A new study says that vegetarians are more likely to have a poorer diet and a poorer quality of life. In fact, it says they’re more likely to get cancer, develop allergies and suffer mental health problems. Is this study reliable?
The study, conducted by the Medical University of Graz in Austria, and published this month in the peer reviewed journal PLOS One, attempted to utilize data from the Austrian Health Interview Survey to examine what effects a vegetarian diet appears to be having compared to that of a meat-eating diet.
For the purposes of this study, and this is important, the researchers characterized a vegetarian diet as one with a low consumption of saturated fat and cholesterol due to their increased intake of fruits, vegetables and whole-grains. It was not characterized as one where the respondent didn’t eat any meat or animal products. In this case, the group included everything from vegans all the way to vegetarians who ate eggs and, crucially, white meat.
In total, the study involved 1,320 subjects (55 percent female) from Austria who self reported their dietary habits. The data was collected from a wider survey sampling the years 2006/2007. Taking that sample, the researchers matched people according to their age, sex and what’s known as their socioeconomic status or, in very simple terms, how wealthy they are. Within that sample there were 330 so-called vegetarians (again, some did eat meat), 330 people who said they balanced eating meat with a diet rich in vegetables and fruits, 300 so called “normal” eaters, and 330 who described their dietary habits as heavy in meat.
The researchers then compared the groups using a range of different health metrics. Perhaps unsurprisingly, vegetarians had lower BMIs than the rest of the groups, especially the meat eaters. They also had lower alcohol consumption rates and had a decreased likelihood of urinary incontinence than heavy meat eaters (2 percent vs 3 percent-6 percent). They didn’t differ on activity levels or smoking rates, though. If the study holds water, that’s where the good news for the so-called vegetarians ends.
The research shows that among its groups, the “vegetarians” were more likely to self-report poorer health and physical disability. They were also more likely to say they had more chronic diseases overall. In terms of specific diseases, a few significantly more common ailments among vegetarians included a 31 percent elevation in allergies, as much as a 4 percent increase in cancer rates, and as much as a 5 percent increase in “mental illness” rates (meaning: anxiety and depression).
The research also found some curious things. For instance, it says that “vegetarians” in its sample were less likely to get vaccinated than the so-called carnivore groups, and were less likely to have preventative check-ups than those who ate both meat and vegetables. Over all, vegetarians reported having a lower quality of life and poorer social relationships.
The researchers are billing this as an important look into the vegetarian diet and an examination of whether it is true that a vegetarian diet, or the Mediterranean diet, for that matter, really does offer health benefits over meat eating. A lot of research has found strong associations with positive health outcomes. But not this research.
Say the researchers: “Our study has shown that Austrian adults who consume a vegetarian diet are less healthy (in terms of cancer, allergies, and mental health disorders), have a lower quality of life, and also require more medical treatment.”
In case you’re getting rather anxious because of this news, and the fact that the mainstream media has appeared to take this research and run with it without bothering to report on its limitations, it is worth our time explaining that this study has some serious problems: chiefly, that it says absolutely nothing about vegetarians at all.
As noted above, the study didn’t actually use any kind of firm definitions for how it broke people down into their dietary groups, and the fact that vegetarians within that sample ate meat means, simply, that the group included people that we wouldn’t actually class as vegetarian, at least in the accepted sense of the word. Even among those who didn’t eat meat, their diets may have differed so much so as to make the study’s term of “vegetarian” almost meaningless. That’s a major flaw.
There is at least one other serious problem with this study and that is that there appears to have been no control on how long someone had been a “vegetarian.” Why does this matter? Consider the following scenario: You are diagnosed with having a moderate to serious health complaint. During the course of your treatment you are asked to look at your lifestyle and make improvements where you can. One of the areas you look into is your diet. Based on the information you have been given about healthy diets, you therefore take on a predominantly vegetarian lifestyle to try to improve your health. However, you still have an underlying health condition.
That’s caused reverse causality: the disease (whatever it is, in this case depression, cancer or an allergy) led the person to becoming vegetarian, not, as the researchers seem to be implying, the vegetarian diet having caused the ailments screened for in this study.
There’s another issue about definitions, and that comes down to how the researchers looked into the 18 specific diseases it tracked among the participants. None of the diseases were medically verified and there seems to have been no control to gauge the severity of any of the ailments and whether in fact they met diagnostic criteria at all. That is concerning because, even if we were to accept that vegetarians in the sample were more likely to get certain diseases, say depression, how did the study rate depression? How severe was that depression? And how did the most severe kinds break down by diet? These are all questions that the study has left unanswered and ones that really did need to at least be approached if the research was to have significant results.
There are some more mundane but no less valid caveats that undercut the study: the small sample size for each group, the self-reporting, the fact that it sampled respondents from only one country, and that the study doesn’t appear to have used any strict measures in how it assessed quality of life and other health variables, among others.
In the face of these serious criticisms, the researchers have defended their work. The Independent quotes researcher Nathalie Burkert as acknowledging some of these limitations, but sticking with the assertion that the research has merit, saying: “We did find that vegetarians suffer more from certain conditions like asthma, cancer and mental illnesses than people that eat meat as well, but we cannot say what is the cause and what is the effect. There needs to be further study done before this question can be answered.”
Indeed, there will need to be more research — and it will have to be much more thorough than this in order to tell us anything about how a vegetarian diet compares to a meat eating diet in terms of health outcomes. Fortunately, there are a number of such studies with far more rigorous research methods that demonstrate a vegetarian lifestyle may carry certain benefits. At the very least, there is a lot of evidence to show that a diet rich in fruit and vegetables can increase health, well-being and possibly even lifespan.
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