From the Guidelines
Dairy products are unlikely to cause black stool, as black or tarry stool is typically a sign of bleeding in the upper digestive tract. The relationship between dietary factors and gastrointestinal symptoms is complex, and while some patients may believe that dairy products exacerbate their symptoms, there is no clear evidence to suggest that dairy consumption causes black stool 1. In fact, the British Society of Gastroenterology guidelines for the management of irritable bowel syndrome suggest that some patients with lactose intolerance may benefit from a low-lactose diet, but this is not related to the color of their stool 1. Some key points to consider include:
- Black or tarry stool (melena) is usually caused by bleeding in the upper digestive tract, such as from ulcers, gastritis, or certain medications
- Dairy products are not known to cause black stool, but some foods can darken stool, including blueberries, licorice, and foods with dark food coloring
- If you're experiencing black stool, it's essential to seek medical attention promptly as it could indicate internal bleeding
- Persistent black stool, especially if accompanied by abdominal pain, fatigue, or dizziness, could indicate a serious medical condition requiring treatment.
From the Research
Dairy Products and Black Stool
- There is no direct evidence in the provided studies that links dairy products to black stool.
- However, some studies suggest that dairy products can cause gastrointestinal issues, such as lactose intolerance 2, 3, 4, 5 and cow's milk enteropathy 6, 4, 5, which may lead to bleeding or other symptoms.
- Cow's milk enteropathy has been shown to cause rectal bleeding or occult intestinal bleeding in children 6, but it is not explicitly stated that the stool is black.
- Lactose intolerance and cow's milk allergy are two distinct conditions that are often confused with each other 5, and their symptoms may include gastrointestinal complaints, but black stool is not a commonly reported symptom.
- It is possible that an underlying condition, such as gastrointestinal bleeding, could cause black stool, but this would require further investigation and is not directly related to dairy products.