Vitamin D is a nutrient you need to keep your calcium levels stable--the vitamin helps calcium absorb into your body. Milk is fortified with vitamin D, and the sun's rays also provide you with the nutrient. According to the National Institutes of Health Office of Dietary Supplements, you need between 200 and 600 international units--IU--of vitamin D daily, though the upper tolerance for most adults is 2,000 IU daily. Upper tolerance is the amount of vitamin D you can take without suffering from health problems due to an overdose. Taking 50,000 IU of vitamin D weekly is significantly above the recommended upper tolerance range, and may be lead to symptoms of toxicity.
Stores in Body
According to the Office of Dietary Supplements, short-term, high-level dosing of vitamin D at 50,000 IU weekly does not always lead to adverse effects. Short-term in this sense is considered a period of two months or less. The effect of taking this amount of vitamin D is that your body will store it and use the stores to regulate your blood levels of vitamin D and calcium during times when you do not take in as much through diet or sun exposure. Taking 50,000 IU weekly may cause health problems with long-term usage, however.
MayoClinic.com reports that you might suffer from an upset stomach, nausea, vomiting or constipation if you regularly take higher-than-normal levels of vitamin D. You'll be more likely to experience these symptoms of toxicity if you have pre-existing kidney or liver disease or if you take diuretic medications that remove excess fluids from your body through urination.
Hypercalcemia is the state of having too much calcium in your blood. Vitamin D maintains your calcium levels, so if you are getting significantly more vitamin D than you need, you might show symptoms of high blood calcium, explains MayoClinic.com. Nausea and a poor appetite can indicate hypercalcemia; mental confusion, an increased risk of developing kidney stones--one type of stone is made up of calcium--and heartbeat irregularities can also be effects of taking 50,000 IU of vitamin D.