Vitamin D will stay in the body until the body uses it.
Vitamin D Is Fat-Soluble
Vitamin D is a fat-soluble vitamin, which means any intake is stored in the fat cells until it is needed. You can get vitamin D through your diet, sun exposure, and supplements. Very few foods contain vitamin D naturally, which is why many foods are fortified with vitamin D such as milk and cereals.
Excessive Vitamin D Health Risks
It is unlikely that an individual eating a well balanced diet will have to worry about ingesting excessive amounts of vitamin D. According to the National Health and Nutrition Examination Survey, only 24% of adult men and 17% of adult women get their vitamin D from food sources.
Side effects of excessive amounts of vitamin D are generally minimal and include nausea, constipation, weakness, weight loss, and poor appetite. Though the recommended daily intake for healthy individuals between the ages of 19-50 is 5 mg/200IU, according to the National Institute of Health's Office of Dietary Supplements, the tolerable upper intake levels for vitamin D are substantially higher at 50mg/2,000IU. Recent studies have placed the tolerable upper intake levels even higher at 10,000IU daily.