According to nutritionist Beth Kitchin for Health, you cannot get toxic doses of nutrients through food, but you can get them through dietary supplements. Vitamins that can cause overdose include: calcium, iron, vitamin A, vitamin D, and vitamin E. Too much calcium can increase the risk of heart disease and prostate cancer. However, research is mixed. Not all studies support these findings. Overdosing on iron can cause coma or hypotension (low blood pressure). It can damage the intestines or liver. Too much vitamin A can lead to coma and death. It can harm pregnant and breastfeeding women and the fetus during pregnancy. Vitamin D increases the amount of calcium your body absorbs, which can cause high levels of calcium in the blood or urine. Rarely, vitamin D toxicity can cause kidney failure, arrhythmias (heart rhythm disorders), and death. Excessive intake of vitamin E can increase the risk of hemorrhagic stroke or sudden bleeding in the brain. Many nutrients can be toxic in large amounts. However, vitamin K and water-soluble vitamins, such as B vitamins, usually do not cause toxicity. Recognizing the signs of vitamin overdose Overdosing on multivitamins usually causes symptoms that may include: bone, joint, or muscle pain, cloudy urine, diarrhea, dry, cracked lips or skin, headache, irregular or rapid heartbeat, mood changes, nausea or vomiting, seizures, and stomach pain. Some nutrients can cause specific symptoms. Calcium or vitamin D can cause loss of appetite, kidney stones, and muscle weakness. Iron can cause bloody, dark diarrhea and weakness, while vitamin A can cause blurred vision and dizziness. How much of each vitamin is too much Tolerable Upper Intake Levels (ULs) are the maximum doses of a nutrient that are unlikely to harm most people. UL is not the same as the recommended daily intake. Always consult a doctor or pharmacist before starting a new dietary supplement. They can tell you whether it can prevent or treat a condition or pose a safety risk.