It is not uncommon for poop to change color. The two main causes of poop color change are diet and conditions that change how fast food travels through our intestine.

Dietary causes of loose green poop may include:

• Broccoli, green leafy vegetables, kale, spinach, wheatgrass
• Iron supplements
• Licorice
• Green or black food coloring.

Conditions that could cause loose green stools include those that change how fast food travels through the intestine because bile (a yellow-green fluid that digests fats) doesn’t have time to break down.

Bile is produced by our liver and stored and released in our gallbladder. Anytime we eat food that contains fat, even a small amount of fat, a signal is sent to our gallbladder to release bile, which flows into the upper part of our small intestine through two small tubes (the cystic duct and common bile duct). Bile digests fats and also eliminates old red blood cells and some toxins from our bodies.

As bile travels down our intestine it is chemically altered by enzymes, and the color changes from green to brown. However, this process takes time. Conditions that can quicken intestinal transit time, meaning that bile retains some of its yellowish-green color, include:

• Infection from bacteria, viruses, or parasites (eg, E. coli, Giardia, norovirus, salmonella)
• Crohn’s disease
• Gall bladder disease
• Irritable bowel syndrome
• Some medications, including Depo-Provera (medroxyprogesterone birth control shot), indomethacin, and iron supplements, have reported green poop as a side effect
• Ulcerative colitis.

Generally, a color change accompanied by other symptoms, such as abdominal pain, diarrhea, cramps, weight loss, or fever should be investigated further.

Yellow poop changes may be a sign of infection, poor absorption, liver and gall bladder disease, celiac disease, pancreatic disorders, or dietary reasons. Bright red or black poop may indicate the presence of blood and you should seek medical advice straight away.

For more information see Green stool.