The Power of a Plant-Based Diet
By EUROPEAN SOCIETY OF CARDIOLOGY
According to a comprehensive evaluation of randomized trials published since 1982, both vegan and vegetarian diets are associated with decreased cholesterol and fat levels in the bloodstream.
This research, which was published in
the European Heart Journal, indicates that plant-based
diets can significantly contribute to the reduction of arterial blockages. This
consequently decreases the risk of cardiovascular diseases including stroke and
heart attacks, as per the authors of the study.
The researchers looked at 30 randomized trials with 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, often known as ‘bad’ cholesterol), triglycerides (a type of fat or ‘lipid’ found in the blood) and apolipoprotein B (apoB – a protein that helps to carry fat and cholesterol in blood and is a good indicator of the total amount of bad fats and cholesterol in the body).
Although previous meta-analyses have investigated this, none have been
published since 2017, none have addressed the impact of continent, age, body
mass index, and health status, and none have looked specifically at the effect
of diet on concentrations of apoB.
Professor Ruth Frikke-Schmidt, Chief
Physician at the Rigshospitalet in Copenhagen, Denmark, who conducted the study
together with medical student Ms. Caroline Amalie Koch and Dr. Emilie Westerlin
Kjeldsen, also from the Rigshospitalet, said: “We found that vegetarian and
vegan diets were associated with a 14% reduction in all artery-clogging
lipoproteins as indicated by apolipoprotein B. This corresponds to a third of
the effect of taking cholesterol-lowering medications such as statins and would
result in a 7% reduction in the risk of cardiovascular disease in
someone who maintained a plant-based diet for five years. Statin treatment is
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 an even larger
beneficial effect.
“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. Importantly, we found
similar results across continents, ages, different ranges of body mass index,
and among people in different states of health.”
The participants in the 30 studies were
randomized to follow either a vegetarian or vegan diet or to continue with an
omnivorous diet (which includes meat and dairy products). The length of time on
the diets ranged from ten days to five years, with an average of 29 weeks.
Compared to people eating an omnivorous diet,
those who were 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 LDL cholesterol levels, and a 14% reduction in apoB
levels.
“We saw significant effects from both
vegetarian and vegan diets and people ranging from a normal weight to obese,”
said Prof. Frikke-Schmidt.
Over 18 million people die from
cardiovascular disease (CVD) each year around the world, 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 an increased focus on the effect of
what we eat on the environment.
“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,” said Prof. Frikke-Schmidt.
“Furthermore, populations globally are aging and, as a
consequence, the cost of treating age-related diseases such as atherosclerotic
cardiovascular disease is increasing. 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.”
The meta-analysis by Prof. Frikke-Schmidt and
her colleagues could not assess the potential benefits of diets that directly
compare fish versus omnivorous diets due to the lack of such studies in the
scientific literature. “However, the Mediterranean diet is rich in plant-based
foods and fish and is well-established as being beneficial 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 research, comment in an
accompanying editorial: “The results reported by Koch et al add to the body of
evidence supporting favorable effects of healthy vegan and vegetarian dietary
patterns on circulating levels of LDL-C [LDL cholesterol] and atherogenic
lipoproteins, which would be expected to reduce ASCVD [atherosclerotic CVD]
risk. While it is not necessary to entirely omit foods such as meat, poultry,
and fish/seafood to follow a recommended dietary pattern, 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 topic, and the first to include apoB.
However, limitations include the fact that the
individual randomized controlled trials were relatively small, the length of
time participants were on diets was under a year in many studies, and it was
impossible to blind the participants to which diet they were placed on, and
this could have influenced their other behaviors that might affect cholesterol
and fat levels.
The researchers and the authors of the editorial say that more, larger studies with longer duration, which include apoB and other biomarkers for conditions such as inflammation and insulin resistance are needed.