Which vitamin is fat-soluble and can be toxic in excess?

Vitamin A is the fat-soluble vitamin that can become toxic when consumed in excessive amounts. Unlike water-soluble vitamins, which are typically excreted through urine and thus have a lower risk of causing toxicity, fat-soluble vitamins are stored in the body's fatty tissues and liver. This means that excessive intake can accumulate to toxic levels over time.

Vitamin A plays essential roles in vision, immune function, and skin health, but an overdose can lead to hypervitaminosis A, which can cause a range of symptoms, including nausea, headache, dizziness, and more severe complications. This makes it crucial to be mindful of the dosage in food sources and supplements.

In contrast, Vitamin C, a water-soluble vitamin, is not stored in the body and is usually eliminated through urination, so toxicity is rare. Vitamin K and Vitamin B12 are also generally considered safe at higher levels, with Vitamin K having a low potential for toxicity and Vitamin B12 being non-toxic even in high doses.