The popularity of plant-based diets is on the rise, and accompanying it is the development of plant-based meat substitutes, commonly known as mock meats. These have undergone quite a radical transformation over the past decade, from bland and tasteless soy patties to burgers that quite literally bleed, such as the Impossible Burger, and many people have been taken by surprise by the similarity in textures and flavours of these plant-burgers in comparison to the meat burgers they attempt to mimic.
With the rise of these plant-based meat alternatives, it now begs the question – are these plant-based mock meats in fact healthy? Can you have your plant-burger and eat it too?
An argument that is commonly raised is that if you simply look at the ingredients of the different burgers, you’ll find your answer. A beef burger usually contains one ingredient if no spices or marinades are added: beef. On the contrary, most plant-based substitutes, such as the beyond meat burger, are considered ultra-processed foods and contain several ingredients, including canola oil, potato starch, beet juice extract (for the color), maltodextrin, yeast extract etc. Surely a logical conclusion would be that the beef burger is the healthier option, right? I mean despite already being a WHO Group 2A carcinogen? (1)
When you compare the macronutrients (see table above) (2), they weigh up quite equally. Although beef burgers are slightly lower in protein and higher in total and saturated fat. And specifically, beef burgers contain cholesterol, which is an independent, linear, and dose-dependent risk factor for cardiovascular disease (CVD), (3) of which plant-burgers, including the Beyond Meat burger, are devoid.
The Beyond Meat burger does have over 5x the amount of sodium than that of a beef burger, which is an important and well-recognized risk factor for hypertension (4), however, the 390mg sodium in a Beyond burger still falls well below the recommended daily allowance (RDA) of 2300mg per day.
One of the benefits of plant-burgers is that they do contain some fiber which is absent in all meat. Fiber is the indigestible and unabsorbable part of plants which stays in your gut and is excreted with your stool and can lower the risk of gastrointestinal tract diseases such as diverticulitis and colon cancer. (5,6,7) One Beyond Meat burger provides almost 25% of a woman’s fiber RDA and 15% of a man’s, and that’s without garnishing or a bun.
These issues aside, how do plant-burgers and meat burgers compare in clinical trials?
To establish which is healthier, you need to look at the impact these burgers have on the health outcomes of people, as that’s our best end measurement. You can argue ingredients and mechanisms until you’re blue in the face, but if health outcome data doesn’t agree with the mechanisms, you should rethink your position.
Stanford university enrolled 36 participants into a randomized crossover trial, named the SWAP-MEAT trial, (2) to compare the effects of Beyond Meat products and organic, grass-fed, 80% lean beef. They were instructed to eat 2 or more servings a day of meat or Beyond Meat products for 8 weeks, while keeping the rest of their diet and lifestyle the same, and then to switch groups.
The primary outcome they measured was serum trimethylamine-N-oxide (TMAO), which is a relatively new marker that may be a risk factor for CVD, as well as a predictor of adverse cardiac events, such as heart attacks. (8) TMA is a molecule that is produced by bacteria in the gut. It is derived from two main amino acids, namely choline and carnitine, which are predominantly found in red meat and eggs, and found in lower concentrations in plant-based foods. TMA travels in the blood stream to the liver, where it is converted into TMAO by hepatocytes. Researchers found that the group that started with meat for 8 weeks, and then switched over to Beyond Meat for 8 weeks, dropped their TMAO levels significantly, from 4.7 μM to 2.7 μM.
Interestingly, the group of participants that ate the Beyond Meat first, followed by the meat, had no significant changes in TMAO levels. It has been noted previously that if you feed vegetarians carnitine, their levels of TMAO do not raise significantly, which is speculated to be a result of a difference in the gut microbiome (suggesting vegetarians eventually deprive and lose the bacteria that produce TMA from choline and carnitine). (9)
Looking at secondary outcomes, participants that started with meat for 8 weeks followed by Beyond Meat lost on average 1 pound of bodyweight, which may not seem significant, but considering that the singular change was the source of their meat (or “meat”), this should not be overlooked, and the change may result in further weight loss if adopted for a longer period of time. LDL-cholesterol (aka “bad” cholesterol associated with an increased risk of CVD) also fell significantly after the Beyond Meat phase despite the presence of saturated fat in the burgers. Blood pressure, blood glucose, other blood lipids (HDL-cholesterol and triglycerides), insulin and insulin-like growth factor (IGF-1) did not change significantly.
In another study published in 2021, butyrate-producing bacteria (butyrate is a short-chain fatty acid produced by health-promoting bacteria in the gut, which is the primary source of energy for the cells that line the colon, called colonocytes) were shown to increase in a randomized control trial where the experimental group replaced 5 meat servings per weak with plant-based mock meats, indicating a more healthful gut microbiome after a reduction in meat consumption. (10)
When looking at the healthfulness of a food, it is important to clarify what we are comparing that food to. If we compare Beyond Meat to beef, we have seen in the SWAP-MEAT trial that Beyond Meat may have more favourable health outcomes than beef. However, if we were to compare Beyond Meat or other mock meats to more whole food/less processed sources of protein, such as legumes or tofu, I would presume that the latter would have improved health outcomes. My view is that mock meats are a great substitution food for those who are transitioning to a plant-based diet and can be included in a healthy plant-based diet, but we should always try to get most of our protein and calories from whole food sources and should not rely on mock meats as our primary source of protein in our diet.
References
1. Turesky RJ. Mechanistic evidence for red meat and processed meat intake and cancer risk: A follow-up on the International Agency for Research on Cancer Evaluation of 2015. Chimia (Aarau). 2018;72(10):718–724.
2. Crimarco A, et al. 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). Am J Clin Nutr 2020;112:1188–1199.
3. Ference BA, et al. Low-density lipoproteins cause atherosclerotic cardiovascular disease. Evidence from genetic, epidemiologic, and clinical studies. A consensus statement from the European Atherosclerosis Society Consensus Panel. Eur Heart J. 2017;38(32):2459-2472.
4. Grillo A. Sodium Intake and Hypertension. Nutrients. 2019;11(9):1970.
5. Carabotti M, et al. Role of Dietary Habits in the Prevention of Diverticular Disease Complications: A Systematic Review. Nutrients 2021;13(4):1288.
6. Brandão V, et al. The Relation Between the Diet and the Diverticulitis Pathophysiology: An Integrative Review. Arq. Gastroenterol. 2021; 58 (03):394-398.
7. Mashup M, Nindrea RD. Dietary Fibre Protective against Colorectal Cancer Patients in Asia: A Meta-Analysis. Open Access Maced J Med Sci. 2019;7(10):1723–1727.
8. Schiattarella GG, Sannino A, Toscano E, Giugliano G, Gargiulo G, Franzone A, Trimarco B, Esposito G, Perrino C. Gut microbe-generated metabolite trimethylamine-N-oxide as cardiovascular risk biomarker: a systematic review and dose-response meta-analysis. Eur Heart J. 2017 Oct 14;38(39):2948-2956.
9. Keoth RA, et al. l-Carnitine in omnivorous diets induces an atherogenic gut microbial pathway in humans. J Clin Invest. 2019;129(1):373–387.
10. Toribio-Mateas MA, Bester A, Klimenko N. Impact of Plant-Based Meat Alternatives on the Gut Microbiota of Consumers: A Real-World Study. Foods. 2021 Aug 30;10(9):2040.
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