(Note that I am neither a vegetarian nor a vegan.)
Because of old age. Being vegan increased your odds threefold to die of old age instead of prematurely from disease.
Apologies for not having a link to the source
[1]: https://globalactiontoendsmoking.org/research/tobacco-around...
[2]: https://www.cdc.gov/tobacco/about/cigarettes-and-cardiovascu...
People in India smoked just as much when they weren't living such sedentary lifestyles.
A healthy, whole-food plant-based diet is linked to a lower risk of ischemic stroke, with studies showing reduced risk compared to meat-eaters. The conclusion of this paper[1] for example reads that "Lower risk of total stroke was observed by those who adhered to a healthful plant-based diet."
Additionally, researchers at Harvard found that a plant-based diet may lower overall stroke risk by up to 10%. [2]
1: https://pmc.ncbi.nlm.nih.gov/articles/PMC8166423/
2: https://hsph.harvard.edu/news/healthy-plant-based-diet-assoc...
> People in India smoked just as much when they weren't living such sedentary lifestyles.
I suspect they also lived shorter lives for the aforementioned all-round mortality reasons.
(If you have resources that show otherwise, that would be interesting. But smoking really does seem like the obvious historical outlying factor for heart disease in India, with calorie-dense diets playing catch up as the country has become wealthier.)