I write this article in response to a reader’s question. Rather than giving a yes or no answer to that reader, I thought it was better to give a detailed answer that can help many people.
Original question: I have been taking a vitamin D supplement for the last 2 months. Since then I have been constipated. Can vitamin D cause constipation? Or is it a coincidence?
Before coming to the answer, I would like to tell some important information about vitamin D.
Vitamin D is essential for many important functions of the body. It gives strong bones and muscles. Vitamin D regulates calcium metabolism in the body.
Calcium in the diet is absorbed by the digestive system. Vitamin D is essential for the calcium absorption. In addition, it helps deposit the calcium into the bones and teeth.
Vitamin D is soluble and can be stored in the body for many months. Too much vitamin D in the body can cause elevated levels of calcium in the blood. It is called hypercalcaemia.
High levels of calcium in the blood can cause constipation.
So, the answer to her question is yes, vitamin D can cause constipation.
However, taking the supplement at the recommended dose should not cause any problems. You can take up to 1000 IU of vitamin D3 a day without any side effects. If you are vitamin D deficient, your doctor may recommend a higher dose.
Taking high potency supplements without any medical advice is the root cause of the problem. It may cause vitamin D toxicity that can make you constipated.
What about diet?
Very few foods naturally contain vitamin D. Oily fish, mushrooms, and eggs are some dietary sources. However, they contain only a moderate amount of vitamin D. So, there is no chance of getting toxicity from eating a normal diet.
The main, natural source of vitamin D is sunshine. Our skin produces this vitamin with the help of ultraviolet light from the sun. This process is well controlled by a feedback mechanism in the body. Too much sunshine doesn’t cause vitamin D toxicity.
However, prolong exposure to sunshine on a hot day can cause constipation. This is due to dehydration, nothing else.
Bottom line:
There is a link between too much vitamin D and constipation. So, don’t exceed the recommended dose of any medication, including supplements.