Vitamin C Supplements Linked to Kidney Stones in Men: Study

New research has linked the use of vitamin C supplements among men to a higher risk of forming kidney stones.  

A Swedish based study published in the journal Internal Medicine found men who took ascorbic acid supplements (vitamin C) more than seven times per week had an increased risk of developing kidney stones.

Researchers from the Karolinska Institutet in Stockholm studied more than 48,000 men aged 45 to 79 years old in 1997. Based on a questionnaire, information regarding diet, lifestyle and supplement use was taken. More than 22,000 men reported not taking any kind of supplement, however 907 men said they took vitamin C regularly.

Three percent of the men who reported taking vitamin C at least once per day developed kidney stones for the first time. Their risk of kidney stones increased nearly two-fold compared to the men who did not take vitamin C. Nearly two percent of the men who did not take any type of supplement developed kidney stones.

The men were followed up for 11 years and a total of 436 first-time cases of kidney stones were recorded. Laura Thomas, author of the study, found multivitamin use was not associated with the development of kidney stones and the findings were not equally true for women who take vitamin C supplements. Women typically have a lower kidney stone risk than men.

The men who consumed ascorbic acid supplements of 1,000 mg daily had the highest risk of kidney stone formation.

Researchers also performed an extracorporeal shockwave lithotripsy of 3,176 men in Stockholm. The analysis of their kidney stones found calcium oxalate made up nearly 93% of the stones. Calcium oxalate is a key component in the formation of kidney stones. Vitamin C is often excreted in the urine in its unmetabolized form and as an oxalate.

Vitamin C deficiency is often associated with scurvy, a disease that causes weakness, anemia, gum disease and skin hemorrhages. Scurvy is rare in the United States and is usually only seen in malnourished elderly persons. The average person typically consumes enough vitamin C in their regular diet to prevent the disease.

While the average dosage of Vitamin C in Sweden is 1,000 mg, vitamin C is often sold in the United States as 500 mg and 1,000 mg doses. The U.S. Institute of Medicine recommends 90 mg per day of vitamin C for men and 75 mg for women, 90 mg is approximately equivalent to a small glass of orange juice. Some research suggest approximately 25% of all Americans take a vitamin C supplement.