In a recent study published in the journal Nutrition & Metabolism, researchers evaluated the impact of the lacto-ovo vegetarian diet (VD) and Mediterranean diet (MD) on apolipoprotein levels and cardiovascular disease (CVD) risk factors among low-moderate-risk individuals.
CVD is the leading cause of global mortality, necessitating the development of novel biomarkers for prevention, early diagnosis, and treatment. Apoproteins, which regulate lipoprotein metabolism, are considered a risk marker for CVD. The European Society of Cardiology (ESC) recommends ApoB as a CVD risk marker. ApoA-I, mainly found in high-density lipoprotein (HDL) lipids, play protective roles in reverse cholesterol transport. However, data on diet's influence on apolipoproteins is limited.
Study: Effects of a dietary intervention with lacto-ovo-vegetarian and Mediterranean diets on apolipoproteins and inflammatory cytokines: results from the CARDIVEG study. Image Credit: Brian A Jackson / Shutterstock
About the study
In the present study, researchers assessed the influences of MD and VD diets on circulating apolipoproteins and their association with cardiovascular disease risk estimators, such as inflammatory cytokine levels and lipid profiles.
The study included 52 participants (39 women; mean age of 49 years) in the Cardiovascular Prevention with Vegetarian (CARDIVEG) diet randomized, crossover clinical trial. All individuals were at low-moderate CVD risk (<5.0% at ten years, using the ESC guidelines) and selected from the Clinical Nutrition Department of Careggi Hospital, Italy.
Eligibility individuals were overweight or obese with body mass index (BMI) ≥25 kg/m2 and ≥1.0 cardiovascular disease risk factors: low-density lipoprotein (LDL) beyond 115 mg dL-1; triglyceride levels above 150 mg dL-1; total cholesterol above 190 g/dL; and fasting blood glucose ranging from 110 to 125.0 mg dL-1. The researchers excluded individuals with unstable medical conditions, medication prescriptions, expecting or breastfeeding women, and those who consumed poultry, fish, meat, or meat products or participated in weight loss programs in the previous six months.
The participants followed the MD (27 individuals) and VD (25 individuals) diets for three months. Both diets comprised 50% to 55% carbohydrates, 15% to 20% proteins, and 25% to 30% total fats (≤7.0% of saturated fat, less than 300 milligrams of cholesterol). The team provided the participants with one-week menu plans, different recipes, and precise data on foods to consume and avoid.
The primary outcomes were changes in body weight, fat mass, and BMI, and the secondary outcomes included changes in circulating CVD risk markers and apolipoprotein levels. The team obtained medical history, demographics, comorbidities, risk factors, lifestyle, and dietary data at study initiation. They collected blood samples with body composition and BMI data before and after the interventions.
The team used the Medi-Lite and National Health and Nutrition Examination Survey (NHANES) questionnaires to assess adherence to MD and VD diets, respectively. They conducted a primary analysis using general linear modeling, evaluating differences in apolipoprotein levels by sex, age, and CVD risk factors. They used linear regressions to examine the association between these changes and lipid profiles, inflammatory profiles, and dietary components.
Results
MD and VD improved lipid profiles and anthropometric variables, reducing total energy, fats, and cholesterol and increasing total carbohydrates. VD lowered protein and increased dietary fiber, while MD decreased body weight, fat mass, and BMI. VD also reduces fat-free body mass. VD reduced LDL by 5.0%, while MD reduced serum triglycerides by 9.0%. Both diets lowered inflammatory parameters, with MD significantly decreasing interleukin-10 by 37% and interleukin-17 by 49%.
Both diets reduced inflammatory parameters, with significantly higher (24%) ApoC-I levels after VD. Both diets increased ApoA-I (2.7% by VD and 6.1% by MD), ApoC-I (24% by VD and 11% by MD), and ApoD (6.5% by VD and 6.2% by MD) levels. However, ApoB/ApoA-I ratios reduced by 1.9% and 7.4% after VD and MD, respectively. Conversely, the team observed opposite trends for ApoB (+0.7% by VD and −1.6% by MD), ApoC-III (−5.6% by VD and +1.8% by MD), and ApoE (+14% by VD and −1.6% by MD).
The team found negative correlations between apolipoprotein C-III and carbohydrates after MD and between ApoD levels and saturated fats after VD. In contrast, they found positive correlations between HDL and ApoD after VD and between serum triglycerides, ApoCI, and ApoD after MD. IL-17 positively correlated with ApoB and ApoC-III after VD. However, they found significant negative correlations between ApoC-III and carbohydrate percentage after MD and between ApoD and saturated fat percentage after VD. Serum triglycerides showed positive correlations with ApoC-I and ApoD levels after MD.
HDL changes positively correlated with ApoD levels after VD. Linear regressions confirmed the results, adjusted for potential confounders such as weight change and the treatment order. The subgroup analyses showed that both diets positively influenced circulating apolipoproteins, especially in women aged ≥50 years with less than three cardiovascular disease risk factors.
The study findings showed that VD and MD improve cardiovascular disease risk in low-moderate CVD-risk individuals by regulating lipid and inflammatory profiles. MD more positively affects apolipoprotein levels, especially in women, individuals aged >50 years, and those with one or two CVD risk factors. The study also found differences in associations between apolipoprotein levels and specific nutrients, with an unexpected inverse association between carbohydrate intake and ApoC-III after MD.
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