Can Protein Powder Cause Constipation? Plus 5 Informative Tips

If you’re into fitness or nutrition, chances are you’ve had a protein shake before. For those who drink protein shakes on the regular, buying protein powder can be a norm. 

But there are concerns that raise the question, “can protein powder cause constipation?” 

Constipation is a common gastrointestinal issue the can be uncomfortable and disruptive to daily life. 

As a certified personal trainer, I’ve done my due diligence to research this topic and present you with facts straight to the point. Let’s look at the impact of protein powder on digestion and 5 tips to mitigate the risks. 

Here’s what’s coming up. 

Can Protein Powder Cause Constipation?
Constipation & Its Causes 
Milk Protein Allergy Vs. Lactose Intolerance
4 Reasons Why Protein Powder Could Cause Constipation
More On Diet & Lifestyle 
5 Tips To Avoid Protein Powder Constipation
Bottom Line 

Can Protein Powder Cause Constipation? 

Can protein powder cause constipation?

Yes it can, but mostly in those with a milk protein allergy, and in very small cases of lactose intolerance. 

There could also be other factors that are causing constipation, and not the protein powder.

An important note: It’s not the protein powder itself that causes constipation. 

Rather, it’s the allergy to milk derived ingredients and/or other ingredients in protein powder that may cause constipation.

We’ll get into that later in this article, especially the fact that milk protein allergy is different than lactose intolerance. 

There’s no solid evidence yet that protein powder directly causes constipation. 

This 2021 study showed that there was low odds of constipation for women who consumed dairy, and no associations between dairy consumption and constipation in men. 

Constipation & Its Causes 

can protein powder cause constipation

Constipation is a common gastrointestinal condition. The NIDDK {National Institute of Diabetes and Digestive and Kidney Diseases) defines it as consisting of:

  • Less than 3 bowel movements per week
  • Hard, dry, or lumpy stool 
  • Poop that is uncomfortable or even painful to pass 
  • A feeling that there’s still more stool left after you’ve released

Now that you know the basics of what constipation is, let’s try to answer the question, can protein powder cause constipation? 

It’s a tricky question to answer because you may assume that protein powder is the determining factor of constipation.

But the facts are that there can be a multitude of reasons why you may have constipation. 

Protein powder may worsen the condition, but let’s look at factors that can be the cause of being backed up. 

  • It could be that your poop just moves slowly though the colon.
  • You could have a gastrointestinal disorder or other medical condition. 
  • Certain medications can cause constipation.
  • Constipation could a mental health symptom. 
  • Aging can cause the pooping process to slow down. 
  • Being a woman can be a factor (women have slower colon movements than men).
  • Diet related issues like eating little fiber, having low fluid intake, or a high protein low-carb diet.
  • Lifestyle related issues like being sedentary or having obesity. 

Occasional constipation is usually not a cause for concern and can often be relieved with simple lifestyle changes.

But chronic constipation may require medical evaluation and management to address underlying issues and alleviate symptoms. 

Milk Protein Allergy
Vs. Lactose Intolerance 

Can protein powder cause constipation on its own? It can if you have milk protein allergies and are sensitive to whey protein. 

To be clear, milk allergy is different form lactose intolerance. Milk protein allergy means that the body’s immune system recognizes milk proteins as harmful and creates antibodies to fight them. 

Consuming milk proteins could then trigger an immune response which can lead to the digestive issue of constipation. 

Lactose intolerance, on the other hand, means that your body doesn’t have the right enzyme (lactase) to break down the lactose protein in milk.

The bacteria in the gut eat the lactose, causing possible symptoms of bloating, gas, and diarrhea. 

Whey protein does have both milk proteins and lactose. It’s is a product of the cheese making process. Milk is processed and separates into solid curds and liquid whey. 

For a more detailed look into whey protein, check out my article, “Is Whey Protein Really Bad For You?”

4 Reasons Why Protein Powder
Could Cause Constipation

Protein powder is widely used for muscle building and weight management, but it’s important to note that certain factors may contribute to constipation in some individuals.

Here’s 4 possible reasons why protein powder could potentially cause constipation. 

The Milk Protein A1 Beta-Casein 

This milk protein A1 beta-casein is not necessarily in whey protein but rather in varieties of milk. It could be in the milk used for whey protein. But this is a big maybe.

This protein could potentially lead to constipation because it has an inflammatory effect on the intestines.

The inflammation causes the stool forming in the intestines to slow down while moving into your colon for release. 

Lactose Intolerance 

I mentioned before that lactose intolerance causes symptoms like bloating, gas, and diarrhea. 

So can it actually cause constipation? 

Well, this review states that 30% of lactose intolerance cases can result in constipation. To answer the question, can protein powder cause constipation, it can in small cases of lactose intolerance. 

Low Fiber Content 

Many protein powders, especially those derived from animal sources like whey or casein, often lack significant fiber content. 

Fiber plays a crucial role in promoting regular bowel movements by adding bulk to stool and aiding in its passage through the digestive system. Insufficient fiber intake can lead to constipation.

Artificial Sweeteners
& Additives  

Some protein powders contain artificial sweeteners, preservatives, or additives that may have a laxative effect on some individuals. But other individuals might experience the opposite effect, leading to constipation. 

Additionally, certain additives may disrupt gut bacteria, affecting digestive regularity. Remember that protein powder affects different people in different ways. 

Each person’s digestive system is unique, and what causes constipation in one individual may not affect another. Later on we’ll talk about tips to avoid protein powder and constipation. 

More On Diet & Lifestyle

Diet and lifestyle are cornerstones when it comes to health. Aim for a diet rich in fiber, stay hydrated, do regular physical activity, and watch your protein intake to help prevent constipation. 

Here’s factors that can cause constipation. 

Low-Carb Diets

  • High-protein, low-carbohydrate diets, like ketogenic or Atkins diets, can be deficient in fiber rich foods like fruits, vegetables, and whole grains. 
  • While protein is crucial for muscle growth and repair, insufficient fiber intake can lead to constipation.
  • Some individuals may experience digestive discomfort when consuming high amounts of protein, which can slow down the digestive process and contribute to constipation.

Insufficient Fiber Intake

  • Fiber adds bulk to poop so its not runny, absorbs water in the gut, and promotes regular bowel movements.
  • Diets high in processed foods, meats, and dairy products, can lead to constipation. These diets may result in hard, dry stool that is difficult to pass.
  • Increase dietary fiber with fruits, vegetables, whole grains, legumes, nuts, and seeds.
  • These will help you to go regularly to the bathroom and feel better when it comes to gut health.

Insufficient Fluid Intake

  • Hydration is essential for softening stool and promoting bowel movements. 
  • Diets low in fluids, especially water, can increase constipation. Certain beverages like caffeinated or alcoholic drinks can have a diuretic effect, leading to increased fluid loss and dehydration.
  • Make sure to drink plenty of fluids throughout the day. The general recommendations are 13 cups for men and 9 cups for women. A cup is 8 ounces. 
  • Drink more water instead of soda, or opt for fruits and vegetables that have high water content. 

5 Tips To Avoid
Protein Powder Constipation 

Tip 1: Stay Regular
With Fluids & Fiber

  • Be sure to drink plenty of water throughout the day, as it helps soften the poop and keep it flowing easily. 
  • Fiber will also make it much easier to go and promote healthier digestion.
  • There are products like fiber bars or supplements in case you’re not a fan of fruits or vegetables.  

Tip 2: Move Often!

  • Regular physical activity is major for better bowel function and preventing constipation. 
  • Aim for at least 30 minutes of moderate-intensity exercise most days of the week.
  • Do activities that get your leg muscles and abdominal muscles involved. Even simple activities like walking or stretching can contribute to bowel regularity. 

Tip 3: Try Whey Protein Isolate

  • This form of whey protein undergoes additional processing to remove most of the lactose, making it better for individuals with lactose intolerance or sensitivity.
  • This is better for individuals with lactose intolerance or sensitivity.

Tip 4: Try A Different Protein Powder Product

  • If you experience constipation after using a particular protein powder product, try switching to a different brand or type. 
  • Look for protein powders that contain sugar alcohols like sorbitol and mannitol. These have a laxative effect that will make you go, so it could be beneficial to prevent constipation. 

Tip 5: Switch To
Plant-Based Proteins

  • Plant based protein powders, like pea protein, soy protein, rice protein, or hemp protein, are excellent alternatives to dairy based options like whey or casein. 
  • These plant-based proteins are often gentler on the digestive system and may be better tolerated by individuals prone to constipation. 
  • Pea protein is the easiest on digestion. Be aware that the plant-based proteins could also cause constipation in case you are sensitive!
  • Experiment, research, and try out what works best for you. 

Bottom Line

While protein powder can be a convenient and effective way to support muscle growth, it’s essential to be mindful of its potential impact on digestive health. 

So can protein powder cause constipation? It can if you have a milk allergy, or in 30% of cases of lactose intolerance. 

There are also other factors that may contribute to constipation, so preventative measures like more fiber, fluid, and exercises can be a big help to stay regular. 

As with any dietary supplement, it’s always wise to consult with a healthcare professional or registered dietitian to ensure that the protein powder is ok with your health conditions.

If you have other questions about protein powder, check out my comprehensive Protein Powder Guide.


Shalom is a content creator, musician, and a teacher at heart. As a certified personal trainer, his goal is to encourage others to lead healthier lives and to get buff in the process!

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