A healthy, plant-based diet can result in sizable cardiac benefits, new research confirmed.
A new study, published last month in JAMA Network Open, found that a healthy vegan diet is significantly more protective for heart health compared to a healthy, omnivorous way of eating.
The study included 22 sets of identical twins. In each pair of twins, one ate a vegan diet and one ate an omnivorous diet. Researchers designed both diets to be balanced and heart-healthy. They then monitored each participant’s cholesterol levels.
”But because we created a healthy omnivorous diet, I was surprised that we got the magnitude of change that we did,” Christopher Gardner, PhD, study co-author and a professor of medicine at Stanford University, told Health.
The fact that the study was conducted in identical twins lent “more scientific rigor” to the research, Gardner explained.
While scientists can make adjustments in human trials that can try to account for other habits that could impact heart health, such as exercise habits, other factors—like genetics—can skew the data.
Since identical twins have the same DNA, it makes it easier to infer whether a person’s genetics or their environment—including diet—likely had a bigger impact on any changes logged in a study.
Here’s how a vegan diet can positively impact cholesterol levels and overall heart health.
Getty Images / LeoPatrizi
With 22 sets of twins, 44 people were involved in the randomized clinical trial that put a diet that includes meat and plant-based foods head-to-head with a plant-only diet that did not include meat, eggs, dairy, or any other animal product.
The median participant age was 40 years when the study began and none of them had a body mass index (BMI) of over 40 nor diabetes or high blood pressure.
More than 77% of the participants were women; about 11% were Asian, 4.5% were Black or African American, 2.3% were Native Hawaiian/Pacific Islander, 9% were multiracial and nearly 73% were white.
Nearly 80% of participants lived with their twin. All participants were omnivores before the study began.
During the trial, one twin from each pair was assigned to each diet and received meal deliveries from the research team for the first four weeks of the study. They were then in charge of their own meals and snacks for the second half of the eight-week study, as long as those foods adhered to their assigned way of eating.
Gardner explained that it’s important that both diets, at least during the first four weeks, were considered heart-healthy.
“It’s easy, as a researcher, to make your favorite diet really good and the other not so good,” he told Health. “But we worked really hard to make it a healthy vegan diet and a healthy omnivore diet.”
The prescribed omnivore diet included at least one serving of fish, meat, or chicken every day, as well as one egg and a serving and a half of dairy.
The vegan diet contained no animal foods, including eggs and dairy, and included a lot of beans and vegetables.
While nutritional intervention studies typically recruit people who have improvements to make, such as those with risk factors for developing heart disease, Gardner explained that the priority of recruiting twins meant the participant pool was fairly healthy at the beginning of the study.
Still, positive progress was made by switching to a plant-based eating plan.
A the beginning of the study, the average baseline LDL cholesterol level (commonly referred to as “bad” cholesterol) was 110.7 mg/dL for the vegan diet group and 118.5 mg/dL for the omnivore group.
At the end of the eight weeks, LDL cholesterol levels dropped to an average of about 96 mg/dL for the vegan twins and 116 mg/dL for omnivores. This change became noticeable around the month mark (week four).
In addition to a drop in LDL cholesterol levels, twins who went vegan experienced a roughly 20% drop in fasting insulin, a risk factor for developing diabetes.
“I was a little bit surprised by the magnitude of the improvement, especially since they had smaller room for improvement to begin with,” said Gardner.
Neither of the studied diets lowered glucose levels, another risk factor for diabetes, and both groups lost weight, though weight loss was slightly higher in the vegan group.
Gardner is careful to point out that simply going vegan doesn’t mean a person’s diet will be better for heart health.
“Soda pop is vegan, lots of sugary candy and snacky things are vegan, but they aren’t healthy,” he said.
However, a healthy vegan diet may be better than a healthy omnivore diet for a few reasons.
First, many vegan diets are high in legumes, or beans, which are rich in fiber and known to be good for heart health, Julia Zumpano, RD, a registered dietitian with the Center for Human Nutrition at Cleveland Clinic who specializes in heart health told Health.
Vegan diets also don’t contain saturated animal fat, which is harmful to cardiovascular health, she added.
People living in the United States eat more meat per capita than almost any other country and more than twice the global average. While eating a fully plant-based diet may not be for everyone, cutting back on the amount of meat you eat and adding more vegetarian sources of protein can go a long way, Gardner explained.
“You don’t have to go full vegan,” he said, “but I hope this encourages more people to try more vegan meals.”
