Molasses is a thick, dark, syrupy byproduct created during the refining process of sugarcane or sugar beets into crystallized sugar. The juice is boiled repeatedly, extracting sugar and leaving behind a progressively darker, more concentrated syrup. The final stage yields blackstrap molasses, which retains the least amount of sugar but the highest concentration of non-sugar compounds. For individuals seeking to understand its impact on digestion, the direct answer is that molasses, particularly when consumed in larger quantities, can cause diarrhea. This effect is a direct result of its unique nutritional makeup.
Key Nutritional Components That Influence Digestion
The potential for molasses to trigger a laxative response stems primarily from its high mineral content, most notably magnesium. Magnesium acts as an osmotic agent within the digestive tract, meaning it is poorly absorbed and draws water from surrounding bodily tissues into the intestines. This influx of fluid increases the volume of water in the colon, softening the stool and promoting peristalsis, the muscular contractions that move waste through the bowel. This mechanism is identical to how saline laxatives work.
Molasses also contains a significant amount of sugar, ranging from 10 to 15 grams per tablespoon. Unabsorbed sugars that reach the large intestine are fermented by gut bacteria, producing gas and additional fluid that contribute to a laxative effect and general digestive upset.
How Much Molasses Causes Digestive Distress
Whether molasses causes digestive distress is highly dependent on the amount consumed, as the effect is dose-dependent. When molasses is used in typical culinary amounts, such as a teaspoon in baking or as a flavoring agent, it is unlikely to cause any issues for most people. The small amount of magnesium in a single teaspoon is easily tolerated by the body.
However, many people consume molasses, especially the blackstrap variety, for its perceived health benefits, often taking it by the tablespoon as a daily supplement. A single tablespoon of blackstrap molasses can contain approximately 40 to 48 milligrams of magnesium. While this is a small fraction of the 350 milligrams daily tolerable upper intake level (UL) for supplemental magnesium, consuming several tablespoons throughout the day can significantly increase the total mineral load.
When an individual takes multiple tablespoons, the cumulative magnesium intake can quickly approach or exceed the threshold that triggers the osmotic effect. For example, consuming four to five tablespoons of blackstrap molasses could deliver close to 200 milligrams of magnesium. This amount, combined with dietary magnesium and the unabsorbed sugars, is sufficient to induce loose stools or diarrhea in many sensitive individuals.
Individual Sensitivity and Molasses Variety
The likelihood of experiencing diarrhea is also influenced by the specific type of molasses consumed and an individual’s personal digestive sensitivity. Molasses is classified based on the number of times the cane syrup has been boiled; blackstrap molasses is the most concentrated residue. Blackstrap has the highest concentration of minerals, including magnesium and sulfur compounds, making it the most potent variety in terms of laxative potential.
Some commercial varieties are processed with sulfur dioxide as a preservative, resulting in “sulfured molasses.” Individuals sensitive to sulfites may experience digestive symptoms, including diarrhea, independent of the magnesium content.
Furthermore, people with pre-existing gastrointestinal conditions, such as Irritable Bowel Syndrome (IBS) or sensitivity to high FODMAP foods, may react poorly even to smaller doses. The high sugar and mineral content can exacerbate underlying sensitivities, causing discomfort, bloating, and loose stools. For those who suspect sensitivity, choosing unsulfured molasses and starting with a very small amount is the most prudent approach.