The mechanism behind increasing HDL is not totally understood but it seems to be done in various ways. Niacin increases apolipoprotein A1 levels due to anti catabolic effects resulting in higher reverse cholesterol transport. It also inhibits HDL hepatic uptake, down-regulating production of the cholesterol ester transfer protein (CETP) gene.  Finally, it stimulates the ABCA1 transporter in monocytes and macrophages and up-regulates peroxisome proliferator-activated receptor γ results in reverse cholesterol transport. 
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WHO is continuing these studies in collaboration with the United Nations Environmental Programme (UNEP), in the context of the ‘Stockholm Convention’, an international agreement to reduce emissions of certain persistent organic pollutants (POPs), including dioxins. A number of actions are being considered to reduce the production of dioxins during incineration and manufacturing processes. WHO and UNEP are undertaking global breast milk surveys, including in many developing countries, to monitor trends in dioxin contamination across the globe and the effectiveness of measures implemented under the Stockholm Convention.