People who followed a vegan or vegetarian diet had lower blood levels of low-density lipoprotein cholesterol (LDL-C), total cholesterol, and apolipoprotein B (apoB) than people who followed an omnivorous diet, in a new meta-analysis of 30 trials.
The results suggest that “plant-based diets have the potential to reduce the atherosclerotic burden of atherogenic lipoproteins and thereby reduce the risk of cardiovascular disease,” write Caroline Amelie Koch, a medical student at the University of Copenhagen, Denmark. , and his colleagues. Their findings were published online May 24 in the European journal of the heart.
“Vegetarian and vegan diets were associated with a 14% reduction in all artery-clogging lipoproteins, as reported by apoB,” said lead author Ruth Frikke-Schmidt, DMSc, PhD, Rigshospitalet and professor at the University of Copenhagen, in a press release from his university.
“This is one-third of the effect of taking cholesterol-lowering drugs such as statins,” she added, “and would lead to a 7% reduction in the risk of cardiovascular disease in someone who maintained a plant-based diet for 5 years.
“Importantly, we found similar results, across continents, ages, different body mass index (BMI) ranges, and among people in different health states,” Frikke-Schmidt pointed out.
And combining statins with plant-based diets would likely produce a synergistic effect, she speculated.
“If people start eating vegetarian or vegan at an early age,” she said, “the potential for reducing the risk of cardiovascular disease caused by clogged arteries is significant.”
Further, the researchers conclude, “Switching to plant-based diets at the population level will significantly reduce greenhouse gas emissions – making these diets effective means towards more sustainable development, while also reducing same time the growing burden of atherosclerotic cardiovascular disease (ASCVD).”
More support for vegan and vegetarian diets
These new findings “add to the body of evidence supporting the favorable effects of healthy vegan and vegetarian diets on circulating levels of LDL-C and atherogenic lipoproteins, which should reduce the risk of ASCVD,” Kevin C. Maki, PhD, and Carol Kirkpatrick, PhD, MPH, write in an accompanying editorial.
“While omitting foods such as meat, poultry, and fish/seafood entirely is not necessary to follow a recommended diet, reducing consumption of these foods is a reasonable option for those who prefer do it,” notes Maki, from Indiana. University School of Public Health, and Kirkpatrick, from Idaho State University.
The plant-based diet should be ‘Well planned‘
Several experts who were not involved in this meta-analysis shed light on the study and its implications in comments to the UK Science Media Center.
“While a vegetarian and vegan diet can be very healthy and beneficial in terms of cardiovascular risk, it is important that it is well planned so that nutrients it may be poor in are included, including iron, iodine, vitamin B12 and vitamin D,” said Duane Mellor, PhD, Registered Dietitian and Lecturer, Aston Medical School, Aston University, Birmingham, UK.
Some people “may find it easier to follow a Mediterranean-style diet that includes lots of fruits, vegetables, legumes, whole grains, fish, eggs, and low-fat dairy products, with only small amounts of meat,” Tracy Parker, senior dietitian at the British Heart Foundation, London, UK, suggested.
“There is considerable evidence that this type of diet can help reduce your risk of developing heart and circulatory diseases by improving cholesterol and blood pressure levels, reducing inflammation and controlling blood sugar,” he said. -she adds.
And Aedin Cassidy, PhD, Chair of Nutrition and Preventive Medicine, Queen’s University Belfast, noted that “Not all plant-based diets are created equal. Healthy plant-based diets, characterized by fruits, vegetables and whole grains improve health, but other plant-based diets (e.g. those containing refined carbohydrates, processed foods high in fat/salt, etc.) do not.”
This new study shows that plant-based diets have the potential to improve health by improving blood lipids, “but this is one of many potential mechanisms, including impact on blood pressure, maintenance weight and blood sugar,” she added.
“This work represents a well-conducted analysis of 30 clinical trials involving more than two thousand participants and highlights the value of a vegetarian diet in reducing the risk of heart attack or stroke through lowering the rate of blood cholesterol,” said Robert Storey, BM, DM. , Professor of Cardiology, University of Sheffield, UK.
However, it also demonstrates that the impact of diet on an individual’s cholesterol level is relatively small, he added.
“That’s because people inherit their liver’s tendency to produce too much cholesterol, which means that high cholesterol is more strongly influenced by our genes (DNA) than by our diet,” he said. -he explains.
This is “the reason why statins are needed to block cholesterol production in people who are at higher risk or have had a heart attack, stroke, or other cholesterol-related disease. the accumulation of cholesterol in the blood vessels”.
Beneficial effect on ApoB, LDL-C and total cholesterol
ApoB is the main apolipoprotein in LDL-C (“bad” cholesterol), the researchers note. Previous studies have shown that particles containing LDL-C and apoB are associated with an increased risk of ASCVD.
They aimed to estimate the effect of vegetarian or vegan diets on blood levels of total cholesterol, LDL-C, triglycerides and apoB in people randomized to a vegetarian or vegan diet compared to an omnivorous diet (this i.e. including meat and dairy products).
They identified 30 studies published between 1982 and 2022 and conducted in the United States (18 studies), Sweden (2), Finland (2), South Korea (2), Australia (1), Brazil ( 1), Czech Republic (1), Italy (1), Iran (1) and New Zealand (1).
Dietary interventions lasted from 10 days to 5 years with an average of 29 weeks (15 studies ≤ 3 months; 12 studies 3-12 months; and three studies > 1 year). Nine studies used a crossover design, and the rest used a parallel design in which participants followed only one diet.
Studies had 11 to 291 participants (mean, 79 participants) with a mean BMI of 21.5 to 35.1 kg/m2 and an average age of 20 to 67 years. Thirteen studies included participants treated with lipid-lowering therapy at baseline.
The dietary intervention was vegetarian in 15 trials (three lacto-vegetarian and 12 lacto-ovo-vegetarian) and vegan in the remaining 15 trials.
On average, compared to people on an omnivorous diet, people on a plant-based diet had a 7% reduction in total cholesterol from baseline (-0.34 mmol/L), a 10% reduction in LDL-C from baseline (-0.30 mmol/L) and a 14% reduction in apoB from baseline (–12.9 mg/dL) (all P < .01).
Effects were similar across age, continent, study duration, health status, intervention regimen, intervention program, and study design subgroups.
There was no significant difference in triglyceride levels in patients in the omnivorous groups compared to the plant-based diets.
Such diets could significantly reduce greenhouse gases
Lead author Frikke-Schmidt noted: “Recent systematic reviews have shown that if people in high-income countries adopt plant-based diets, it can reduce net greenhouse gas emissions by 35% to 49%.”
“Plant-based diets are key instruments for shifting food production to more environmentally friendly forms, while reducing the burden of cardiovascular disease” in an aging population, she said.
“We should have a varied diet, rich in plants, not too much, and quench our thirst with water,” she concluded.
The study was funded by the Lundbeck Foundation, the Danish Heart Foundation and the Leducq Foundation. The authors, columnists, Parker, Cassidy and Storey reported no relevant financial relationships. Mellor revealed that he is a vegetarian.
Eur Heart J. Published online May 24, 2023. Article, Editorial
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