Too Much Vitamin C

Is it possible to have too much vitamin C? Vitamin C is relatively non-toxic. However, there are some studies that suggest too much of it is possibly linked with an increased prevalence of kidney stones. Vitamin C is metabolized to a urinary product called oxylate and many kidney stones are oxylate-based. In these clinical trials individuals are consuming 1000 milligrams a day or more. In individuals with iron deficiency, taking up to ten times the recommended amount can destroy significant amounts of vitamin B12. Vitamin C overdose can affect the bioavailability of vitamin B12. In healthy people, excess vitamin C can cause bowel irritation (diarrhea).

One of the most disconcerting things with excess vitamin C is that it can interfere with diagnostic tests. For example, if the doctor is trying to know if you’re a candidate for colonoscopy or not, a lot of vitamin C can actually interfere or react with the agent that is testing for blood. So, if you’re taking a lot of vitamin C, you should tell your doctor.

Vitamin C can also interfere with the test for glucose or sugar in your urine. It can show that you have sugar in your urine when you don’t, it’s just the excess vitamin C.

What should the upper limit of intake be? It should be about 2000 mg per day. Keep that in the back of your mind, although it is difficult to reach that amount without supplements.