The effect of plant-based meat on cardiometabolic health Original paper

In this randomized controlled trial in adults in Singapore with prediabetes, replacing animal-based protein sources (i.e., meat) with plant-based meat analogs did not meaningfully affect cardiometabolic health.

The effect of plant-based meat analogs (PBMA) on cardiometabolic health in adults in Singapore with prediabetes.

The primary outcome was LDL-C. The secondary outcomes included HDL-C, triglycerides, total cholesterol, body composition (measured using DXA), high-sensitivity C-reactive protein, blood glucose levels, fasting glucose and insulin, fructosamine, and blood pressure.

82 participants (average age of 59; 61% women, 39% men) with prediabetes who were living in Singapore.

In this 8-week randomized controlled trial, the participants were instructed to replace their usual protein-rich foods with either approximately 2.5 servings per day of animal-based protein or plant-based protein.

The researchers provided the animal-based protein group with beef mince, pork mince, chicken breast, burger patty, sausage, and chicken nuggets. The PBMA group received Impossible Beef, OmniMeat Mince, Chickened Out Chunks, Beyond Burger, Beyond Sausage, and Little Peckers. The participants were instructed to minimize their consumption of other protein-rich foods.

To monitor dietary adherence, the participants completed 3-day food records at baseline and weeks 2, 5, and 8.

Researchers monitored blood glucose levels over a 14-day period using a continuous glucose monitor. During days 0–3, the participants completed a full-feeding period in which they were served breakfast, lunch, and dinner by the research staff, and the only difference between the meals was whether the main protein source was animal-based or plant-based.

Compared to the animal-based protein group, there was a reduction in diastolic blood pressure in the PBMA group, although the reduction was small and of unclear clinical significance (–2 mmHg). Furthermore, this reduction was only found via clinic-measured blood pressure. There was no difference between groups for 24-hour ambulatory blood pressure.

During the full-feeding period, the animal-based protein group spent more time in the appropriate blood glucose range (between 3.9 and 7.8 mmol/L/70 and 140 mg/dL) than the PBMA group (94.1% vs. 86.5%).

There were no other differences between groups.

The interest in studying the effects of replacing animal-based protein with plant-based protein stems from evidence from observational studies indicating that doing so can reduce the risk of all-cause mortality, as well as the risk of developing conditions like cardiovascular disease and type 2 diabetes.^[1][2] Additionally, evidence from randomized controlled trials suggests that diets containing plant-based protein sources (like legumes and nuts), as opposed to red meat, are better for LDL-C.^[3]

However, it bears highlighting that these data are based on replacing animal-based protein (often red meat, specifically) with nuts, seeds, and legumes — not PBMA. PBMA are highly processed, which can result in the loss of beneficial phytochemicals that are present in minimally processed plant foods. Additionally, the processing of PBMA, plus the variety of other ingredients they contain, results in a very different food matrix than that of minimally processed plant foods. Thus, 2 foods can provide the same plant protein but produce different metabolic responses in the body due to differences in how the plant protein is packaged,^[4] and so the data concerning minimally processed plant foods is not necessarily generalizable to PBMA.

Common ingredients in plant-based meat analogs

Larger, bolder font indicates that the ingredient is more frequently included in plant-based meat analogs. Adapted from Romao et al., 2023, Foods.

The interest in PBMA is fairly recent, and thus there is limited research evaluating whether replacing animal-based protein with PBMA improves cardiometabolic health. The summarized study found that an animal-based protein diet and a PBMA-based diet had similar effects on cardiometabolic health. One minor difference was that during the full-feeding period, the animal-based protein group spent more time in the appropriate blood glucose range, although other measures of glycemic control (e.g., average absolute glucose level, mean amplitude of glycemic excursion, 24-hour blood glucose incremental area under the curve) did not differ between groups. Presumably, the slightly lower time spent in the appropriate blood glucose range in the PBMA group was due to the higher carbohydrate content of the diet because the PBMA contain more carbohydrate than the animal-based proteins, and carbohydrate amount is the primary determinant of the postprandial (postmeal) blood glucose level.^[5][6]

There has been one other well-controlled trial that evaluated the effects of replacing animal-based proteins with PBMA like those used in the summarized study. In this 8-week randomized crossover trial, known as the SWAP-MEAT trial, 36 participants without apparent health conditions who lived in the area of Stanford, California, consumed about 2.5 servings per day of either animal-based protein or PBMA, all of which were provided to the participants by the research staff.^[7] Notably, aside from being mostly white, these participants were similar to the participants in the summarized study because their average BMI was in the overweight category and their fasting glucose was 96 mg/dL.

At the end of each 8-week intervention, LDL-C (110 vs. 121 mg/dL) and body weight (78.7 vs. 79.6 kg) were lower with the PBMA diet than the animal-based protein diet. However, like the summarized study, there were no differences between diets for fasting glucose, insulin, HDL-C, triglycerides, or blood pressure.

So why did replacing animal-based protein with PBMA improve LDL-C in this study, but not in the summarized study? It could be related to differences in the populations studied. Although the amount of PBMA and animal-based protein was controlled and similar between studies, what constituted the remainder of the diet was up to each participant. Because one study included people who lived in California and the other study included people who lived in Singapore, it’s likely that the background diets of the participants differed substantially, which may have influenced the results. Ethnic differences may have also contributed to different metabolic responses to the intervention foods.^[8]

Another possibility relates to differences in the PBMA provided to the participants. In the SWAP-MEAT trial, all of the PBMA were Beyond Meat products, whereas in the summarized study, 2 of the 6 PBMA were Beyond Meat products. This is notable because not all PBMA are nutritionally equivalent.^[9]

In the SWAP-MEAT trial, saturated fat intake was significantly lower with the PBMA diet than the animal-based protein diet (26 grams vs. 33 grams per day). However, in the summarized study, saturated fat intake did not significantly differ between diets. This variable alone may primarily explain why LDL-C improved in the SWAP-MEAT trial because an increase in saturated fat intake has been consistently shown to increase LDL-C.^[10][11]

Additionally, caloric restriction can reduce LDL-C.^[12] Considering the fact that weight did not differ between groups in the summarized study, although weight was a little bit lower with the PBMA diet in the SWAP-MEAT trial, it’s possible that caloric restriction contributed to the different results for LDL-C.

Finally, the researchers of the SWAP-MEAT trial speculated that a higher fiber intake contributed to the reduction in LDL-C with the PBMA diet. Although fiber intake was higher with the PBMA diet than the animal-based protein diet (28 grams vs. 22 grams per day), the difference wasn’t statistically significant. Also, fiber intake was significantly higher in the PBMA group in the summarized study (15 vs. 31 grams per day), but there was no difference in LDL-C between groups.

There is some evidence to suggest that increasing increasing total fiber intake can reduce blood cholesterol levels,^[13][14] but it seems that the type of fiber consumed, rather than the total amount, is the primary determinant of this effect.^[15] Specifically, viscous soluble fiber is the most effective for reducing LDL-C.^[16] As such, it’s possible that differences between studies in the type of fiber within the PBMA provided to the participants played a part in the contrasting results for LDL-C, although it’s unclear whether this was actually the case, as information on the type of fiber within the PBMA was not reported in the studies.

In sum, not all PBMA are created equal, and so replacing animal-based proteins with PBMA is not a guaranteed way to improve diet quality and cardiometabolic health. For example, replacing meat with mycoprotein-based meat analogs has been consistently shown to significantly reduce LDL-C. This is related to mycoprotein being rich in viscous soluble fiber, but also because the mycoprotein-based products are low in saturated fat, and so replacing meat with mycoprotein-based products typically results in a significant reduction in saturated fat intake.

Many PBMA, like those used in the studies mentioned above, have a similar saturated fat content as commonly consumed meats,^[9] and not all of them are rich in fiber. Similarly, although many PBMA contain fewer calories per serving than commonly consumed meats,^[9] this isn’t always the case — it ultimately depends on the specific meat and the PBMA it’s replaced by.

All intervention foods were sourced from independent retailers that were unaffiliated with the study and research team.