Can a vegan diet slow aging? – Zoë Harcombe

Executive summary

* Professor Christopher Gardner, who presided over the randomised controlled trials called DIETFITS and KETO-MED, is the senior researcher on the Twins Nutrition Study (TwiNS).

* This study has been featured in a Netflix documentary. It randomised 22 pairs of identical twins to either a whole food vegan diet or a whole food omnivore diet. (The twins were not identical in all characteristics). The trial lasted 8 weeks. Food was provided for the first 4 weeks and self-provided for the second 4 weeks.

* The first output from this trial was published in November 2023. It claimed that LDL-Cholesterol was lower on the vegan diet. It would be because the vegan diet was higher in plant sterols, which lower cholesterol.

* The second publication from this trial claimed that a short term vegan diet was associated with improved aging markers and reduced calorie intake.

* The food provided/consumed in the first 4 weeks was lower in calories for those assigned to the vegan diet. It was an average of 345 calories fewer than they had been eating. It was nearly 200 calories lower than the food provided to/consumed by the omnivores.

* Since the early 1980s, the academic literature has presented evidence that calorie restriction can improve aging markers.

* By reducing calorie intake, the trial changed more than one thing and, therefore, no claims can be made for the impact of a vegan diet when the calorie intake was also changed (and so dramatically).

* I ask whether this was researcher error or design.