Ask Giz: Why Is My Poo Green?

Welcome to Ask Giz, where we answer reader-submitted questions about anything Gizmodo adjacent.

If you’d like to submit a question for us to answer, you can do so through our submissions page.

Today’s question was actually similar to that found in our list of “weird stuff to answer”, so let’s ponder: why is my poo green?

I’m sure you’ve had the unpleasant experience of standing up, turning around and noticing a bowel movement in a colour quite different to what it should be.

Well, like most things, I can assure you there’s a scientific explanation behind it. Allow me to explain.

Why your poo is green

As you may have guessed, green poo is mostly determined by what you eat. It’s nothing to worry about and it’s not really something that requires much more thought beyond “hey, that’s odd”.

Foods that can give you green poos include kale, spinach, broccoli and blueberries. You know, foods that contain chlorophyll. Eating enough chlorophyll will change your poo colour.

Interestingly, though, that’s not where it ends. The green colouring can also be associated with antibiotics or even an infection. If you suspect an infection, monitor for other symptoms and talk to your GP. Yes, your poo can be other colours.

But why is poo brown in the first place?

While all shades of brown are considered normal for poo (it’s the consistency that matters), why is it normally brown? Well, poo is actually made up of 75 per cent water. The remaining 25 per cent is made up of a mixture between carbohydrates, fibre, fat, protein, bacteria, mucus, old red blood cells, intestinal secretions and liver chemicals like bile.

However, as Healthline says, it’s mostly brown due to bile and bilirubin. Bile (used for breaking down fats) is typically yellowish-green and bilirubin (used for forming red blood cells) is typically yellow. When they mix and leave your body, the result is brown. Sometimes, if there’s more bile than bilirubin, the result can be green poo.

Why do babies have green poo?

The first poo a baby takes actually has a special name: meconium. It’s usually green.

It’s completely normal for babies to have a different coloured poo. High amounts of iron in baby formula can usually lead to green stools, but breastfed infants can also have off-coloured poo from their diet.

Other colours are possible, but there’s very little to worry about.

Poo with confidence

If you have any questions about your stool, it’s a good idea to take it up with your GP.

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