Very good question! I'm also trying to interpret metabolomic data and there are not that many tools available (look this website for a more comprehensive list http://www.metabolomicscentre.ca/software). I'm not an expert in the field, but metaboanalyst seems to be the best or among the best tools. I also tried IPA that has also metabolic analysis tool, but it's not free and has not all the options Metaboanalyst has. The good of IPA is that it usually refers back to papers for whatever connections it gives you. But with my very little experience I prefer Metaboanalyst.