Warnings About Health Risks From Excessive Vitamin C Supplement Use

Vitamin C supplements are generally safe for most people. However, excessive long-term consumption can lead to serious health issues, including kidney stones and digestive disturbances, according to “Verywell Health”.

Studies indicate that high doses of this vitamin increase oxalate levels in the urine — a substance that can bind with calcium and form stones, especially in individuals with a history of kidney stones or chronic kidney disease.

Exceeding the recommended doses can cause common symptoms such as diarrhea, nausea, stomach cramps, and gas. These effects are linked to the vitamin’s acidic nature and its ability to draw water into the intestines, which may irritate the digestive system, particularly when intake exceeds 2,000 mg per day.

Vitamin C also enhances the absorption of non-heme iron in the body, which can pose a danger to individuals with hemochromatosis, a disorder that leads to iron buildup in vital organs like the heart and liver. Additionally, excessive intake may interfere with the accuracy of certain medical tests — such as blood glucose measurements and urine analyses — resulting in misleading readings that could affect diagnosis and treatment.

Another concern affects those who consume chewable vitamin C supplements: their high acidity can erode tooth enamel over time, increasing sensitivity and the risk of cavities. Doctors recommend rinsing the mouth after taking them to reduce this effect.

People most at risk from excessive vitamin C intake include: individuals with kidney disease, those with iron-overload disorders, diabetic patients (due to the impact of high doses on glucose-monitoring devices), and cancer patients undergoing chemotherapy or radiation therapy.