A meta-analysis of 30 trials suggests that plant-based diets are associated with significant reductions in total cholesterol, LDL cholesterol and apolipoprotein B.
Published in the European Heart Journal, the Danish researchers undertook a systematic review and meta-analysis, to estimate the effect of vegetarian and vegan diets on plasma levels of the main lipid fractions, TC, LDLC, triglycerides (TGs) and ApoB.
Randomised trials looking at the effect of both plant-based diets on the different lipid fractions were considered in comparison to an omnivorous diet in adults over 18 years of age. A total of 30 eligible trials were identified, which included an equal number of both types of plant-based diets and had an overall sample size of 2,372 participants.
Compared to the omnivorous group, the plant-based diets significantly reduced TC (mean difference, MD = -0.34 mmol/L 95% CI -0.44 to -0.23, p < 0.001). Significant reductions were also seen with LDLC (MD = -0.30, 95% CI -0.40 to – 0.19, p < 0.001) and ApoB (MD = -0.34, 95% CI -0.44 to -0.23, p < 0.001). However, no significant reductions were seen in the level of triglycerides compared to an omnivorous diet.
Despite these significant reductions, the researchers also reported substantial heterogeneity in the findings for TC, LDLC and ApoB (ranging from 69-74%).
Benefits from lipid reductions
To get a better understanding of the impact of these reductions, it is worth putting the changes into context.
A previous analysis of the benefits from lipid reductions indicated that for every 1 mmol/L decrease in TC, there was a 17.5% reduction the risk of all-cause mortality, a 24.5%, reduction in coronary heart disease (CHD)-related mortality and 29.5% for any CHD-related event.
Using TC as an example, a 0.34 mmol/L reduction, as found in the current analysis, equates to a 6% decrease in the risk of all-cause mortality and a 10% reduction in the risk of a CHD-related event.
Consequently, whilst relatively modest for an individual, these reductions would become substantial at the population level, thereby potentially reducing the society burden and mortality associated with cardiovascular disease.
Diet and cardiovascular disease
Data from the World Health Organization suggests that cardiovascular diseases result in nearly 18 million annual deaths, emphasising the importance of any strategies that could reduce this risk. One strategy at the individual level is to move away from an omnivorous diet. In fact, this approach was advocated in guidance from the European Society of Cardiology in 2021. The guidance suggested that individuals could reduce their risk of cardiovascular disease through adoption of a more plant-based and and less animal-based food pattern. In recent years there has been an increase in vegetarian eating patterns in several continents around the world, including Europe and North America. In addition, there are also reported increases in the number of people eating a vegan diet.
In a previous analysis from 2015, it was shown that a vegetarian diet reduced lipid markers such as total cholesterol (TC) and LDL cholesterol (LDLC). However, the analysis did not examine the impact of this plant-based dietary pattern on levels of apolipoprotein B (ApoB), despite strong evidence that this lipid is a more accurate indicator of cardiovascular risk than either TC or LDLC.