blood pressure as well as slow down tumour

formation and decrease platelet aggregation, thus lowering the risk

of thrombus formation.

If the balance of prostaglandins is,however, disturbed then the opposite effects

are achieved.

It is interesting to note that tumour cells produce large amounts of the

prostaglandin PGE2 and cancer patients can produce four times the

normal amount of this prostaglandin.

It has an immunorepressive effect and leucotriene B4 is a potent chemotactic and

chemokinetic agent.[v]

The correct balance of fats in the diet, inclusive of the essential fatty acids,

can provide a substantial anticarcinogenic effect.[vi]

A whole-food diet, which includies organic whole grains, legumes, seeds and nuts

will provide the ideal blend of fatty acids and total fat composition to ensure

the optimal

fuctioning of the immune system.

Fatty Acid Profiles of Foods High in Beneficial Monounsaturated Fats

Hazelnuts-highest in monounsaturated fats at 82%

Avocadoes- monounsaturated fat content at 80%

Sunflower,mono-75%

Sunflower,mono-75%

Olive Oil-73%

Almonds- 72%

Pistachios-72%

Sesame-60%

Peanuts-56%

Source: Resnicow, K., Barone, J., Engle, A., Mliler, S., Haley,

N.C., Fleming, D., Wynder, E. 1991. Diet and serum lipids in vegan

vegetarians: A model for risk reduction. J. Am. Diet. Assoc. 91:447-

453

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www.amazingdiet.org

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References:

Maki, P.A., Newberne, P.M. 1992. Dietary lipids and immune

function. J.Nutr. 122:610-614.

[ii] Chandra, R.K. 1981. Immune response in overnutrition. Cancer

Res. 41:3795-3796.

[iii] Byman, L.D. 1991. Dietary fat and natural killer cell

function. Nutrition Today. Jan/Feb 1991, pp.31-36.

[iv] Lee, L.B. 1976. " Prostaglandins and blood pressure control "

(Combined clinical and basic science seminars) Am. J. of medicine

61:681.

[v] Jonnalagagadda, S.S., Mustad, V.A., Yu, S., Etherton, T.D., Kris-

Etherton, P.M. 1996. Effects of individual fatty acids on chronic

diseases. Nutrition Today. 31 (3) May/June 1996.

[vi] Barone, J., Hebert, J.R., Reddy, M.M. 1989. Dietary fat and

natural killer cell activity. Am.J.Clin.Nutri. 50:103-106.

Hebert, J.R., Barone, J., Reddy, M.M., Backlund, J.Y. 1990.

Natural killer cell activity in a longitudinal dietary fat

intervention trial. Clin.Immunol.Immunopathol. 54:103-1

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