Studies show vegetarians have poorer health, more cancer, more allergies and more mental health disorders
That finding comes from a single cross-sectional survey, which records diet and health at one moment and cannot say which came first. People often change their diet after falling ill. Large studies that follow people over many years find vegetarians and vegans do about as well as meat eaters or better on most outcomes, with a few specific risks worth knowing about.
You hear constantly that plant-based diets are healthier, yet a peer-reviewed study comparing over a thousand people found vegetarians reporting more cancer, allergies and mental health problems, more doctor visits and lower quality of life. Nutrition science is messy and no study is perfect. Findings like this show the health case is not settled. Anyone considering the diet deserves to hear the evidence that cuts the other way, not only the favourable studies.
The study behind this line is an Austrian survey of about 1,300 adults, published in 2014, with a few hundred vegetarians among them. It asked people about their diet and their health at the same point in time. A design like that can show that two things appear together. It cannot show that one caused the other, and the authors said so in the paper.
The direction matters here. People with cancer, allergies, digestive problems or depression often change what they eat afterwards, sometimes on medical advice and sometimes in search of relief. A survey taken at one moment will then find more illness among vegetarians even if the diet harmed no one. That is reverse causation, and it is especially likely for allergies and mental health. Health was also self-reported, and the vegetarian group was small.
The better evidence comes from prospective cohorts, which record diet first and follow people for years. EPIC-Oxford and the Adventist Health Study-2 have tracked tens of thousands of vegetarians and vegans. They find similar or lower all-cause mortality, lower rates of heart disease, and modestly lower overall cancer incidence. They also find real risks. EPIC-Oxford reported higher rates of haemorrhagic stroke and of bone fractures among vegans, probably linked to low calcium, vitamin D, B12 or protein intake. Those findings are worth taking seriously. They point to specific nutrients to plan for, not to a general decline in health.
One survey shows that the literature has noise in it, which is true of every area of nutrition. It does not outweigh the larger body of longer-term evidence. And the study concerned vegetarians, not vegans, so it says even less about a vegan diet specifically.
- Studies show vegetarians are less healthy and have a lower quality of life than meat eaters
Different wording, same argument. The response above answers all of them.
Inferring that one thing caused another from the fact that they occurred together or one after the other. Correlation and sequence are not causation.
How it applies here: The survey only found that vegetarianism and certain illnesses showed up together at one point in time. Offering that as evidence the diet worsens health treats co-occurrence as cause. It ignores the obvious alternative that people who were already ill changed their diet.