Reduction of serum cholesterol in hypercholesterolemic rats by Guar gum

In the previous issue of AJP an article under the title of «Reduction of serum cholesterol in hypercholesterolemic rats by Guar gum» was published (Samarghandian et al., 2011), which raised some question to be discussed more. In the “Animal Experimental Procedure” section, for induction of hypercholesterolemia, rats have been fed a chow supplemented with 18% corn oil. This diet is absolutely a high fat diet but it could not induce hypercholesterolemia because cholesterol is an animal or fungus steroid and oils with plant origin have no or little amount of cholesterol (Horton et al., 2002, Behrman et al. 2005). Therefore plant oils could not increase cholesterol levels in rats and are not used routinely for induction of hypercholesterolemia. Authors have cited five studies in order to support their protocol (Pratchayasakul et al., 2011, Guo et al., 2011, Bajerska et al., 2011, Suanarunsawat et al., 2010, Zhao et al., 2011). However in all cited references (except for Zhao et al that has not been listed in references list), animal fat such as lard with or without corn oil were used as the hypercholesterolemic diet that is not used in the current study. It is clear that authors and coworkers have not followed the exact procedure mentioned in the articles they cited, therefore elevation of serum total cholesterol levels mentioned in the figure 2 (results section) may not be possible. In my opinion this can be a typing error, but there is not any animal fat as an ingredient of the diet of hypercholestrolemic group (control) as detailed in table 2 either. In conclusion the exact model of hypercholesterolemia has not been produced by the mentioned procedure and none of the provided results in the remaining paper could be accurate. However there is an article cited in the body of the manuscript (Zhao et al., 2011) which has not been listed in the references section. In my opinion the above-mentioned issues warrant further clarification by the authors.