How Foods Change Stool Color
A reddish tint in your stool after eating tomato-based pasta sauce is typically a harmless result of how certain food pigments interact with your digestive system. Lycopene, a natural pigment in tomatoes, is responsible for their vibrant red hue.
Lycopene is a carotenoid, a compound known for imparting color in plants. When you consume foods high in lycopene, such as tomatoes in pasta sauce, your body does not fully digest or absorb all of this pigment. This is particularly true when large quantities are consumed, or when the digestive transit time is relatively fast.
As undigested lycopene travels through the intestines, it retains its reddish color. This pigment then mixes with the stool, imparting a reddish-orange or reddish-brown tint as it exits the body. This phenomenon is a normal physiological response and does not indicate any underlying health issues.
Beyond Pasta Sauce: Other Red Foods
While pasta sauce is a common culprit, many other red foods can also temporarily change stool color. These foods contain strong natural or artificial pigments that, like lycopene, are not fully broken down or absorbed, allowing them to pass through and color the stool.
Beets are a common example, often causing stool to appear red or even purple. Similarly, cranberries and red grapes, when consumed in significant amounts, can impart a reddish shade. Artificially colored foods, such as red velvet cake, cherry-flavored drinks, or gelatin desserts with abundant red food dye, can also lead to noticeable red discoloration in stool.
When Red Stool Signals a Health Concern
While dietary causes are common, bright red stool can sometimes indicate a more serious health issue: bleeding in the gastrointestinal (GI) tract. Bright red stool typically suggests fresh blood from the lower GI tract, which might stem from conditions like hemorrhoids, anal fissures, or diverticulosis.
Bleeding higher up in the colon or a slower transit time can result in stool appearing maroon. In contrast, very dark, tarry black stool, known as melena, usually points to bleeding in the upper GI tract, such as ulcers in the stomach or small intestine. Unlike the uniform reddish-orange or reddish-brown tint from pasta sauce, blood in stool often appears as distinct streaks, clots, or a more intense, uniform red or black color.
Certain medications can also alter stool color, though typically not to a bright red. Iron supplements, for instance, can cause stool to become black or very dark green. Bismuth subsalicylate, in some anti-diarrhea medications, can also lead to dark or black stool, which some individuals might misinterpret as a very dark red.
When to Consult a Doctor
It is generally not a cause for concern if your red-tinged stool is clearly linked to consuming red foods like pasta sauce and resolves once those foods are out of your diet. However, there are specific signs that warrant a medical consultation. If you notice bright red blood in your stool, especially if it’s persistent, or if your stool appears maroon or black and tarry, seek medical advice promptly.
Other accompanying symptoms should also prompt a visit to a healthcare professional. These include unexplained abdominal pain, fever, vomiting, dizziness, weakness, or unintended weight loss. If you are uncertain about the cause of red stool, or if the discoloration persists beyond a day or two after stopping consumption of red foods, consult a doctor.