Conjugated Linoleic Acid Supplementation Increased Insulin Resistance

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Hi folks:

I realize there are studies apparently showing benefits to be derived

from conjugated linoleic acid (CLA). This is just to record there

may be another side to the story:

" Unexpectedly ......... CLA increased insulin resistance (19%; P <

0.01) and glycemia (4%; P < 0.001) and reduced HDL cholesterol (-4%;

P < 0.01) compared with placebo " .

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" Treatment with dietary trans10cis12 conjugated linoleic acid causes

isomer-specific insulin resistance in obese men with the metabolic

syndrome.

Riserus U, Arner P, Brismar K, Vessby B.

Department of Public Health and Caring Sciences/Geriatrics, Uppsala

University, Uppsala, Sweden. ulf.riserus@...

OBJECTIVE: Conjugated linoleic acid (CLA) is a group of dietary fatty

acids with antiobesity and antidiabetic effects in some animals. The

trans10cis12 (t10c12) CLA isomer seems to cause these effects,

including improved insulin sensitivity. Whether such isomer-specific

effects occur in humans is unknown. The aim of this study was to

investigate whether t10c12 CLA or a commercial CLA mixture could

improve insulin sensitivity, lipid metabolism, or body composition in

obese men with signs of the metabolic syndrome. RESEARCH DESIGN AND

METHODS: In a randomized, double-blind controlled trial, abdominally

obese men (n = 60) were treated with 3.4 g/day CLA (isomer mixture),

purified t10c12 CLA, or placebo. Euglycemic-hyperinsulinemic clamp,

serum hormones, lipids, and anthropometry were assessed before and

after 12 weeks of treatment. RESULTS: Baseline metabolic status was

similar between groups. Unexpectedly, t10c12 CLA increased insulin

resistance (19%; P < 0.01) and glycemia (4%; P < 0.001) and reduced

HDL cholesterol (-4%; P < 0.01) compared with placebo, whereas body

fat, sagittal abdominal diameter, and weight decreased versus

baseline, but the difference was not significantly different from

placebo. The CLA mixture did not change glucose metabolism, body

composition, or weight compared with placebo but lowered HDL

cholesterol (-2%; P < 0.05). CONCLUSIONS: These results reveal

important isomer-specific metabolic actions of CLA in abdominally

obese humans. A CLA-induced insulin resistance has previously been

described only in lipodystrophic mice. Considering the use of CLA-

supplements among obese individuals, it is important to clarify the

clinical consequences of these results, but they also provide

physiological insights into the role of specific dietary fatty acids

as modulators of insulin resistance in humans.

Publication Types:

Clinical Trial

Randomized Controlled Trial

PMID: 12196420 [PubMed - indexed for MEDLINE] "