Some of the effects of excess vitamin D include digestive problems, fatigue, and dehydration. Vitamin D affects the muscles, bones, and blood vessels, and when taken in excess amounts, it can lead to health problems in those areas. Excess vitamin D can also interfere with certain medications and health conditions. The vitamin is produced in the skin through exposure to sunlight and can also be obtained from a few foods and supplements.
In general, excess vitamin D does not build up from dietary sources, such as fish and vitamin D-fortified foods or from too much sunlight exposure. Rather, a vitamin D toxicity generally only occurs when vitamin D supplements are taken in high amounts or for a prolonged period of time. The amount of vitamin D required for optimal health can vary from person to person. For adults, it is generally safe to take up to 2,000 International Units (IU) a day, but anything over 4,000 IU per day can pose a threat, especially if taken for a prolonged period of time.
Too much vitamin D can cause calcium to build up around the heart, which can potentially damage it in the long run. It can also result in hypercalcemia, which is a condition wherein the serum calcium levels increase to abnormal levels. This condition can lead to the formation of kidney stones and poor kidney function due to calcification around them.
Although it is essential for good bone health, excess vitamin D levels can have adverse effects and often result in bone loss and bone pain. In the same way, it is essential for healthy muscle function, but in high amounts, it can lead to muscle weakness and overall fatigue. Weight loss, diarrhea, and thirstiness are also seen in individuals with excess vitamin D.
Vitamin D supplements are often prescribed to those who do not get enough sunlight on a regular basis. They are also prescribed to those who have diabetes, arthritis, and certain skin conditions. A deficiency of vitamin D has been linked to cochlear deafness, certain types of cancer, and depression. In young children, a deficiency is often linked to rickets, which is a condition wherein the bones become weak and deformed.
Regardless of the necessity of vitamin D, the supplements should never be taken without the advice of a health care provider. The supplements can interfere with a variety of medications, including calcium channel blockers, corticosteroids, and antacids. Individuals with heart conditions or kidney problems are advised not to take vitamin D supplements as they can potentially worsen the conditions.