Low-Calorie Vegetarian vs. Mediterranean Diets

Study Questions:

What is the effect on weight loss and cardiovascular risk profile of the lacto-ovo vegetarian diet (Vd) as compared to the Mediterranean diet in clinically healthy omnivorous subjects?

Methods:

Clinically healthy participant omnivores (18–75 years of age) with a low-to-moderate cardiovascular risk profile (<5% at 10 years according to the European Society of Cardiology) were recruited through public media. Eligibility criteria included being overweight (body mass index [BMI] ≥25 kg/m2) and the simultaneous presence of ≥1 of the following: total cholesterol >190 mg/dl, low-density lipoprotein cholesterol (LDL-C) >115 mg/dl, triglycerides >150 mg/dl, and glucose >110 but <126 mg/dl. Subjects were randomly assigned to a low-calorie Vd compared with a low-calorie Mediterranean diet, each lasting 3 months, with a crossover design. The primary outcome was the difference in weight, BMI, and fat mass changes between the two groups. Secondary outcomes were differences in circulating risk factor parameter changes between the two groups.

Results:

One hundred eighteen subjects (mean age: 51.1 years, females: 78%) were enrolled. The total participation rate at the end of the study was 84.7%. No differences between the two diets in weight were observed with each significant: Vd (‒1.88 kg) and Mediterranean diet (‒1.77 kg). Similar results were observed for BMI and fat mass. Compared to the Mediterranean diet, the Vd reduced LDL-C by an additional 9.1 mg/dl (p = 0.01), and vitamin B12 by 32.3 pg/ml, while the MD decreased triglycerides by an additional 12.70 mg/dl (p < 0.01). No significant difference was found between Vd and Mediterranean diet interventions in oxidative stress markers and inflammatory cytokines, except for interleukin-17, which improved only in the MD group. Forty-six participants during the Vd period and 35 during the MD period reached the target values for ≥1 cardiovascular risk factor. Only 15.3% of participants reported a less-than-optimal compliance to the prescribed diets and were excluded at different time points.

Conclusions:

Both Vd and MD were effective in reducing body weight, BMI, and fat mass, with no significant differences between them. However, the Vd was more effective in reducing LDL-C, whereas the Mediterranean diet led to a greater reduction in triglyceride levels, but not in insulin, glucose, or homeostatic model assessment of insulin resistance (HOMA-IR).

Perspective:

The study was done on very low-risk Italians whose usual diet is likely the Mediterranean and compliance was measured by unscheduled 24-hour recalls, which may not be truthful. While interesting, particularly the equality in markers of oxidative stress and inflammation, the probability of equal compliance with lacto-ovo vegetarian and Mediterranean diets in the clinical setting is unlikely.

Clinical Topics: Diabetes and Cardiometabolic Disease, Dyslipidemia, Prevention, Hypertriglyceridemia, Lipid Metabolism, Nonstatins, Statins, Diet, Stress

Keywords: Body Mass Index, Caloric Restriction, Cholesterol, LDL, Diet, Mediterranean, Diet, Vegetarian, Glucose, Insulins, Interleukin-17, Overweight, Oxidative Stress, Primary Prevention, Risk Factors, Triglycerides, Diet, Vegetarian, Vitamin B 12, Weight Loss


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