Vegetarian and vegan diets lead to lower blood levels of cholesterol and fats, according to a major new analysis of all evidence from clinical trials published since 1982.
Compared to people eating an omnivorous diet, those following 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 "bad" LDL cholesterol levels, and a 14% reduction in apoliprotein B, a blood protein used to estimate cholesterol level, the analysis found.
Those results showed that plant-based diets can play a significant role in reducing blocked arteries, thereby lowering the risk of stroke and heart attacks, researchers concluded in the review published May 24 in the European Heart Journal.
"If people start eating vegetarian or vegan diets from an early age, the potential for reducing the risk of cardiovascular disease caused by blocked arteries is substantial," said researcher Dr. Ruth Frikke-Schmidt, chief physician at the Rigshospitalet in Copenhagen, Denmark.
"Importantly, we found similar results across continents, ages, different ranges of body mass index, and among people in different states of health," Frikke-Schmidt said in a journal news release.
Vegetarian and vegan diets benefitted people ranging from normal weight to obese, researchers found.
For the review, researchers analyzed data from 30 clinical trials, with nearly 2,400 participants, published between 1982 and 2022.
Participants in the 30 studies were randomly assigned to follow either a vegetarian or vegan diet or to continue with an omnivorous diet that included meat and dairy products. The length of time on the diets ranged from 10 days to five years, with an average of 29 weeks.
It is the first such evidence review comparing omnivorous and vegetarian diets published since 2017, and none before had considered apoliprotein B levels or the impact of continent, age, body mass index and health status, the researchers said.
More 18 million people die from heart disease each year around the globe, making it the world's leading cause of death, researchers noted.
They added that a shift to vegan or vegetarian eating also can help stem climate change.
"Recent systematic reviews have shown that if the populations of high-income countries shift to plant-based diets, this can reduce net emissions of greenhouse gases by between 35% to 49%. Our study provides robust evidence that plant-based diets are good for our health for people of different sizes, ages and health conditions," Frikke-Schmidt said.
"Furthermore, populations globally are aging and, as a consequence, the cost of treating age-related diseases such as atherosclerotic cardiovascular disease is increasing," she continued. "Plant-based diets are key instruments for changing food production to more environmentally sustainable forms, while at the same time reducing the burden of cardiovascular disease. We should be eating a varied, plant-rich diet, not too much, and quenching our thirst with water."
Frikke-Schmidt noted that cholesterol-lowering statin medicines are still superior to plant-based diets in reducing fats and cholesterol levels.
However, one regimen does not exclude the other, and combining statins with plant-based diets is likely to have a synergistic effect, resulting in even larger benefits, Frikke-Schmidt said.
The meta-analysis also could not directly compare the fish-based "Mediterranean" diet against omnivorous diets, due to lack of such studies in the scientific literature, researchers noted.
"However, the Mediterranean diet is rich in plant-based foods and fish and is well-established as being beneficial in dietary guidelines," Frikke-Schmidt said.
The researchers said that more, larger studies are needed. These studies should last longer and track additional factors like apoliprotein B and other biomarkers linked to conditions such as inflammation and insulin resistance.