Can Dietary Fatty Acids Influence RA Symptoms

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Rheumatoid Arthritis

Research News

Vol.1, #11: December, 1999

Volume 1.11 © 1999 Mediconsult, Inc. December 1999

Complete Index Other Reviews in This Issue

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Can Dietary Fatty Acids Influence RA Symptoms?

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Paper: Changes in plasma free fatty acid concentrations in rheumatoid arthritis

patients during fasting and their effects upon T-lymphocyte proliferation

Authors: Fraser, DA, et al

Ref: Rheumatology. 1999;38:948-952.

Type: Clinical study

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Summary: For reasons that are not understood, fasting sometimes improves

clinical and laboratory features of rheumatoid arthritis (RA). It is

hypothesized that fasting-induced changes in serum levels of free fatty acids

(FFAs), which may play an immunomodulatory role, might inhibit lymphocyte

function and result in anti-inflammatory effects. This study examined the

effects of fasting and an FFA mixture on in vitro T-lymphocyte proliferation in

RA patients.

A group of 9 patients with active RA followed a 7-day supervised subtotal fast

(less than 50g carbohydrate/day, total energy less than 215 kcal/day). Blood

samples were taken before and after the fast, and the concentration and

composition of plasma FFAs were measured. Based on these findings, an FFA

mixture was made up, including 20% linoleic acid, 43% oleic acid, 10% stearic

acid, and 27% palmitic acid. Mitogen-induced lymphocyte proliferative responses

were measured after co-culture of peripheral blood mononuclear cells (PBMC) from

healthy individuals in the presence of increasing concentrations of this FFA

mixture and in the presence of FFA mixtures where the relative proportions of

fatty acids were altered.

Both the concentration of the FFA mixture and the ratio between the

unsaturated and saturated fatty acids significantly influenced in vitro

lymphocyte proliferation. Unexpectedly, the highest concentrations of the FFA

mixture actually increased, rather than inhibited, the proliferation of

lymphocytes. Altering the amounts of oleic and linoleic acids relative to

stearic and palmitic fatty acids had a potent inhibitory effect on the

proliferation of lymphocytes: substitution of only 50 micromoles of the

saturated fatty acids with 50 micromoles of the unsaturated fatty acids

inhibited proliferation, while substitution of 50 micromoles of the unsaturated

fatty acids with 50 micromoles of the saturated fatty acids reversed the

inhibitory effect.

" Fasting-associated increases in total plasma FFA concentrations did not

inhibit, but rather enhanced, in vitro lymphocyte proliferation, " concluded the

investigators. " An inhibitory effect could only be achieved by manipulating the

balance between the unsaturated and the saturated fatty acids. "

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