Vegetarians may live longer, but not necessarily because they have given up meat, according to a study in Preventive Medicine.
The researchers looked at data from 243,096 adults over the age of 45, with an average age of 62, living in New South Wales in Australia. They found no significant difference in all-cause mortality between omnivores and vegetarians.
Six years later 16,836 participants had died, of which 80 were vegetarians. Having adjusted for other contributory factors, no significant difference was found in longevity between meat eaters and those with a mostly plant-based diet.
The researchers say that one possible explanation for their finding is recent changes in the average vegetarian’s consumption. As plant-based diets become more popular, more vegetarian junk food has become available, bringing vegetarianism more in line with a ‘normal’ diet.
An earlier study suggested that vegetarians and vegans suffer socially. Meat eaters, who make up a significant majority of the population, evaluated vegetarians and vegans more negatively than other common targets of prejudice. ‘Strikingly, only drug addicts were evaluated more negatively than vegetarians and vegans,’ the authors wrote.
As noted by the authors, a vegetarian diet is believed to have health benefits, reducing risks of type-2 diabetes, hypertension and obesity. This study was the first to compare different categories of diet according to how often one eats meat — that is, either never or less than once a week. Vegetarians who ate fish were a separate category and regular meat eaters another.
Diet status was confirmed using a questionnaire which, like patient diaries, are notoriously inaccurate and can also change over time. Furthermore, adults over 45 may have already suffered the harms of poor diets earlier in life, the influence of which will not be captured.
The mean age of the participants was 62.3 years and the follow-up surprisingly short at only six years, so we wouldn’t expect most of the participants to die so soon. The study also didn’t look at how long participants had been vegetarian for, or if, indeed, they actually were vegetarian, by assessing their diet. It didn’t look at the nutritional components of their diet — for example, a vegan who just ate crisps and drank fizzy pop versus an omnivore who ate meat sparingly but with plenty of fruit and vegetables.
After adjusting for possible confounders — in particular, vegetarians were shown to have healthier lifestyles — the researchers concluded that there was no significant difference in mortality between those who ate meat and those who didn’t. No significant difference existed between any of the diet categories.
This may reflect the fact that meat eaters now have a more healthy, balanced diet, or perhaps the vegetarians have become less healthy, with more soy-based, high-sugar and processed foods.
This study supports other work suggesting that the link between vegetarianism and better health is not as clear-cut as it once seemed to be. Now we need studies that investigate why.
Research score: 4/5