From the study:
"Potential limitations of our results are due to the fact that the survey was based on cross-sectional data. Therefore, no statements can be made whether the poorer health in vegetarians in our study is caused by their dietary habit or if they consume this form of diet due to their poorer health status"
And
"Our results have shown that vegetarians report chronic conditions and poorer subjective health more frequently. This might indicate that the vegetarians in our study consume this form of diet as a consequence of their disorders, since a vegetarian diet is often recommended as a method to manage weight[10] and health"
Don Matesz also addressed a similar paper from this same study:
http://donmatesz.blogspot.com/2014/02/do-flesh-freed-diets-damage-mental.htmlI have addressed vegetarian diets and reverse casualty previously.
"The results of a recent study from the Netherlands illustrates the critical importance of considering reverse causality in research on plant-based diets. The researchers found that 75% of the vegetarian participants with cancer adopted a vegetarian diet after diagnosis, consistent with previous research which found that cancer survivors are highly motivated to adopt a more plant-based diet with the intention of improving poor health."
http://healthylongevity.blogspot.com/2014/02/death-by-veggiephobia.htmlBoth Don and myself have provided references from forward looking studies addressing vegetation diets and heart disease, cancer and mental health. Forward looking studies have an advantage over cross-sectional studies due to a lower risk of being complicated by reverse causality.
