It's more of a hypothesis paper by a retired scientist. Bruce Ames, the author used to do experiments on vitamin and mineral deficiencies in animals 20+ years ago. What he found was things like increased DNA strand breaks. Nothing positive was found in terms of longevity or healthspan when supplementing excess anti-oxidants. It's possible to search Ames B[author] on pubmed to see his old publications.
"Maybe some these things would extend healthspan if people have a less than optimal diet."
I think some people are eagerly clamoring to supplement based on this list, which is just fueling the 30bn dollar a year supplement industry.
https://www.nytimes.com/2018/08/01/style/wellness-industrial...
Why not fund basic research into age related disease instead?
i.e. [ https://www.lifespan.io/the-rejuvenation-roadmap/, http://dogagingproject.com, http://sens.org ]