How Does Lactose Affect Gastrointestinal Function?

Lactose is a disaccharide sugar found mainly in cow’s milk and milk derivates. It is basically “milk sugar.” Lactose, in its disaccharide form, cannot be broken down in your gut. It needs an enzyme to get the job done. Enzymes are proteins that speed up a chemical reaction.

Lactase, the enzyme directed to break down lactose, is secreted in the villi of the gut. The products of this chemical reaction are two simple sugars named galactose and glucose.

Now, the body can absorb galactose and glucose. Time to put those simple sugars to work!

Recap: Lactose=Galactose + Glucose

Enzymatic hydrolysis of lactose to Galactose and Glucose by the action of the enzyme lactase


How can some drink milk with no reaction while others experience bloating, diarrhea, abdominal cramping and gas?

Well, the body cannot absorb lactose in the disaccharide form. If lactase, that cool enzyme hanging out in your gut, is not present, lactose will ferment and become food for bacteria.

The bacteria ingest the fermented “milk sugars” and leads to bloating, gas, and diarrhea. This is not the type of party you want happening in your gut, if you can help it.

The great news is that there are tons of options available to those who are considered lactose-intolerant. Look for lactose-free milks, cheeses, or try milk from other sources like almond, hemp, or coconut (yummy!).

So you may be thinking… I’m lactose intolerant, am I missing a gene?

Mammals produce lactase, the enzyme that breaks down lactose, at birth and its production usually declines after breastfeeding age. T

he main job of lactase is to break down breast milk fed to infants. Yet if milk was a vital part of your ancestors’ food culture, you are more likely to produce lactase beyond infancy into adulthood. The longer you expose your body to milk, the longer you produce lactase.

Wow, talk about a huge genetic component! Our DNA is truly a reflection of our ancestry and their environment.

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  • About 70 % of lactose-tolerant individuals are of Western European descent.

This means that Western Europeans tend to have a higher tolerance to milk. The consumption of milk will not cause these folks gas, bloating, and diarrhea.

  • Over 30 % of African and East Asian descendants are lactose intolerant.

This has nothing to do with a defective gene; more so, it is due to lack of exposure to milk beyond infancy. Over time, the body stops producing lactase because you are no longer exposed to breast milk. With that said, it is normal for the lactase enzymes to decrease over time.

So, for all of my lactose intolerant peeps, you are normal! A decrease in lactase production over time is how our DNA was originally programmed.

Over 75 % of the world’s population has some varying degree of lactose intolerance because, technically, we are not equipped to breastfeed until we are 80 years old. We continued to drink mammal’s milk over centuries simply for cultural reasons.

Now, I’m sure your stomach is gurgling due to hunger and not that tall glass of milk you just chugged.

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  • Wow.. What an amazing article now i came to know everything about lactose , the milk sugar… thank you very much Miss Stacy Mobley.

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