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Vegetarian, Mediterranean diets equally effective for CVD prevention
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In a new study, adults with overweight who followed a vegetarian diet or a Mediterranean diet had similar reductions in body weight, BMI and fat mass, leading researchers to conclude that both diets appear similarly effective to reduce the risk for CVD and stroke.
However, some differences between the two diets emerged, such as a greater improvement in LDL with a plant-based diet and a greater improvement in triglycerides with a Mediterranean diet.
“The take-home message of our study is that a low-calorie lacto-ovo-vegetarian diet can help patients reduce cardiovascular risk about the same as a low-calorie Mediterranean diet,” Francesco Sofi, MD, PhD, professor of clinical nutrition at the University of Florence and Careggi University Hospital in Italy, said in a press release. “People have more than one choice for a heart-healthy diet.”
Comparison of diets
Previous research demonstrated CV risk factor reduction with both diets. However, the CARDIVEG study is the first to compare the effects of the two distinct eating patterns, according to the researchers.
The study was designed to evaluate whether switching to a lacto-ovo-vegetarian diet would also be heart healthy among adults with overweight who were used to eating meat and fish. The researchers enrolled 118 adults in Italy aged 18 to 75 years (78% women; mean BMI, 30.6 kg/m2). Participants were healthy but overweight, with a low to moderate CV risk profile.
After a 2-week run-in period, participants were randomly assigned to follow a low-calorie vegetarian diet (n = 60) or a low-calorie Mediterranean diet (n = 58) for 3 months. After 3 months, participants switched diets. Participants were also instructed to maintain their typical lifestyle and exercise habits during the study period.
The lacto-ovo-vegetarian diet excludes meat, poultry, fish and seafood, but allows consumption of eggs and dairy. The Mediterranean diet includes poultry, fish and some red meats, as well as fruits, vegetables, beans and whole grains.
Adherence to both dietary plans was high, as most participants were able to stay on both diets, according to the researchers.
Overall, participants on either diet lost about 4 lb of weight overall (–1.77 kg to –1.88 kg) and about 3 lb of body fat (–1.23 kg to –1.46 kg). Change in BMI was similar at about –0.64 kg/m2 to –0.67 kg/m2. The mean reduction in LDL was 5.44% with the vegetarian diet; however, the researchers observed no significant change after the Mediterranean diet period. The mean reduction in triglycerides was 5.91% with the Mediterranean diet vs. the vegetarian diet. The difference in end-of-diet values between the groups was 9.1 mg/dL for LDL (P = .01) and 12.7 mg/dL for triglycerides (P < .001). In subgroup analyses, changes in lipid profile during the vegetarian diet were more evident in men, those older than 50 years, nonsmokers, those with sedentary lifestyle and those who were obese.
Another finding was a significant difference in vitamin B12 levels with the two diets.
“As expected, in the intervention period with the [vegetarian diet], a significant reduction in vitamin B12 levels was observed. This reduction, despite being clinically irrelevant and within the normal range, confirms that the vegetarian diet may lead to lower levels of the vitamin, as previously reported by other studies,” Sofi and colleagues wrote in Circulation. “This issue warrants further investigation because, over an extended period, a decrease in vitamin B12 associated with [a vegetarian diet] can lead to a deficiency that may be clinically relevant.”
In addition, both diets resulted in significant improvement of the participants’ CV risk profiles.
Two strategies for weight loss, CV health
“Nearly every health care provider has to manage obesity or its consequences in the clinical setting or in his or her personal life. Low-calorie vegetarian or Mediterranean dietary patterns are two strategies for weight loss that can be promoted in the clinical setting,” Cheryl M. Anderson, PhD, MPH, MS, associate professor of preventive medicine at University of California, San Diego, wrote in an editorial accompanying the study.
Anderson noted similarities between the two diets that potentially explain the results. For instance, both dietary patterns emphasize “a healthy dietary pattern rich in fruits and vegetables, legumes, whole grains and nuts, focusing on diet variety, nutrient density and appropriate amount of food, and limiting energy intake from saturated fats.”
There are several study limitations, including its small sample size, limited duration and lack of BP data. Also, participants had relatively low risk for CVD at baseline. The researchers and Anderson called for future research to extend these study findings. – by Katie Kalvaitis
Disclosures: The authors and Anderson report no relevant financial disclosures.
Perspective
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Kim Allan Williams Sr., MD, MACC, FAHA, MASNC, FESC
Both diets have concerns, since it would be better to look at hard CV outcomes (death, MI and stroke) as the PREDIMED trialists did, showing a 70% relative persistence of cardiac events (described as a 30% reduction [Estruch R, et al. N Engl J Med. 2013;doi:10.1056/NEJMoa1200303]) with a seafood-containing diet.
Weight loss is not the ultimate goal — eg, 53% increase in mortality with the ketogenic diet post-infarction patients (Li S, et al. J Am Heart Assoc. 2014;doi:10.1161/JAHA.114.001169), if it results in a CV event.
The bottom line is that any diet that contains animal products increases CV death and all-cause mortality (Song M, et al. JAMA Intern Med. 2016;doi:10.1001/jamainternmed.2016.4182).
Perhaps it pushes the point a bit too far, but comparing one animal-containing diet vs. another for short-term surrogate outcomes (body weight) will be likened by some to rearranging the deck chairs on the Titanic, but I would say it’s more like rearranging the life boats. There is some benefit, but why not avoid the iceberg in the first place?
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