The Impact of Plant-Based Diets on Gut Health

Introduction

Globally, meat intake is slowly rising. However, in some regions, plant-based, vegetarian, and vegan diets are also on the rise. Although people switch from meat for a number of reasons, two important ones are the impacts of animal products on human health and the health of the planet. It’s now well established that a high intake of red and processed meat is linked to poorer health. On the other hand, eating a diverse range of plants is associated with better health. At ZOE, we know that a thriving gut microbiome is vital for good health. So, it’s important to understand how shifting to a plant-based diet influences our microbes. However, because studying links between diet and the microbiome is challenging, there are few large-scale studies on how these different dietary patterns influence our gut bacteria.

Research Study

We decided to investigate how following a vegan or vegetarian diet might impact your gut bacteria. Our results were recently published in the high-impact scientific journal, Nature Microbiology.

Methodology

We analyzed poop samples from 21,561 participants, which included all participants based in the United Kingdom, United States, or Italy. They provided us with detailed information about their diet.

Findings

First, we analyzed the quality of participants’ diets using the Healthful Plant-Based Diet Index (hPDI). Based on this index, we found that on average, vegans had the healthiest diets, followed by vegetarians, and then omnivores. Next, we looked at their gut microbiome alpha diversity, which is one indicator of gut microbiome health. When alpha diversity is measured via species richness, it looks at how many different types of bacteria an individual has in their gut microbiome. We found that species richness was lower in vegetarians and vegans than in omnivores. This might seem counterintuitive, but experts are moving away from using alpha diversity alone as a measure of microbiome health because it doesn’t take into account the type of microbes present.

Dietary Patterns and Gut Microbiome

The gut microbiome composition of vegans, vegetarians, and omnivores were significantly different from each other. The greatest difference was between non-meat eaters and meat eaters. We saw that each dietary pattern had its own microbial “signature”. The omnivore signature featured more bacteria related to meat consumption and digestion, while the vegan signature featured more species of bacteria that specialize in fermenting fiber. Vegetarians had a different microbial signature due to their consumption of dairy products.

Microbiome and Health

Most of the ranked bacteria that appeared in the omnivore microbiome were linked to poorer cardiometabolic health markers. Conversely, most of the ranked bacteria that appeared in the vegan/vegetarian microbiome signatures were linked to better cardiometabolic markers. The study found that the gut microbiomes of vegans are healthier than those of vegetarians, and vegetarians’ gut microbiomes are healthier than the omnivore microbiome.

Conclusion

The researchers concluded that dietary pattern has a strong influence on the gut microbiome and specific gut microbes that are associated with better health. Following a healthy plant-based diet could potentially lead to a microbiome composition linked to better health. Further studies are needed to investigate whether this is true.

Overall, the study sheds light on the impact of plant-based diets on gut health and highlights the importance of a diverse and plant-rich diet for maintaining a healthy gut microbiome.