Vegetarians have more favorable levels of a number of biomarkers including cardiovascular-linked ones – total cholesterol, low-density lipoprotein cholesterol, and apolipoprotein A and B – than meat eaters, according to results of the largest study of its kind to date.
Results of the cross-sectional, observational study of 178,000 participants were presented as an electronic poster at this year’s online European Congress on Obesity by Jirapitcha Boonpor of the Institute of Cardiovascular & Medical Sciences, University of Glasgow (Scotland).
“We found that the health benefits of becoming a vegetarian were independent of adiposity and other sociodemographic and lifestyle-related confounding factors,” senior author Carlos Celis-Morales, PhD, also from the University of Glasgow, said in an interview.
Total cholesterol and LDL cholesterol concentrations for vegetarians were 21% and 16.4% lower than in meat eaters. But some biomarkers considered beneficial – including vitamin D concentrations – were lower in vegetarians, while some considered unhealthy – including triglycerides and cystatin-C levels – were higher.
Vegetarian diets have recently become much more popular, but there is insufficient information about the health benefits. Prior reports of associations between biomarkers and a vegetarian diet were unclear, including evidence of any metabolic benefits, noted Dr. Celis-Morales.
Importantly, participants in the study had followed a vegetarian or meat-eater diet for at least 5 years before their biomarkers in blood and urine were assessed.
“If you modify your diet, then, 2 weeks later, you can see changes in some metabolic markers, but changes in markers of cardiovascular disease will take 5-10 years,” he explained.
No single biomarker can assess health
Asked to comment on the findings, John C. Mathers, PhD, noted that they clearly confirm the importance of not reading any biomarker result in isolation.
Health is complex and individual markers tell you just part of the story,” said Dr. Mathers of the Human Nutrition Research Centre, Newcastle (England) University.
He says a vegetarian diet can be nourishing but cautioned that “just because someone excludes meat from their diet does not mean necessarily that they will be eating a healthy diet.”
“Some of the biomarker differences seen in this work – such as the lower concentrations of total cholesterol and LDL cholesterol, GGT [gamma-glutamyl transferase], and ALT [alanine transaminase] – are indicators that the vegetarians were healthier than the meat eaters. However, other differences were less encouraging, including the lower concentrations of vitamin D and higher concentrations of triglycerides and cystatin-C.”
Also reflecting on the results, Jose Lara Gallegos, PhD, senior lecturer in human nutrition at Northumbria University, Newcastle upon Tyne, England, said they support previous evidence from large studies such as the European Prospective Investigation into Cancer and Nutrition (EPIC), which showed that a vegetarian diet is associated with a lower risk of heart disease.
“A vegetarian diet might also be associated with lower risk for liver diseases such as nonalcoholic fatty liver disease,” Dr. Gallegos said, but added that some levels of biomarkers considered to be “healthy” were lower in the vegetarians, and it is important to remember that strictly restricted diets might be associated with potential risks of nutritional inadequacies.
“Other, less restrictive dietary patterns, such as a Mediterranean diet, are also associated with ... health benefits,” he observed.