• Sarah Greenfield, RD

Why Does Poo Smell?

The age old question, something our ancestors sat around camp fires and discussed. Well, not really, but going #2 is a commonality that ties us all together. Today I want to focus on an area that most are too shy to discuss, the odor that is associated with poo. We will look at how poo is made, what causes it to smell and how you can decrease the odor.

How Poo 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 is 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 straight forward, right? Enter bacteria! Most of our lives we have 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. We will discuss bacteria in the “what causes poo to smell” section. 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 now poo and 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 foods journey to become a doodie. This whole process typically takes around 40 hours.

What Causes it to Smell

Knowing what poo is made of, you now know there will be a smell associated with it. But it should be a mild smell, not a “room clearing” smell. If you are finding that your poo is so stinky you are embarrassed to go in public, there are a couple things to consider.

  • Eating a diet high in sugar – sugar is a fuel for the “bad” bacteria in the digestive tract. When these bacteria are fed sugar, they produce and release gas (typically hydrogen and methane) which increases the bad smells in poo.

  • Underlying absorption issues – When the digestive system is out of whack, the body is unable to fully breakdown certain macronutrients, specifically fats. When their is a higher fat content in the poo it can become very stinky.

  • Eating high sulfur containing foods – foods like meat, brussels sprouts, broccoli and garlic have sulfur containing compounds that make the poo smell more “eggy.”

  • You are Taking a Medication – some meds are coated in sorbitol which can increase the frequency and smell of your poo.

  • You have an intolerance – In some cases the body can’t breakdown certain molecules and this results in foul smelling poo. For example if you are lactose intolerant, your body can’t breakdown lactose. If you have celiac disease, your body can’t breakdown gluten.

Decreasing the Odor

  1. Eat More Soluble Fiber – This type of fiber is found in foods like bananas, oats, apples, and lentils and 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 fragrant poo. Digestive enzymes can 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-time is a great way to help your body restore its gut flora.

  5. Movement – walking is an often under-rated form of exercise. Moving your body, even 20 minutes a day, can do wonders for your digestion.

The way your poo smells is impacted by many different factors, but one of the first places to look is at your diet. Having a clean diet can help with regularity, feeling better and having a more socially acceptable doodie odor. If you want to change your diet, need a little extra support and accountability, sign up for the Optimize Digestion Challenge starting on April 2nd.

#poop #digestion #poopsmells


Sarah Greenfield RD, CSSD


16550 Riverside Drive


Studio City CA 91602 



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