Vitamin C Supplements Linked to Kidney Stones

Men who take vitamin C supplements may have an increased risk for developing kidney stones, according to a new study.

Vitamin C (ascorbic acid) is a water-soluble vitamin that is necessary for the formation of collagen in bones, cartilage, muscle and blood vessels. It also helps the body absorb iron. Dietary sources of vitamin C include fruits and vegetables, particularly citrus fruits, such as oranges.

Many uses for vitamin C have been proposed, but few have been found to be beneficial in scientific studies. In particular, research on asthma, cancer and diabetes remains inconclusive, and no benefits have been found for the prevention of cataracts or heart disease. The use of vitamin C in the prevention or treatment of the common cold and respiratory infections remains controversial, and research is ongoing.

In a new study, researchers reviewed data on 48,850 men from the Cohort of Swedish Men to assess the potential link between vitamin C supplementation and kidney stone risk. Data on vitamin C supplement use was collected through questionnaires. Data on men who had a history of kidney stones and reported using supplements other than vitamin C were excluded from the analysis. Kidney stone cases were collected through registry data.

Throughout the 11 year follow-up period, 436 men developed their first case of kidney stones. The researchers found that vitamin C supplement use was significantly linked to twice the risk of developing kidney stones when compared to men who did not take supplements. However, the authors noted that a link between multivitamin use and kidney stones was lacking.

Addition research assessing this potential link is warrented.

For more information about vitamin c, please visit Natural Standard's Foods, Herbs & Supplements Database.

Comments

[Amber]

Couple things that stood out to me: Why only men? Another thing that popped out to me was the follow up period - 11 years! Interesting findings, indeed. Would these same results apply to women?

For vitamin C in general - I just checked out the Natural Standard monograph, and I was previously under the impression that vitamin C couldn't PREVENT colds, but it COULD shorten the duration of your cold. Natural Standard gave it an evidence grade of B for common cold prevention (in extreme environments). Though, I'm not sure exactly what the 'in extreme environments' part means. But, for general common cold prevention and treatment the evidence grade is D.

[ML]

What an interesting connection, I was not aware of the link between vitamin C and kidney stone formation. Though a limitation of the study may be the lack of standardization of the vitamin C supplementation. I don’t know if the study used the same dose or brand of vitamin C supplements. I am also curious to know if the results would be different in women. I think more research is needed and I wonder if counseling practices will change due to this finding.

[kj]

Adding to the comments above, I would like to see what other pre-existing conditions these men had. 436 seems like high number, however it is out of 48,850! Which only turns out to be less than 1% of this patient population. And also, I would like to see the results of women and this effect. Other contributing factors to kidney stones include family history, dehydration, diet (high in protein, sodium and sugar), and obesity.

[bp]

This actually doesn't surprise me - on my first day ever in a hospital IV room, the pharmacist asked me what I knew about ascorbic acid and TPN's. At that time the answer was something like "nothing, but they're water soluble, right?" I learned that day that the ascorbic acid added to TPN's was adjusted for decreased kidney function due to the possibility of - kidney stones! Once the full analysis is available, I will be interested to see if kidney function is also related to kidney stones (I hope this is included in the analysis!).

[SB]

I have never heard of vitamin C causing kidney stones, but I have heard of it causing painful urination, presumably from making the urine more acidic.
I would be interested in seeing the doses related with the increase risk of kidney stones.

[MS]

I never thought of vitamin C (ascorbic acid) of having any dangers for the body since it is water soluble. Any excess would be urinated out. I guess the crystal structure can accumulate in the kidneys. It would be interesting to see the risk of developing kidney stones in females. A daily amount of 500mg of vitamin c per day is absorbed by the body therefore more than this amount is eliminated from the body. If other studies are able to repeat this data, individuals need to be educated about the consumption of vitamin C and all marketed products need to have the risk on their label.

[AM]

From working in community pharmacy, I have definitely heard a lot of positive feedback from patients who have used Vitamin C for their common colds. I wonder if the patients who were studied in this research had a history of renal impairment, and at what doses they were taking their vitamin C. It is obvious that this topic needs to be delved into further before pharmacists can start discouraging patients from using this supplement.

[AR]

I have heard this before that too much vitamin C can lead to kidney stones. This article stated that vitamin C is eliminated as both the oxalate and the unchanged form in the urine. Kidney stones are formed of calcium oxalate. Only men were included in this study, so the data cannot be extrapolated to women. Men already have a higher risk of developing kidney stones, so I wonder if the men who developed the kidney stones were already more prone to it.

[bc]

I also work in a community and a lot of people have been asking about emergen-c and its efficacy. It is good to know that taking too much of vitamin C may have adverse effects such as kidney stones. I will make sure to keep this in mind when educating patients who inquire about vitamin C use.

[bz]

This is certainly interesting information, as I always thought the opposite was true - that taking vitamin c would acidify the urine and prevent kidney stones from forming. With the large scale of this study, the findings are definitely significant. I do think that more research is needed before a definitive recommendation can be made to patients worried about kidney stones.

[SS]

This is a very interesting study especially with the flu season we had. I say that because although the use of vitamin c in cold in controversial a lot of people still believe that it helps and use it quite often. I work in a community pharmacy and many people come up asking where the emergen-c multiple times a day. Some people swear by it and use it religiously. It is kind of shocking to see that the repeated use over time can cause a negative effect. More research does need to be done but maybe due to this article people with think twice before over using vitamin C supplements.