In a recent study published in the journal Nutrition and metabolismresearchers evaluated the effects of a lacto-ovo vegetarian diet (VD) and a Mediterranean diet (MD) on apolipoprotein levels and cardiovascular disease (CVD) risk factors among individuals at low-moderate risk.
CVD is the leading cause of global mortality, necessitating the development of new biomarkers for prevention, early diagnosis and treatment. Apoproteins, which regulate lipoprotein metabolism, are considered a CVD risk marker. The European Society of Cardiology (ESC) recommends ApoB as a CVD risk marker. ApoA-I, found mainly in high-density lipoprotein (HDL) lipids, plays a protective role in reverse cholesterol transport. However, data on the effect of diet on apolipoproteins are limited.
Study: Effects of a dietary intervention with a lacto-ovo-vegetarian and Mediterranean diet on apolipoproteins and inflammatory cytokines: results from the CARDIVEG trial. Image credit: Brian A Jackson / Shutterstock
About the research
In the current study, researchers evaluated the impact of MD and VD diets on circulating apolipoproteins and their relationship with cardiovascular disease risk estimators such as inflammatory cytokine levels and lipid profiles.
The study included 52 participants (39 women; mean age 49 years) in a randomized, crossover clinical trial of cardiovascular prevention with a vegetarian diet (CARDIVEG). All subjects were at low to moderate CVD risk (<5.0% at ten years using ESC guidelines) and were selected from the Clinical Nutrition Department of Careggi Hospital, Italy.
Eligible individuals were overweight or obese with a body mass index (BMI) ≥25 kg/m2 and ≥1.0 cardiovascular risk factors: low-density lipoprotein (LDL) greater than 115 mg dL-1; triglyceride levels above 150 mg dL-1; total cholesterol greater than 190 g/dL; and fasting blood glucose ranging from 110 to 125.0 mg dL-1. The researchers excluded individuals with unstable medical conditions, prescribed medications, pregnant or lactating women, and those who had consumed poultry, fish, meat or meat products or participated in weight loss programs in the previous six months.
Participants followed the MD (27 subjects) and VD (25 subjects) diets for three months. Both diets contained 50% to 55% carbohydrate, 15% to 20% protein, and 25% to 30% total fat (≤7.0% saturated fat, less than 300 milligrams cholesterol). The team provided participants with one-week menu plans, various recipes and precise data on foods to eat and avoid.
Primary outcomes were changes in body weight, fat mass and BMI, and 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 the National Health and Nutrition Examination Survey (NHANES) questionnaires to assess adherence to the MD and VD diets, respectively. They conducted a primary analysis using general linear modeling assessing differences in apolipoprotein levels by sex, age, and CVD risk factors. They used linear regressions to examine the relationship between these changes and lipid profiles, inflammatory profiles and dietary components.
Results
MD and VD improved lipid profiles and anthropometric variables, decreasing total energy, fat, and cholesterol and increasing total carbohydrates. VD decreased 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 reduced inflammatory parameters, with MD significantly reducing 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 levels of ApoA-I (2.7% of VD and 6.1% of MD), ApoC-I (24% of VD and 11% of MD), and ApoD (6.5% of VD and 6 .2% of MD). However, ApoB/ApoA-I ratios decreased by 1.9% and 7.4% after VD and MD, respectively. In contrast, the team observed opposite trends for ApoB (+0.7% of VD and −1.6% of MD), ApoC-III (−5.6% of VD and +1.8% of MD), and ApoE (+ 14% of VD and − 1.6% of MD).
The team found negative correlations between apolipoprotein C-III and carbohydrates after MD and between ApoD levels and saturated fat after VD. Conversely, 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 percent carbohydrate after MD and between ApoD and percent saturated fat after VD. Serum triglycerides showed positive correlations with ApoC-I and ApoD levels after MD.
Changes in HDL positively correlated with ApoD levels after VD. Linear regressions confirmed the results adjusted for potential confounders such as change in weight and order of treatment. Subgroup analyzes showed that both diets positively affected circulating apolipoproteins, particularly in women aged ≥50 years with fewer than three CVD risk factors.
Study results show that VD and MD improve cardiovascular disease risk in individuals at low and moderate CVD risk by regulating lipid and inflammatory profiles. MD affected apolipoprotein levels more positively, especially in women, individuals over 50 years of age, and those with one or two CVD risk factors. The study also found differences in the associations between apolipoprotein levels and specific nutrients, with an unexpected inverse relationship between carbohydrate intake and ApoC-III after MD.
