Vegetarians Less Healthy

An issue we've come back to several times here on COTTonLINE is the confusion surrounding correlation. Let's say data shows that when A occurs, B is more likely to occur than would otherwise be the case. We call that a positive correlation. It does not mean that A causes B, or that B causes A, although either is possible. Some other factor C may cause both, or the correlation may be the result of chance alone. Apologies for the boring mini-lecture.

The reason we review correlation is because of an interesting study done by epidemiologists at Medical University of Graz, in Austria. Surveying 1320 individuals, they found the following, cited from the abstract of their article in the journal PLOS One.org:

Our results showed that a vegetarian diet is associated with poorer health (higher incidences of cancer, allergies, and mental health disorders), a higher need for health care, and poorer quality of life. Therefore, public health programs are needed in order to reduce the health risk due to nutritional factors.

This otherwise fascinating finding leads the researchers to an entirely unwarranted conclusion, namely that we need to help poor vegetarians get better nutrition. In truth, they do not know why vegetarians have poorer health, all they know is an association between not eating meat and poorer health.

It is highly likely that poor health leads people to experiment with a vegetarian diet, so that not eating meat may be more often a result of poor health, rather than a cause.