Schaut mal was auf wiki steht:

Studies on CLA in humans shows a tendency for reduced body fat[4] particularly abdominal fat, changes in serum total lipids and decreased whole body glucose uptake. The maximum reduction in body fat mass was achieved with a 3.4 g daily dose[5]. CLA supplementation has, however, been shown to increase C-reactive protein levels and to induce oxidative stress[6] and to reduce insulin sensitivity and increase lipid peroxidation.[7]

Possible side effects of CLA in humans

There are concerns that the use of CLA by overweight people may actually cause insulin resistance, leading to an increased risk for developing diabetes.[8]. [1]

A recent study (2006) conducted in mice by the US Department of Agriculture gives account of some highly concerning effects of CLA: it can dramatically induce essential fatty acid redistribution (DHA and AA) in various organ tissues. The same study raises the concern that it might pose significant risks, especially regarding cardiovascular health and inflammatory diseases. DHA content in heart tissue for instance was found to be reduced by no less than 25% by certain CLA isomers, while spleen DHA increased 6-fold and spleen AA was reduced to only 5% of its normal levels in that tissue. [9]. Another study (2005) of CLA supplementation of hatching chicks showed high mortality and low hatchability rate among the CLA-supplemented groups, and also a decrease in brain DHA levels of CLA-incubated chicks. [2]
http://en.wikipedia.org/wiki/Conjugated_linoleic_acid

C-reaktives Protein sollte niedrig sein und steht meines Wissens nach mit dem Herzinfarktrisiko in Zusammenhang.