No single vitamin is clearly proven to “cause” heart attacks, but high-dose supplements are the bigger concern.
The vitamin most often discussed:
- Vitamin D – Taking too much vitamin D can raise calcium levels in the blood (hypercalcemia), which may affect the heart rhythm and heart function in severe cases.
Also often mentioned:
- Niacin (Vitamin B3) – Newer research suggests that excess niacin may be linked to a higher risk of cardiovascular disease, including heart attack and stroke, though this does not mean normal dietary niacin is dangerous.
Important clarification:
- Vitamin E has also been studied a lot, but large reviews generally show it does not clearly prevent or cause heart attacks in most people.