Vitamin D supports bones, muscles, and immune function, but high-dose vitamin D can become toxic. Vitamin D toxicity usually happens from excessive supplementation, not from normal sunlight exposure or food. It can lead to high calcium levels in the blood, which may cause nausea, weakness, confusion, dehydration, frequent urination, kidney stones, or kidney damage.
Vitamin D should ideally be guided by a blood test, especially if someone is taking strong doses, has kidney disease, has high calcium levels, or is also using calcium supplements.
3. Niacin, Also Called Vitamin B3
