“Vegetarians Found to Have More Cancer, Allergies, and Mental Health Disorders.” That’s the alarming headline from a website called Science 2.0 (which also declares vegetarianism to be a “fad diet.”)
They are referring to new research in Austrian vegetarians published in the journal PLoS One. The study compared self-reported health among 1,320 subjects who were divided into groups according to the type of diet they consumed. Although the media jumped all over it, there has been plenty of more thoughtful discussion among nutrition experts about the shortcomings of this research.
The researchers themselves recognized some of these shortcomings as well and they outlined them in the discussion section of the paper. Here are some of the problems that have been noted.
- It’s a cross-sectional study. That means it looked at habits and disease rates at one point in time. We don’t know how long any of the subjects were following their diet or why. Many people who go vegetarian do so because they are experiencing health problems.
- The meat-eaters in this study (annoyingly referred to as “carnivores”) were divided into three groups according to whether they ate lots of fruits and vegetables and whether they were high or low meat consumers. Vegans, vegetarians and pesco-vegetarians, on the other hand, were all lumped into one group. So we get a little bit of insight about what type of diet the omnivores were eating, but none at all about the diverse habits among vegetarians.
- The subjects were simply asked what dietary group they belonged to, and they were not given any clear guidelines about this. That is, they could simply declare themselves to be meat-eaters who eat a lot of fruits and vegetables. Since there was no actual dietary assessment, there was no way to know what these subjects were really eating.
There may also have been problems with the way the subjects were matched. Admittedly, this is not something I would have picked up on, but Paul Appleby, who is the senior statistician for the EPIC-Oxford study and who knows everything in the world about study design, commented that it was possible that vegetarians were being compared to subjects who were a few years younger. That’s something that could affect outcome.
One important thing that the researchers did not share in their discussion was that this was actually their second study on the health of vegetarians. Their first study came to completely different conclusions. That research gathered data from 15,474 people who participated in the Austrian Health Interview Survey. It found better self-reported health among the vegetarians as well as the omnivores who ate lots of fruits and vegetables. In fact, they concluded that public health measures are needed to reduce the health risks associated with “carnivorous” diets.
The study that found poorer health among vegetarians used a subset of the same study population. The subset was predominantly female and nearly half of them were under the age of 30. We can’t extrapolate these findings to the vegetarian population at large.
Finally, while the media like to jump all over provocative studies, no single study provides definitive answers about diet and health. When we look at the research as a whole, it seems pretty clear that people who eat plant-based diets, including vegetarians and vegans, have some health advantages regarding chronic disease. At the very least, we seem to have lower risks for hypertension and diabetes. And as long as we are eating a well-balanced diet, there is no reason to believe that vegetarians are at a disadvantage.
Can you offer any insight into the people who performed the study and why on earth they conducted a study which even they acknowledge has so many flaws as to be essentially worthless – irrespective of which diet its conclusions might have favoured?
Also, while PLOS One is admirable in allowing more papers to be made available for scrutiny by true peers, it is a lousy resource for popular media to use because, as I am sure is the case here, the reporters lack the knowledge to be able to assess the papers, the conclusions of which they are “reporting”.
I don’t know. All studies have flaws, which the authors always acknowledge. This study did seem to have a lot of them! But you are right that the real problem is the media. As well as whoever press releases these studies.
This is an interesting article about the differing opinions about health and diet. As you have said in your last paragraph ‘And as long as we are eating a well-balanced diet, there is no reason to believe that vegetarians are at a disadvantage.’ This should be said for everyone. If everyone is eating a well balanced diet, which should incorporate fruit and vegetables, overall health should improve.
In addition to the problems of the study, it is easy to see the large bias in the article, since the abstract of the study doesn’t call for eliminating “vegetarian” diets but says “public health programs are needed in order to reduce the health risk due to nutritional factors.”
I do wonder about the mental disorders bit – anxiety/depression/stress – not that I think it’s causative, but if someone is making radical dietary changes, they may already have been under stress or have a history of fear-based mental health issues. Again I don’t think this is a byproduct of vegetarian diets; rather, I think it’s a self-selection bias.
I agree. And there is one other study that found young female vegetarians suffered more from mood disorders. There is always the possibility that some women are adopting a vegetarian diet as a way to cover up an eating disorder, too, which is associated with depression.
I commented on the exact same study in the LinkIn group Nutrition and Metabolism study and said the exact same things! (I also thought about the age and sex thing as women are more likely to be vegetarian and more likely to seeks help from health care providers) and though the authors say they matched for sex and age I rather wonder how well it was done.
As a researcher, this study left much to be desired but the media will be all over it (as will groups promoting meat based diets) as it will be sensational it terms of the response from the public. It certainly contradicts info gathered from the studies done on the 7th day Adventists. I also find it interesting that the earlier work by the same group is contradictory as well. I didn’t check for disclosures but hopefully they were independent!
Especially when you consider the information that just came out of Britain that found that vegetable and fruit intakes of 10 servings a day was associated with significant improvements in health!
They should’ve also done some more matching in my opinion. With the small percentage of the population being vegetarian compared to 3 different sets of vegetarians, you’ve got low statistical power and a high chance for random/coincidental associations. Covered that a bit over here: http://tinyurl.com/l32wh4d
I’m so tired of this war between omnivores and carnivores. Saw way too many comments rejoicing that something finally proved meat is essential
Wow! Thank you for digging into this! I was just going to write you and ask you about your thoughts on this article. I spent quite a bit of time reading and reflecting on it and to me it seemed like they hand picked cases that would show a specific outcome. This was not a blind test and the group that wrote up the article had no direct connection to it. They simply sifted through a larger study and found specific people that fit their requirements such as 3 women age 15-18 that were of the 4 eating groups. It was a completely bogus writeup yet it immediately gets horrible press because it pushes the agenda for the animal abuser industries in the world. Thank you for clarifying. 🙂 Have a great day 🙂
Hi Virginia, thought I would add Dr. Garth Davis’ insights here as well:
“Social media, and its infinite viral wisdom, strikes again. A ridiculously bad article was published in an online crappy journal and it is now spreading like wildfire as if it is the truth handed down by God.
The article states that vegetarians are less healthy than meat eaters. What?! There has never been a study that has been so bold as to state such a fact! They must have something big, right? I mean this goes against the vast majority of recent science. Anytime an article is an outlier it needs to be well understood, and for it to have meaning it should be replicated. So lets take a look.
This study is from Austria. They looked at over 15,000 people. So since this is a comparative study I would imagine there must be quiet a few vegetarians right? WRONG!!!! 0.2% where vegetarian. That is it. A few measly vegetarians. With such a low amount there is no way that you can do an adequately powered statistical analysis, so the authors didn’t try. Instead they matched the few vegetarians they had with age matched meat eaters. Some of the vegetarians had no age matched counterparts so they were dropped from the study!!!!! Even fewer vegetarians now.
OK so we are going to take these few vegetarians and compare them with meat eaters and follow them for years and see how the do, right? WRONG!!!!! They just did one interview with them to assess their health and their eating habits. So do we know how long they have been vegetarian? No. Could they have turned vegetarian because they were sick. Of course. Many people facing a diagnosis of heart disease turn to vegetarian diet. In this case the heart disease would have been equated with being vegetarian. This was a 1 day study not a multiple year prospective study like the Adventist Health Study.
Well at least we should be able to discern exactly what “vegetarian ” means, right? We should at least know that these vegetarians are in fact eating vegetables, right? Wrong! They applied labels on people but never assessed their exact meal plan. There is no mention as to how many fruits and veggies they were eating. In fact, they noted that the vegetarians were less likely to pursue preventative health, which in itself could explain their poor health. What this means is that these people were unlikely vegetarian for health reasons. In predominately meat eating populations when you find very few people abstaining from meat, and not going in for regular doctors visits, it could be that they are “ethical” vegetarians. In other words, they do not eat meat because of the cruelty aspect. Often times these people eat quite a junk food diet. Lots of processed carbs and not much actual fruit and veggies.
In the end this is just bad science. Their conclusion is not worth the paper this would have been printed on had it actually been printed. Instead this wound up on an online journal known for poor peer review. This was not debated at a large scientific conference. This study would have gotten F had a student turned it into me, regardless of the findings, just based on the poor experimental design. In the end, this study would have been never looked at again, except that social media loves a good controversial study that confirms what everybody wants to believe. Now it is showing up all over the internet as if Harvard had just released the study in The New England Journal of Medicine. And this is why people get so confused!” (facebook)
haha! love Dr. Garth Davis! he doesn’t hold back.
Wow, this is helpful, thanks! Some people have no integrity and are just trying to get the result that supports their beliefs! This sounds too sloppy to be worthy of any consideration.
I’m not sure that these researchers had any particular anti-vegetarian agenda or set of beliefs about it. Again, I think the fault lies with the media because of the ways in which they report these findings.
As to the question of bias, my first question when I saw the media reports was ‘who funded this study and are there corporate contributors to this university?’ Knowing that might shed some light on how subjective this study may or may not be. I wonder if there is any way of finding that out.
[…] Are Vegetarians Less Healthy than Meat-Eaters? – Oh wait. NOPE! EDB contributor Ginny Messina, a.k.a. The Vegan R.D., slices through the […]
Folks, studies like this are released every week and I really don’t want be bad but do you really think that vegetarianism is so serious problem? Ok, vegetarians can have more allergies or some mental health disorders (actually not because of vegetarianism itself) but I don’t think that eating only vegetables can cause cancer. We can wait for some other study, what do you think? What else can cause some serious health problems? Watching TV?
[…] Please read the full piece here. […]
They did verifiy the effectiveness of matching. “Since we matched the subjects one-by-one, no differences in age, sex, or SES exist between the groups. The socio-demographic characteristics of the subjects are shown in Table 1. Age was only measured in age-groups spanning 5 years (e.g. 20- to 24-year-olds) in the AT-His and the oldest age group covered persons aged 80 years or older. The percentage of subjects having a low, middle, or high SES is reported in Table 1. The mean SES in all dietary habit groups was 8,14 (SD=2,72).” Regardless this is unlike to be a big problem; 5 years brakets are not unreasonable. A greater concern is the external validity, ie generalizability. These vegetarians are young females, possibly with a specific profile (prone to anxiety/depression, atopic, eschew medical preventative care, not affluent, etc) that hardly represents vegetarians at large.
But the greatest limitation of the study is being crossectional. It is quite possible that these young anxious atopic women espouse their diet because of their poorer health.
Longitudianal studies on the health of individuals with various dietary habits are needed: ideology supporting one or the other has no place in research.
As an aside, I find it disingenuous that vegetarianism and veganism are promoted as being more “healthy”. We all know that we, like most hominidae evolved as omnivores. Why not emphasize the strongest rationale for an animal free diet, which is a moral one, in terms of animal suffering, ecology, and economy?
I agree that the generalizability of the findings is among the biggest problems. I’m not sure whether the 5-year age brackets are an issue or not; I just deferred to someone who knows more about this than I do.
And I also agree that advocacy for veganism should be based on the strongest rationale, which is the ethical one. It’s pretty likely that people can plan healthy diets that include meat.
“As an aside, I find it disingenuous that vegetarianism and veganism are promoted as being more “healthy”.”
It may be disingenuous, but it is likely the only way that the great majority of people will be tempted to at least try veganism/vegetarianism. As humans, we are inherently selfish and in particular most people care deeply about their health and that of their families. We are also deeply speciesist – many people do not even empathize with fellow human beings affected by war or poverty, so how can one expect them to empathize with animals? Yes this is depressing but it is also true. Some good people will inevitably commit to veganism because of moral choices but the vast majority need a health argument to be convinced. And there are indeed good data that vegan diets reduce cholesterol, blood pressure, body mass, diabetes, inflammation and regress coronary artery plaque. Thus one can make an evidence-based argument that a well-balanced vegan diet is health-enhancing.
[…] Kilde: http://www.theveganrd.com/2014/04/are-vegetarians-less-healthy-than-meat-eaters.html […]
I didn’t read through all the comments, so I may be repeating what others have said. It so annoys me that in common parlance, the term “pesco-vegetarians” is used. Fish eaters are not vegetarians.
Thanks for the thorough analysis of the headline grabbing report.
[…] “Are Vegetarians Less Healthy than Meat-Eaters?”:http://www.theveganrd.com/2014/04/are-vegetarians-less-healthy-than-meat-eaters.html […]
Some thoughts about this:
Vegan diets don’t have as good an omega-3 to omega-6 ratio, unless one makes a particular effort to get omega-3’s. Vegetarians likely similar. Perhaps this tends to make allergies worse.
Many vegans have nutrient deficiencies because they aren’t careful about nutrition. Perhaps true to some extent for vegetarians as well.
People with health problems may do a lot of things to improve their health including becoming vegetarian. People with cancer may choose a vegan or vegetarian diet, trying to do what they can to cure the cancer by diet.
People may adopt a vegan or vegetarian diet because of a wish for “purity” and probably more people with mental health problems have that wish for purity.
[…] when a study makes it into the news, look at the actual study. Check out the study for yourself. The Vegan RD did a nice post about this particular […]
I was vegetarian for 9 years. During that time, by age 22 I lost hair, became anemic, and had no energy. My health got worse until I started eating meat again. I know others who also became anemic on vegetarian diets. Someone once told me “if you need vitamins to supplement a loss of essential nutrients found in meat, then how is a vegetarian diet good for you. All you at doing is cutting nutrients your body needs. If you need to take pills to offset the effects of such a diet, then vegetarianism clealy is not a beneficial diet.” I also noticed something while in the navy. Navy SEALS and SWCC are he most physically fit people you will meet. And how many of these men are vegetarians? None that I have met. Think about that.
Aaron, you only need to suplement with B12 and vitamin D if you are a vegan, and you don’t need to take any supplements if you are a vegetarian. Your diet obviously was not planned good enough (which is always required even if you are not a veg*n) if you were anemic and weak. As to hair loss, this is something men are vurnerable to and in most cases it has nothing to do with diet. There are lots of vegan bodybuilders, wheightlifters and srongmen (take Patrick Babumian for example). Even gladiators were vegetarian. Veg*an diet is suitable for everyone but needs to planned well and that’s something people in the west are not taught when they grow unlike in India where vegetarianism is has been widespread for centuries and is a tradition.
Aaron, anemia is no more common among vegetarians than meat-eaters. Were you eating good sources of vitamin C at all of your meals? That’s the best way to maximize iron status on a vegan or vegetarian diet. Did you see a dietitian who has expertise in vegan nutrition?
The same group of scientists published another study in December and the results showed that “a vegetarian diet is associated with a better health-related behavior, a lower BMI, and a higher SES. Subjects eating a carnivorous diet less rich in meat self-report poorer health, a higher number of chronic conditions, an enhanced vascular risk, as well as lower quality of life”. [http://link.springer.com/article/10.1007%2Fs00508-013-0483-3]
We have been meat and dairy for over a year and feel great. My own cholesterol went from 334 to 196 in less than a year!
My brother and his wife have become interested and started to make changes with their diet. They have a 3 year old with leukemia and are wanting to give him the best chances for a full and fast recovery and that is why many of the vegan ideas seem so ‘right’ for them. They are excited about how they feel and how their child feels with the few changes they have made. They are tired of the french fries, hamburgs and milk that the hospitals serve, when they brought up taking dairy out of their sons diet the doctor was not happy. He told them there is a lot of good stuff in milk and made a real point of saying he needs all the calcium he needs because of the medications he is on.
Does anyone have any thoughts, ideas or experience with this? They really feel that a change in diet would help their son but their doctor is telling them it would be a bad idea.
This study may be flawed, but it seems that all the other studies positively comparing a veg*n diet to that of omnivores have been even more flawed. This is one of the few studies that looked at the *type* of omnivorous diet, and factored in age and activity level, I believe.
Other studies have compared veg*ns to meat-eaters in general, which could include those on the SAD, an obviously unhealthy diet. Since veg*ns in general are more concerned about their health, I’ve felt these studies didn’t really look at the difference between a *healthy* omnivorous diet vs a veg*n one. This was one of the few that ever have, to my knowledge.
Am I missing the other studies that did this – factored in quality of diet, age, and activity level for both types?
Thanks for this, Ginny. It is something we should keep in mind when we choose what messages to use for advocacy, knowing that these type of “studies” will get widespread coverage.