Why Do Farts Smell (Bad)?

(What The Smell Of Your Farts Says About Your Health!)

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Oh gross!

Where did that smell come from? It’s a miracle of science, but boy can it be stinky.

Poo Doctor here to give you the facts about smelly farts.

Your gut is constantly working to break down the food you eat and depending on what you put down there you might get some nasty stink. This can be caused by byproducts like ammonia or hydrogen sulfide.

And just because your farts smell doesn’t mean you’re eating the wrong thing, but it could definitely mean that your digestive system needs some help.

And to do this, I recommend one “stinky” nutrient as the best way I’ve found to fix your farts and supercharge your gut.

Click below and get a fart head start.

And remember, like for good poop, share for great poop.

Though few people talk about farts in “polite” company, passing gas is normal, necessary, and good for your health. Everyone does it…and often. According to research, most people release gas between 14 and 23 times a day.1 (It is released by farting and burping.) And what you don’t release during the day, you’ll let it rip at night while you sleep.

The average person produces about 1 to 4 pints of gas per day. However, it is released gradually throughout the day/night because humans can hold only 200 milliliters of gas at a time.2

But Why Do My Farts Smell So Bad?

If you suffer from frequent smelly farts, it might surprise and anger you to learn that most farts are odor-free.3 But that doesn’t mean that a stinky release is a bad thing. On the contrary, smelly farts are normal in most cases. They are, after all, a byproduct of digestion.

When gas builds up in your digestive system from breaking down food, it must be released to relieve the pressure. Otherwise, you’ll suffer from bloating, abdominal pain, and other gastrointestinal (GI) issues.

However, there are a few things you can do to reduce your smelly eruptions. But first you need to know what causes them.

Causes of Smelly Farts

There are several reasons why your farts smell bad. Most of the time it’s caused by dietary factors. But there can be more serious causes of stinky gas. Here are a few of them.

High-Fiber Foods

Dietary fiber plays an important role in digestive health and may help reduce your risk of developing chronic diseases.4 Consequently, it is an important part of a well-balanced diet. According to the Institute of Medicine, men aged 50 and younger should get 38 grams of fiber per day and women should eat 25 grams. Yet, most Americans get less than half that amount.5

But eating a lot of high-fiber foods can make for smelly gas, especially if you significantly increase your fiber intake. That’s because fiber stays in your digestive system a long time while bacteria tries to break it down.

But not all types of fiber are created equal as far as their gas-producing abilities go. There are two types of fiber, soluble and insoluble. Many foods contain both types but are usually richer in one type than the other. Your body processes soluble and insoluble fiber differently.

Soluble Vs Insoluble Fiber

For example, insoluble fiber cannot be broken down and digested by your body. Instead, it passes through the digestive tract relatively intact. This type of fiber speeds up digestion and adds bulk to stool and is essential for bowel regularity. Because it accelerates digestion, it causes less gas than soluble fiber.

Sources of insoluble fiber include:6

  • Wheat brain
  • Beans
  • Green beans
  • Potatoes
  • Wheat flour
  • Cauliflower
  • Broccoli

Soluble fiber, on the other hand, is converted to a gel-like substance in your small intestine and then broken down and fermented by the beneficial bacteria in your colon. This fermentation process causes gas and some of it can be quite stinky, especially if you eat foods with certain chemical elements and/or natural sugar. More about that in the next section.

Sources of soluble fiber include:7

  • Oats
  • Peas
  • Beans
  • Apples
  • Oranges and other citrus fruits
  • Carrots

Sulfur Rich Foods

Have you ever passed gas that smelled like rotten eggs? That foul smelling release typically comes from eating sulfur rich foods.

Sulfur is one of the most abundant chemicals in the human body. It is important for the synthesis of amino acids cysteine and methionine, which helps support cell health and prevents damage. This may translate to many health benefits, which might be the reason so many foods contain sulfur.

Sulfur-rich foods include:

  • Broccoli
  • Cauliflower
  • Cabbage
  • Brussel Sprouts
  • Onions
  • Legumes
  • Garlic
  • Cheddar cheese
  • Nuts
  • Wine
  • Eggs
  • Meat
  • Milk

Whew…that’s a long list. No wonder egg-smelling farts are so common!

Lactose Intolerance

Lactose intolerance is a condition in which you are deficient in the enzyme needed to digest the lactase, a type of sugar found in dairy products. We’re talking milk, ice cream, cheese, sour cream, etc.

If you’re lactose intolerance, you’re not alone. An estimated 30 to 50 million Americans suffer from this condition.8

If you have a deficiency of this enzyme, lactose is not absorbed in the small intestine and instead travels to the colon. Once there, trillions of bacteria interact with the lactose. This alone can cause stinky gas, but many dairy products are also high-sulfur foods that make your farts smell like rotten eggs. Talk about a double whammy!

Keep in mind that dairy foods contain different amounts of lactose, so certain foods may affect you more intensely than others.

In addition to smelly gas, symptoms of lactose intolerance include:

  • Bloating
  • Diarrhea
  • Nausea
  • Stomach cramps

Raffinose Foods

Raffinose, a type of sugar, is found in beans and other foods. There’s only one problem; namely, the human GI tract lacks the enzyme necessary to break down and digest this type of sugar. This can cause smelly gas and bloating.

Foods that contain raffinose include:

  • Beans
  • Lentils
  • Legumes
  • Asparagus
  • Cauliflower
  • Broccoli
  • Brussels Sprouts

These foods contain important nutrients, complex carbs, and dietary fiber that your body needs, so don’t cut them out of your diet entirely. Instead, try to eat smaller portions.

As for beans, studies suggest that soaking dried beans before cooking them will reduce flatulence. It’s certainly worth a try.

Gluten Intolerance

Gluten intolerance, also called non-celiac gluten sensitivity, is a condition that causes unpleasant digestive symptoms after eating gluten, a protein found in wheat, barley, and rye. Between 0.5–13% of the U.S. population may have non-celiac gluten sensitivity.9 The reason this condition is unknown

The other type of gluten intolerance is celiac disease, and it’s a more serious condition. Celiac disease is an autoimmune disorder in which gluten ingestion damages the small intestine. A estimated 3 million people in the U.S. have celiac disease.10

In addition to smelly farts, the symptoms of gluten intolerance are varied and include:

  • Bloating
  • Diarrhea
  • Constipation
  • Stomach pain
  • Headaches
  • Fatigue
  • Depression
  • Unexplained weight loss

If you frequently have these symptoms after eating foods containing gluten, talk to your doctor to rule out the more dangerous celiac disease.

Sugar Alcohols

Sugar alcohols, such as Xylitol and sorbitol, are popular these days because they are not absorbed by the body and thus do not add calories to the diet. Instead of being absorbed, they end up in the large intestine where bacteria interacts with them. This causes smelly farts.

Foods the contain sugar alcohols include:

  • Diet drinks
  • Sugar-free candy
  • Sugar-free gum
  • And many other sugar-free products

You can also buy Xylitol and other sugar alcohols to add to your beverages, cereals, and other foods.

Digestive Disorders

Inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) are digestive disorders that can cause smelly gas. This is because they affect either the large intestine or the digestive tract in general, leading to distressing and even painful issues with the GI tract.

Occasional or even frequent smelly farts are usually nothing to worry about. But if you have smelly emissions combined with symptoms of a digestive disorder, talk to your doctor.

Symptoms of a digestive disorder include:

  • Changes in bowel habits
  • Excess gas
  • Indigestion
  • Diarrhea
  • Fatigue
  • Unexplained weight loss
  • Abdominal pain and cramping
  • Blood in your stool


It doesn’t seem fair that you can release foul smelling gas but not be able to poop, but that’s a common feature of constipation.

The reason? When you’re constipated, your poop is stuck in your colon for much longer than it’s supposed to, giving bacteria the chance to “go to town” on it. This produces lots of gas, much of it stinky.

The symptoms of constipation include:

  • Infrequent bowel movements, i.e., fewer than 3 bowel movements a week
  • Straining to have bowel movements
  • Passing hard or lumpy stools


Certain medications can cause smelly gas. Antibiotics, for example, destroy good gut bacteria as well as the bad kind, which leads to often foul smelling gas.

In addition, some diabetes drugs that slow carbohydrate absorption can cause gas with stinky farts, too. Even dietary supplements can make passing gas quite stinky. Iron supplements, for instance, are known to cause gas and bloating.

If you notice stinky gas after taking a new medication or supplement, this is likely the cause of the problem.

Colon Cancer

Though not as common, colon cancer can also cause stinky farts. This is because tumors or polyps may cause partial blockages in the colon, leading to a gas buildup.

Unfortunately, there are usually no symptoms until the later stages of the disease, which is why doctors recommend colon screening tests for those aged 50 and older.

The symptoms of colon cancer are similar to those of digestive diseases and include:

  • Fatigue
  • Diarrhea
  • Constipation
  • Bloating
  • Bloody stool
  • Abdominal pain
  • Unexplained weight loss

When to See a Doctor

Smelly gas on its own is usually not a serious matter. However, if it continues for a few days and is accompanied by adverse symptoms of the digestive tract, you should speak to your doctor immediately.

Some of these symptoms include:

  • Bloating
  • Fatigue
  • Fecal incontinence
  • Bloody stool
  • Diarrhea
  • Vomiting
  • Fever
  • Stomach pain/cramps


Though you can never get rid of flatulence or the stench that often accompanies it, there are a few things you can do to reduce gas and minimize the stink:

  • Avoid foods known to contribute to stinky gas, such as beans.
  • Increase your fiber intake gradually
  • Eat slowly
  • Avoid carbonated drinks
  • Eat probiotic foods like yogurt to add good bacteria to your digestive system
  • Avoid trigger foods like those containing gluten, lactose, or sugar alcohols
  • Drink lots of water to help move the waste through your system

And One More Thing…

You can help fix so many of your digestive and bathroom issues, such as stinky gas and bloating, and improve your overall health with this patented molecule that is backed by Harvard Doctor’s. Click here to learn more about it and to place your order today. What do you have to lose except excessive gas and smelly farts?!!!


1- Hasler WL. Gas and Bloating. Gastroenterol Hepatol (N Y). 2006;2(9):654-662

2- Rodriguez D. Gas: How Much Is Too Much? Everyday Health. Aug 1, 2013. Accessed Apr 8, 2021. https://www.everydayhealth.com/hs/gas-and-bloating/gas-how-much-is-too-much/#:~:text=Your%20body%20has%20to%20release%20that%20gas%20to,at%20Duke%20University%20Medical%20Center%20in%20Durham%2C%20N.C.

3- Pallarito K. Why Do My Farts Smell So Bad? Here’s What Doctors Have to Say About Stinky Farts. Health.com. Feb 12, 2020. Accessed Apr 8, 2021. https://www.health.com/condition/digestive-health/why-farts-smell-bad

4- Harvard Health Letter. Fiber linked to lower risk for chronic disease and early death. Harvard Health Publishing. Apr 2019. Accessed Apr 8, 2021. https://www.health.harvard.edu/staying-healthy/fiber-linked-to-lower-risk-for-chronic-disease-and-early-death

5- Mayo Clinic Staff. Dietary fiber: Essential for a healthy diet. Mayo Clinic. Jan 6, 2021. Accessed Apr 8, 2021. https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/fiber/art-20043983

6- Mayo Clinic Staff. Dietary fiber: Essential for a healthy diet. Mayo Clinic. Jan 6, 2021. Accessed Apr 8, 2021. https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/fiber/art-20043983

7- Mayo Clinic Staff. Dietary fiber: Essential for a healthy diet. Mayo Clinic. Jan 6, 2021. Accessed Apr 8, 2021. https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/fiber/art-20043983

8- Kloberdanz K. Lactose Intolerance FAQ. HealthDay. Dec 31, 2019. Accessed Apr 5, 2021. https://consumer.healthday.com/encyclopedia/food-and-nutrition-21/food-and-nutrition-news-316/lactose-intolerance-faq-647337.html#:~:text=For%2030%20to%2050%20million%20Americans%2C%20a%20big,to%20digest%20lactose%20as%20we%20grow%20into%20adulthood.

9 – Molina-Infante J, Santolaria S, Sanders DS, Fernández-Bañares F. Systematic review: noncoeliac gluten sensitivity. Aliment Pharmacol Ther. 2015 May;41(9):807-20. doi: 10.1111/apt.13155. Epub 2015 Mar 6. PMID: 25753138.

10- Rubio-Tapia A, Ludvigsson JF, Brantner TL, Murray JA, Everhart JE. The prevalence of celiac disease in the United States. Am J Gastroenterol. 2012 Oct;107(10):1538-44; quiz 1537, 1545. doi: 10.1038/ajg.2012.219. Epub 2012 Jul 31. PMID: 22850429.

What Are 7 types of poop?

  • Type 1: Separate hard lumps, like nuts (difficult to pass and can be black)
  • Type 2: Sausage-shaped, but lumpy
  • Type 3: Like a sausage but with cracks on its surface (can be black)
  • Type 4: Like a sausage or snake, smooth and soft (average stool)
  • Type 5: Soft blobs with clear cut edges
  • Type 6: Fluffy pieces with ragged edges, a mushy stool (diarrhea)
  • Type 7: Watery, no solid pieces, entirely liquid (diarrhea)

Types of poop one encounters is categorized by the Bristol Stool Chart. This chart is a generalized indicator of how or why different types of poops look and feel a certain way. The 7 types of poop are broken up into categories based on a 2,000-person study!

Bristol Stool Scale

Does your poo look this good? If you have Bristol Type 3 or 4 – your poop is considered “normal”!  Bristol Type 1 or 2, is where the poop is hard and difficult to pass, are indicative of constipation. Often, these types of stool can be painful to pass – but don’t worry – Doctor Poo has a recommended healthy-gut switch solution…just keep reading!

 Should you ever worry about your poop?

Always consult your healthcare provider if you have any concerns about what your poop means. People are asked to call their health care providers if: They experience severe levels of abdominal pain or discomfort with diarrhea that does not go away when you poop or fart. Also, if diarrhea is accompanied by fever of 101 degrees Fahrenheit or higher, chills, vomiting, or fainting, call your physician immediately.

What is an unhealthy poop?

An unhealthy poop is when one poops too often (hence, your doctor asking you if you poop more than three times daily) or not pooping often enough (As such, less than three times a week) and also excessive straining when pooping. Poop that is colored red, black, green, yellow, or white. greasy, or fatty stools is unhealthy.

Help fix so many of your digestive and bathroom issues, such as gas and bloating and improve your overall health with this patented molecule that is backed by Harvard Doctor’s by clicking here!

Doctor Poo Provides More Valuable Answers for Those Hard to Ask Questions Below:

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