Vegetarian and vegan diets are linked to lower levels of cholesterol and fats in your blood, according to an analysis of all evidence from randomized trials published since 1982.
The authors of the study, which is published in the European heart journal say that today this means that plant-based diets can play an important role in reducing clogged arteries, lowering the risk of cardiovascular diseases such as strokes and heart attacks.
The researchers looked at 30 randomized trials involving a total of 2,372 participants, published between 1982 and 2022, that quantified the effect of vegetarian or vegan diets versus omnivorous diets on levels of all types of cholesterol (total cholesterol), low-density lipoprotein cholesterol (LDL). cholesterol, also called “bad” cholesterol), triglycerides (a type of fat or “lipid” found in the blood), and apoliprotein B (apoB – a protein that helps to transport fat and cholesterol in the blood and maintain proper indicator for the total amount of bad fats and cholesterol in the body).
While previous meta-analyses have examined this, none have been published since 2017, none have addressed the impact of continent, age, body mass index, and health status, and none have specifically looked at the effect of diet on levels of ApoB .
Professor Ruth Frikke-Schmidt, chief physician at Rigshospitalet in Copenhagen, Denmark, who conducted the study with Ms Caroline Amalie Koch and Dr Emilie Westerlin Kjeldsen, also from Rigshospitalet, said: “We found that vegetarian and vegan diets were associated with a 14% reduction in all artery-clogging lipoproteins, as indicated by apoliprotein B.
“This is equivalent to one-third of the effect of taking cholesterol-lowering drugs such as statins, and would result in a 7% reduction in the risk of cardiovascular disease in someone following a plant-based diet for five years. statins are superior to plant-based diets in lowering fat and cholesterol levels, however, one regimen does not preclude the other, and combining statins with plant-based diets is likely to have a synergistic effect resulting in an even greater benefit.
“If people start eating vegetarian or vegan diets from a young age, the potential for reducing the risk of cardiovascular disease caused by blocked arteries is significant. Importantly, we found similar results across continents, ages, different ranges of body mass index and between people in different health conditions.”
The participants in the 30 studies were randomized to follow a vegetarian or vegan diet or to continue an omnivorous diet (including meat and dairy products). The duration of the diets ranged from ten days to five years, with an average of 29 weeks.
Compared to people on an omnivorous diet, those on a plant-based diet experienced an average 7% reduction in total cholesterol levels from levels measured at the start of the studies, a 10% reduction in LDL cholesterol levels, and a 14% reduction in ApoB levels.
“We saw significant effects from both vegetarian and vegan diets and people ranging from normal weight to obese,” said Prof. Frikke-Schmidt.
Each year, more than 18 million people worldwide die from cardiovascular disease, making it the leading cause of death. The United Nations Sustainable Development Agenda states that premature deaths from non-communicable diseases, such as CVD, should be reduced by a third by 2030. In addition, there is more attention for the effect of what we eat on the environment.
“Recent systematic reviews have shown that switching populations of high-income countries to plant-based diets could reduce net greenhouse gas emissions by 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,” said Prof. Frikke-Schmidt.
“Moreover, populations are aging worldwide and, as a result, the cost of treating age-related diseases, such as atherosclerotic cardiovascular disease, is increasing. Plant-based diets are important tools for transforming food production into more environmentally sustainable forms, while at the same time allowing time to to reduce the burden of cardiovascular disease. We must eat a varied and plant-rich diet, not too much, and quench our thirst with water.”
The meta-analysis by Prof. Frikke-Schmidt and her colleagues was unable to assess the potential benefits of diets directly comparing fish versus omnivorous diets due to the lack of such studies in the scientific literature. “However, the Mediterranean diet is rich in plant foods and fish and is known to be favorable in dietary guidelines,” she said.
Professor Kevin Maki, of Indiana University School of Public Health Bloomington, and Midwest Biomedical Research, USA, and Professor Carol Kirkpatrick, of Midwest Biomedical Research and Idaho State University, USA, who were not involved in the study, comment in an accompanying editorial comment: “The results reported by Koch et al add to the body of evidence supporting beneficial effects of healthy vegan and vegetarian diets on circulating levels of LDL-C [LDL cholesterol] and atherogenic lipoproteins, which are expected to reduce ASCVD [atherosclerotic CVD] risk. While it is not necessary to completely cut out foods such as meat, poultry and fish/seafood to follow a recommended diet, reducing consumption of such foods is a reasonable option for those who prefer to do so.”
A strength of the study is that, to the authors’ knowledge, it is the largest systematic review of the subject, and the first to include apoB. However, limitations include the fact that the individual randomized controlled trials were relatively small, that the length of time participants were dieting was less than a year in many studies, and that it was impossible to blind the participants to which diet they were placed on, and this may have influenced their other behaviors that may affect cholesterol and fat levels.
The researchers and the lead authors say more, larger, longer-duration studies are needed, including apoB and other biomarkers for conditions such as inflammation and insulin resistance.
Ruth Frikke-Schmidt, Vegetarian or vegan diets and blood lipids: a meta-analysis of randomized trials, European heart journal (2023). DOI: 10.1093/eurheartj/ehad211
Plant-based diets and atherogenic lipoproteins. European heart journal (2023). DOI: 10.1093/eurheartj/ehad239
Offered by the European Society of Cardiology
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