Understanding Why and How: Can Premier protein shakes cause diarrhea?

October 16, 2025 •

5 min read

According to the National Institutes of Health, an estimated 65% of the world's population has a reduced ability to digest lactose, the milk sugar found in many protein products. This common intolerance is one of several potential reasons why someone might ask, "can Premier protein shakes cause diarrhea?".

Quick Summary

Several factors in Premier Protein shakes, including dairy content, artificial sweeteners, and additives, can trigger digestive upset. The shakes' high protein load, rapid consumption, and the timing of intake can also play a role in causing loose stools or digestive discomfort.

Key Points

Lactose Sensitivity: As a dairy-based product, Premier Protein contains lactose, which can cause diarrhea in individuals with lactose intolerance.
Artificial Sweeteners and Additives: The sweeteners (sucralose, acesulfame K) and thickeners (inulin) in Premier Protein can have a laxative effect or cause gut fermentation in sensitive people.
Overwhelming Intake: Consuming a large amount of concentrated protein at once can overwhelm the digestive system, leading to loose stools.
Timing of Consumption: Drinking a shake immediately after intense exercise can trigger digestive distress, as the gut's normal function is slowed.
Solutions: To reduce symptoms, try a smaller serving, sip slowly, wait after a workout, or switch to a lactose-free, plant-based, or hydrolyzed protein alternative.
Hydration and Fiber: Proper hydration and a balanced diet with sufficient fiber are crucial for mitigating digestive issues related to high protein intake.

For many, protein shakes are a convenient and effective way to meet nutritional goals, support muscle growth, and aid recovery. Premier Protein shakes, in particular, are a popular choice due to their high protein content and taste. However, for some individuals, these shakes can lead to unpleasant gastrointestinal side effects, most notably diarrhea. This digestive discomfort is often not from the protein itself but from other ingredients or the way the supplement is consumed.

Exploring the Ingredients and Their Impact

To understand why a Premier Protein shake might cause diarrhea, it's essential to look beyond just the protein. The composition of these shakes includes several components that can affect a sensitive digestive system.

Milk Protein and Lactose

Premier Protein shakes are made with milk protein concentrate and calcium caseinate. Both are derived from milk and contain lactose, a natural sugar. Many people have a deficiency of the enzyme lactase, which is needed to break down lactose. If you are lactose intolerant, undigested lactose travels to the large intestine, where gut bacteria ferment it. This process produces gas, bloating, and draws excess water into the colon, causing watery stools and diarrhea. While the processing of milk protein concentrates can reduce the lactose content, it doesn't eliminate it completely, which can be enough to trigger symptoms in sensitive individuals.

Artificial Sweeteners and Sugar Alcohols

Premier Protein shakes are sweetened with sucralose and acesulfame potassium to provide a sweet taste without the sugar content. Artificial sweeteners and their relatives, sugar alcohols (though not present in Premier Protein to the same degree as some other products), can have a laxative effect, particularly when consumed in large quantities. They are not fully absorbed by the small intestine and can cause digestive issues as bacteria in the gut ferment them. Even without sugar alcohols, some individuals are simply sensitive to artificial sweeteners, which can disrupt normal gut function.

Added Fibers and Thickeners

To achieve their smooth texture, Premier Protein shakes include thickeners and stabilizers such as inulin, cellulose gel, and carrageenan. For some people, particularly those new to increased fiber intake, inulin can cause digestive distress, including gas, bloating, and diarrhea. While fiber is important, a sudden increase can overwhelm the system. The effects of these additives vary from person to person.

How to Mitigate Digestive Symptoms

If you find that Premier Protein shakes are causing you digestive issues, there are several strategies you can employ to lessen or eliminate the problem.

Adjust Your Consumption Method

Sip, Don't Chug: Gulping down a protein shake quickly can introduce air and overwhelm your digestive system, which works best when it's given time to process nutrients. Sipping slowly can make a significant difference.
Consider Timing: For those who experience exercise-induced gastrointestinal symptoms, waiting about 30 minutes after an intense workout before consuming a shake allows your digestive system to return to normal function.
Reduce Serving Size: If you are consuming a whole shake at once, try having a half-serving to see if a smaller dose is more tolerable for your body. Your body can only absorb a certain amount of protein at one time, usually 25-35 grams.

Explore Alternative Protein Sources

If adjusting your intake doesn't solve the problem, the issue may be the ingredients themselves. Trying an alternative protein source can be a good next step.

Non-Dairy Alternatives

Plant-Based Protein: Options made from pea, hemp, or brown rice protein are naturally lactose-free and may be easier on the digestive system for many people. Some, like hemp protein, also contain fiber, which can aid digestion.
Egg Protein: Protein powders made from egg whites are dairy-free and highly digestible for most individuals.

Dairy-Based, Lower-Lactose Options

Whey Protein Isolate: This is a more highly filtered form of whey protein than concentrate, with most of the fat and lactose removed. It may be a better option for those with mild lactose intolerance.
Hydrolyzed Protein: This type of protein is partially pre-digested, meaning the protein molecules are already broken down into smaller peptides. This can make them easier and faster for the body to absorb, reducing the potential for digestive distress.

Comparison of Common Protein Sources


Feature	Whey Concentrate (in Premier Protein)	Plant-Based (e.g., Pea, Hemp)	Whey Isolate	Hydrolyzed Protein
Lactose Content	Moderate to Low	None	Very Low	Very Low
Digestibility	Good, but can cause issues for the lactose-sensitive.	Highly digestible; may contain more fiber.	Highly digestible, especially low in lactose.	Very highly digestible (pre-digested).
Common Side Effects	Bloating, gas, diarrhea, especially for lactose-intolerant individuals.	Gas and bloating if not accustomed to higher fiber content.	Fewer digestive issues due to lower lactose.	Designed for minimal digestive upset.
Cost	Generally affordable.	Varies, can be more expensive.	More expensive than concentrate due to additional processing.	Can be the most expensive option.

The Role of Gut Microbiome and Overall Diet

Your overall diet and gut health play a significant role in how you tolerate concentrated protein sources. A diet lacking in fiber from fruits and vegetables can worsen digestive issues. Similarly, the balance of bacteria in your gut (the microbiome) influences how you process the various components of a protein shake. Ensuring adequate hydration is also crucial, as water helps move protein through your digestive tract and supports overall digestive function.

Conclusion

While a Premier Protein shake can be a convenient source of high-quality protein, it can, for some, be a source of digestive upset, including diarrhea. The most common culprits are the dairy-based protein (lactose intolerance), the inclusion of certain sweeteners and additives, or simply consuming too much too quickly. By understanding these factors, you can take control of your nutrition diet. Solutions range from adjusting your intake methods to exploring alternative protein sources like plant-based or whey isolate options. Listening to your body and making gradual changes is key to finding a protein supplement that works for you without the unwanted side effects. If problems persist, it is wise to consult a healthcare professional to rule out any underlying conditions. A simple switch in your shake could be all it takes to find digestive relief.

For more detailed information on whey protein and its side effects, consult this authoritative resource from the National Institutes of Health: Protein Intolerance - StatPearls - NCBI Bookshelf.

Frequently Asked Questions

Diarrhea from Premier Protein can be caused by lactose in the milk protein, a sensitivity to artificial sweeteners like sucralose, or a reaction to thickeners such as inulin. Consuming a large protein dose quickly can also overwhelm the digestive system.

No. The reaction to protein shakes is highly individual. It depends on factors like lactose tolerance, overall gut health, and personal sensitivity to the additives. Many people can consume them without any issues.

While Premier Protein contains milk protein, the amount of lactose is typically reduced during processing. However, if you are lactose intolerant and experience symptoms, you should consider a lactose-free or plant-based protein alternative.

Artificial sweeteners like sucralose are generally recognized as safe for consumption. However, in sensitive individuals, or in high doses, they can have a laxative effect and cause digestive issues like bloating and diarrhea.

Lactose intolerance is a digestive issue caused by a lactase enzyme deficiency, leading to symptoms like diarrhea. A milk allergy is an immune system response to milk proteins (like whey or casein), which can cause more severe symptoms, including hives or breathing difficulty.

For those with sensitive digestion, alternatives include plant-based proteins (pea, hemp, rice), whey protein isolate (which is very low in lactose), or hydrolyzed protein powder (pre-digested for easier absorption).

To prevent digestive issues, try sipping your shake slowly, having a smaller portion, or consuming it with a meal. Staying well-hydrated and ensuring a balanced diet with enough fiber can also help.