It is easy to overdose if we take various nutritional supplements for our health. Rather than be healthy, it can be harmful to our bodies. Let’s look into the side effects of excessive intake of such nutrients.

Fat-soluble vitamins
Fat-soluble vitamins A,D,E, and K. These are stored in the body’s fat tissues, especially in the liver. And so they are not excreted in urine like other water-soluble vitamins. As a result, they are likely to pose a higher risk of toxicity when consumed in large amounts over long periods. Primary symptoms of this overdose can be nausea, vomiting, diarrhea, headaches, and any others.
Vitamin A. Overdosing on vitamin A is probably well-known for pregnant women. This vitamin, particularly from many supplements, can lead to a condition called hypervitaminosis A. Accumulated vitamin A may lead to blurred vision, hair loss, liver damage, and several severe symptoms like birth defects if consumed during pregnancy.
Vitamin D. Vitamin D aids in calcium absorption strengthens bones and enhances immunity. In the sun, vitamin D is synthesized in the liver and kidneys. If overdosed, calcium and phosphorus levels rise excessively and may cause abnormalities in the parathyroid gland. Also, lots of vitamin D intake may linked to hypercalcemia, a condition characterized by high levels of calcium in the blood. Typical symptoms are loss of appetite, vomiting, and muscle weakness. Symptoms may include frequent urination and in severe cases, kidney damage and cardiovascular issues. The recommended daily dose of vitamin D is 400 to 800 IU (10 μg). People with vitamin D levels below normal can take up to 1000 IU.
Vitamin E. High doses of vitamin E sometimes can interfere with blood clotting and increase the risk of bleeding, particularly in individuals already taking blood-thinning medications.

Water-Soluble Vitamins (B vitamins, vitamin C)
Water-soluble vitamins, so excess amounts are typically excreted in urine. However, extremely high doses of water-soluble vitamins, mainly through supplements, can still cause adverse effects. For example, excessive intake of vitamin B6 can lead to nerve damage. In contrast, excessive intake of vitamin C can cause gastrointestinal upset and diarrhea.
Vitamin C. Vitamin C, an antioxidant nutrient, is known to be effective in preventing aging, relieving fatigue, and improving immunity. Because it is a water-soluble vitamin, it is commonly discharged from the urine if you take an appropriate amount or more.
However, diarrhea, nausea, and stomach cramps may occur if excessive vitamin C intake persists. A study also suggests kidney stones and urinary stones can occur. This is because components not discharged from the urine remain to produce stones. The recommended amount of vitamin C is 100 mg per day.

Calcium
Related with vitamin D intake, hypercalcemia should be a problem. Calcium is a nutrient that forms bones and teeth and is used for contraction and relaxation of blood vessels and nerve stimulation transmission. Since it is not produced by the human body, an appropriate amount of calcium should be consumed daily.
However, excessive calcium intake can cause angina, arteriosclerosis, and myocardial infarction as calcium debris builds up in blood vessels. When taking calcium as a supplement, one-time intake should be kept below 500 mg. This will help the body absorb more quickly and reduce the risk of gastrointestinal disorders as side effects.

Iron
Iron is essential for producing hemoglobin, which transports oxygen throughout the body. Proper supplementation helps blood vessel health, muscle cell formation, and liver and brain function improvement. However, excessive intake can lead to vomiting, diarrhea, joint pain, gastrointestinal disorders, and bleeding.
People with dizziness suspect anemia and often take iron nutritional supplements recklessly. Still, since dizziness occurs for various reasons other than anemia, it is better to get a blood test at a hospital first. Adults recommend daily iron intake to 10 mg for men and 14 mg for women. Pregnant women need 20 to 24 mg, which is more.

Zinc
Zinc enhances immunity, helps heal wounds, and synthesizes proteins. However, excessive intake of zinc can rather suppress immune function. According to a study, people who consumed 30 times the recommended amount of zinc decreased immune function due to decreased lymphocyte-stimulating responses, which are immune cells in the body. The daily recommended daily zinc intake is 7-10 mg.

Overdosing on vitamins, although less common than deficiencies, is still possible and can have adverse effects on your health. It’s important to note that most people can meet their vitamin needs through a balanced diet without the need for supplementation.

Abstract
What happens if you overdose on nutrients?
Vitamin A. Overdosing, particularly from many supplements, can lead to hypervitaminosis A. Accumulated vitamin A may lead to blurred vision, hair loss, liver damage, and several severe symptoms like congenital disabilities if consumed during pregnancy.
Vitamin C. Because it is a water-soluble vitamin, it is commonly discharged from the urine if you take an appropriate amount or more.
However, diarrhea, nausea, and stomach cramps may occur if excessive vitamin C intake persists. A study also suggests kidney stones and urinary stones can occur.
Vitamin D. If overdosed, calcium and phosphorus levels rise excessively and may cause abnormalities in the parathyroid gland. Also, lots of vitamin D intake may linked to hypercalcemia, a condition characterized by high levels of calcium in the blood. Typical symptoms are loss of appetite, vomiting, and muscle weakness.
Vitamin E. High doses of vitamin E sometimes can interfere with blood clotting and increase the risk of bleeding, particularly in individuals already taking blood-thinning medications.