Can ascorbic acid powder affect my gut health and my digestion in a negative way if taken in larger amounts with big glasses of water?

Yes, high doses of ascorbic acid powder very commonly cause severe acid reflux, Diarrhea, nausea, vomiting, and can result in kidney stones and severe migraines. These side effects are not eliminated by drinking larger amounts of water. You can also affect the absorption and function of other medications. Best to take no more than 2000 mg per day, less if side effects occur.. Good luck