Lactose Intolerance and Diarrhea

I know, I know. Oy with the poo already! But I swear, this is the last one (for now). Since I’ve talked about diarrhea due to gastrointestinal infections, I should probably explain why some people get diarrhea as a symptom to lactose intolerance.

Difference between diarrhea caused by GI infections and Lactose Intolerance

Last week, we learned that our bodies don’t absorb the water we ingest when there is a GI infection, which means we don’t gain any water in our systems. In contrast to diarrhea as a result of an infection, water is actually taken from the body and enters the intestinal tract; that means we actually lose water we already had. But why?

Diarrhea as a symptom of Lactose Intolerance

When you have lactose intolerance, you have a decreased efficiency in the digestion of lactose. While there are bacteria in your intestinal tract that are capable of digesting the lactose, they may not be able to digest all of the lactose you’ve consumed. This means that there is a concentration of lactose in your intestines that has not been taken up by your body. This is where the water loss comes in.

Remember that pesky biology lesson about Osmosis? Well, it’s actually applicable here (thank you, high school!). So, you have a high concentration of sugar (lactose) in your intestines and a lower concentration in the external environment of the intestine. Water likes to do this thing where it moves from areas of low concentrations of solutes, like sugars, to higher concentrations of solutes. Basically, water is a gold-digger and the more solutes an area has, the richer it is. So the water flows into your intestinal tract until the concentration of the sugars in your intestine is roughly the same as the concentration of the sugars outside of the intestine (this is called an equilibrium). This increased volume of water in your intestines causes a watery stool (aka diarrhea!).

Always remember that it’s important to stay hydrated anytime you have diarrhea.

Lesson here is: don’t ingest crazy amounts of lactose, especially if you’re lactose intolerant… unless you’re taking lactase pills. If you’re taking lactase pills, you can eat all the poutine that your heart allows! (That reminds me, happy belated Canada day!)


Aw, poo! Is diarrhea getting you down? Well, seeing as I’ve mentioned diarrhea a few times, I thought it was about time that I explored the topic. So let’s find out what diarrhea is and why we get it. You may be surprised to find out just how great diarrhea can be, even though it’s definitely not pleasant in the moment.

What is diarrhea?

Diarrhea is runny or watery bowel movements (poo), where there is the characteristic loss in the form of the stool.

What causes diarrhea?

Diarrhea is usually an immune response indicating that you are suffering a gastrointestinal infection that has been caused by an endoparasite. In other words, diarrhea is the symptom of an infection in your gastrointestinal tract.

These infections are usually highly contagious as it can be spread via dirty hands contaminating food or water. These hands could have been changing a diaper or a pet’s fecal matter or simply cleaning the toilet but not washed properly (c’mon guys, just wash your hands!).  Kids usually get diarrhea frequently due to their tendency of putting their fingers into their mouths.

When we suffer from gastrointestinal infections, our bodies want to excrete the ingested endoparasite that is causing the infection out as quickly as possible. In order to do this, the muscles in your digestive tract contract at a faster rate than usual. This can cause a sharp pain in your abdomen.

These fast contractions also prevents your intestines from absorbing water from your waste; this means that the water in your intestinal tract leaves the body with your fecal matter instead of being retained in your body. This is why you get dehydrated when you have diarrhea, which is why you need to drink a lot of water and electrolyte-containing drinks (as you lose electrolytes and nutrients with your stool too).

Final thoughts

Okay, so basically diarrhea is great in that it helps us recover from an infection faster by excreting the endoparasites once it’s been detected by our immune system.

So while it’s a pain to deal with, it really teaches us the importance of hygiene. If we wash our hands properly and sanitize our hands and other items, there will be less of a risk of getting an infection. However, there are some endoparasites that won’t be phased by this, so diarrhea will be inevitable. The best thing you can do to recover from this infection is to stay hydrated. Your immune system is taking care of you, don’t you fret.

Without diarrhea, your body could become the new home to awful endoparasites. So just remember, it’s for the greater good.

Flatulence aka Farting

Seeing as we touched on the topic of flatulence/farting a bit last week, I thought it would be best to further explore what it is and why it is released.

What is flatulence?

Okay, so flatulence is the release of a mixture of  gases from your intestine via your rectum (where your feces exits). This mixture of gases is referred to as flatus. Flatus can be a mixture of nitrogen gas, oxygen gas, hydrogen gas, carbon dioxide and/or methane gas. These gases do not cause an odour though; there are tiny quantities of other gases. such as hydrogen sulfide, in your flatus that causes the smell of a fart.

Normally, adults release between 200 and 2000mL of flatus per day in 14 spurts (‘spurt’ really paints a picture, doesn’t it?)

What causes the production of flatus?

Well, these gases are introduced into your body in three major ways:

1.) When you eat food, you also swallow air. Air contains a bunch of gases including nitrogen gas, oxygen gas, and small traces of other gases like methane gas and ozone gas. This air goes into your stomach, but most of it is expelled (usually by burping).

These gases form large bubbles, which make a loud sound when released but are odourless. All the embarrassment for none of the smell.

2.) Gases can be generated as byproducts for digestion by colonic bacteria. Methane gas and hydrogen gas are only produced by the bacterial digestion of foods in our intestines. Fruits and vegetables contain complex sugars that can only be digested by bacteria.

The gases released by the bacteria after breaking down the complex sugars form small bubbles. When these bubbles are released, they don’t make a sound but it does cause a smell. They’re the stealthy farts that you can get away with. No embarrassment but all of the smell (okay, maybe some embarrassment but quick, play it off! No one knows it’s you!)

This second way of introducing gas into your body also means that vegetarians pass gas a lot more than other people and it’s, well, smelly. They have more fruits and vegetables in their diet which means there is a higher concentration of complex sugars. This provides more food for the bacteria, who will in turn produce more gases.

And, like I mentioned last week, people who have a deficiency in a digestive enzyme (like lactose intolerance) will also require the bacteria in their intestines to digest certain sugars, producing more gas.

3.) Hydrogen sulfide can also be produced by the bacterial digestion of polysaccharides, which is why the small gas bubbles produced by bacteria are so smelly. Our cells also excrete hydrogen sulfide sometimes.

So, that’s all there is to say about flatulence. You can have embarrassingly loud, but completely harmless toots or stealthily silent and foul-smelling toots. It’s an awful trade-off in my opinion.