There are many questions that perennially plague human existence:
Why are we here?
Are we alone in the universe?
Why is my poop green?
The first two questions are a bit beyond the purview of this site, but the last one can be answered quite readily.
Why is my poop green?
Dark green poop may be surprising or alarming upon your first encounter, but it actually has a very simple biological explanation and, as far as the brilliant rainbow of feces is concerned, is not normally a cause of significant concern. There are also certain steps you can try taking when your poop is green in order to prevent a reoccurrence. But we’re getting ahead of ourselves. Let’s start with the basic question and move on from there.
What Causes Green Stool?
Understanding why you have dark green feces first requires knowing why it’s normally brown in the first place. Poo is a mix of undigested food, bile, bacteria, and dead blood cells. The brown coloration happens during the stool’s journey through the digestive tract where intestinal bacteria break down and feast on the leftover bile and other cell detritus it contains. The underlying process is surprisingly complicated but the main takeaway here is that poo is normally greenish until exposure to intestinal bacteria, where turns it brown.
It’s also important to distinguish between dark green stool (1) in adults and any dark green poop from a baby. During the first few days of life, an infant will pass dark green stool known as meconium. This is normal and is the result of waste that was accumulated during gestation. Meconium usually persists for several days until the baby begins breast or formula feeding, at which point it will start to turn yellow over time. Dark green poop in a breastfed baby or one being bottle-fed is therefore not normally a cause for alarm.
Now that the preliminaries are out of the way, let’s look at what dark green poop might mean.
Sometimes, the color of your poo has less to do with your own body and more with what you’re eating. Consuming large amounts of green, leafy vegetables like kale or broccoli can sometimes result in your poo appearing dark green. Iron-rich foods such as beans or meats will produce a similar effect and may leave you with a dark green, almost black poop. This is more easily seen in the dark green poop a two month old might have if they are fed iron-fortified milk. In all of these cases, the underlying mechanism is the same. There is a biological limit to how much of any nutrient your body can make use, of and anything leftover can get excreted, dyeing the resulting poo. Iron supplements or supplements that contain chlorophyll or fructose can also cause green stools.
Food dyes are generally not absorbed by the body and will get excreted along with other waste. If you have recently eaten a large number of foods that use green coloring (such as promotional St. Patrick’s Day treats), you may find yourself producing green stool over the following days. How susceptible someone is to food coloring will vary from one individual to the next. It’s fully possible, for instance, for you and a friend to eat the same dyed foods but for only one of you to have a green poo as a result.
Antibiotics, particularly the powerful ones that get prescribed for major infections, are capable of reducing the levels of bacteria in your intestinal tract. As mentioned earlier, these are the same bacteria responsible for why poo normally appears brown and their loss means your feces can’t be processed as thoroughly during its trip through the body. Due to this, green stool is a known side effect of some antibiotics.
Anything that causes food to move too quickly through the intestines can produce green stool since this cuts down on the amount of time it can be processed. This means that any situation capable of causing severe diarrhea, such as food poisoning, salmonella, a parasite, or irritable bowel syndrome, would also be able to produce dark green bowel movements. In other words, anything capable of aggravating your bowels will also be capable of producing dark green diarrhea.
A colon cleanse is a type of home treatment some individuals use to try and flush “toxins” from the body. Cleanses come in numerous varieties but typically employ some combination of supplements, enemas, and/or laxatives. Since colon cleanses essentially force-evacuate your bowels, it’s possible for them to produce green stool by virtue of triggering a bowel movement prematurely, before feces has been properly processed.
It’s also possible to have dark green poop while pregnant. During pregnancy, a woman’s body produces more blood, and if she doesn’t get enough iron, she could become anemic. If that happens, she might then take iron supplements, a side effect of which is black or green poop. Iron supplements can cause other discomfort, such as constipation, so it may be in the best interest of pregnant women to increase their iron intake through diet, by consuming liver, red meat, and leafy greens.
Treating Dark Green Poop
Anyone can be affected by dark green poop; toddlers and adults alike. Treatment for dark green poo begins with identifying what the actual cause was. Fortunately, this is not a difficult task. Meconium is easy to rule out simply by asking whether the person was born recently.
Similarly, you should be able to remember whether or not you recently engaged in a colon cleanse (enemas are kind of hard to forget). If you suspect antibiotics or a nutritional supplement are involved, it’s best to consult with your doctor on how this can be determined. It’s strongly inadvisable to discontinue an antibiotic without your doctor’s approval since you were likely prescribed that medicine for a good reason.
Lastly, conditions such as food poisoning or irritable bowel syndrome come with other associated symptoms that can help identify them. In these instances, the green stool is likely accompanied by diarrhea, stomach cramps, nausea, vomiting, or other signs of digestive disagreement.
Once your cause is identified, treatment becomes relatively simple:
- Meconium goes away on its own, so time is the only remedy needed.
- Talk to your doctor about switching to a new, less severe antibiotic to give your intestinal bacteria time to recover.
- Over-enthusiastic eating of green foods or iron-rich items can be curtailed with simple diet adjustments, as can any indulgence in overly-dyed treats.
- Food poisoning requires bed rest, maintaining fluid intake, and easing in to bland foods once you’re able to keep them down. Most food poisoning cases resolve within a few days with or without treatment.
- Avoid giving yourself a colon cleanse.
When to See Your Doctor
A one-off incidence of green stool is rarely a cause for concern and can be safely ignored. If you find that you are having recurrent or repeat episodes of green bowel movements, however, a doctor’s appointment may be in order.
Often, an exam for green stool will involve some questions about any recent dietary or lifestyle changes that may be affecting digestion and the stool itself may get examined if nothing can be ruled out.
One important thing to keep in mind is that although most causes of green stool are benign, this does not stop green stool from occurring alongside other more problematic situations.
If your stool seems to have mucus or blood in it (bright red or tarry, almost black) or is very watery, medical attention may be advised. This also applies if you experience rectal pain, intermittent bouts of constipation, fever, or loss of appetite. These symptoms should always be paid attention to and investigated regardless of whether you have dark green poop or not.