Why does whey protein hurt my stomach?

Why does whey protein hurt my stomach?


Whey protein is a popular supplement among athletes, fitness enthusiasts, and those looking to build muscle mass. It is derived from milk and is known for its high protein content. However, some individuals may experience stomach discomfort after consuming whey protein. In this article, we will explore the reasons why whey protein can hurt the stomach and discuss possible solutions.

Possible Causes of Stomach Discomfort

Lactose Intolerance: One of the primary reasons why whey protein may cause stomach discomfort is lactose intolerance. Whey protein contains lactose, a sugar found in milk. Individuals who are lactose intolerant lack the enzyme lactase, which is responsible for breaking down lactose. As a result, consuming whey protein can lead to bloating, gas, and diarrhea in these individuals.

Allergies or Sensitivities: Another possible cause of stomach discomfort after consuming whey protein is an allergy or sensitivity to dairy products. Some individuals may be allergic to the proteins present in whey, such as beta-lactoglobulin or alpha-lactalbumin. These allergies can cause symptoms like stomach pain, nausea, and vomiting.

High Protein Intake: Whey protein is a concentrated source of protein, and consuming large amounts of protein in a short period can put a strain on the digestive system. This can lead to stomach discomfort, bloating, and even diarrhea. It is essential to consume whey protein in moderation and ensure an adequate intake of water to aid digestion.

Low-Quality Protein Supplements: Not all protein supplements are created equal. Some low-quality whey protein supplements may contain impurities, additives, or excessive amounts of lactose. These substances can irritate the stomach and cause digestive issues. It is crucial to choose high-quality whey protein supplements from reputable brands.

Tips to Reduce Stomach Discomfort

Choose a Lactose-Free Option: If you are lactose intolerant, consider opting for a lactose-free whey protein powder. These products have the lactose removed or broken down, making them easier to digest for individuals with lactose intolerance.

Try a Different Protein Source: If whey protein consistently causes stomach discomfort, you may want to explore alternative protein sources such as plant-based proteins (e.g., pea protein, soy protein) or other animal-based proteins (e.g., egg protein, beef protein). These options may be better tolerated by individuals with sensitive stomachs.

Gradually Increase Protein Intake: If you are new to consuming whey protein or have experienced stomach discomfort in the past, it is advisable to start with a smaller serving size and gradually increase it over time. This allows your body to adjust to the increased protein intake and may help reduce stomach discomfort.

Stay Hydrated: Adequate hydration is crucial when consuming protein supplements. Drinking enough water can help facilitate digestion and prevent stomach discomfort. Aim to drink water before, during, and after consuming whey protein.


While whey protein is an excellent source of protein for many individuals, it can cause stomach discomfort in some cases. Lactose intolerance, allergies or sensitivities, high protein intake, and low-quality supplements are some of the possible reasons why whey protein may hurt the stomach. By choosing lactose-free options, exploring alternative protein sources, gradually increasing protein intake, and staying hydrated, individuals can reduce the risk of stomach discomfort when consuming whey protein.


1. Mayo Clinic: mayoclinic.org
2. National Institute of Diabetes and Digestive and Kidney Diseases: niddk.nih.gov
3. Healthline: healthline.com
4. WebMD: webmd.com