Meat or not to meat? Study challenges health claims of plant-based substitutes

Plant-based meat analogs (PBMA) have grown in popularity, but few studies have assessed their health effects. A recent American Journal of Clinical Nutrition study analyzed the effects of animal-based meat diets (ABMD) relative to PBMA diets (PBMD) on cardiometabolic health. This study was conducted in Singapore and included adults with an elevated risk of diabetes.

Study: Plant-based meat analogues (PBMAs) and their effects on cardiometabolic health: An 8-week randomized controlled trial comparing PBMAs with their corresponding animal-based foods. Image Credit: dropStock / Shutterstock

Background

Plant-based diets (PBDs) have been shown to positively impact cardiometabolic health due to the presence of a wide range of bioactive constituents, e.g., vitamins, dietary fibers, carotenoids, and so on. Despite the advantages, long-term compliance by habitual omnivores can be complex because meat consumption is deeply rooted in culture, history, and societal norms.

PBMAs, developed from sustainable plant-based sources, aim to ape the organoleptic attributes of their animal-based counterparts. With their growing popularity, it is important to critically evaluate their health effects relative to a typical omnivorous diet. In particular, there is a scarcity of research within an Asian dietary context.

About this Study

Addressing the aforementioned gap in the literature, the current study aimed to assess the impacts of ABMD and PBMD on cardiometabolic health among Singaporeans with an elevated risk of type 2 diabetes mellitus (T2DM). The central hypothesis was that substitutions with PBMA would lead to better cardiometabolic health and lower risks stemming from non-communicable diseases.

This was an 8-week parallel design randomized controlled trial with 89 participants. Among them, 44 were instructed to switch to fixed quantities of PBMAs, and the remaining switched to animal-based meats corresponding to the PBMAs. The primary outcome variable was LDL-cholesterol, and the secondary outcomes comprised other risk factors for cardiometabolic diseases (e.g., glucose and fructosamine) and dietary data. Within a sub-population, the secondary outcome also consisted of a measure of ambulatory blood pressure at baseline and post-intervention and continuous glucose monitoring for 14 days.

Study Findings

No significant effects were noted on the lipid-lipoprotein profile; however, both dietary regimes were associated with lower fructosamine and higher HOMA-β over time. No apparent differences were noted between the ABMD and the PBMD groups. The results did not show any clear benefits of PBMD on cardiometabolic health relative to ABMD.

The subpopulation that underwent glucose monitoring reported more effective glycemic management in the ABMD group. Ambulatory blood pressure also showed modest improvements after an ABMD but not a PBMD. These findings suggest that the health benefits of PBDs should not be conflated with PBMDs. This is because PBMDs are distinct from PBDs in terms of nutrition and impact on cardiometabolic health.

When comparing PBMAs with their corresponding animal-based foods, vast differences were noted in the macro- and micro-nutrient profiles. The ABMD group showed higher dietary protein, and in terms of micronutrients, PBMAs were higher in sodium. Potassium and calcium were also found to be higher in some PBMAs.

The better results concerning the glycemic index in the ABMD group could be driven by the lower carbohydrate and higher protein consumption relative to the PBMD group. Here, protein bioavailability was not assessed, but existing research has shown weakened absorption and digestion of PBMA proteins compared to animal-based meats. This leads to differential insulin secretion and production of gut hormones.

The selection and assessment of widely available and popular contemporary PBMAs is a key strength of this study. The mode of intervention was also flexible to enable the assessment of broader dietary consequences following a switch to PBMD. Furthermore, the strictly regulated setting, where provision and consumption of food happened at specific times, contributed to the influence of confounders to be minimized. 

Conclusions

In sum, despite the growing popularity of PBMAs as a source of alternative protein, the results documented here do not support the hypothesis of superior cardiometabolic health benefits linked to PBMDs relative to an omnivorous diet comprising animal-based meats. 

Incorporating PBMAs into the diet could affect nutritional intake and potentially compromise glycemic management. This implies that the health benefits of PBDs should not be conflated with PBMD because PBMDs are distinct from PBDs in terms of their nutrition and impact on cardiometabolic health.

The results documented here provide a stimulus and motivation for the food industry to research and develop the next generation of PBMAs with greater nutritional attributes and bioaccessibility. The current focus is on organoleptic properties, and expanding the remit to consider nutrition and sustainability is expected to benefit producers and consumers alike.