In this article from September 1, 2020, Dr. Martin Juneau of the Montreal Heart Institute looks at a study of the effect of plant-based meat substitutes on cardiovascular health.
• Participants in a study were divided into two groups, for eight weeks, one consumed two daily servings of plant-based meat substitutes (Beyond Meat products: burger, mock beef, sausage, mock chicken), while the other group ate the same amount of real meat (beef, pork, chicken).
• Participants who ate plant-based meat substitutes lost some weight and had significantly lower blood levels of trimethylamine oxide (TMAO) and LDL cholesterol than those who consumed meat during the same period.
• Plant-based meat substitutes appear to be beneficial for health compared to meat since high levels of TMAO and LDL cholesterol are two risk factors for cardiovascular disease.
In an article published in 2019, we discussed the merits and drawbacks of new food products that mimic the taste and texture of meat, such as Beyond Meat and Impossible Burger. These products are certainly more environmentally friendly than red meat (beef and pork in particular), which requires a lot of resources that tax the global environment. On the other hand, they are ultra-processed products that contain significant amounts of saturated fat and salt.
To determine whether plant-based meat substitutes could be healthier than meat, the Beyond Meat company funded Dr. Christopher D. Gardner, an independent and renowned researcher at Stanford University School of Medicine in California, to conduct a randomized controlled study. One must be extremely careful with studies funded by the food industry, since publishing only the results that will support the sale of their products is to their advantage. On the other hand, in the case of this study, all precautions seem to have been taken so that there is no influence on the results: study design (randomized and controlled with a crossover design), statistical analyses conducted by a third party who was not involved in the design of the study and data collection. Beyond Meat was not involved in the design of the study, the conduct of the study, or the analysis of the data. In addition, Dr. Gardner stated that he has already completed six food industry-sponsored studies with null findings from the original hypothesis.
The 36 study participants were randomly divided into two groups. During the first eight weeks, one group of participants were assigned to eat two servings/day of plant-based meat substitutes (Beyond Meat products: burger, mock beef, sausages, mock chicken), while the other group consumed two servings/day of meat (beef, pork, chicken). The two groups then switched their diet for the next eight weeks (crossover study design). Fasting levels of lipids, glucose, insulin, and trimethylamine oxide (TMAO) were measured before the start of the study and every two weeks during both phases of the study.
The main endpoint of the study was the blood level of TMAO, an emerging risk factor associated with atherosclerosis and other cardiovascular diseases. The group that consumed meat during the first eight weeks had a significantly higher TMAO mean level than the group that consumed plant-based meat substitutes (4.7 vs. 2.7 µM), as well as a higher LDL cholesterol (the “bad cholesterol”) mean level (121 vs. 110 mg/dL), while the mean HDL cholesterol (the “good cholesterol”) level was not significantly different.
A surprise awaited the researchers: Participants who first consumed plant-based products during the first eight weeks did not see their TMAO levels increase when they ate meat during the second part of the study. Researchers were unable to identify any changes in the microbiome (gut flora) that could have explained this difference. However, it appears that making the participants “vegetarian” for eight weeks caused them to lose the ability to produce TMAO from meat. This effect of a vegetarian diet on the microbiome has already been demonstrated by Dr. Stanley L. Hazen’s team at the Cleveland Clinic. After a few weeks of returning to a carnivorous diet, the microbiome begins to produce TMAO again from red meat and eggs.
TMAO is a metabolite produced by the gut microbiome from carnitine and choline, two compounds found in large quantities in red meat such as beef and pork. High concentrations of TMAO can promote atherosclerosis and thrombosis. Indeed, numerous observational studies and animal models have shown that there is an association between TMAO and cardiovascular risk, and that it is beneficial to reduce the levels of TMAO. It should be noted, however, that a causal link between TMAO and cardiovascular disease has not been established and that it is possible that it is a marker rather than a causal agent of these diseases.
In addition to the favourable effect on TMAO, participants who ate plant-based meat substitutes lost weight (1 kg on average) and had significantly lower LDL-cholesterol levels than those who ate meat (110 vs. 121 mg/dL). These differences were observed regardless of the order in which participants followed the two diets.
Beyond Meat probably hopes that these results will allow them to respond to criticisms about their products, which areultra-processed and contain a lot of salt and almost as much saturated fat as meat. Many people want to reduce their consumption of red meat, but do not like classic vegetarian dishes. It seems to us that if these meat substitutes appeal to consumers concerned about maintaining good health and allow them to reduce their meat consumption, this will be beneficial for them and may encourage them to cook veggie burgers and other plant-based meat substitutes themselves. Who knows, maybe these products will lead to significant changes in diet in the future. Considerably reducing our meat consumption can only be beneficial to our health and that of the planet.
Originally published September 1, 2020, on observatoireprevention.org