Why Is Urine Yellow?


People don’t like to or enjoy talking about urine. It is the last things they want to think about or discuss. Usually, as urine swirls down the toilet bowl it doesn’t receive a glance. However, urination is an important bodily function. Its color, odor and consistency can give important indicators to a number of diseases. It has been used as an evaluator of health for hundreds of years by doctors and medical experts. Many substances in the body such as bacteria, yeast, excessive protein and sugar are eliminated from the body through urine. Urine is a vital part of the body’s disposal process. The function of urine is to remove excess water and water-soluble wastes that is filtered from the blood by kidneys. It gets rid of toxins and any substance buildup in the body that are harmful to the health. It also includes material such as dead blood cells, muscle breakdown, etc.

Urine, when normal, has a yellow color which it gets from a chemical called urobilins. These chemicals are the products of breakdown of the bile pigment bilirubin, which itself is a breakdown product of the heme part of hemoglobin resulting from worn out red blood cells. Usually, bilirubin breakdowns partly in the liver and stored in the gall bladder, and further in the intestines and is excreted in the feces. However, some of it remains in the bloodstream and is extracted by the kidneys. It is converted to urobilins and which gives urine its yellowish color. Kidney also eliminates salts and minerals as well as urea from protein digestion, creatinine from muscle breakdown, uric acid, hormone waste and toxins via urine, but urobilins have the biggest impact on color. So, when your urine has a lot of urobilins, its quite yellow and when it has low concentration of urobilins, it’s clearer.

The intensity of the color of your urine also depends on the degree of hydration. When your body is properly hydrated, the urobilins get diluted with water and maintains the normal buttercup color. If your urine is dark yellow or ale colored, it is sign of dehydration. And if your urine is not yellow at all, it is an indication of serious health problem. When you don’t hydrate properly, there is not enough water to remove the waste and your urine is clearer. Clear urine does not imply that there are no wastes to be eliminated.

The urine is yellow in color due to a pigment called Urochrome. It is produced when the liver processes dead blood cells. Your body is producing new red blood cells constantly and it is destroying and creating new blood cells at a rate of 2.7 million cells per second. So, it is essential that the dead blood cells are eliminated. And dead cells results in urochrome, which gives urine its yellow color. The function of the liver is to protect your body from damaging effects of harmful substances. It screens the blood for such substances as it flows from your stomach and intestines. And these screened out harmful substances such as urochrome is eliminated from the body with urine, making it yellow in color.

Another cause of yellow color of the urine is the excess of riboflavin, also called vitamin B2. It is the reason when you are taking multi-vitamins daily; your urine is bright yellowish color. And the reason riboflavin gives off a yellowish color is due to light absorption. Light is electromagnetic radiation. And radiation is received in waveform and classified by its wavelength. Hence, the color that appears is depended on whether the wavelengths are absorbed by the material or not. When the wavelength is in the range of 500-700nm, we see green, red or yellow colors. Riboflavin can absorb light at 450nm which gives it the distinctive yellowish color. And as urine is the body’s waste disposal system to get rid of excess, so when it contains riboflavin it turns yellow due to the yellowish color of the chemical.

Studies have shown that around 50% of the excess riboflavin gets eliminated from the body in the urine. The recommended adult daily consumption of riboflavin, which is used by the body, is 1-1.6 mg per day and usually the quantity of riboflavin in multivitamins is 25, 50 or even 100 mg. Hence, the excess amount is removed through urine.

In conclusion, there are number of factors that cause the yellow color in your urine. When your urine is not yellowish color, it means that either you are not drinking enough water or there is some medical condition or disease in your body and it’s time to see a doctor. The common reasons for your urine to be any other color but the normal yellow are: dehydration, certain food such as asparagus, medicines, jaundice and hemolytic anemia. The abnormal colors for urine can be clear, dark yellow, orange, brown, greenish, reddish and even blue.

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References :

[0]Stephanie Watson, 2014, The Truth About Urine, Retrieved from: http://www.webmd.com/urinary-incontinence-oab/features/the-truth-about-urine
[1]Science in Action, 2006, Why is Urine Yellow? Retrieved from: http://sxxz.blogspot.com/2006/07/why-is-urine-yellow.html
[2]Kate Horowitz, 2014, Why Is Pee Yellow? Retrieved from: http://mentalfloss.com/article/55438/why-pee-yellow-and-other-pressing-bladder-questions
[3]Today I Found Out, 2014, Why Do Vitamins Make Urine Bright Yellow? Retrieved from: http://www.todayifoundout.com/index.php/2013/09/why-do-vitamins-make-urine-bright-yellow/
[4]Colourlovers, 2007, The Science of Why Your Pee is a Yellow Color, Retrieved from: http://www.colourlovers.com/blog/2007/06/19/the-science-of-why-your-pee-is-a-yellow-color e taking such as vitamin B type of medical supplement.