Plant power: Vegetarian diets may lower diabetes, hypertension and obesity risk

04 Jul 2023 --- Italian researchers found that vegetarian diets might have a positive impact on cardiometabolic health and hold the potential to protect from several diseases such as Type 2 diabetes, hypertension and obesity in comparison to meat-based diets. 

“Diets emphasizing the consumption of whole plant foods have also been associated with lower oxidative stress, inflammation, better endothelial function and increased insulin sensitivity,” Nicoletta Pellegrini, associate professor in Human Nutrition at the Department of Agricultural, Food, Environmental and Animal Sciences at the University of Udine, Italy, tells Nutrition Insight.

The review was published in Nutrition, Metabolism and Cardiovascular Diseases, and was done by the Vegetarian Diets Working Group of the Italian Society of Human Nutrition.

As vegetarian diets have a higher content of plant foods, it has a complex mixture of carbohydrates, fiber, polyunsaturated fatty acids and several micronutrients – such as magnesium and potassium – and phytochemicals, whose beneficial synergistic combinations have been associated with a reduced incidence of many pathological conditions such as being overweight, Type 2 diabetes and hypercholesterolemia, explains Pellegrini.

Changed view of plant protein
The authors say that diets lacking animals have been seen as a “threat” and an increased risk factor for nutrition deficiency. However, research in the last decade has proven that vegetarian diets are nutritionally adequate and better for human health. 

The review also points to the fact that vegetarian diets are an umbrella term for several different diets.

Pellegrini says that plant-based diets are typically low in saturated fat and cholesterol.The “umbrella” includes vegan, lacto-ovo-vegetarian, ovo-vegetarian, lacto-vegetarian, semi-vegetarian or low-fat vegan or lacto-ovo-vegetarian. There are also raw food and fruitarian diets.

Dietary differences
Meanwhile, there is also a difference in Western and Asian vegetarian diets, as access to food plays a role in whether animal proteins are available, which can be caused by socioeconomic factors.

“A vegetarian diet followed by people living in developed countries has more chances to be well-planned in respect to the vegetarian diet adopted in a developing country, where economic or cultural limits can affect its adequacy,” reads the review.

The researchers did not investigate the differences in meat quality, such as if it’s locally produced or ultra-processed, and how that may have played a role.

Pellegrini says that plant-based diets are typically low in saturated fat and cholesterol.

“The lower fat content of vegetarian diets than omnivorous diets is responsible for a lower energy density and a drop in energy intake and can also help to control body weight and blood lipid levels.”

She underscores that meat derivatives can also contribute to harmful effects related to excess animal protein intake, saturated fats and meat-derived iron.

Pointing to components
The researchers point to differences in non-essential and essential amino acids, as vegetarian diets are dominant in the former, and it also has a more significant impact on glucagon secretion than essential amino acids.

“Since ingested amino acids can modulate the secretion and balance of insulin and glucagon, plant-based diets can promote greater net glucagon activity than omnivorous diets. It has been hypothesized that the amino-acid profile of animal proteins might enhance insulin response to starchy food and thus promote their conversion into fat,” Pellegrini notes.

The review also highlights iron as it’s more easily absorbed when sourced from plants than meat. A recent study from Sweden showed that plant-based meat alternatives marketed as high in iron are also high in phytates – an anti-nutrient making it impossible for the human body to absorb the mineral.Unlike the other lifestyle factors, diet also has an impact on the health of our planet, says the researcher.

“Plant iron (non-heme iron) is not as easily absorbed as iron from meat (heme iron), for which heme iron can lead to higher ferritin levels. High iron tissue concentration can contribute to increased glucose production and hepatic glucose output and decrease glucose utilization impairing glycemic control,” explains Pellegrini.

Sustainable food
The gut microbiome’s role in overall health is a scientific field of growing evidence in mental health and emotion regulation, obesity and longevity.

“Studies have also demonstrated the presence of more protective bacterial species in the gut of vegetarians than non-vegetarians, which can lead to a lower inflammation grade. The reduction of inflammatory markers associated with plant-based diets is central for contrasting the initiation and progression of Type 2 diabetes,” Pellegrini adds.

“Diet is one of the lifestyle habits whose effect on health should be implemented to improve public health and reduce medical costs. But, unlike the other lifestyle factors, diet also has an impact on the health of our planet, and the sustainability of a diet should become a dimension to consider when dietary recommendations are formulated.”

“In this view, a vegetarian diet can represent a valuable option to recommend for the health of the planet and its inhabitants,” Pellegrini concludes.

By Beatrice Wihlander