What Causes Bloating?

This question was sent to us by a visitor:

“How can I manage my ibs so that I do not constantly look several months pregnant ? I am so bloated no matter what I do/do not eat or how little/how much… I feel like I have balloons inside of me day in and out… How do I get rid of my over bloated tummy?”

Can you relate to this? If so, this article is for you.

This article looks at the causes of bloating. In part two, I will cover how to get rid of bloating.
Go to Part Two article.

I don’t think I need to explain what bloating IS. If you are reading this article, you already know that it’s when your abdomen is filled with gas and, as our reader above said, you feel like you’re several months pregnant.

Please note that I am talking about the “bloated stomach” that happens for many IBS sufferers. If you do not have Irritable Bowel Syndrome, there may be other reasons for your chronic bloating, some of which are symptoms of certain diseases. This article does not cover those symptoms or diseases.

If you are a woman who has bloating during your menstrual cycle, much of the information below will also apply to your situation.

So, let’s get to it!

What causes bloating?

If you have looked into this on the internet at all, you have probably come across the statement that one of the causes of bloating is IBS. Well, gee, thanks a lot, that’s really helpful. (Not!)

When we dig a little deeper, we find that there’s a lot more to it.

Bloating is one of the symptoms of Irritable Bowel Syndrome, but the causes are many and varied. People who DON’T have IBS get bloated, too.

The causes of bloating include:

  • Bacterial overgrowth in the small intestine
  • Sugars that disrupt the normal microbes in your intestines
  • Food intolerances and allergies
  • Foods that are hard to digest and produce gas
  • Intestinal parasites
  • Mercury
  • Chemical and perfume sensitivities or intolerances
  • Stress and trauma

These are the causes I’m aware of. There may be others (and if you know of any, please let us know in the Comments at the end of this article.) Now let’s look at the ones I’ve listed above in more detail. We’ll look at some ways to prevent and get rid of bloating in a separate article.

Bacterial overgrowth in the small intestine

Some researchers believe this is actually the cause of IBS. It has also been linked to fibromyalgia and rosacea (although I don’t know how much this has been researched.)

While your large intestine or colon has bizillions of microbes, the small intestine has a relatively low level of bacteria so, when they grow out of control, bloating and gas result.

In addition to a big, uncomfortable, bloated tummy from all the extra bacteria, you might feel nauseated or even vomit, have diarrhea or constipation, and/or lose weight.

Unfortunately, when you have too many bacteria in your small intestine, they gobble up nutrients that your body needs to live on, so you will not get all the nutrition you should be receiving from your food. As you can see, this could lead to malnutrition. Also, the lining of your intestine could become damaged which causes further problems for absorbing nutrients.

From the medical perspective, there are several possible causes of small intestine bacterial overgrowth, including diverticulosis, pancreatitis, scleroderma, bariatric surgery (“stomach stapling”), other surgery that involves the intestines, proton pump inhibitors (drugs that reduce stomach acid) and drugs that suppress your immune system.

Don’t have any of these diseases, surgeries, or drugs in your life? A bacterial overgrowth is also linked to some of the other causes of bloating listed below, including…

Sugars that disrupt your normal microbes

In particular, anything containing fructose or sorbitol is a problem.

However, from what I’ve read regarding other sugars and their destructive effects on the digestive system, I think you could include artificial sweeteners as well as regular sugar (sucrose.) Sucrose or ordinary table sugar is about half fructose anyway!

There are two problems with these sweeteners:

1) They are hard to digest

2) They are the food of the intestinal bacteria and yeast (such as Candida yeast) that cause problems. This is why you often crave sweets or carbohydrates, when you have a bacterial or yeast overgrowth. It’s not you who really wants the sweets, it’s the bacteria or yeast.

Aha! So sweets feed the very bacteria that you need to starve in order to get rid of bloating, especially fructose (that includes regular sugar) and sorbitol. Don’t forget, fructose is in fruit, as well as everything that contains high-fructose corn syrup.

But don’t worry, this doesn’t mean you will have to give up sweet things forever. I’ll explain more in the section on how to get rid of bloating.

Food intolerances and allergies

It’s interesting. A lot of people don’t believe they have any food intolerances or allergies. I used to be one of them. After all, I never went into anaphylactic shock or needed an EpiPen®.

But you don’t have to have a severe reaction to have this problem. There is a long list of other types of reactions to foods including bloating and gas, anxiety, depression, brain fog, skin rashes, headaches, diarrhea, constipation, breathing problems, joint pain, erratic behaviour, and trouble sleeping. And those are just a few of them. If I were to list all the possible food reactions here, I could go on for pages!

The most common food allergen is dairy, closely followed by wheat and other cereal grains (especially corn.)

When you eat (or drink) these foods, especially combined together, you can have some pretty bad digestive reactions. Like bloating.

Some other common problem foods are oranges and citrus, caffeine in coffee, soft drinks and other sources, peanuts, soy, tree nuts, eggs, fish and shellfish.


Curiously, when Kathy and I used to work with people with allergies and intolerances, we found that they often had bad reactions to their multivitamins! I know vitamins are supposed to be healthy, but your vitamins might be one of the causes of your bloating.

How can this be?!

I didn’t understand it myself for many years, until I went to a talk by Raymond Francis. He has a background in biochemistry and was able to save his own life from liver failure through vitamin therapy. (He was given a properly prescribed drug that nearly killed him by destroying his liver when he was 46. He is now 76 and in excellent health.)

In the process of learning everything he could about vitamins, Francis discovered that most vitamins contain very little of the active ingredient and often contain useless fillers and ingredients that aren’t mentioned on the label. It could be these fillers and mystery ingredients that you’re reacting to.

Also, when it comes to multi’s, you might be fine with some of the vitamins and minerals in the combination, but not all of them. There are different sources of individual vitamins and minerals, as well, and your digestion might not like some of them. For example, the website of the Linus Pauling Institute at Oregon State University lists thirteen different types of vitamin C !

Another problem for people with IBS is…

Foods that are hard to digest and that produce gas

These include items that would typically be on most people’s list of healthy foods, such as

  • broccoli, cauliflower and other cruciferous vegetables
  • beans or legumes
  • whole grains.

These foods contain an indigestible sugar called raffinose. The human body doesn’t make the enzyme needed to digest raffinose, so you end up with gas and bloating. Plus, all that fiber, contrary to what we’ve been told, is extremely hard for most people to digest, especially people with Irritable Bowel Syndrome. (Although it might help people who are constipated, unless they are also bloated.)

Actually, the fiber in these foods is indigestible and insoluble (does not dissolve in water) so all it’s really doing is forcing your digestive system to work too hard to get it out.

Intestinal Parasites

Most parasites are very tiny and can enter your body through:

  • contaminated food (for example, raw fish)
  • unclean water
  • walking barefoot
  • exposure to infected feces

Parasites may be protozoa such as cryptosporidium and giardia, which multiply in your body, or helminths, which do not. Helminths include such creatures as tape worm, round worm, whip worm and pin worm.

Strangely enough, in highly sanitized places like North America, helminths are sometimes used as a therapy for autoimmune conditions like Inflammatory Bowel Disease, Multiple Sclerosis, allergies, and asthma. Apparently, being TOO clean means you don’t always develop your immune system well enough, so adding the “bugs” helps to stimulate your immune response. Who knew?!

At any rate, if you have parasites that cause bloating, they need to be dealt with. (see part 3)


I realize that mercury may seem like an odd addition to this list, since many people think of it as a nervous system irritant (to put it mildly!) However, since your nervous system governs your gastrointestinal system, anything that wreaks havoc on one is likely to affect the other.

Mercury is one of the most toxic substances to humans. In your intestines, it acts like an antibiotic. In other words, it kills off the beneficial bacteria in your gut, allowing pathogens (bad stuff), yeast (like Candida yeast) and parasites to flourish. Eek! So, of course, you end up with bloating, gas, and other symptoms.

Unfortunately, mercury tends to suppress your immune system, so your digestion has trouble recovering from its antibacterial effects.

Where does mercury come from?

Besides mercury amalgam dental fillings, it is in fish – typically the larger the fish, the more mercury is in it. Other contaminated sources of fish are the ones caught in a lake near a gold mine, coal mine, metal refinery, or any type of factory or construction that uses mercury. (Hey, did you notice that fish and shellfish are two of the top food allergens? I wonder if that is because of the mercury content?)

Mercury is also used in:

  • latex paint
  • fabric softener
  • floor polish
  • some cosmetics
  • lawn and shrub fungicides
  • some vaccines and injections
  • some eye drops or contact lens solutions
  • fluorescent lights (but you would only be exposed to the mercury if you broke one – it is contained inside the tube or light)

I think tattoos have generally gone the mercury-free route but, if you are considering a tattoo, make sure.

Chemical and perfume sensitivities or intolerances

If mercury wasn’t scary enough, many of the products we use daily in our homes, in the laundry, and on our bodies are quite toxic. It might seem odd to you to read that chemical and perfumed products are related to bloating and gas but, once you inhale them or put them on or near your skin, these seemingly innocent items can bring about reactions inside your body that upset your digestion. Children often have even worse reactions than adults as they are still developing their immune systems (so don’t have as much “resistance” to these toxins as some adults.)

Just to be clear, please note that “chemical products” are produced from a petrochemical source.

They include:

  • cleaning products, polishing products
  • laundry products
  • personal care products
  • fragranced products of any type (unless naturally scented)
  • air fresheners and sprays
  • home renovation products
  • pesticides and fungicides – on foods and on our gardens and lawns

Products made from chemical sources may cause dysbiosis – which is when the normal balance of microbes in your intestines is damaged so that the bad bugs take over and give you all those nasty, uncomfortable symptoms, like bloating. (But you can restore that vital balance.)

Once upon a time, perfumes and scents were made from flowers, plants, herbs and animal glands (i.e. natural sources.) This is no longer true. Most of the scented products in our lives now owe their perfume to the magic of chemicals.

In addition to upsetting your digestion, molecules from chemical and chemically-scented products get in the way of your natural hormones so your body cannot function well. Although many people think that hormones are only about your reproductive system, there are many types of hormones in your body, and they regulate everything from your digestion to your blood sugar and insulin response.

Stress and trauma

As most people with IBS and other digestive problems know, stress and trauma definitely affect your digestion! You’ve probably found that stress and trauma can make bloating worse. There are several reasons for this:

When you’re stressed, your digestion does not function well, so it has trouble processing foods that you might be able to digest when you’re relaxed.

Stress may trigger you to eat – or overeat – foods that don’t work well for you because you think of them as “comfort foods.”

If you were eating or digesting certain foods at a time when there was trauma (e.g. loud arguments at the dinner table, bad news of some sort immediately following a meal, eating in the car at the time of an accident, etc.), your brain may forge a link between that food or meal and almost any reminder of the trauma (a color, a sound, an emotion, the physical position of your body, the weather, etc.) When that reminder occurs again, the link or neural pathway is activated and your digestion triggers the bloating.

As you can see, bloating can happen for many reasons. You may need to deal with one or all of the reasons above to clear up your bloating. The information about how to do that is in Part Two of this series.

Join the discussion:

What is your experience with bloating and what makes it worse for you? Let us know in the comment section below.

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21 thoughts on “What Causes Bloating?”

  1. Thanks…your blogs/emails have been helpful to me to unlock the puzzle of IBS (which seems to bore most medical professionals).
    After much research I realized I had allergies to wheat, dairy, & stopped all white sugar. I added a probiotic. Things steadily improved.

    I also take autoimmune suppressing drugs but since changing my diet, I am experimenting with cutting the dosage in half. If my blood work returns normal & I stay symptom free, I will be revisiting my doctor to get off drugs completely.

    My whole foods, no dairy, wheat or sugar diet works. I still have gut pain but it isn’t as bad as before, & is always at night. As a rule I don’t eat after 8, but for sure nothing at dinner that would be a guess work as to why bloating & gas happens after dinner. Any suggestions would be helpful.

  2. This article boggle my mind. I feel like I have all those causes. My bloating and pain was so bad the other day it I was doubled over, could not eat and the pain radiated into my shoulder. Yesterday I had pain so bad in the middle of my chest I thought it was a heart attack. The bloating makes my clothes tight. I have been through every test in the book and am seemingly healthy!! This is great news, but why am I bloated and in pain most of the time. There is no rhyme or reason to what I eat. One day I can eat it and be fine, the next day pain. It is so frustrating. I am going for CT scan of abdomen next week. Gastro doc wants to rule out any other causes. This article is so overwhelming I wouldn’t know where to begin. Is it in part 2? I am 48 and have been suffering with this most of my adult life . Recently the constipation has reached epic proportions.

  3. This article blew my mind , because right now my tummy is playing all the tunes and rumbling sounds you can think about. Oh the problem s I have with Gas is unthinkable this is a real battle for me.

  4. I have suffered from IBS 30 yrs. I bloat due to stress, and look 6 mo. pg. I was recently put on LINZESS, which has stopped my IBS altogether. I am still having bloating though, but no more painful episodes.

    I found this article very informative.

  5. Thank you ladies for these wonderful posts! I recently was introduced to the GAPS book…. I’m sure you both are familiar with this system. If not I highly recommend it– I feel so much better after only three full days!

  6. Hi Anne,
    Thank you so much for your kind words! I’m glad to hear the GAPS diet is helping you – it has certainly been beneficial for thousands of people and, from what I’ve read, a good way to restore the integrity of the bowel flora and lining. We do have a post about it called “What is the GAPS Diet?” (See list of posts on the right or list of articles on the home page.)

  7. Thank you for article is very informative. I was diagnosed with IBS 25 years ago, I am now 49. I had severe pain and doctors told me that I was severely scared in my large intestine, meaning i was very ill at one time. I have 2 children, but after I had my first child all symptoms went away EXCEPT the BLOATING. (I look like I’m 1O months pregnant , yes 10 Months… I am not exaggerating.) I have kept eating logs and I can eat the same thing one day and be fine and eat the same thing again and it will trigger my bloating. I am VERY FRUSTRATED at this time. I am concerned with having Mercury in my filings and crowns. I will be having a colonoscopy soon and will discuss this with my doctor. (I have a colonoscopy every year now, it used to be every 5 years). Thanks again for this article.

  8. What a great and informative blog! I thought for a very long time that some of my medications may be contributing to my IBS-D, I met with a pharmacology doctor who reviewed my medicines. After researching them, it was found that three of my medications had lactose as a filler. I have a sensitivity to lactose And we are now in the process of finding other pharmaceutical companies that do not use lactose as a filler. Interesting. There are other factors that I know are contributing to my problem but this may be one of them can be corrected and may bring some relief. Thank you for the wonderful work you’re doing .

  9. Good detective work, Helene! It’s unfortunate that the companies who made these drugs didn’t make it easy for you to know the full extent of the ingredients they were using (like by providing an ingredient sheet before you got your prescription filled.)Thanks for the kind words.

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