Plant-Based Diets and Raw Vegetables Linked to Weight Loss and Heart Disease Prevention

Evidence in favour of plant-based diets continues to build. A further review has linked them with improved long-term health, particularly weight loss and the prevention of heart disease.

Medical researcher Yani Xu, of Qilu Hospital at Shandong University, and her colleagues also concluded that eating raw vegetables may make a substantial contribution to these results.

“Obesity and its associated complications not only lead to increased morbidity and mortality, but also to a reduced quality of life,” write Xu and team in their paper.

“A plant-based diet is a viable option for people who want to control their body weight and improve the quality of their diet to prevent and treat metabolic diseases.”

Plant-based diets, weight loss and heart disease

Research has repeatedly identified strong links between vegetarian and vegan diets and a lower risk of major illnesses. Reported associations include healthier cholesterol levels, hearts, brains, bowels and immune systems, as well as greater longevity overall.

This does not mean everyone should immediately give up meat. However, it suggests that cutting down on meat where possible could have a markedly beneficial effect on health.

Xu and her team searched previous scientific research and identified 24 studies examining the connection between plant-based diets and weight loss. Combined data from those studies covered 2,223 people aged from 18 to 82, while the dietary interventions lasted between two and 96 weeks.

According to Xu and colleagues, the beneficial effects of plant based diets appear to grow over time. Participants following entirely vegan diets lost the greatest amount of weight, although their losses were not significantly higher than those of people who continued to eat dairy products and eggs.

Raw vegetables and health outcomes

The researchers found that studies involving higher raw vegetable consumption appeared to show the strongest associations with a reduced risk of obesity and heart problems.

Even randomised controlled trials such as these cannot establish whether raw vegetables themselves directly improve health. The researchers therefore carried out a second assessment using Mendelian randomisation, a method better able to identify cause-and-effect relationships in health.

Using a public database containing whole genomes, the team chose genetic variants that could be statistically linked with factors including plant-based diets, vegetable intake and adverse health outcomes. The Mendelian randomisation analysis indicated that consuming more raw vegetables was more likely than genetic factors to account for weight loss.

“Raw vegetables contain phytosterols and unsaturated fats that lower blood cholesterol concentrations,” Xu and team explain in their review. “They also contain various substances (e.g., tocopherols, ascorbate, carotenoids, saponins, and flavonoids) that can reduce inflammation and oxidative stress, thereby reducing the risk of cardiovascular disease.”

A balanced approach to vegetarian diets

Eating more raw vegetables may be a useful way to support better health, but an overly strict raw plant-based approach can also create health issues. If they are not carefully planned, vegetarian diets may result in nutrient deficiencies.

For instance, vitamin B12 is more readily obtained from animal products, and low levels may cause mouth ulcers, jaundice, vision problems, depression and other mood difficulties. Vegetarianism can also be extremely challenging for people living with diet-related health conditions.

For these reasons, researchers often stress that the key message from such studies is to add more vegetables to the diet, rather than to become strictly vegan.

This review was published in Frontiers in Nutrition.