A Twin Study to Assess Short Term Cardiometabolic Health Benefits of a Vegan Diet
If you're familiar with discussion of veganism as a lifestyle choice, nothing in this material will all that surprising. Vegans tend towards lower calorie intake and the benefits resulting from that, and that may be the dominant effect when looking at commonly measured health metrics in vegan study participants. It would be interesting to see more comparison studies in which the vegans were held to the same calorie intake as the omnivore control participants, but, alas, that is logistically harder and thus not the approach chosen by most study organizers.
Although it's well-known that eating less meat improves cardiovascular health, diet studies are often hampered by factors such as genetic differences, upbringing and lifestyle choices. By studying identical twins, however, the researchers were able to control for genetics and limit the other factors, as the twins grew up in the same households and reported similar lifestyles. The trial, conducted from May to July 2022, consisted of 22 pairs of identical twins for a total of 44 participants. The study authors selected healthy participants without cardiovascular disease from the Stanford Twin Registry - a database of fraternal and identical twins who have agreed to participate in research studies - and matched one twin from each pair with either a vegan or omnivore diet.
The authors found the most improvement over the first four weeks of the diet change. The participants with a vegan diet had significantly lower low-density lipoprotein cholesterol (LDL-C) levels, insulin, and body weight - all of which are associated with improved cardiovascular health - than the omnivore participants. 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. The optimal healthy LDL-C level is less than 100.
Because the participants already had healthy LDL-C levels, there was less room for improvement. Researchers speculated that participants who had higher baseline levels would show greater change. The vegan participants also showed about a 20% drop in fasting insulin - higher insulin level is a risk factor for developing diabetes. The vegans also lost an average of 4.2 more pounds than the omnivores.
Link: https://med.stanford.edu/news/all-news/2023/11/twin-diet-vegan-cardiovascular.html