Evidence-Based Nutrient Recommendations

Clinical Trials using a Vegan Diet

Contents

Recipe for Heart Health and Olive Oil

The Recipe for Heart Health (RFHH) trial compared the effects of consuming extra-virgin olive oil (EVOO) at high (4 tablespoons/day) versus low (<1 teaspoon/day) amount within a whole-foods plant-based vegan diet pattern on LDL-C and other cardiometabolic markers. The study was a crossover trial with a one-week washout period. It was performed with 40 omnivores with an average age of 64 and 75% women (Krenek, 2024).

The vegan diet, whether low-EVOO or high-EVOO, resulted in significant decreases in LDL cholesterol. There was a trend toward lower LDL cholesterol during the low-EVOO versus high-EVOO period that didn’t reach statistical significance. However, this could be due simply to the fact that participants ate an average of 502 more calories per day on the high-EVOO diet.

It wasn’t clear how the participants ate the EVOO on the high-EVOO diet. If they ate it in one bolus or at the end of a meal, it might not have had the effect of increasing satiety enough to counteract the extra calories that spreading the oil out throughout the day might.

C-Reactive Protein

C-reactive protein (CRP) is a marker of inflammation. A high sensitivity CRP (hsCRP) test detects lower levels of CRP, which is useful because chronic CRP in the blood is a risk factor for heart disease (MedlinePlus, 2019, Lab Tests Online, 2019). Elevated hsCRP is common among people with heart disease and reducing hsCRP can reduce the risk for cardiovascular events (Shah, 2018).

A randomized trial published in 2018 investigated the impact on hsCRP of a vegan diet versus a diet recommended by the American Heart Association (AHA). The AHA diet is low in saturated and trans fats, and high in fruits and vegetables (Shah, 2017). The trial lasted over 8 weeks among a sample of 100 adults, mostly white men, with coronary artery disease (Shah, 2018).

The vegan diet resulted in a significant 32% lower mean hsCRP compared with the AHA diet. Weight change, glycemic markers, and lipid levels did not differ significantly between the diet groups. There was a non-significant decrease in LDL among those following the vegan diet.

It’s not clear what aspect of a vegan diet resulted in a lower hsCRP.

References

Heart Diseases. MedlinePlus. https://medlineplus.gov/heartdiseases.html. Updated July 17, 2019. Accessed September 27, 2019.

High-sensitivity C-reactive Protein (hs-CRP). Lab Tests Online. https://labtestsonline.org/tests/high-sensitivity-c-reactive-protein-hs-crp. Updated September 23, 2019. Accessed September 27, 2019.

Krenek AM, Mathews A, Guo J, Courville AB, Pepine CJ, Chung ST, Aggarwal M. Recipe for Heart Health: A Randomized Crossover Trial on Cardiometabolic Effects of Extra Virgin Olive Oil Within a Whole-Food Plant-Based Vegan Diet. J Am Heart Assoc. 2024 Jul 24:e035034.

Shah B, Newman JD, Woolf K, Ganguzza L, Guo Y, Allen N, Zhong J, Fisher EA, Slater J. Anti-Inflammatory Effects of a Vegan Diet Versus the American Heart Association-Recommended Diet in Coronary Artery Disease Trial. J Am Heart Assoc. 2018 Dec 4;7(23):e011367.

Shah B, Ganguzza L, Slater J,et al. The effect of a Vegan versus AHA Diet in Coronary Artery Disease (EVADE CAD) trial: study design and rationale. Contemp Clin Trials Commun. 2017;8:90–98.