Forty years of studies confirm that vegetarian and vegan diets reduce fats in the blood

A review of the results of four decades’ worth of research points to possible cardiac benefits of healthy plant-based eating

Fruits, vegetables and leafy greens are essential elements of healthy diets.
Fruits, vegetables and leafy greens are essential elements of healthy diets.Maria Korneeva (Getty Images)

Vegan and vegetarian diets are associated with a lower concentration of lipids like cholesterol in the bloodstream. As some lipids produce arteriosclerosis when they accumulate along the arterial walls, following these diets can reduce the risk of suffering some cardiovascular diseases. That is the conclusion of an analysis of 30 clinical studies, conducted over the last 40 years, which was just published in the European Heart Journal. The researchers, led by Ruth Frikke-Schmidt at the University of Copenhagen, frame the relevance of their results within the United Nations’ sustainable development agenda, which proposes reducing premature mortality by non-transmittable diseases, like cancer or cardiac illnesses, by a third.

As a possible explanation for the effect of meatless diets, the study points out a higher consumption of polyunsaturated fats and fiber and a lower consumption of saturated and total fats. However, they do not discard that the weight loss associated with these diets could also explain the results. They also emphasize that, beyond diet, genetics are a significant factor for how many lipids accumulate in the arteries. For that reason, many people, despite following lifestyle recommendations, need statins to maintain their cholesterol levels within a healthy margin. In the study, the authors write that “combining statins and plant-based diets will likely have a synergistic effect,” and that vegetarian diets can permit a reduced consumption of these medications.

Pablo Alonso Coello, a researcher at the Iberoamerican Cochrane Center in Barcelona, says that “this study confirms more or less what we knew [about these diets], that they improve the lipid profile,” but he questions the authors’ jump to talking about health impacts. “There is no data about cardiovascular outcomes,” he says. “There are no clinical studies that inform about relevant cardiovascular outcomes such as heart attacks, cardiovascular mortality or stroke, only observational studies.” Alonso cites another analysis of 40 studies with more than 35,000 participants, published recently in BMJ, which observed that the Mediterranean diet, which is not exclusively vegetarian, and a reduction in fats, have the most solid evidence when it comes to reducing cardiovascular problems. “In the same analysis, two diets considered vegetarian did not come out so well,” the researcher adds. He notes that strict vegan or vegetarian diets can be problematic for at-risk populations, like pregnant women or children, because they require good planning and supplements.

In a statement published by the Science Media Center, Tom Sanders, Professor emeritus of Nutrition and Dietetics at King’s College London, noted that “large trials with cholesterol lowering medication show a 1 mmol reduction in LDL cholesterol is associated with a 10% reduction in cardiovascular disease (CVD) mortality and a 20% reduction in CVD events.” For the specialist, the results of the study suggest that a plant-based diet could diminish the rate of mortality by cardiovascular illness by 3% and the impact of non-fatal cardiovascular events by 6%. “These findings are consistent with observational studies that find vegetarians/vegans have a lower incidence of ischemic heart disease but not stroke,” he concludes.

Another important aspect of the results is the type of vegetarian diet followed. A diet rich in fruits, vegetables and whole grains can be beneficial, but not one that includes refined flours, like some type of breads or pasta, or that has a lot of fat and salt, as in the case of some ultra-processed vegetarian food. In those cases, as with all kinds of ultra-processed food, frequent consumption is harmful to health.

The results published by the European Heart Journal point to vegan and vegetarian diets’ possible cardiac health benefits, which had previously been observed. A guide by the American Heart Association looking into heart-healthy eating practices classified these diets in fourth place. The highest ranking went to the Dietary Approaches to Stop Hypertension diet (DASH), a low-salt diet high in fruit, vegetables, whole grains, low-fat dairy and lean protein. It was followed by the Mediterranean diet, the pescatarian diet, in which protein comes from fish and seafood, and a vegetarian diet that includes eggs and dairy products. All these healthy diets have in common the abundance of fruit, vegetables and whole grains, though they are not strictly vegetarian.

In addition to possible cardiovascular benefits, the study’s authors also note the environmental benefits of a population-level change to plant-based diets.

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