Question: what vitamins should i not take too much of?
Answer: Vitamin C. Although vitamin C has relatively low toxicity, high doses of it can cause gastrointestinal disturbances, including diarrhea, cramps, nausea, and vomiting. ... 
Vitamin B3 (niacin). ... 
Vitamin B6 (pyridoxine). ... 
Vitamin B9 (folate).