Proteins are broken down intoamino acids.
Digestion begins in the mouth as you chew food into smaller pieces.
From there, digestive enzymes in your saliva start to break down carbohydrates and fats.
Protein digestion begins in the stomach, where pepsin is secreted to break down protein into smaller peptides.
“The stomach produces hydrochloric acid (HCl) and pepsinogen, an inactive form of the enzyme pepsin.
Protein powderis generally digested in the same way asdietary protein.
However, the absorption rate may differ depending on thetype of protein powderand what it’s mixed with.
For example,whey proteinis absorbed faster thancasein protein.
“Fiber has so many roles in the gut,” says Sauve.
“It improves gut motility (helps keep things moving in the gut) and feeds beneficial bacteria.”
Consuming ahigh-protein dietmay crowd out other macronutrients, like carbohydrates, which provide beneficialfiber, vitamins, and minerals.
What to do
It contains more fiber than you’re used to.
For people with chronic constipation or bowel diseases, anincreased fiber intake can worsen constipation2and its associated symptoms.
You’re lactose intolerant.
Common signs of lactose intolerance include diarrhea, bloating, and gas.
It contains artificial sweeteners.
“These artificial sweeteners can have alaxative effect5if consumed in large amounts, potentially leading to loose stools.”
It’s disrupting your gut microbiome.
Protein canaffect the gut microbiome6in various ways, both positively and negatively.
“A healthy gut includes a greater diversity of microbes,” says Kulp.
These bacteria are associated with improved immune function, gut barrier function, and anti-inflammatory properties.
However, the long-term consequences of the decrease in these bacteria for gut health are unknown.
More research is needed to determine how altering gut microbiota diversityaffects gut health and overall health outcomes10.
The source of the protein can also influence the gut microbiome.
Plant-based proteins likely havemore effect on microbiota11than animal proteins because of their fiber content.
Some protein powders, such as whey protein isolate,contain lactoferrin and immunoglobulins that can act as prebiotics12.
You have low stomach acid.
Pepsin is the main enzyme involved in protein digestion13, requiring an acidic environment to be activated.
Not having enough stomach acid to break down protein can lead todigestive issues like gas or bacterial overgrowth.
According to Sauve, low stomach acid is quite common and can be triggered by stress or nutrient deficiencies.
Inanother study15, the protein digestion of eight protein sources was compared.
Whey protein isolate andpigeon peashad the highest amino acid release.
Fiber helps youstay fuller longerand your body will still get the amino acids you need.”
There are so many different types of protein powder available on the market.
If the one you’re using hurts your stomach, try another brand or protein source.
“Be sure to check for sugar alcohols and other additives, which could be triggering digestive issues.”
Add fiber to your protein shake.
Eat a balanced diet.
Athletes and fitness enthusiasts might inadvertently follow dietary strategies thatadversely impact the gut microbiota17.
Drink enough water.
When you consume a lot of protein, excess nitrogen is flushed with fluids and water.
Adequate hydration also helps fiber do its job properly.
Fiber absorbs water as it passes through your digestive tract to soften your stools and prevent constipation.
It’s always best practice to follow the serving instructions and directions of the supplements you are using.
The proper ratio of liquid to powder could help you avoid gastrointestinal distress.
On that note, don’t dry-scoop your supplements.
(Dry-scooping is a popular TikTok trendwhere people consume powder supplements like pre-workout or protein powder without liquid.)
FAQ
Does protein affect bowel movements?
Consuming protein in moderation as part of a balanced diet is generally beneficial for gut health.
Why does protein make me poop more?
Artificial sweeteners and sugar alcohols added to protein powder can irritate the gut and make you poop more.
What are the signs of too much protein?
Healthy adults can tolerate eating2g/kg protein per day and up to 3.5 g/kg for a prolonged period.
The takeaway
Protein in and of itself shouldn’t cause digestive problems for most people.
