Plant-based proteins, fibre and metabolic response

Aim

It has become clear that to improve both human health and our environment, it is essential to consume less meat and switch to a more plant-based diet.

There has been an increased availability and consumption of reconstructed plant protein products, which aim to make plant-based alternatives more accessible to consumers.

According to projections in this paper, between 2019 and 2026, this trend will result in a 63% increase in plant protein revenue and a threefold increase in the value of the meat analogue industry.

As the market has expanded, so has the interest in the nutritional profile and health benefits of these meat analogues.

This critical review investigated plant-proteins and how the inclusion of fibre in these protein sources plays a role in gut-derived health effects and metabolism.

Method

This critical review examined key topic areas including, digestion and metabolism of plant proteins, the role of fibre and starch in digestion of plant proteins, effects of plant proteins in gut microbiota, and the effect of fibre in plant protein induced metabolic responses in the colon.

Key findings

The majority of meat alternatives are processed with extrusion of soy, pea, potato, corn or wheat protein as the raw material.

Although based on whole foods, these products can also contain high levels of saturated fat, sodium, sugar, and additives. But in contrast to animal proteins that have zero fibre, the higher consumption of fibre that goes along with these proteins might be linked to gut microbiota-derived health impacts.

Dietary fibre metabolises in the lower digestive system which exerts numerous health effects such as decreasing blood pressure, lowering serum cholesterol and low-density lipoprotein levels, raising satiety, reducing postprandial glycemia, and favourably modifying the gut microbiota and its by-products, which include hydrogen, methane, carbon dioxide, and short-chain fatty acids (SCFAs).

The gut microbiota is a complex network of microbes that play a crucial role in maintaining our overall health. The diet we consume plays a significant role in the composition and diversity of the gut.

A more plant-based diet has shown to promote a more diverse microbiota, promoting health benefits.

However, as processed plant proteins rarely retain their natural food matrix, the health effects of new protein products may differ from those of whole plant protein sources.

Therefore, the review suggests that it is crucial to focus on the increased fibre content, rather than the source of protein, as this is probably what accounts for most of the gut-mediated health benefits of plant-based proteins.

Most of the data used in this review came from studies conducted in vitro and on animals.

Although these studies provide better control over confounding variables, the impact of plant proteins on the composition of the gut microbiota is complex, with study findings demonstrating wide variation.

Conclusion

The authors conclude plant proteins can produce either beneficial or detrimental health effects depending on the type and amount fibres present within the product.

Since there are many different types and sources of plant proteins, it is crucial to avoid making assumptions when classifying plant proteins as a single variable.

The review calls for more well-designed human studies with special attention to gut barrier function and inflammatory markers, in addition to their effect on gut microbiota activity.

To better understand the significance and mechanisms underlying the proteolytic activity and the availability of substrates in shaping the gut microbiota and their implications for human health, research that considers the protein source, food matrix, and fibre content in the study design is greatly needed.

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