A demand for the average American to eat more meat would have to explain, as a baseline, why our already positive trend in meat consumption isn't yielding positive outcomes. There are potential explanations (you could argue increased processing offsets the purported benefits, for example), but those are left unstated by the website.
[1]: https://www.agweb.com/opinion/drivers-u-s-capita-meat-consum...
[2]: https://ers.usda.gov/data-products/chart-gallery/chart-detai...
Meat is as well. Maybe organic in small quantities, not too often can help.
Fish is problematic as much is contaminated with mercury and other heavy metals (we poisoned the ocean).
Dairy (in certain forms) offers the same benefits.