Men who consume high levels of vitamin C are at twice the risk of kidney stones than men who do not.
The new finding does not strongly establish that vitamin C is responsible for the occurrence of kidney stones, however it may make us wonder whether large amounts of vitamin C are harmful to the body.
Kidney stones are tiny masses of crystals that can painfully obstruct the urinary tract.
Signs and symptoms of a kidney stone include:
- severe pain from the flank to groin or to the genital area and inner thigh.
- urinary urgency
- blood in the urine
Kidney stones may be caused by diets rich in animal protein, sodium, refined sugars, high fructose corn syrup, and cola drinks. Low fluid intake can also increase stone formation. Women have a typically much lower overall risk of kidney stones than men. Therefore, the outcomes of this study do not apply to women.
The researchers suspected that greater amounts of vitamin C could elevate the risk of kidney stones because the body breaks down the vitamin into material known as oxelate – a part of the stones.
Study co-author Agneta Akesson, an associate professor with the Karolinska Institute in Stockholm, Sweden, said:
“It is important that the public is aware that there may be risks associated with taking high doses of vitamin C. Those with a history of kidney stones should consult their doctor before taking high-dose vitamin C supplements.”
In the current study, published in JAMA Internal Medicine, the investigators followed over 23,000 Swedish men who were between 45 and 79 years old in 1997 up to the year 2009. None of them had kidney stones at baseline.
Close to 900 of the men took 1,000-milligram doses of vitamin C, and 3 percent of them (31 men) later had kidney stones. Less than 2 percent of those in the rest of the group developed kidney stones.
The researchers adjusted for factors which could undermine the reliability of the findings, such as education levels, ages, and body weights.
They revealed that those men who received the high-dose supplements had an elevated kidney stone risk ranging between 1.7 and 2.2 times.
The authors point out that there are no significantly proven reasons for any person to take such large amounts of vitamin C. The results of the study do not apply to vitamin C that comes from food.
Another outcome of the study was that multivitamin supplements that don’t have large doses of vitamin C did not increase the risk of kidney stones.
The authors point out that more studies are needed to back up these findings, and they emphasize that people should not stop consuming vitamin C after reading this report. If you are concerned about your vitamin C intake or any health consequences related to vitamin supplementation, talk to your doctor.
Last year, a study presented at the Endocrine Society’s 94th Annual Meeting in Houston, revealed that vitamin C and vitamin D supplements are associated with high calcium levels in the urine and blood,. High urine/blood calcium levels are linked to a higher risk of kidney stones.
Written by Kelly Fitzgerald