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Can Protein Powder Cause Stomach Issues?

Michael Garrico
Published by Michael Garrico | Co-Founder & Marketing Director
Fact checked by Donald Christman, BHSc FACT CHECKED
Last updated: April 12, 2023
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Most athletes think that stomach upset from a protein shake is a normal occurrence, but it usually happens due to artificial additives and food intolerances.

Throughout my years as a fitness expert, I've recommended protein powders to many of my clients.

With additional precautions for consumption and protein selection, we avoided causing discomfort even to those with food intolerance.

In this article, you will learn why certain protein powders cause an upset stomach and how to avoid it while reaping its full benefits.

Let's begin.

Quick Summary

  • Protein powder might contain some unnecessary fillers like artificial sweeteners, sugar alcohols, and thickeners, which might cause stomach upset.
  • Some artificial sweeteners that cause stomach bloating, indigestion, and ache include maltitol, xylitol, and sorbitol.
  • Side effects from protein powder are caused by consuming it quickly, exceeding the recommended dose, and drinking it immediately after a workout.

What Is In Common Protein Powders That Causes Stomach Cramps?

stack of protein powder with a scoper

Standard protein powders may contain unnecessary fillers such as thickeners, sugar alcohols, and artificial sweeteners.

The body doesn't always digest these additives, resulting in persistent stomach ache, indigestion, and bloating.

Common artificial sweeteners include:

  • Sorbitol
  • Xylitol
  • Maltitol

Furthermore, proteins are derived from various sources, which may be the reason for digestive distress. Here are the sources of some well-known protein powders:

Whey Protein Isolate

Quality and affordable whey protein, which comes from cow's milk, is the most common type of protein found in dietary supplements.

Milk contains the highest lactose content of all dairy products [1]; people who have lactose intolerance or milk allergy due to enzyme lactase deficiency are likely to experience an upset stomach when consuming dairy-based whey protein shakes.

Research suggests that 68 percent of the human population has a reduced ability to digest lactose [2], and Southeast Asians hold a startling 90 percent rate of having lactase deficiency.

When lactose is not fully digested, it travels to the intestines to be fermented. The process of fermentation may result in a stomach ache.

Fortunately, whey protein powders can be made from either whey isolate or whey concentrate. Most people prefer whey isolate because it contains less lactose than whey concentrate, containing 3.5 times more lactose.

Hydrolyzed Collagen Protein

glass of water getting filled with white powder

The collagen in dietary supplements is derived from animal tissues such as skin, hides, cattle and pig bones, and fish scales.

Though collagen is beneficial to your gut health, you may experience diarrhea, bloating, and fullness as your body attempts to break down its high levels of the amino acids glycine, glutamine, and proline.

Fortunately, most collagen supplements are hydrolyzed, which means that the amino acid chains have been subdivided into smaller units, making them more convenient for the body to digest and absorb [3].

Plant-Based Protein

Protein-rich powders made from soy, pea, rice, and hemp naturally contain soluble and insoluble fibers.

However, soluble fibers such as xanthan gum, cellulose gum, and guar gum used as fillers can cause an upset stomach because the bacteria ferment them in the colon [4].

Inulin, another soluble fiber found in plants, can dissolve quickly in your gut. However, it forms a gelatinous substance that slows digestion and causes an upset stomach [5].

Furthermore, insoluble fibers like plant cellulose may cause diarrhea due to their laxative effects, especially when you have a sensitive stomach.

Are There Other Side Effects To Taking Protein Supplements?

man holding his stomach in pain and a woman holding her head in pain

For most people, taking protein supplements can cause other digestive issues and discomfort. However, these side effects may vary from one person to another.

Whey protein may lead to stomach cramps, bloating, and excessive gas if you have food allergies and lactose intolerance.

As a result, some people may continue to feel unexplained exhaustion, irritability, headaches, and nausea.

A small percentage of people allergic to whey have also reported having a stuffy nose, congestion, and mucus build-up due to inflammatory immune response [8].

It is critical to seek medical supervision to address your symptoms because taking proteins for an extended period may also increase the risk of developing kidney problems.

"Overconsumption of protein can damage your kidneys over time since they have to work extra hard to metabolize the protein."

- Nikola Djordjevic, Doctor of Medicine, Surgeon, Medical Writer

Also, improper protein shake consumption for weight loss may increase the risk of nutritional deficiencies and caloric deficits.

Related: Does Pre-Workout Cause Bloating?

What Causes These Side Effects?

spilled milk and a woman in disgust

The improper use of high-quality, digestible proteins could be the source of digestive problems.

Here are some instances of missteps you might be making:

You Consume It Too Quickly

Shakes are a convenient way to satisfy post-workout hunger and thirst after a long, strenuous workout.

On the other hand, protein shakes are high in amino acids and may tax your stomach's ability to digest and absorb nutrients if consumed too quickly.

If you put your digestive system under such strain, it may result in bloating and stomach pain.

You Drink It Too Soon After Finishing Your Workout

Allowing your body to cool down for a few minutes before consuming your post-training shake will help absorb the nutrient.

Your digestive system slows down during strenuous exercise because your body's energy is focused on your brain and the muscles you're working out.

Although experts recommend consuming your protein shake during your anabolic window, which is 30 to 45 minutes after your workout, that doesn't mean you should start drinking the shake as soon as your last rep is completed.

Increasing the serving size of your proteins may not always be beneficial.

If you have a challenging workout, you may think of adding more scoops of protein-rich powders to your post-workout shake.

However, protein is a problematic macronutrient to break down and digest, and consuming too much of it may cause an upset stomach.

Benefits Of Taking Protein Shake

woman in gym clothes holding up a container and her thumbs up

Experts recommend that you drink a protein shake after your workout to replenish your protein stores.

Proteins comprise amino acids, which are the building block of your muscles and organs [6]. It gives your body plenty of nutrients to build from while living an active lifestyle.

They are essential in building muscle because your body needs enough proteins to maintain, repair, and grow muscle tissues [7].

Having enough proteins after the workout helps you recover from microtrauma or small-scale damage to the muscle fibers during exercise.

Taking proteins regularly also helps you lose weight by reducing your hunger hormone levels and curbing your appetite. Eating whole food with the right amount of proteins may help you eat less while feeling more satisfied.

How To Choose The Best Protein Powder Supplement

hand view of a person pouring powder into a cup

You should not experience protein powder side effects if you have the right protein shake and drink it correctly. Rather than bloating after a workout, you should be able to recover from muscle soreness and feel better quickly.

When choosing a post-workout protein supplement, keep the following factors in mind:


In terms of digestibility, you want a protein supplement that is easy to digest and high in digestive enzymes.

Digestive enzymes aid the body's ability to digest the food it consumes by breaking down complex nutrients for effective absorption by your body.


In terms of bioavailability, you should select a highly absorbable protein supplement.

You can choose a supplement in hydrolyzed form or one that contains high-quality digestive enzymes.

Some people lack enzymes, so supplementing with hydrolyzed protein forms and loads of digestive enzymes can help your body absorb proteins more effectively, increasing your bioavailability.

Protein Type

scoopers with different protein powders

Your diet and lifestyle influence the type of protein you consume.

Endurance athletes should consider a hydrolyzed collagen supplement because the body uses collagen to rebuild connective tissues [9]. Also, consuming the hydrolyzed form helps the digestive system absorb them faster.

Whey protein powder means faster muscle recovery if you can handle dairy. However, if you have lactose intolerance, you may avoid digestive issues by switching to a non-dairy alternative.

A plant-based protein powder like hemp protein may be the answer if you're looking for a gut-friendly option. It is easy to digest, dairy-free, allergen-free, and gluten-free, and highly absorbable.

Added Ingredients

It is always important to read all of the ingredients in your protein supplement to avoid sugar alcohols, sweeteners like xylitol, and unnecessary fillers.

Furthermore, a good protein shake should include all of the essential amino acids.

What Is The Best Protein Powder To Avoid Stomach Upset?

The best protein powder to avoid stomach upset is easily digestible, highly absorbable, allergen-free, with few additives.

It may take some time to test a few protein brands of whey isolate, hydrolyzed collagen, and plant proteins to find the right supplement that works well with your particular digestive system.

Some people experience abdominal discomfort, such as a stomach ache resulting from overeating protein and drinking too soon after working out.

Start drinking your protein shakes slowly during the anabolic window and become aware of your food intolerances to avoid these side effects.

To prevent nutritional and calorie deficits, you can combine your chosen brand of protein with a balanced diet abundant in whole foods such as fruits and vegetables.


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