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Adopting a vegetarian diet may benefit heart health. Jen Grantham/Stocksy
  • Researchers investigated the effects of vegetarian dietary patterns on those with a high risk of cardiovascular disease.
  • They found that eating plant-based diets for six months improved several measures of cardiometabolic risk, such as cholesterol and blood sugar.
  • Eating a more plant-based diet may benefit those at high risk of cardiovascular conditions.

In 2019, 17.9 million people had a form of cardiovascular disease (CVD) at the time of death, accounting for 32% of deaths worldwide. Of these deaths, 85% were due to a heart attack or stroke.

Studies show that CVD often develops due to lifestyle factors, such as diet, smoking and physical inactivity. Practical interventions that may improve cardiometabolic risk profiles are thus key to reducing CVD rates.

An increasing amount of research shows that vegetarian diets may be effective in preventing CVD. However, little is unknown about how these diets may affect those with or at high risk of CVD.

Recently, researchers from the University of Sydney and Royal Prince Alfred Hospital in Australia, and Brescia University in Italy investigated how vegetarian diets affect major cardiometabolic risk factors among people with or at high risk for CVD.

They found that consuming a vegetarian diet for six months was linked to improved measures of cholesterol, blood sugar, and body weight among those at high risk of CVD.

Dr. Dana Hunnes, a senior clinical dietitian at the UCLA Medical Center in Los Angeles, who was not involved in the study, told Medical News Today:

“Vegetarian diets are not only better for CVD health, but they are also better for the environment — lowering greenhouse gases, using less water, and using less land — which is better for all of us.”

The paper — a systematic review and meta-analysis of the latest evidence — was published in JAMA Network Open.

For the study, the researchers analyzed 20 randomized controlled trials involving 1,878 participants with a mean age of 28–64 years who either had CVD or were at a high risk of CVD.

Not all the studies included the main measures of LDL, weight, HbA1C, and systolic blood pressure, and therefore the number of participants varied by analysis. Most patients were taking medication to manage their cardiometabolic symptoms.

The studies lasted for an average of 6 months. While four targeted people with CVD, seven focused on diabetes, and nine included people with at least two CVD risk factors, such as high blood pressure, high low-density lipoprotein (LDL) cholesterol, and diabetes. Participants ate different varieties of either vegan or vegetarian diets over the study periods.

Patient data included measures of blood glucose, systolic blood pressure — the pressure in the arteries when the heart pumps out blood — and LDL levels (19 studies included this measure, 1,661 participants). Body weight was included as a secondary measure.

Ultimately, the researchers found that consuming vegetarian diets for an average of 6 months was linked to small but significant decreases in LDL levels and measures of blood glucose.

They added that people with a high risk of CVD saw the greatest reductions in LDL, and that those with type 2 diabetes experienced the largest reductions in blood sugar levels.

They further noted that participants (1,395 in 16 studies) lost an average of 3.4 kilograms over the study period but that no major changes were noted in blood pressure readings (955 participants in 14 studies).

The researchers suggested that vegetarian diets may be used alongside drug-based therapies to prevent and treat various cardiometabolic conditions.

MNT spoke with Dr. Hunnes about how vegetarian diets may reduce CVD risk and how they might benefit those with the condition or at high risk.

She noted that vegetarian diets tend to be much higher in anti-inflammatory fiber and antioxidants due to their higher intake of fruits, vegetables, grains, nuts, seeds, beans, and legumes, as well as their lack of animal-based foods containing inflammatory saturated fats.

“Because of the contents of this type of diet, cholesterol levels, body weight, and inflammation tend to be lower. [These factors] act synergistically to lower [the] risk of CVD,” she added.

The researchers wrote that their findings for blood sugar, blood pressure, and cholesterol might have been obscured by patients’ use of medications to manage these areas. If this is true, they noted that vegetarian diets may have a larger effect on these measures than observed.

MNT also spoke with Dr. John P. Higgins, a sports cardiologist at McGovern Medical School at The University of Texas Health Science Center at Houston (UTHealth), who was not involved in the study, about its limitations.

He noted that the findings are limited by the possibility that a person’s adherence to a specific diet may reduce over time. He also pointed out that the study did not compare vegetarian diets with other diets known to benefit heart health, such as the Mediterranean diet.

MNT also spoke with Dr. Zahir Rahman, a cardiologist at Staten Island University Hospital, who was also not involved in the study. He noted that the findings are limited as they come from meta-analyses in trials with low numbers of participants. He said, however, that higher quality and larger randomized trials would likely produce similar findings.

Dr. Clyde Yancy, chief of Cardiology at Northwestern Medicine and Past President of the American Heart Association, who was not involved in the study, noted that the study examined multiple variants of vegetarian dietary patterns, including:

  • the ornish diet, which predominantly includes fruits, vegetables, whole grains, legumes, and soy with limited quantities of nonfat dairy,
  • the lacto-ovo-vegetarian diet, which is a meat-free diet that includes dairy products and eggs,
  • the lacto-vegetarian diet, which is a meat-free diet that includes dairy products but not eggs.

He noted that the study emphasized how there is no one standard vegetarian diet. He further cautioned that not all vegan choices are low-fat, and that some may even have high levels of preservatives.

“The greater take-away message is the benefit of a plant-sourced diet with lots of [variety] in composition,” Dr. Yancy noted.

Dr. Robert Pilchik, a board certified cardiologist with Manhattan Cardiology, not involved in the study, told MNT:

“The implication of this meta-analysis is that a vegetarian diet works synergistically with optimal medical therapy to lower LDL, [blood sugar], and body weight. These are all factors that are associated with increased risk of developing cardiovascular disease.”

Dr. Clancy added, however, that it may also be able to improve cardiometabolic health without becoming vegetarian.

“[The American Heart Association’s] Life’s Essential 8 is a plan anyone can implement today. No person need become a vegan or vegetarian but every person ought to realize the benefit of a plant-slant diet,” he concluded.