A Taiwanese doctor is warning against excessive consumption of vitamin C, particularly through effervescent tablets taken to combat colds. While often perceived as harmless, high doses of vitamin C can lead to the formation of kidney stones. The body only needs a limited amount of vitamin C daily, and exceeding this amount results in the excess being converted into oxalate, a key component of kidney stones. Individuals frequently taking these tablets, believing they are boosting immunity, may be unknowingly damaging their kidneys. The doctor emphasizes that relying on high-dose vitamin C is not an effective preventative measure against colds and can pose significant health risks. He advises moderation and consulting a healthcare professional for appropriate vitamin intake.