Vitamin D ingested in excessive amounts can cause constipation.
Excessive Vitamin D
Excessive amounts of Vitamin D can cause nausea, weakness, fatigue, poor appetite, and weight loss as well as constipation. In higher amounts, excess intake of vitamin D has the potential to cause heart rhythm abnormalities, confusion, and can increase the body's blood calcium level, which can lead to kidney stones.
Vitamin D a Fat-Soluble Vitamin
Vitamin D is a fat-soluble vitamin, which by definition means the body will store the vitamin until it is needed by the body. Generally, a fat-soluble vitamin carries more of overdose than a water-soluble vitamin because it compounds over time. Vitamin D can be obtained through food and exposure to sunlight.
Excessive Vitamin D Intake from Food
It is highly unlikely that the body can get too much vitamin D from food alone. Because very few food sources contain vitamin D naturally, many foods such as milk and cereal are fortified with vitamin D. Even with the addition of vitamin D, only 29% of adult American men and 17% of adult American women get the recommended daily intake of Vitamin D through food sources.
Excessive Vitamin D Intake from Sun Exposure
Most people receive an adequate intake of vitamin D through sun exposure. Excessive intake of vitamin D from sun exposure is thought to be unlikely as the constant heat on the skin photodegrades the vitamin.
Excessive Vitamin D Intake from Supplements
The most likely way to ingest excessive amounts of vitamin D is through supplementation. The recommended daily intake for both adult men and women, ages 19-50 is 5mg/200IU. But according to recent studies, the body can handle ingesting far more vitamin D safely, the upper limits of which have been tested safely at 10,000 IU for healthy adults.