Can Protein Powder Cause Constipation?

By Matt Smith

Published: April 8, 2025

Constipation is not fun for anyone, but can protein powder cause constipation? This article will take an in-depth look at whether protein can be the cause, and how to prevent constipation while consuming protein shakes.

Can Protein Powder Cause Constipation?

Protein powder may be a cause of constipation, but there are many other possible causes that are just as likely.

If you are constantly suffering from constipation and you can directly link this to drinking whey protein shakes, then there are several things that you can do to prevent this happening in the future.

Protein powder constipation is a common complaint among gym goers. This can be caused by lactose intolerance, an issue with artificial sweeteners and sugar alcohols, or it can be caused by high protein diets that are low in fibre.

What is Constipation?

Constipation is a common condition where your regular bowel movements are disrupted and become irregular. Constipation affects everyone at some point, but there are a small minority of people who suffer from it long-term.

There are a number of causes of constipation, some of them are related to diet, some to mental health, and sometimes it can be caused by illness.

Common Causes of Constipation

There are many causes of constipation, too many to list in this article. But here is a quick rundown of five common causes of constipation.

A Change in Routine

Travelling is a very common cause of constipation, as is any activity that disrupts your regular routine. Having people coming to stay at your house, for example, can lead to your normal bathroom schedule being changed.

Your body doesn’t like this very much, and it can affect the digestion process. Travel and socialising can also affect your diet and the foods that you eat. Particularly around the holiday season.

You may end up consuming very little fiber, and not eat enough dark leafy greens, fresh fruit, and foods such as kidney beans.

A change in routine can also cause constipation by affecting your regular exercise routine. Exercise plays a crucial role in helping you have a healthy bowel movement.

If you normally exercise 3-5 times per week and suddenly stop exercising then it can affect your digestion and cause constipation.

A Lack of Fiber

Fiber plays a crucial role in digestion, helping the bacteria in your gut to flourish. A healthy balanced diet should be high in fiber, but this is rarely the case.

Though there is some evidence that fiber intake is increasing slightly [1], the majority of people are not getting enough fiber each day.

A low-fiber diet can lead to many issues with digestion and can cause constipation. It is probably the biggest cause of constipation.

Mental Health

Interestingly, your mental health can have a huge impact on your digestive system. Depression and anxiety have both been shown to cause constipation in certain people [2].

The theory goes that a lack of serotonin (people with depression produce less) affects serotonin storage in the gut, that causes the gut lining to become damaged and this causes the slow movement of stools [3].

How anxiety and stress affects constipation is not completely understood, but there is a belief that the gut-brain axis is disrupted, causing slower stool movement [4].

Dehydration

Another common cause of constipation is dehydration. When you are dehydrated, your body attempts to extract as much water as it can from the food you are digesting. Too much moisture loss from your stool can lead to constipation [5].

Lactose Intolerance

If you are lactose intolerant, then your body is not able to handle the lactose found in whey protein powders, milk, yoghurt, and other dairy products.

This is because they lack a specific enzyme required to break it down. The enzyme is called lactase.

Consuming these foods can lead to many digestive issues, which we have covered in our article on whether protein powders can cause nausea.

For someone who is lactose intolerant, eating foods that contain lactose can lead to an increase in methane gas, which slows down digestion and can cause constipation.

A 2022 study found that lactose intolerance caused constipation in 30% of children who struggle to digest lactose [6]. Constipation is just one of many digestive issues that sufferers experience.

Many Other Causes

As you can see, there are a vast number of causes, many of them are not linked to protein powder in any way. But, that does not mean that your protein powder is not responsible. In the rest of the article, we will be looking at how protein powders can cause constipation.

Can A High-Protein Diet Cause Constipation?

A properly implemented protein-rich diet should not cause constipation. Provided that your diet is balanced with fats, carbohydrates, and fiber you should not see any problems.

The issues occur when diets choose to limit your carbohydrate intake. If you are not eating whole food sources of carbohydrates then you will have less fiber in your day.

Diets such as Atkins or the South Beach diet, tended to contain a lot of protein, but were very low in fiber and carbohydrates. Some diets recommend you take extra fiber from supplements, but this is not as good as getting it from several grains and cereals.

The bottom line is that a higher protein diet should not cause constipation unless the diet is also low in carbohydrates and fiber. Most higher protein diets do not cause constipation.

People claim that too much protein can be bad for you, but unless you have a kidney disease then you should be fine. It’s not too much protein that is the issue, it is a lack of other macronutrients.

Can Whey Protein Powder Cause Constipation?

The most common protein powder is whey protein powder. This is because whey protein is very cheap to produce, has a higher ratio of protein to calories, and for many people the protein in whey protein is easy to absorb. There is also whey protein isolate which is even better from a protein absorption point of view.

Whey protein powder is derived from milk solids, it is essentially milk powder with all of the fats and carbohydrates removed. Crucially, it still contains lactose, making it unsuitable for people who are lactose intolerant.

As we have already established, constipation affects around 30% of people who cannot process lactose. If you are lactose intolerant, then your whey protein shake could indeed be causing constipation.

Another condition that can be affected by whey protein is milk allergies. This is an allergy to milk protein, and it can cause a number of symptoms with constipation being one of them.

As milk protein is one of the most typical key ingredients in whey protein powders anyone with a milk allergy should avoid them.

If you can tolerate lactose and you don’t have a milk allergy, can whey protein still cause constipation? Yes, it is certainly possible. Many protein powders contain artificial sweeteners and sugar alcohols, both of which have been associated with digestive issues.

Sugar alcohols are interesting because they are best known for having the opposite effect, in fact they are sometimes used to relieve constipation.

But any food sources that disrupt digestion over a prolonged period of time can lead to constipation, even ones that initially cause diarrhea.

Artificial sweeteners can also affect the digestive enzymes and gut microbiome, leading to constipation and other digestive issues [7]. Whey protein shakes are not the only protein powders that contain artificial sweeteners though.

Can Vegan Protein Powders Cause Constipation?

Considering the many ways in which whey protein can cause constipation, it might be a good idea to look for a dairy free protein powder, or a vegan protein shake.

There are some protein shakes that are dairy free but not suitable for vegans. They can use egg albumin, or even meats such as chicken and beef. But they are very rare, and not really worth covering.

Instead, we will focus on vegan protein shakes such as:

Hemp Protein
Pea Protein
Soy Protein

Vegan protein shakes have become very popular thanks to massive improvements in how they are made and how they taste. A common complaint was that many did not have all of the amino acids that are required to build muscle mass.

But these days, the people who make dietary supplements will either use pea protein (a complete protein) or they will create their own protein blends.

Because they don’t use dairy, most protein powders from vegan companies will claim that they don’t cause constipation. However, if they use artificial sweeteners or sugar alcohols to sweeten the taste then you may still be at risk.

If they are used to massively increase your protein intake and you aren’t consuming enough fiber then you may also experience constipation. But this is not the fault of the protein powder itself.

How to Avoid Constipation With Protein Powders

Do protein shakes affect your digestion? Yes, but only if you pick poor products, have specific allergies, or aren’t using them correctly. So, here is a quick guide to avoiding constipation when drinking protein shakes.

Stay Hydrated
Avoid Protein Shakes that Contain Artificial Sweeteners
Increase Your Soluble Fiber Intake
Experiment With Other Protein Powders

Alternatives to Protein Powder

Of course, you don’t need protein powder to increase the amount of protein you consume. There are other options available.

High Protein Foods

Finding higher protein versions of the foods that you eat is a great way to increase your protein without resorting to protein powder.

Searching for recipes that have more protein in them is a great start, then you can swap out low-protein snacks with higher protein alternatives. For example, swap out a candy bar for a protein bar.

You can also increase the serving size for protein in meals that you already eat regularly. But make sure that your calorie intake is not too high or you may see some accidental weight gain.

Meal Replacement Shakes

An excellent alternative to protein shakes are meal replacement shakes. They are high in protein, but also contain lots of fiber and carbohydrates. For most people, swapping out one meal with a meal shake could see their daily fiber consumption rise rather than fall.

Why Rootana is the Perfect Alternative to Protein Powder

Rootana is perfect for replacing protein powder for several reasons. It is high in pea protein, high in fiber, contains healthy fats, and it avoids the use of artificial ingredients such as sweeteners.

Rootana is also free from low-quality carbohydrates such as maltodextrin, instead using highly effective oat powder. It is much better than a protein powder and will help you to improve your health, nutrition, and digestion.

Can Protein Powder Cause Constipation? Final Thoughts

Protein shakes can cause constipation if they are low in quality, or if you have a specific allergy. If your protein shakes are consumed as part of a diet that is low in fiber, you can also expect digestive issues down the line.

Finding protein shakes that are free from artificial ingredients, or protein shakes that avoid whey can help to prevent constipation. But a better option would be to use a meal replacement shake such as Rootana, which can improve your overall diet.

References

[1] https://www.nature.com/articles/s41430-021-00933-2

[2] https://pubmed.ncbi.nlm.nih.gov/36004635/

[3] https://www.gastrojournal.org/article/S0016-5085(19)36715-0/fulltext

[4] https://www.mindsethealth.com/matter/anxiety-and-constipation

[5] https://pubmed.ncbi.nlm.nih.gov/14681719/

[6] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9105309/

[7] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5093271/

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