July 26, 2023 – Ditching meat and eating vegetarian may lower your cholesterol, help you lose weight, and improve your blood sugar control, new research shows.
Those benefits help those of us with heart or other vascular diseases, or are at a high risk of having them.
The findings were published this week in the journal JAMA Network Open.
The results “demonstrate that consuming a vegetarian diet exerts a modest but significant effect in … reducing multiple key risk factors,” including the “bad” LDL cholesterol; HbA1c – a measure of average blood sugar over 3 months; and body weight, especially in high-risk patients, the study’s authors said.
Vegetarian diets, which exclude meat and fish, have gotten more popular in recent years, with plant-based alternatives offered more, even at mainstream fast-food chains. While the diets have been shown to benefit the heart and blood vessels in the general population, there has been little research on people who already have, or are at high risk of, heart disease.
Meta-Analysis Included 20 Trials
To investigate, Tian Wang, a research dietitian at the University of Sydney in Australia, identified 20 trials involving 1,878 people with, or at high risk of, cardiovascular disease. They compared outcomes among those on vegetarian diets with other diets, including key measures of cholesterol, blood sugar, or blood pressure.
Overall, the results showed that people who ate vegetarian for an average of 6 months had significantly greater reductions in cholesterol beyond what’s seen with standard therapy.
The vegetarians in the study also saw their blood sugar drop 0.24% and lost an average of 7.5 pounds. The studies, overall, did not show a significant reduction in blood pressure.
“The greatest improvements in [blood sugar and cholesterol] were observed in individuals with type 2 diabetes and people at high risk of cardiovascular disease, highlighting the potential protective and synergistic effects of vegetarian diets for the primary prevention of cardiovascular disease,” the authors report.
The studies were done in the U.S., Asia, Europe, and New Zealand between 1990 and 2021, and included anywhere from 12 to 291 people, with ages ranging from 28 to 64.
The most commonly prescribed diets in the studies were: vegan, consisting strictly of plant-based foods; lacto-ovo-vegetarian diets, excluding meat, poultry, and seafood, but allowing dairy products and eggs; and lacto-vegetarian diets, excluding meat, poultry, seafood, and eggs, but allowing dairy products.
While lacto-ovo-vegetarian diets were linked to the greatest reduction in cholesterol, a caveat is that 4 out of 5 of these trials required people to restrict their daily calories.
The research, overall, shows a moderate level of evidence for reductions in cholesterol and blood sugar with the vegetarian diet, the researchers say.
Not All Vegetarian Diets are Healthy
Among the key features of vegetarian diets that could explain the improvements in key risk factors include that the diets can have lower saturated fat content and other substances that could explain the health benefits.
The diets may also be high in dietary fiber, mono- and polyunsaturated fatty acids, potassium, and magnesium, and be better for blood sugar, the authors said.
But the authors caution that not all vegetarian diets are necessarily healthy, with the potential for empty calories and deep-fried foods rich in trans-fatty acids and salt, which could potentially increase the risk of type 2 diabetes and coronary heart disease.
They said that “more than one-third of the studies included in our meta-analysis did not emphasize the importance of consuming minimally processed plant-based whole foods.”
So, “well-designed nutrition clinical trials with comprehensive dietary information are warranted to investigate the full effect of high-quality vegetarian diets in combination with optimal pharmacological therapy in people with cardiovascular diseases.”