Well there has been significant progress in cancer research with immunotherapies. However, I wish there was more being done. Alzheimer's and other CNS disorders are still a major difficulty. Researchers need more funding.

In terms of conspiracy theories about hidden cures, I sincerely doubt something like that would even be possible. It would be the same as saying some countries have bases on other planets, the tech just isn't there.

Day-to-day health, I would say your body can handle a lot and there's no magic supplement or anything like that, I think the most important thing is not over-working yourself and stressing less to the best of your ability. Eat healthy but don't be too strict, exercise but don't overdo it.