Blackberries have been traditionally used for centuries to alleviate the symptoms of acute diarrhea. Whether they are beneficial, however, depends entirely on how the fruit is consumed. The plant contains a complex mix of compounds that can both soothe an irritated digestive tract and, under different circumstances, act as a mild laxative. Understanding which components are at work determines whether blackberries will provide relief or potentially worsen symptoms.
The Dual Nature of Blackberries on Digestive Health
Historically, the leaves and roots of the blackberry bush have been used as a remedy for intestinal distress, particularly diarrhea. This traditional application is based on the plant’s astringent qualities, which help tighten and tone the digestive tract lining. This action reduces the secretion of fluids into the intestine, thereby firming the stool.
Conversely, consuming large quantities of the fresh, raw fruit may have the opposite effect, potentially exacerbating loose stools. This paradox is due to the concentration of different bioactive substances in the raw fruit versus the processed leaves or roots. For those dealing with acute diarrhea, consuming only dried berries or the juice is traditionally recommended.
Key Components Influencing Stool Consistency
The primary compounds responsible for the anti-diarrheal effect are tannins, a group of polyphenols concentrated in the leaves and roots. Tannins act as astringents by binding to proteins in the intestinal mucous membranes, creating a protective layer. This action helps reduce inflammation and decreases the excessive fluid secretion that contributes to watery stools. Laboratory research suggests these tannins also decrease the speed of intestinal movement, or motility, giving the stool more time to firm up.
Working against the tannins is the fruit’s high concentration of dietary fiber, which averages about 7.6 grams per cup of fresh berries. The insoluble fiber content adds bulk to the stool and can speed up intestinal transit time, which is undesirable during a bout of diarrhea. Furthermore, the fruit contains high levels of fermentable carbohydrates, known as FODMAPs, specifically fructose and the sugar alcohol sorbitol. These sugars are poorly absorbed by the small intestine, leading to fermentation in the colon that draws water into the bowels.
The fruit’s natural water content, approximately 88%, also plays a role in stool volume. This high liquid volume, when combined with the fiber and FODMAPs, contributes to the overall bulk that moves quickly through the digestive system. This combination of compounds creates the dual potential for both binding and laxative effects, depending on the preparation method.
Optimal Ways to Consume Blackberries During Diarrhea
To maximize the stool-firming effect, the preparation must focus on concentrating the tannins while minimizing the impact of raw fiber and fermentable sugars. The most effective method is consuming a tea made from the dried leaves of the blackberry plant. This process extracts the beneficial astringent tannins while leaving behind most of the problematic fiber. The German Commission E monograph suggests a daily intake of 4.5 grams of blackberry leaf, prepared by steeping approximately 1.5 grams of dried leaves in 250 ml of boiling water for ten to fifteen minutes.
If using the fruit itself, it should be consumed in moderation and processed to break down the tough insoluble fiber. Cooking or stewing the berries helps soften the fiber and may be a less irritating option than eating them raw. It is important to limit the quantity of fresh fruit, as consuming large amounts can lead to increased fluid in the colon due to the high FODMAP content.