Can casein protein powder cause diarrhea?

Casein protein powder can cause diarrhea in some individuals, especially those who are sensitive to dairy products or lactose-intolerant. Casein, a major protein found in milk, digests slowly, which can sometimes lead to gastrointestinal issues, including diarrhea, in susceptible individuals¹.

There are several reasons why casein protein powder might lead to diarrhea:

• Lactose Content: Some casein protein powders contain lactose, which can cause diarrhea in lactose-intolerant individuals. The inability to properly digest lactose leads to its fermentation in the colon, resulting in gas, bloating, and diarrhea².
• Dairy Sensitivities: Aside from lactose intolerance, some people have a sensitivity to dairy proteins like casein, which can trigger an inflammatory response in the gut, leading to diarrhea³.
• High Protein Intake: Consuming high amounts of protein, particularly in supplement form, can sometimes overwhelm the digestive system, particularly if dietary fiber intake is not sufficient to help manage digestion⁴.

To mitigate the risk of diarrhea when using casein protein powder, consider the following tips:

• Choose casein protein powders that are low in lactose or lactose-free, especially if you are lactose intolerant.
• Increase your intake of dietary fiber to help support digestive health and prevent constipation, which can sometimes accompany the use of protein supplements.
• Introduce casein protein slowly into your diet to allow your digestive system to adjust.
• Stay hydrated by drinking adequate amounts of water, as dehydration can contribute to digestive problems.

If diarrhea persists despite taking these measures, it may be advisable to consult with a healthcare provider to rule out other underlying causes or to consider an alternative protein supplement⁵.