Veganism, documentary cinema and it's political/activist use

Vegucated, What the Health and Earthlings are my intended documentary examples. https://books.google.co.uk/books?id=u_h6oAEACAAJ&dq=vegan+documentary&hl=en&sa=X&ved=0ahUKEwih4Ov_4fHcAhWsKcAKHdu5BgUQ6AEIKTAA. (potential discussion points) Changing attitudes promoting vegan documentary. Is there a problem in pushing a political agenda. To what extent is it a balanced objective?