Newcastle researchers are examining the health effects of plant-based diets, amid rising interest in food that protects the environment and animals.
Hunter Medical Research Institute and University of Newcastle researchers are seeking adults aged from 35 to 70 to participate in the study. They're looking for people without diagnosed heart disease, who follow any of the following diets: vegetarian, pescatarian, flexitarian and regular meat eaters.
Dr Jessica Ferguson said studies in other parts of the world show people following plant-based diets had lower incidence of cardiovascular disease and chronic illnesses like diabetes and cancer.
"We know these diets help manage various risk factors like obesity and high cholesterol, but we don't have many Australian-based population studies in this area," Dr Ferguson said.
"As dietitians, we're passionate about establishing some specific Australian evidence around this."
The researchers want to know what Australians consume when they follow plant-based diets.
"And how does that compare to a regular, traditional meat-eating diet," she said.
She said Australia has one of the world's highest levels of meat consumption, with a yearly average of about 95 kilograms per capita.
"But we are not set out on a war of meat versus vegetables. As researchers, we're open-minded. We don't actually know if a plant-based diet is healthier than a traditional animal-eating diet in the long run."
A key part of the research involves looking at the risk of developing chronic disease.
"We're mainly focusing on the risk of developing heart disease with this study."
Researchers will examine people's risk of developing heart disease. This will involve looking at markers like blood cholesterol level, age, gender, blood pressure and smoking.
The research team's previous study on a group of more than 9000 Australian women found following a plant-based diet led to significantly lower levels of obesity around the waistline and lower prevalence of diabetes and pre-diabetes.
"What makes our study novel, though, is we're purposely sampling people who already follow plant-based diets," Dr Ferguson said.
She said there are many different definitions for what constitutes a plant-based or vegetarian diet.
"A clear definition of plant-based diets would help consumers make informed choices."
While there are indications that plant-based diets can improve health, they may also worsen health if they're not followed without proper guidance.
"Diets across the plant-based spectrum can be quite restrictive in certain food groups," she said.
"We want to uncover whether there are any potential nutrient deficiencies or inadequacies in people who follow these diets.
"How is it affecting other things like bone health? We're measuring bone density, bone mass and muscle mass and looking at vitamin D and other nutrients."
Dr Ferguson said the study would help inform the Australian Dietary Guidelines. The National Health and Medical Research Council is reviewing the guidelines, which were established in 2013. New guidelines are due for release in 2024.
"Across the globe, the US has just released their most revised dietary guidelines. They've referred to a more 'plant-forward' eating pattern as the way they want to head," she said.
"They've provided a vegetarian diet as an example of a healthy eating style for Americans. That's in accordance with some European countries as well.
"Australia is a bit behind. Our guidelines don't refer to vegetarian or plant-forward eating. We're eager to see what the revised guidelines will look like."
She said the study would detail what Australians eat when they follow various plant-based diets.
This would provide information for authorities to help develop the dietary guidelines in the plant-based section.
The study includes vegans, but enough of these people have been recruited.
The researchers particularly need people who follow pescatarian (fish/seafood, no other animal flesh), vegetarian (includes dairy and/or eggs), flexitarian (minimal animal flesh) and regular meat-eating diets.
"The pescatarians are hard to find," she said.
The researchers are seeking about 150 more people to complete the study. Contact lead investigator Grace Austin at firstname.lastname@example.org or 0422 650 262.