Previously, it was thought that vitamin C had little toxicity, and even if it was taken orally in excess, it would only cause slight nausea, vomiting and diarrhea. However, in recent years, according to clinical observation and animal experiments, long-term overdose of vitamin C will lead to a series of adverse reactions. The author refers to various materials at home and abroad, which are summarized as follows:
(1) Studies by foreign authoritative organizations show that people who want to increase their resistance to colds and take too much vitamin C for a long time will reduce their vitamin C content. This is because taking a large dose changes the regulation mechanism of vitamin C in the body and accelerates the decomposition and excretion. Therefore, once the drug is stopped, it can lead to withdrawal reaction and early scurvy symptoms (including swollen gums and loose teeth).
(2) Growing children taking large doses of vitamin C will make them prone to bone diseases in the future, because large doses of vitamin C will destroy the formation process of osteoblasts.
(3) If vitamin C4 and above are taken orally every day, urinary calcium oxalate stones and kidney calculi may appear one week later, and hematuria and renal colic may appear in severe cases. Too much vitamin C will make the urine acidic, which will lead to oxalate stones.
(4) High-dose vitamin C can resist the anticoagulant effect of heparin and dicoumarin, leading to thrombosis, which makes patients with cardiovascular and cerebrovascular diseases more prone to cerebral infarction (stroke).
(5) Intake of high-dose vitamin C can increase urine excretion, because its reducibility can produce false positive reaction of urine sugar, which hinders the diagnosis and treatment of diabetic patients and accurately grasps the dosage of hypoglycemic drugs.
(6) High dose of vitamin C can reduce female fertility and affect embryo development. Because a large dose of vitamin C is easy to form an "acidic constitution" in the body, which is not conducive to the development of germ cells.
(7) When the daily dose of vitamin C exceeds 3 grams, it can lead to increased intestinal peristalsis in some people, causing abdominal cramps and diarrhea.
(8) Taking vitamin C together with foods containing vitamin B 12 can destroy a considerable amount of vitamin B12; However, vitamin B 12 is destroyed in large quantities, which makes people prone to anemia.
To sum up, although vitamin C is an essential substance to maintain human metabolism and has important clinical value for the prevention and treatment of various diseases, excessive intake is not beneficial or even harmful to human body.