People with sickle cell anemia, as well as people with a metabolic disorder called G6PD, can have serious side effects when taking high levels of vitamin C. Patients with thalassemia and hemochromatosis may be adversely affected by increased iron absorption, which can result from vitamin C supplementation. Most people get enough vitamin C through a balanced diet. People who may be susceptible to vitamin C deficiency may benefit from using vitamin C supplements.
For example, people who have conditions that increase their risk of iron overload or who are prone to kidney stones should take vitamin C cautiously (11, 12, 1). In addition, vitamin C improves the absorption of iron from plant-based foods and helps the immune system work properly to protect the body from disease. It's also not clear if vitamin C helps prevent cardiovascular disease from worsening in people who already have them. In some people, oral vitamin C supplements can cause kidney stones, especially when taken in high doses.
Under these circumstances, taking vitamin C in excess can lead to iron overload, which can cause serious damage to the heart, liver, pancreas, thyroid, and central nervous system (11, 12, 1.In a large study of older people with AMD who were at high risk of developing advanced AMD, those who took a daily dietary supplement with 500 mg of vitamin C, 80 mg of zinc, 400 IU of vitamin E, 15 mg of beta-carotene, and 2 mg of copper for approximately 6 years) were less likely to develop advanced AMD. People who consume a lot of vitamin C from fruits and vegetables may have a lower risk of many types of cancer, including lung, breast and colon cancer. However, if you take higher-than-normal doses of this vitamin, your body may have difficulty processing it and this can cause negative effects (. However, people who regularly take vitamin C supplements may have slightly shorter colds or somewhat milder symptoms when they have a cold.
Eating more than 2000 mg of vitamin C a day can cause gastrointestinal complaints, including symptoms such as diarrhea and nausea. Vitamin C is also available as an oral supplement, usually in the form of capsules and chewable tablets. Fortunately, many of the best food sources of vitamin C, such as fruits and vegetables, are often eaten raw. Dietary supplements of vitamin C and other antioxidants may interact with chemotherapy and radiation therapy for cancer.
In people with a condition called hemochromatosis, which causes the body to store too much iron, high doses of vitamin C may worsen iron overload and damage body tissues. Oral doses of vitamin C cannot raise blood levels of vitamin C nearly as much as intravenous doses given through injections. A severe vitamin C deficiency can result in a condition called scurvy, which causes anemia, bleeding gums, bruising, and poor wound healing.