Identical Twins Study Shows Vegan Diets Helping the Heart (Stanford)

I’m an omnivore, and not planning to change any time soon, but this is interesting:

A Stanford Medicine-led trial of identical twins comparing vegan and omnivore diets found that a vegan diet improves overall cardiovascular health.

At three time points — at the beginning of the trial, at four weeks and at eight weeks — researchers weighed the participants and drew their blood. The average baseline LDL-C level for the vegans was 110.7 mg/dL and 118.5 mg/dL for the omnivore participants; it dropped to 95.5 for vegans and 116.1 for omnivores at the end of the study.

“Based on these results and thinking about longevity, most of us would benefit from going to a more plant-based diet,” said researcher Christopher Gardner, a professor of medicine at the Stanford University School of Medicine.

The study published Nov. 30 in JAMA Network Open. Gardner is the senior author. The study was co-first authored by Matthew Landry, PhD, a former Stanford Prevention Research Center postdoctoral scholar, now at the University of California, Irvine, and Catherine Ward, PhD, a post-doctoral scholar at the center.


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These twins were not the same at baseline, especially the men, the vegan group had much lower BMI, lower waist circumfere, blood pressure, higher B12, lower ldl-c (and not even the same race at baseline :face_with_hand_over_mouth:). In spite of this the vegan group ended up with lower b12 and triglyceride levels than the omnivore group


The studies from that group are always heavily biased toward a vegan diet. They don’t even pretend to be neutral in their introduction:

Plant-based diets have gained recent popularity not only for their lower environmental impact compared with an omnivorous dietary pattern but also for their health benefits[…]
Abundant evidence from observational and intervention studies indicates that vegan diets are associated with improved cardiovascular health and decreased risk of cardiovascular disease

As you can see below the vegan group went from 1973 to 1658 calories on average (-315 so -13%) while the omnivore group went from 1952 to 1838 on average (-113 so -5.8%).

Obviously a 13% calorie restriction is going to loose more weight and improve more biomarkers than a 5.8% one.

Assuming they only lost fat (which is not true as they also lost some proteins and water) 315 calories x 7 days x 8 weeks / 9cal/g = 1.9kg and they lost 1.4 kg so basically 100% of the weight loss is explainable just by the calorie restriction.


Yeah, this is totally not a high-quality study. Lowering someone’s LDL-C over a one- or two-month period does not “improve their cardiovascular health.” Their heart health over such a short period is not “improved.” Maybe they could say something like, “if they kept up this diet over several decades they might reduce their risk of a CVD event by x%.” What lowered their LDL-C was most likely caused by a significant reduction in saturated fat, not being plant-based.

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I’m not convinced either that eating plant-based per se is better for health than being an omnivore. It all comes down to saturated fat (and dietary cholesterol), protein intake, fiber and total calories in the end.

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Yes the devil is in the details and I wish there was more high quality data to consider. Sort of like Peter Attia says about his dosing choices with Rapamycin, I feel like I’m “flying blind” with my dietary choices. Maybe a bit of an overstatement, but I’ve made some overall choices and am just crossing my fingers for now.

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Not a surprising or particularly novel result, the headline grabbing part of the study is the twins (gimmick). We know from RCTs and epidemiology that vegans tend to have lower LDL cholesterol, tend to have lower BMI etc.

Both diets were what most would consider pretty healthy, higher LDL in the omnivores can be explained by the higher saturated fat and cholesterol along with the lower fibre. The lower calorie consumption specifically in the 2nd half of the study would be predominantly due to fibre and caloric density of the diet. Worth noting that the vegan groups LDL was actually lower at the end of the 1st half of the study than the 2nd implying that when they had to feed themselves they couldn’t keep the healthy diet up.

You could of course design an omnivorous diet with very low saturated fat and cholesterol and high fibre intake to get the blood lipid and weight benefits or take a statin etc.