Seeing an alarming red color in the toilet bowl, especially after eating something rich in color like pizza, can cause immediate panic. Changes in stool color are frequent and are most often a harmless result of diet rather than a sign of a serious medical issue. While stool color is generally dictated by the breakdown of bile, strong pigments from food can temporarily override this normal process. This article explores the connection between concentrated red foods like pizza sauce and temporary color changes, and outlines how to distinguish a benign pigment from a medical concern.
The Science of Red Pigments in Digestion
Pizza sauce can make stool appear red due to the presence of lycopene, a powerful red carotenoid pigment found in high concentrations in tomatoes. When tomatoes are cooked and concentrated into a sauce, the lycopene becomes more available but remains difficult for the body to fully absorb.
Lycopene is resistant to being fully broken down by digestive enzymes. This pigment travels mostly intact through the intestines and is excreted in the feces, imparting a reddish-orange hue. Indigestible fibrous skins of tomato pieces may also pass through whole, appearing as small red flecks.
The more concentrated the tomato product, such as a thick sauce or paste, and the larger the quantity consumed, the more noticeable this temporary effect will be. This discoloration typically passes completely within 24 to 48 hours as the digestive system clears the remnants of the meal.
How to Differentiate Pigment from Blood
While food-related red stool is common, it is important to know the visual characteristics that separate harmless pigment from true gastrointestinal bleeding. Stool discoloration caused by food like pizza sauce is generally a uniform reddish-orange or has scattered, non-clotted red material mixed throughout the waste. This color change resolves quickly, often within one or two subsequent bowel movements.
True blood in the stool, known as hematochezia, usually appears as bright red streaking or clots on the surface of the waste or in the toilet water. This indicates bleeding from the lower gastrointestinal tract, such as the rectum or colon. This fresh, bright red blood is typically a sign of a source near the exit, such as hemorrhoids or an anal fissure.
Bleeding that originates higher up in the digestive system, such as the stomach or small intestine, appears very differently. When blood is digested, it becomes chemically altered, resulting in a dark, sticky, tar-like substance known as melena. This black, viscous stool is a serious indicator of upper gastrointestinal bleeding and requires immediate medical attention.
You should seek professional medical evaluation if the red color persists for more than two days, if the stool is black and tarry, or if the color change is accompanied by other concerning symptoms. Associated symptoms include abdominal pain, vomiting, fever, dizziness, or a significant change in bowel habits.
Other Foods That Temporarily Change Stool Color
Many other foods contain strong natural or artificial pigments that can travel through the gut undigested, leading to temporary and surprising color changes.
Beets are a well-known example, containing the pigment betalain which can turn stool pink, red, or maroon. The intensity of this color depends on the individual’s digestive process and the acidity level in the colon.
Consumption of large quantities of dark leafy green vegetables, such as spinach or kale, can result in a distinctly green-colored stool due to the presence of chlorophyll. Artificial food dyes, especially vibrant colors found in candies and frostings, are notorious for tinting waste an unnatural shade of blue, green, or red.
Dark-colored items like black licorice, blueberries, or iron supplements can cause stool to darken to a shade that appears nearly black. In all these instances, the discoloration is a result of an undigested pigment and is a normal, temporary variation that resolves once the food has cleared the digestive system.