Stool color is an observation that most people make on a daily basis. It is a constantly changing characteristic of stool that is both helpful and potentially misleading to a clinician. This stems from the fact that alterations in stool color result from a wide range of causes, including disease or diet. Disease-induced color changes are naturally more concerning that diet-induced ones, but for both patient and physician, it can be difficult to distinguish the two by color alone.
Stool is the final product that your body produces from your daily intake of food and drink. It is basically the leftovers after your body has extracted as many nutrients as possible from the food. Since it passes through so many organs on its journey through the body, stool characteristics such as color can provide extremely helpful clues for diagnosis of gastrointestinal diseases. On the other hand, since it is composed almost entirely of digested food, stool color very much depends on your diet as well.
Though everyone has a different normal stool color, a generally accepted rule of thumb states that any shade of brown is typically normal. Your own stool may vary greatly in brown shading from day to day, depending on what you eat and how much yellow-green colored bile is released by your body to break it down. When the color of your stool varies from brown, it may indicate a serious health risk, though it is most likely the result of a specific type of food.
Normal Color Change
Yellow-green colored bile is the major determinant of final stool color. If your stool itself is yellow or green in color, it indicates that either bile didn't have enough time to break down, such as during diarrhea, or that you ate green colored food ranging from leafy vegetables to green popsicles. If your stool is light brown or white colored, there is either a lack of bile release or coloration change due to certain medications, such as anti-diarrhea drugs.
Other color changes are more often associated with severe medical issues, though they also result from dietary changes as well. Black stool, termed melena, can indicate upper gastrointestinal bleeding, a medical emergency. However, it can also be caused by ingestion of black licorice, iron supplements or anti-diarrhea drugs. Similarly bright red-colored stool could mean lower gastrointestinal bleeding, or could result from eating red food such as beets or Jell-O.
When you notice a color change in your stool, you should consider what foods you've eaten in the past day to explain it. If you believe the color change is not explained by your diet or if it is persistently changed, you should consult your physician. Additionally, if the color change in your stool is associated with other gastrointestinal symptoms such as pain, cramping or diarrhea, you should discuss it with your doctor.