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I was reading some science news the other day and came across this headline from late November: Twin research indicates that a vegan diet improves cardiovascular health!
Talk about a sensational headline!
Basically, the study used 22 sets of identical twins and one of them ate a vegan food plan, while they other was omnivorous (included animal proteins). Both were instructed to include mostly whole, unprocessed foods. Food was provided to the participants for 4 of the 8 weeks, and for the other 4 weeks, participants were responsible for their own food. Researchers found that the twin who ate the vegan food plan had higher health marker improvements than the omnivore.
BUT WAIT A SECOND.
I have nothing against Veganism and fully support anyone who opts for that lifestyle. However, I think this headline is exaggerated!
If we look at the full study, we can see that there was no account for caloric differences between the two plans, which could certainly account for some changes in these metrics.
We also see that BOTH the vegan and omnivore participant’s health markers improved (weight loss, cholesterol, fasting insulin, etc.)
In my opinion, these are some significant limitations to go with this headline.
This section is literally listed in the limitations of the study: “Our study was not designed to be isocaloric; thus, changes to LDL-C cannot be separated from weight loss observed in the study. We designed this study as a “free-living” study; thus, the behavior of following a vegan diet may induce the physiological changes we observed. However, the biological mechanisms cannot be determined to be causally from solely the vegan diet alone because of confounding variables (weight loss, decrease in caloric intake, and increase in vegetable intake).”
In layman’s terms… we cannot say that the positive changes in health markers were ONLY due to the vegan lifestyle, but could also be due to weight loss, caloric deficits, and eating more vegetables.
For many of us, those kinds of factors WOULD cause positive changes in health markers, and we wouldn’t necessarily have to go Vegan to achieve that.
Maybe I’m feeling some type of way about this headline because I do eat animal products, and I support my clients to eat enough plant- or animal-based protein, (Protein amounts also weren’t looked at in this study….) but regardless of that, I think the researchers/article writers took the results to the extreme here.
Yes, I think everyone can benefit from eating more vegetables and fewer highly-processed foods. And probably quite a few of us can benefit from a caloric deficit. That’s just not the same thing as going Vegan.
I’m happy to have further conversation on this topic too, as I do admit to having a bit of a bias here, so please comment below or email me at sara@nutritionforlifeproject.com to share your thoughts!
As always, thank you for reading,
xoxo,
Sara
Agree that the broad claims of this study are exaggerated, but also tend to believe that some of the contention could be exaggerated. A “healthy” vegan diet (versus the many ways to make it unhealthy) leads naturally to a caloric deficit and more vegetables versus a similarly “healthy” omnivore diet so controlling for those variables would not prove much of anything. I think the bigger limiters are the duration of study and n of participants (though using identical twins is fascinating)