In a recent study published within the journal JAMA Network Open, researchers in the USA compared the cardiometabolic impact of vegan diets versus omnivorous diets after eight weeks of intervention amongst adult equivalent twins.

Study: Cardiometabolic Effects of Omnivorous vs Vegan Diets in An identical Twins. Image Credit: Foxys Forest Manufacture / Shutterstock

Background

Plant-origin diets are rising in popularity as a consequence of their low environmental impact and health advantages. Non-communicable diseases and climatic change are major worldwide health issues, and eating more vegetables and fewer meat can optimize health and the environment. Vegan diets often have a lower energy density but a greater concentration of phytonutrients, fiber, minerals, and vitamins.

In accordance with previous observational and interventional studies, veganism is related to enhanced cardiovascular wellness and a lower heart problems risk as a consequence of the next intake of fruits, vegetables, whole grains, legumes, seeds, and nuts. Vegan diets, then again, might restrict a number of nutrients like calcium, iron, and vitamin B12. Most studies on vegan diets are epidemiologic, with only a number of clinical investigations recorded.

In regards to the study

In the current population-based, single-center randomized controlled trial (RCT), researchers comparatively evaluated the cardiometabolic effects of vegan and omnivorous diets in equivalent twins.

The parallel-group, open-label RCT included 22 twin pairs (n=44) randomized to the vegan or omnivorous food plan group for eight weeks (one twin per food plan). All participants were exposed to fruits, vegetables, whole grains, legumes, seeds, and nuts, limiting the exposure to sophisticated grains and added sugar. The participants were recruited from the Stanford Twin Registry between March 28 and May 5, 2022. Data were obtained through July 20, 2022.

The team provided diet-specific meals through national meal delivery services for 4 weeks, following which the study participants self-prepared their meals. The meals comprised minimally processed foods, protein, vegetables, starch, and healthy fat, variety in all food groups, and catered to individual requirements and preferences. All participants were advised to eat until satisfaction with no calorie restriction.

The first data comprised three 24-hour food plan recalls (one weekend and two weekdays); registered dieticians administered telephonic structured interviews to acquire detailed foods and drinks intake data inside per week of every timepoint (study initiation, fourth week, and eighth week). The participants provided secondary data by recording their food intakes within the Cronometer application; health educators used secondary data to guide the participants in real-time. All participants provided blood and stool samples. The first study end result was altered low-density lipoprotein cholesterol (LDL-C) concentration in serum eight weeks post-intervention.

Secondary study outcomes included alterations in cardiometabolic parameters (blood glucose, insulin, lipid, and trimethylamine N-oxide (TMAO) levels), serum vitamin B12 levels, and weight. Exploratory measures included dietary adherence, difficulty or ease in adhering to the diets, energy levels of the participants, and a way of well-being.

Changes within the intestinal microbiome, inflammatory biomarkers, and metabolites were also assessed. Linear mixed modeling was performed for the evaluation. The team excluded individuals weighing ≤45 kg with a body mass index (BMI) of ≥40, LDL-C ≥190 mg/dL, systolic-type blood pressure ≥160 mm of Hg, diastolic-type blood pressure ≥90 mm of Hg, and people who were pregnant.

Results

Among the many participants, 77% (n=34) were female, 73% (n=32) were white, and 79% (n=33) lived with their twin; the mean values for participant age and BMI were 40 years and 26, respectively. Each groups consumed fewer calories within the two four-week phases (food delivery and self-prepared) than at baseline.

After eight weeks, in comparison with twins allocated to the omnivorous food plan group, the vegan food plan group twins showed significantly reduced LDL-C (14 mg/dL), fasting insulin (3.0 μIU/mL), and weight (2.0 kg). As well as, vegans showed a greater but non-significant decrease in serum high-density lipoprotein cholesterol (HDL-C), vitamin B12, triglycerides, TMAO, and glucose levels after eight weeks of intervention compared with omnivores.

Within the sensitivity analyses, after eliminating outliers, vegans showed a mean reduction of two.1 μM within the difference of TMAO from baseline to eight weeks in comparison with omnivores. The exploratory evaluation findings indicated that omnivores had nominally higher dietary satisfaction within the fourth and eighth weeks than vegans.

Overall, the study findings showed that the vegan food plan improved cardiometabolic profiles in comparison with the omnivore food plan, with decreased LDL-C and insulin levels. Vegans devour less protein, have poorer dietary satisfaction, and have higher vegetable and iron consumption. They do, nevertheless, devour less vitamin B12. Clinicians should consider veganism a healthy alternative for patients, and long-term vegans are incessantly urged to take a cyanocobalamin complement. More studies on TMAO risk aspects and patient preferences are required.