Vitamin C is an essential vitamin that is not stored in your body as it is a water soluble vitamin. Instead, the vitamin C that you consume gets transported to your tissues via body fluids, and any extra gets excreted in urine. Since your body does not store vitamin C or produce it on its own, it is important to consume foods that are rich in vitamin C daily, however too much vitamin C can cause health issues.
Too much vitamin C can cause digestive distress. This can happen from supplementing too much vitamin C, mainly if you consume over 2000mg per day. Symptoms of digestive distress include nausea, diarrhea and acid reflux. Vitamin C is also known to enhance iron absorption. It has the ability to bind with non-heme iron, which is found in plant foods. Non-heme iron is not absorbed by your body as efficiently as heme iron, the type of iron found in animal products and so vitamin C makes it easier for your body to absorb iron from animal based products. Taking too much vitamin C can lead to an iron overload which can be dangerous to your liver, heart, pancreas and central nervous system. Too much iron can irritate the stomach and the digestive tract and iron poisoning can also lead to severe liver damage, however this only happens when someone is also supplementing too much on iron and vitamin C.
Since vitamin C is not stored in your body, it is excreted from the as an oxalate, a body waste product. Oxalate mainly exits the body through urine, however, sometimes it may bind with minerals to form into crystals that causes the formation of kidney stones. High vitamin C intake is associated with a high amounts of urinary oxalate, which is linked to developing kidney stones leading to kidney failure. However, this is really rare in healthy individuals, you would have to be taking over 2000mg of vitamin C every day for years to gather an unhealthy amount in your body.
Regardless of the harmful effects of too much vitamin C, it is actually really difficult to get too much of this vitamin alone in your diet. In healthy people, extra vitamin C gets excreted out of the body. The risk is only higher for those who get majority of vitamin C through supplementation, so if you are deficient in vitamin C it is best to choose one that contains no more than 100% of your daily needs and that’s 90mg a day for men and 75mg a day for women.