Editorial NexoScience
If you have ever swapped a steak for a lentil stew and wondered whether it actually changes anything inside your body, beyond the ethics of it or the planet, there is now a clear scientific answer.
Cutting out meat and dairy does something measurable to your blood, and it happens across every group researchers tested. A team of Danish cardiologists pooled the results of 30 separate clinical trials, spanning four decades and nearly 2,400 participants, to settle a question that had not been properly updated since 2017: what does switching to a vegetarian or vegan diet actually do to the fats circulating in your bloodstream.
The trials, published between 1982 and 2022 and carried out mostly in the United States, randomly assigned participants to either a vegetarian or vegan diet or to keep eating a normal omnivorous diet, then measured their blood lipids afterward. That randomization matters. Unlike the observational studies that dominate nutrition headlines, where people who already eat healthier tend to have healthier outcomes for a dozen other reasons, a randomized trial can actually show cause and effect.
The numbers are modest in absolute terms, but they showed up almost everywhere researchers looked. Compared with people who kept eating meat and dairy, those on a plant-based diet saw their total cholesterol drop by 0.34 mmol/L, roughly 13 mg/dL, their LDL cholesterol, the kind doctors call bad cholesterol, drop by 0.30 mmol/L, about 12 mg/dL, and their apolipoprotein B, a newer and arguably more precise marker of how many artery-clogging particles are floating in the blood, drop by nearly 13 mg/dL. Triglycerides, on the other hand, barely moved.
The effect held up no matter who was tested. The researchers broke the results down by age, continent, how long the trial lasted, whether participants were healthy or already at cardiovascular risk, whether the diet was vegetarian or fully vegan, and whether it was a simple diet change or part of a bigger lifestyle program. None of those factors meaningfully changed the outcome. The one group that responded a bit less was people with obesity, whose cholesterol production in the liver and gut tends to run higher no matter what they eat.
There is a straightforward biological reason behind the drop. Plant-based diets are naturally lower in saturated fat, dietary cholesterol, and total fat than the average omnivorous diet, and richer in polyunsaturated fats, especially linoleic acid, which pushes the liver to build more LDL receptors and pull more cholesterol out of the bloodstream. Less fat going in, more cholesterol being cleared out. Both effects point the same direction.
None of this means a vegetarian or vegan diet is the only route to lower cholesterol, and the authors are upfront about the caveats. Most trials lasted under a year, so nobody yet knows if the effect holds for decades. None of the studies could blind participants to what they were eating, which can affect how strictly people stick to a diet. And the apolipoprotein B result, arguably the most clinically interesting number, comes from just six of the 30 trials, so it deserves more caution than the cholesterol figures.
Still, with 2,372 participants across 30 randomized trials, this is now the largest body of trial evidence ever assembled on the topic, and the first to include apolipoprotein B at all. For a dietary shift that also happens to cut the greenhouse gas emissions tied to food production by roughly a third to a half, the case for eating a bit less meat keeps getting harder to dismiss on health grounds too.
Source: Koch, C.A., Kjeldsen, E.W., Frikke-Schmidt, R. “Vegetarian or vegan diets and blood lipids: a meta-analysis of randomized trials.” European Heart Journal, Volume 44, Issue 28, July 2023, Pages 2609-2622. DOI: 10.1093/eurheartj/ehad211.
