February 5, 2013
Vitamin C Associated With Increased Risk Of Kidney Stones In Men
Lawrence LeBlond for redOrbit.com - Your Universe Online
Several studies have come to light of the beneficial role vitamin C may play in human health. Some recent studies have shown the essential nutrient helps reduce pain and inflammation in rheumatoid arthritis patients and also helps guard against dementia. But another recent study, published in this week´s JAMA Internal Medicine, has found vitamin C is not all good news, especially in men.
Dr. Brian Matlaga, a urologist who studies kidney stones at Johns Hopkins Medicine in Baltimore, said he wouldn´t tell patients they “shouldn't take vitamin C, and here's the evidence.”
But when it comes to such patients, often times you may find they are “taking non-prescribed medications, like vitamin supplements“¦ and there may not be great evidence that there's an actual health benefit associated with these," he told Reuters Health.
Matlaga, who was not involved in the new study, added the findings suggest that “stone formers who take regular vitamin C may actually place themselves at increased risk.”
The research is based on data from a large study of middle-aged and elderly men in Sweden who answered a questionnaire on their diet and lifestyle and were subsequently tracked for 11 years. The research identified more than 22,000 men who had no history of kidney stones and who took either no dietary supplements or vitamin C supplements only.
During the course of the study, 436 of the patients developed kidney stones requiring medical attention. The researchers compared the risk of kidney stones in men who took vitamin C with those who did not take any vitamins. They then repeated the analysis for men who took multivitamins.
The results showed of the men who used vitamin C regularly, 3.4 percent developed kidney stones for the first time during the study, compared to 1.8 percent who did not use any supplements. Men who took vitamin C supplements at least once per day had the highest risk of kidney stones, the researchers reported.
The overall results show men who take vitamin C supplements are twice as likely to develop kidney stones as men who do not take any supplements. The researchers found no link between regular use of multivitamins and increased risk of kidney stones.
The team believes both the dose and combination of nutrients with which the vitamin C is ingested are significant. For this reason, the observed risk increase does not apply to a normal intake of vitamin C via fruits and vegetables. With vitamin C content in most supplements generally running about 1,000 mg per tablet, people are often getting a considerably higher dose of the ascorbic acid than they would in food. In Sweden, the recommended daily intake (RDI) for vitamin C is 75 mg.
"It has long been suspected that high doses of vitamin C may increase the risk of kidney stones as some of the vitamin C absorbed by the body is excreted in urine as oxalate - one of the key components of kidney stones," Dr. Laura Thomas, lead researcher in the study, told Reuters Health by email.
Thomas said the findings do not mean men should avoid getting plenty of vitamin C through fruits and veggies. It is important for proper bone and muscle health, and severe deficiency can lead to scurvy.
Despite the alarming results, more research is needed to determine which dosages of vitamin C are most associated with increased risk of kidney stones, according to Matlaga. For those men who haven´t had kidney stones before, there should be no concern about any related risks tied to vitamin C, he added.