[1]: https://www.pbs.org/wgbh/nova/article/how-a-worm-gave-the-so...
If you have 2-10 hookworms and eat a modern diet (higher in iron), you're probably going to be fine.
If you have 30-50, you're going to have abdominal discomfort and some side effects.
If you have insane allergies or autoimmune disease, the risk/reward seems pretty incredible.
Worst case scenario if you're an adult with hookworms is you take some antibiotics and they go away.
This https://twitter.com/jimmybernot/status/1354443837897388033 is one person's story about participating in those studies.
[1]: https://www.pbs.org/wgbh/nova/article/how-a-worm-gave-the-so...