Several external factors, such as vitamin intake and diet, can change urine color. These effects typically are temporary and harmless. However, in certain cases, the effect of vitamins on urine can have negative consequences, especially if your doctor has ordered urine tests to diagnose a particular condition. The effects of vitamins on urine occur because of the chemical nature of certain vitamins.
Water-Soluble Vitamins
A common cause of bright-colored urine is vitamin intake. Vitamins can be either fat or water soluble. The latter will have a marked impact on urine characteristics. These vitamins are not stored in significant quantities. Rather, the body uses what it needs and excretes the rest. Riboflavin, or vitamin B2, is notorious for causing this effect in urine. Another factor is the rate of absorption. Some vitamins such as vitamin C have a limit to how much the body can absorb at one time. If you are taking mega-doses of water-soluble vitamins, you might not be receiving the health benefits they offer.
Fluid Intake
Your fluid intake might also impact urine characteristics such as color. The intensity of the yellow color is one indication of your fluid levels. If you are dehydrated, your urine will take on a darker yellow color. Combined with the effects of vitamins, the color might appear abnormally bright. It will also affect other aspects of your urine test, including specific gravity or the density of the urine. This characteristic is used to evaluate kidney function. The bright yellow color of your urine might lead to a false positive.
Other Impacts
Dietary sources of riboflavin and other vitamins might also impact urine color. Foods high in riboflavin such as fortified breakfast cereals and might might have a similar effect as taking a vitamin in pill form. Other foods might intensify the yellow color, such as beets or blackberries, by adding a reddish tint. Some medications such as diuretics might also affect the color of your urine.
Test Results
The risk of taking vitamins prior to urine tests is they might impact the results, especially tests that use color as an indicator of a certain characteristic. An exaggerated yellow color might mask other problems that the urine test is trying to determine. Other test results might be affected by vitamins such as serum bilirubin, serum creatinine and the guaiac assay for occult blood from taking high doses of vitamin C. The yellow color from vitamins might also mask the pale color that can indicate kidney disease or uncontrolled diabetes. For the most accurate results, you should refrain from taking vitamins prior to any urine tests.
References
- Colorado State University Extension; "Water-Soluble Vitamins"; J. Anderson et al.; August 2008
- Linus Pauling Institute; "Riboflavin"; Victoria Drake; June 2007
- University of Maryland Medical Center; "Dehydration -- All Information"; August 8, 2009
- Linus Pauling Institute; "Vitamin C"; Victoria Drake; November 2009
- "Principles of Anatomy and Physiology"; G. Tortora et al.; 2005
