Known as the warm sunshine vitamin, vitamin D plays a truly crucial role in our body. It assists the absorption of calcium and phosphorus, which are key to strengthening bones, and is deeply involved in our overall health, including enhancing immunity, regulating cell growth, and maintaining nerve function. In particular, because modern people spend a lot of time indoors and use sunscreen, vitamin D deficiency is common, leading many people to supplement it through nutritional products. However, the saying 'excess is as bad as deficiency' fits this vitamin D perfectly.
Consuming vitamin D in excess can cause a dangerous condition in our body called hypercalcemia. While it is good that vitamin D promotes calcium absorption, when its level becomes too high, the blood calcium level surges abnormally. When the blood calcium level rises, our body sends warning signals in various ways.
One of the most common symptoms is unexplained fatigue and lethargy. For no apparent reason, you may continually feel drowsy, weak, and find daily life burdensome. It also affects the digestive system, producing symptoms such as loss of appetite, nausea, vomiting, and constipation. In particularly severe cases, it causes dehydration and thirst, and as urine volume increases, it places a burden on the kidneys that can lead to kidney stones or kidney hypofunction. Even though you took it for bone health, paradoxically, bones may weaken and develop pain, or in severe instances, it can even provoke neurological symptoms such as confusion and depression.
Then how much intake is considered excessive? The daily recommended intake for adults is usually around 400 to 800 IU, but when blood vitamin D levels are low, people may take 1,000 to 2,000 IU or more based on a professional evaluation. However, long-term intake exceeding 4,000 IU per day generally warrants caution, and it is known that taking 10,000 IU or more can significantly increase the risk of toxicity. Because vitamin D is a fat-soluble vitamin, it is not easily excreted outside the body and accumulates in adipose tissue; thus, consistent excessive intake increases the likelihood that it will build up and trigger toxic reactions. Therefore, accurately identifying your vitamin D level through a blood test and consulting a healthcare professional to take the appropriate dose that fits you is more important than anything else. Please remember that taking a large amount unconditionally is not necessarily a good thing.
