Why Does Poop Smell?

an explanation for why poop smells

The age old question, something our ancestors sat around campfires and discussed. Well, not really, but going number two is a commonality that ties us all together. This article focuses on an area that most people are too shy to discuss: the odor that’s associated with poo. Let’s take a closer look at how poo is made, what causes it to smell and how you can decrease the odor.

How Poop is Made

Digestion begins in your mouth. As you chew your food, enzymes in your saliva begin the process of digestion. Food then travels to the stomach where it’s exposed to more enzymes and an acidic environment. The goal is to get this food broken down so the small intestines can absorb nutrients into the bloodstream for the body to utilize. Pretty straightforward, right? Enter bacteria!

Most of our lives, we’ve been told to wash our hands, to be careful of dirty surfaces and to use hand sanitizer, but there are some strains of bacteria that are extremely important for digestion and absorption. After food passes through the small intestines, it moves to the large intestines where the majority of water is removed and absorbed into the body. The food is ready to be eliminated. At this point, it primarily consists of fibrous food particles, dead bacteria, and byproducts of nutrient breakdown. And there you have it – a fascinating tale of a food’s journey to become a doodie. This whole process typically takes around 40 hours.

What Causes the Smell

Considering what poo is made of, you know that there would be a smell associated with it. But it should be a mild smell, not a "room clearing" smell. If you find that your poo is so stinky that you’re embarrassed to go in public, there are a couple potential causes to consider:

  • A Diet High in Sugar – Sugar is fuel for the "bad" bacteria in the digestive tract. When these bacteria are fed sugar, they produce and release gases, like hydrogen and methane, which increase the bad smells in poo.
  • Underlying Absorption Issues – When the digestive system is out of whack, the body is unable to fully break down certain macronutrients, specifically fats. When there’s a higher fat content in the poo, it becomes very stinky.
  • Eating High Sulfur Foods​ – Foods, like meat, Brussels sprouts, broccoli and garlic, have sulfur-containing compounds that make the poo smell more "eggy."
  • Taking Certain Medication – Some meds are coated in sorbitol, which can increase the frequency of bathroom trips and intensify the smell of your poo.
  • Having an Intolerance – In some cases, the body can't break down certain molecules, resulting in foul-smelling poo. For example, if you’re lactose intolerant, your body can't break down lactose. If you have celiac disease, your body can't break down gluten.

Decreasing the Odor

  1. Eat More Soluble Fiber​ – This type of fiber is found in foods like bananas, oats, apples, and lentils. It pulls water into the GI tract, allowing food to pass more quickly. Getting things moving is an important part of keeping the smell of your poo to a minimum.

  2. Drink Water​ – Water helps flush out the body and move food through the digestive tract. Stay hydrated!

  3. Take a Digestive Enzyme​ – Ensuring all food particles are broken down is the key to better health and a less rank poo. Digestive enzymes help support the body in breaking down larger particles and enhance nutrient absorption.

  4. Take a Probiotic​ – Adding good bacteria to your diet can help keep the bad bacteria in check. Taking a probiotic at night is a great way to help your body restore its gut flora.

  5. Movement​ – Walking is often an underrated form of exercise. Moving your body, even for 20 minutes a day, can do wonders for your digestion.

Many different factors influence the way your poo smells, but one of the first places to look into is your diet. Having a clean diet can aid with regularity, helping you feel better while also producing a more socially acceptable doodie odor.

Registered Dietitian, Certified Specialist in Sports Dietetics

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