Vegetarian and vegan diets are associated with lower levels of cholesterol and fats in the blood, according to a study analyzing the results of 30 clinical trials conducted between 1982 and 2022.
The authors of the paper, which is published in the European Heart Journal, claim that plant-based diets may play an important role in reducing clogging of the arteries, thus lowering the risk of heart and vascular diseases, such as stroke and myocardial infarction.
To reach their conclusions, the researchers analyzed 30 randomized trials with a total of 2,372 participants, which quantified the effect of vegetarian or vegan versus omnivorous diets on the levels of all types of cholesterol (total cholesterol).
On low-density lipoprotein cholesterol (LDL cholesterol, often referred to as “bad” cholesterol), triglycerides (a type of fat or lipid found in the blood) and apolipoprotein B (apoB, a protein that helps transport fat and cholesterol in the blood and is a good indicator of the total amount of bad fats and cholesterol in the body).
Participants in the 30 studies were randomly assigned to follow a vegetarian or vegan diet, or to continue with an omnivorous diet (including meat and dairy products). The duration of these ranged from 10 days to five years, with a mean of 29 weeks.
Compared to those on an omnivorous diet, those on a plant-based diet experienced an average reduction in total cholesterol levels of 7% from levels measured at the start of the studies, a 10% reduction in LDL cholesterol levels and a 14% decrease in apoB levels.
“We found that the vegetarian and vegan diets were associated with a 14% reduction in all artery-clogging lipoproteins, as indicated by apolipoprotein B,” emphasizes Ruth Frikke-Schmidt, chief physician at Rigshospitalet in Copenhagen, Denmark.
This, she adds, corresponds to one third of the effect of taking cholesterol-lowering drugs such as statins, and would mean a 7% reduction in the risk of cardiovascular disease in someone who maintained a plant-based diet for five years.
Statin treatment is superior to these diets in reducing fat and cholesterol levels, but one regimen does not preclude the other; “it is likely that the combination of statins with plant-based diets has a synergistic effect, leading to an even greater beneficial effect.”
Importantly, similar results were found across continents, ages, different body mass index ranges and among people with different health states, adds Frikke-Schmidt, who mentions that these diets are also better for the environment.
Among the limitations of the study is that the individual randomized controlled trials were relatively small or that the duration of the participants’ diets was less than one year in many studies.
This meta-analysis was unable to assess the potential benefits of diets that directly compare fish versus omnivorous diets because of the lack of such studies in the scientific literature, states a release from the European Society of Cardiology.
“However, the Mediterranean diet is rich in plant foods and fish and is well established as beneficial in dietary guidelines,” reminds Frikke-Schmidt.