Released in January of this year, the Netflix Documentary ‘You Are What You Eat’ was a popular topic of conversation. Identical twins change their diets and lifestyles for eight weeks in a unique scientific experiment designed to explore how certain foods impact the body.

Let’s delve into the research paper the documentary was based on, an 8-week intervention exploring the Cardiometabolic Effects of Omnivorous vs Vegan Diets in Identical Twins.

Question❔ - What are the cardiometabolic effects of a healthy plant-based (vegan) vs a healthy omnivorous diet among identical twins during an 8-week intervention?

Importance 🌿 - Increasing evidence suggests that, compared with an omnivorous diet, a vegan diet confers potential cardiovascular benefits from improved diet quality (ie, higher consumption of vegetables, legumes, fruits, whole grains, nuts, and seeds).

Study Design 🥼

• Single-site, parallel-group, dietary intervention randomised clinical trial randomised healthy, adult identical twins to a healthy vegan or omnivorous diet for 8 weeks.
• Participant enrollment began on March 28, 2022, and continued through May 5, 2022.
• The date of final follow-up data collection was July 20, 2022.

Dietary Intervention Method 🥦 🍗

• The study consisted of two 4-week phases: delivered meals and self-provided meals.
• Participants were provided all no-cost meals for the first 4 study weeks by a nationwide meal delivery company (Trifecta Nutrition).
• Then expected that after 4 weeks of food delivery and health educator counseling participants would understand the amounts and types of foods they should purchase and prepare to achieve maximum adherence to the diets when self-providing meals.
• (1) choose minimally processed foods; (2) build a balanced plate with vegetables, starch, protein, and healthy fats; (3) choose variety within each food group

Collection of Dietary Intake 📞

• For the primary reporting data, 3 unannounced 24-hour dietary recalls—a structured interview—were administered within a 1-week window (2 weekdays and 1 weekend day) of each time point (baseline, week 4, and week 8).
• Data were collected via telephone by a registered dietitian (L.R.D.)
• Participants were also asked to log their food intake using the Cronometer app

Anthropometric and Metabolic Data 🩸

• At 3 time points, participants visited the Stanford Clinical and Translational Research Unit after an overnight fast of 10 to 12 hours: baseline, 4 weeks (phase 1), and 8 weeks (phase 2). Blood draw and clinical measures were assessed
• Stool samples were collected for future analysis to examine changes to the gut microbiome, metabolites, inflammatory markers, and additional health factors.

🤓 Key Results: Compared to twins following an omnivorous diet, twins following a vegan diet experienced the following changes:

• Significant decrease in low-density lipoprotein (LDL) cholesterol concentration-13.9 mg/dL
• Significant mean decrease of 2.9 μIU/mL in fasting insulin
• A greater decrease in body weight after 8 weeks (-1.9 vs. -0.29 kg)
• No significant differences were observed between the vegan and omnivorous diets for triglycerides or HDL cholesterol

📢 The Conclusion - In this randomised clinical trial, the healthy vegan diet improved cardiometabolic outcomes compared to a healthy omnivorous diet.

🌿 Why is this important - While we acknowledge the paper’s limitations, including the small sample size and duration, this documentary promoted a plant-based diet for potential cardiovascular benefits from an improved diet quality (ie, higher consumption of vegetables, legumes, fruits, whole grains, etc.).

❔ Our question to Health Care Professionals - Does promoting a fully vegan narrative effectively encourage consumers to incorporate more plant-based foods, or does it have the opposite effect?