Not really? People across the planet have had predominantly or exclusively vegetarian (not necessarily vegan) diets since forever and have been perfectly healthy.

I think there are - might be misrembering - more credible studies that you can live on a diet of exclusively potatoes without ill effects aside from, well, that kind of diet itself.

I looked over the article and was expecting to see something on it like "Funded by [Tuscany's version of the Beef Producers Council]."