Niacin is an essential B vitamin, but high doses of nicotinic acid have also been used medically to influence cholesterol levels.
At nutritional doses, niacin is not normally associated with liver damage.
At pharmacological doses, however, it can cause elevations in liver enzymes and, in some cases, clinically significant liver injury.
Certain sustained- or extended-release formulations have been particularly associated with liver toxicity when used improperly.
Possible warning signs can include:
* unusual fatigue
* persistent nausea
* pain in the upper abdomen
* dark urine
* yellowing of the skin or eyes
High-dose niacin should not be treated like an ordinary daily vitamin.
## 5. Iron Supplements
Iron is essential for producing hemoglobin and carrying oxygen through the body.
Iron supplements can be very useful when someone has confirmed iron deficiency, but taking iron when it is not needed can be harmful.
Unlike some nutrients, the body has limited ability to eliminate excess iron.
Large amounts can accumulate and potentially damage organs, including the **liver**. NIH guidance notes that excess iron may damage the liver and other organs.
This is why iron should generally not be taken long-term simply because someone feels tired.
Fatigue has many causes, and blood tests can help determine whether iron deficiency is actually present.
### Warning:
Accidental iron overdose can be particularly dangerous in children, so iron supplements should always be stored securely.
## 6. Green Tea Extract
