Researchers analysed blood glucose levels, lipid status, blood pressure, waist size, and body mass index in more than 700 adults. The vegetarians were lower than non-vegetarians on all counts except cholesterol.
In the study, 23 out of every 100 vegetarians were found to have at least three metabolic syndrome factors, compared with thirty-nine out of every 100 non-vegetarians and 37 out of every 100 semi-vegetarians.
"I was expecting there should be a difference," said Dr Nico Rizzo of Loma Linda University, the lead researcher on the study. "But I didn't expect that it would be that much."
Using questionnaires on eating habits, the researchers categorised participants as vegetarians (eating meat of any kind less than once a month), semi-vegetarians (eating meat or poultry less than once a week), and non-vegetarians.
Vegetarians' average BMI of 25.7 was four points lower than that of non-vegetarians, who, on average, had BMIs close to 30.
Semi-vegetarians fell in the middle, with a BMI and waist size smaller than non-vegetarians, but larger than vegetarians.
The pattern held when the measurements were combined to determine the presence of metabolic syndrome.
Dr Rizzo said that he is not sure what's behind the differences.
Meat intake vs. plant intake
"Is it primarily the meat intake, the plant food intake or a combination of both?" Dr Rizzo said.
It's also possible that diet is not the cause; the research showed only an association between food choices and health factors, not cause-and-effect.
High BMI, for instance, a component of the metabolic syndrome profile, itself contributes to high blood pressure, and indirectly, blood sugar, and thereby potentially raising a person's risk of heart disease and diabetes.
The current study, published online in Diabetes Care, did not follow the subjects over the long term to see whether those who abstained from meat actually had lower rates of diabetes or heart disease.
The data for this research, which was funded by the National Institutes of Health, came from the Adventist Health Study 2, a long term study of Seventh Day Adventists. This religious group has considerably more vegetarians than the general population.
In this study, 35% of the subjects did not eat meat, whereas only about 5% of all Americans are vegetarian.
One of the differences Dr Rizzo discovered between the groups was age. Vegetarians, on average, were three years older than the meat-eaters.
"Even though they're older, they're in better shape," Dr Rizzo said. "That's something I found quite interesting." (Reuters Health/ March 2011)
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