High cholesterol is one of the most significant risk factors for heart disease (CVD) and strokes. Globally, a third of ischaemic heart disease can be attributed to high cholesterol, and according to the World Health Organization (WHO), raised cholesterol is estimated to cause 2.6m deaths annually.
Plant-based diets rich in fruits, vegetables, whole grains, legumes, nuts and seeds are known to improve risk factors for CVD, including blood pressure, body weight, and cholesterol. But these days, plant-based diets often also include ultra-processed food meat alternatives, with proteins sourced from soy, wheat, peanut, pea, or fungi.
Until now, it has been unclear whether plant-based diets containing large amounts of meat alternatives come with the same cardiovascular benefits as plant-based diets based on unprocessed foods. But researchers in the UK are on the case.
Meat alternatives from fungi and plants
In a study published this month, lead author Joshua Gibbs and co-author Gah-Kai Leung from the University of Warwick reveal the results from a systematic review and multiple meta-analyses on the effect of meat substitute consumption on total cholesterol, LDL- and HDL-cholesterols, triglycerides, fasting blood glucose, systolic and diastolic blood pressure, and weight.
“We reviewed 12 studies involving 459 participants, in which the effects of meat alternative consumption on [these indicators] were studied in controlled clinical trials,” explained Gibbs.
The study focused on two types of meat alternative – plant-based and mycoprotein-based – which aim to replicate the texture, taste, appearance, or chemical characteristics of its conventional counterpart.
Mycoprotein is a form of single-cell protein derived from fungi for human consumption. The fermented product is best known as the primary ingredient in Marlow Foods-owned Quorn products – which first launched the product on the market in 1985.
The study also included data from studies using plant-based meat alternatives, with primary protein sources coming from pea protein (as used by Beyond Meat, for example), gluten, soy, and peanut protein.
Findings and study strengths
The most significant findings of the meta-analysis showed that meat alternative consumption lowers total cholesterol, LDL-cholesterol (otherwise known as ‘bad’ cholesterol), and triglyceride levels.
“Elevated levels of low-density lipoprotein (LDL) cholesterol, otherwise known as ‘bad’ cholesterol, can lead to the build-up of fatty plaques in your arteries which restrict blood flow and increase your risk of heart attack and stroke,” explained Gibbs.
Specifically, meat alternative consumption reduced total cholesterol by half a point (0.5mmol/L) and LDL cholesterol by 0.39 (mmol/L) when compared with omnivorous diets.
Statistically, the researchers described this finding as a ‘highly significant result’, since it highlights that consumers may be able to acquire the cardioprotective benefits of plant-based diets by eating foods that mimic the eating experience of meat and better align with their preferences than vegetables.
However, the study comes with strengths and, importantly, limitations, which means the results should be ‘interpreted with caution’, noted the study authors.
Amongst its strengths are that it is the ‘first’ meta-analysis conducted on meat substitutes has includes a comprehensive list of cardiometabolic outcomes. Further, 92% of the analyses were randomised controlled trials, which the researchers believe ‘promotes confidence’ in the results.
And limitations…
The study’s limitations, of which there are several, are ‘noteworthy’. Some of the trials had small sample sizes, one was not randomised, and many did not blind study personnel. Further, many of the included studies were funded by meat substitute manufacturers. This, the researchers explain, could mean the results are subject to funding bias.
Amongst the various limitations, which are not listed exhaustively here, is the fact that the results only show the short-term health effects of meat consumption. “Long-duration random controlled trials and prospective cohort studies are required to determine the long-term effects of meat substitute consumption on human outcomes.”
The researchers’ findings also beg the question: is it definitely the alternative protein – i.e. mycoprotein or soy/pea/wheat/gluten/pea protein – in the meat alternatives that is responsible for the lowering of total cholesterol, LDL cholesterol, and triglyceride levels?
Indeed, the researchers acknowledge that it could be the nutritional composition differences between meat substitutes and traditional meat products responsible for the health benefits.
Mycoprotein, for example, contains dietary fibre and is free from trans fats and dietary cholesterol. The vast majority of plant-based meat alternatives (with the exception of Beyond Meat’s products) investigated were also low in saturated fats compared with traditional meat products.
Human and planetary health
Overall, the study suggests that potential health benefits – for both humans and planet – of switching to a plant-based diet could be significant.
“An LDL cholesterol reduction of the scale caused by meat alternative consumption would reduce the risk of developing heart disease by about 25% over a two-year period,” explained Gibbs.
“This is a significant finding as it highlights that people can obtain some of the benefits of healthy plant-based diets whilst making minimal dietary change i.e., swapping animal meat with meat alternatives.”
And this is important because the livestock sector is a significant contributor to overall anthropogenic greenhouse gas emissions. Globally, it is thought to account for just under 20% of global GHG emissions. Plant-based meat substitutes, on the other hand, have a GHG footprint of between 34-93% less, per 100g of protein.
The researchers’ findings support the pledge to switch to meat alternatives to meet environmental sustainability goals, explained Gibbs. “Plant-based and mycoprotein-based meat substitutes have been shown to have smaller carbon, land, and water footprints than conventional meat by up to 90% depending on the type of animal being substituted.”
From a public health perspective, the researchers have raised some health concerns around meat alternative products, however. No long-term human studies have been conducted on the effects of soy leghaemoglobin – a haem iron-containing molecule used by Impossible Foods in the US – on human health, for example. Another ingredient of concern, according to the researchers, is seaweed-derived carrageenan. The ingredient is used for thickening, gelling, or stabilising.
High sodium levels in meat alternatives is another red flag. Sodium is known to be the leading dietary factor in terms of the global burden of disease due to its role in the causation of hypertension and CVD. Coconut oil, which is often used in meat alternative products, is high in saturated fatty acids – which raise LDL-cholesterol and consequently could increase risk of CVD.
“People interested in making the switch to meat alternatives should try to avoid regularly consuming products that are high in saturated fat and salt as these ingredients may undermine the cardiovascular health benefits observed in our study,” noted Gibbs.
Industry responds
Findings from the University of Warwick study, published in academic journal Dietetics, were not surprising to US plant-based meat company Beyond Meat – a company best known for its Beyond Burger, based on pea protein.
Back in 2021, Beyond Meat established a five-year research programme with the Stanford University School of Medicine, known as the Plant-Based Diet Initiative. The programme’s first clinical trial, published in American Journal of Clinical Nutrition, was one of the study’s examined in the University of Warwick study.
The trial assessed a group of healthy adults who alternated between an eight-week period consuming animal protein two or more times a day and an eight-week period consuming Beyond Meat products two or more times a day.
For the eight-week period when participants consumed Beyond Meat products, researchers found a statistically and clinically significant drop in LDL cholesterol, a Beyond Meat spokesperson told FoodNavigator.
Researchers further found a decline in TMAO, a compound found in the gut that is associated with heart disease and certain cancers.
“We will continue to support such studies, without control over the design or outcome, and have recently expanded our work in this area through a three-year agreement with the American Cancer Society to advance research on plant-based meat and cancer prevention while expanding the relevant clinical database,” the spokesperson told this publication.
Source: Dietetics
‘The effect of plant-based and mycoprotein-based meat substitute consumption on cardiometabolic risk factors: a systematic review and meta-analysis of controlled intervention trials’
Published 8 March 2023
DOI: https://doi.org/10.3390/dietetics2010009
Authors: Joshua Gibbs and Gah-Kai Leung
The American Journal of Clinical Nutrition
‘A randomized crossover trial on the effect of plant-based compared with animal-based meat on trimethylamine-N-oxide and cardiovascular disease risk factors in generally healthy adults: Study With Appetizing Plantfood – Meat Eating Alternative Trial (SWAP-MEAT)’
Published 11 August 2020
DOI: https://doi.org/10.1093/ajcn/nqaa203
Authors: Anthony Crimarco, Sparkle Springfield, Christopher Gardner et al.
