Green Stool, Why Is it So?

Actually there should be no cause for alarm. Stool comes in a range of colors. All shades of
brown and even green are considered normal.
Only rarely does stool color indicate a potentially
serious intestinal condition.
Stool color is generally influenced by what you
eat as well as by the amount of bile — a yellow-
green fluid that digests fats — in your stool. As
bile pigments travel through your gastrointestinal
tract, they are chemically altered by enzymes —
changing the pigments from green to brown.
Consult your doctor if you're concerned about
your stool color. If your stool is bright red or
black — which may indicate the presence of blood
— seek prompt medical attention.
Stool color
What it may mean
Possible dietary causes
Green
Food may be moving through the large intestine
too quickly, such as due to diarrhea. As a result,
bile doesn't have time to break down completely.
Green leafy vegetables, green food coloring, such
as in flavored drink mixes or ice pops, iron
supplements.
Light-colored, white or clay-colored
A lack of bile in stool. This may indicate a bile
duct obstruction.
Certain medications, such as large doses of
bismuth subsalicylate (Kaopectate, Pepto-Bismol)
and other anti-diarrheal drugs.
Yellow, greasy, foul-smelling
Excess fat in the stool, such as due to a
malabsorption disorder, for example, celiac
disease.
Sometimes the protein gluten, such as in breads
and cereals. But see a doctor for evaluation.
Black
Bleeding in the upper gastrointestinal tract, such
as the stomach.
Iron supplements, bismuth subsalicylate
(Kaopectate, Pepto-Bismol), black licorice.
Bright red
Bleeding in the lower intestinal tract, such as the
large intestine or rectum, often from hemorrhoids.
Red food coloring, beets, cranberries, tomato juice
or soup, red gelatin or drink mixes.