http://www.vitamins-supplements.org/vitamin-A.phpVitamin A overdose and toxicity
An vitamin A overdose can be harmful to bones and skin, causing weakness and brittleness, even leading to fatigue and vomiting. Excessive intake of vitamin A is toxic, at dosages of around 20-25,000 IU daily. Consuming more than 25,000 IU of vitamin A per day (adults) and 10,000 IU per day (children) from either food or supplements or both is known to be toxic. For those 19 and older, the tolerable upper limit for vitamin A consumption has been set at 10,000 IU per day. An excess of vitamin A taken during pregnancy can cause birth defects in the fetus. Symptoms of a vitamin A overdose include tiredness, discomfort, lethargy, upset stomach, decreased appetite, vomiting, slow or decreased growth, joint soreness, irritability, headache, drying and cracking of the lips and skin, hair loss, and yellowing of the skin.
http://www.vitamins-supplements.org/vitamin-D.phpVitamin D (calciferol) overdose, toxicity, side effects
There is a high health risk associated with consuming too much vitamin D. Taking too much vitamin D (more than 1,000 IU daily) can cause a number of adverse effects including excessive thirst, metal taste, poor appetite, weight loss, bone pain, tiredness, sore eyes, itching skin, vomiting, diarrhea or constipation, a need to urinate, and muscle problems. Vitamin D toxicity can cause nausea, vomiting, poor appetite, constipation, weakness, and weight loss. An excess of vitamin D increases the absorption of calcium which leads to high levels of calcium in the blood and result in increased calcium absorption from the intestinal tract. Long-term overconsumption of vitamin D at any dose greater than 1,000 IU day may cause high blood pressure and premature hardening of the arteries. Vitamin D toxicity (hypervitaminosis D) induces abnormally high serum calcium levels (hypercalcemia), which could result in bone loss, kidney stones, and calcification of organs like the heart and kidneys. The hypercalcemia associated with hypervitaminosis D may cause multiple debilitating effects. Anorexia, nausea and vomiting have been observed in hypercalcemic individuals treated with 1,250 to 5,000 micrograms (50,000 to 200,000 IU)/day of vitamin D.
http://www.vitamins-supplements.org/vitamin-E.phpVitamin E (tocopherol) overdose, toxicity, side effects
The health risk of too much vitamin E is low. Vitamin E appears to be safe when consumed in amounts up to 1,000 IU a day. The National Academy of Sciences has established the daily tolerable upper intake level for adults to be 1,000 mg of vitamin E, which is equivalent to 1,500 IU of natural vitamin E or 1,100 IU of synthetic vitamin E. Doses of over 800 IU a day of vitamin E may interfere with the body's ability to clot blood, posing a risk to people taking blood thinners (anticoagulants).
http://www.vitamins-supplements.org/vitamin-K.phpVitamin K overdose, toxicity, side effects
There is no known toxicity associated with high doses of phylloquinone (vitamin K1), menaquinone (vitamin K2), or menadione (vitamin K3) and its derivatives. High intake of vitamin K is not recommended for individuals taking anticoagulant medications such as Warfarin (coumadin).
BONUS:
http://www.vitamins-nutrition.org/vitamins/vitamin-overdose.html
With the increasing popularity of vitamins and nutritional supplements, it is necessary to look at all sides of this phenomenon, particularly from the safety angle.
Fortified foods and supplements are in these days. They are ideal for both the busy and the health conscious. A vitamin pill or a liquid multivitamin seems the ideal solution to compensate for a missed dinner. For dieters, it means you can limit your calories while still getting all the nutrients you need, right?
What’s more? These supplements are little regulated if at all. You can pick anyone of them up at your neighborhood grocery. More and more people today add nutrients to their diet by selecting foodstuffs fortified with vitamins and minerals. Manufacturers add iron to your breakfast cereals or they even add vitamin C to sweets or vitamin A to margarine. This is something that is done regularly by the food industry and most people would argue this is a very good thing.
These products are intended to boost your health, but they can be anything but healthy if you grossly overdo it. Taken to excess, you actually can overdose on vitamins and other food supplements. The food industry needs to desist from advertising health benefits that are not backed up by science or putting far too much of certain items, like iron in their products.