Despite similar caloric intake, vegetarians tend to have lower Body Mass Index (BMI) than non-vegetarians, with vegans being the most slender of all, suggests new research on more than 70,000 Seventh-day Adventists by researchers from Loma Linda University Health to be published in the December edition of the Journal of the Academy of Nutrition and Dietetics.

In strict vegetarians, low dietary intakes of vitamins B-12 and D, calcium and omega 3 fatty acids, in addition to iron and zinc, have often been of concern. However, in the present study, mean intakes of these nutrients were above minimum requirements in strict vegetarians.

A cross-sectional study of the subjects from the Adventist Health Study 2, possibly the largest study involving vegetarians, compared the subjects’ five dietary patterns: non-vegetarians (meat eaters), semi-vegetarians (occasional meat eaters), pesco-vegetarians (people who consume fish), lacto-ovo vegetarians (people who consume dairy products) and vegans (strict vegetarians).

The results show the average BMI was highest in non-vegetarians and lowest in strict vegetarians, with higher BMI levels for those who consume more animal-derived foods. Non-vegetarians had the most number of people who are classified as obese, with 33.3% having BMIs of over 30; semi-vegetarians, 24.2%; pesco-vegetarians, 17.9%; lacto-ovo vegetarians, 16.7%; and strict vegetarians, 9.4%.

The subjects had similar energy intake of close to 2,000 kcal per day, except for semi-vegetarians, who had an intake of 1,707 kcal per day. The results were adjusted for age, race, sex and physical activity.

The study tried to determine variations in nutrient intakes between vegetarian and non-vegetarian dietary patterns, in hopes of determining if those differences can contribute to the prevention or development of disease.

The findings showed that nutrient intakes varied significantly between dietary patterns. Non-vegetarians have the lowest intake of plant proteins, fiber, beta carotene and magnesium, compared with those following vegetarian dietary patterns; and the highest intakes of fatty acids associated with coronary heart disease.

“There was a clear association between higher proportions of obesity, higher BMI averages and dietary patterns characterized by progressively higher intakes of meat and dairy products,” said the study’s first author, Nico Rizzo, Med. Dr., Ph.D., assistant professor at the Department of Nutrition at Loma Linda University School of Public Health.

“These marked differences in BMI are of particular interest given that total energy intakes were similar between dietary patterns, and mean macronutrient composition and micronutrient intakes were markedly different between the dietary patterns,” he said.

He said a thorough description of nutrient profiles and the findings will serve as a point of reference for future studies that will look at possible associations between dietary patterns and health outcomes.