Meat or no meat? Study disputes health claims for plant-based substitutes

Plant-based meat analogs (PBMA) have grown in popularity, but few studies have evaluated their health effects. Recently American Journal of Clinical Nutrition The study analyzed the effects of animal-based meat diets (ABMD) compared with PBMA diets (PBMD) on cardiometabolic health. This study was conducted in Singapore and included adults at increased 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 animal-based food counterparts. Image credit: dropStock / Shutterstock

Background

Plant-based diets (PBDs) have been shown to positively influence cardiometabolic health due to the presence of a wide range of bioactive ingredients, e.g. vitamins, dietary fiber, carotenoids, etc. Despite the benefits, long-term compliance by habitual omnivores can be complicated because meat consumption is deeply rooted in culture, history, and societal norms.

PBMAs developed from sustainable plant-based sources aim to mimic the organoleptic characteristics of their animal-derived counterparts. With their increasing popularity, it is important to critically evaluate their health impact relative to the typical omnivorous diet. In particular, there is a paucity of research in the context of the Asian diet.

About this study

Addressing the aforementioned literature gap, the present study aimed to assess the impact of ABMD and PBMD on cardiometabolic health among Singaporeans at increased risk of type 2 diabetes mellitus (T2DM). The central hypothesis is that PBMA substitutions will lead to better cardiometabolic health and lower risks arising from non-communicable diseases.

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

Survey results

No significant effects on the lipid-lipoprotein profile were noted; however, both dietary regimens were associated with lower fructosamine and higher HOMA-β over time. No obvious differences were noted between the ABMD and PBMD groups. The results showed no clear benefits of PBMD on cardiometabolic health over ABMD.

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

When comparing PBMAs to their animal-based food counterparts, vast differences in macro- and micro-nutrient profiles were noted. 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 glycemic index results in the ABMD group may be due to the lower carbohydrate consumption and higher protein consumption compared to the PBMD group. Here, the bioavailability of the protein was not assessed, but existing studies show impaired absorption and digestion of PBMA proteins compared to animal meats. This leads to different insulin secretion and intestinal hormone production.

The selection and evaluation of widely available and popular modern PBMAs is a key strength of this study. The mode of intervention was also flexible to enable assessment of wider dietary implications after switching to PBMD. In addition, the tightly regulated setting in which the provision and consumption of food occurred at specific times helped to minimize the influence of confounding factors.

Conclusions

In summary, despite the growing popularity of PBMAs as an alternative protein source, the results documented here do not support the hypothesis of superior cardiometabolic health benefits associated with PBMDs compared to an omnivorous diet including meats of animal origin.

Inclusion of PBMA in the diet may affect nutritional intake and potentially compromise glycemic control. This means that the health benefits of PBMD should not be confused with PBMD, as PBMDs differ from PBDs in terms of their nutrition and effects on cardiometabolic health.

The results documented here provide incentive and motivation for the food industry to research and develop the next generation of PBMAs with better nutritional qualities and bioavailability. The current focus is on organoleptic properties, and expanding the mission to consider nutrition and sustainability is expected to benefit both producers and consumers.