NCSF Sport Nutrition Specialist Certification (SNS) Practice Test

What nutrient has a higher risk for toxicity when taken in excess?

1. Calcium

2. Vitamin A

3. Iodine

4. Iron

The correct answer is: Iron

Iron has a higher risk for toxicity when taken in excess compared to the other nutrients listed. While all nutrients can potentially cause issues when consumed in excessive amounts, iron's potential for toxicity is particularly pronounced. Iron overload can lead to a condition known as hemochromatosis, which can damage organs like the liver, heart, and pancreas, leading to serious health complications. This is due to the fact that the body has no active mechanism for excreting excess iron, making it difficult to regulate iron levels within the body. In contrast, both calcium and iodine have established tolerable upper intake levels, and while high doses can lead to certain health issues, they typically do not carry the same level of risk as iron. For example, excessive calcium can lead to kidney stones, and excessive iodine can disrupt thyroid function, but these conditions are generally easier to manage and reverse. Vitamin A is also at risk for toxicity, especially in its preformed state (retinol), but the instances of actual toxicity from iron are more prevalent due to the body's inability to eliminate surplus iron efficiently. Therefore, while multiple nutrients can pose risks when taken excessively, iron's unique challenges make it a significant concern in terms of toxicity.