Does Molasses Help With Constipation?

Blackstrap molasses has real evidence behind it as a constipation remedy, not just folklore. In the only randomized controlled trial to test it head-to-head against a standard pharmacy laxative, blackstrap molasses performed just as well, with no significant difference in outcomes between the two groups. The evidence base is still thin compared to conventional treatments, but what exists is genuinely encouraging, and understanding how and why molasses works can help you decide whether it belongs in your own approach to staying regular.

What the Clinical Trial Actually Found

The strongest piece of evidence comes from a double-blinded randomized trial that enrolled 92 children with functional constipation. Half received blackstrap molasses syrup and half received polyethylene glycol (PEG), the active ingredient in MiraLAX and other over-the-counter osmotic laxatives. Both were given at the same dose of 1 mL per kilogram of body weight per day for one month.¹

The results were striking in their equivalence. Bowel movements per week increased in both groups. Symptoms like painful or hard stools, withholding behavior, and large fecal masses in the rectum all decreased at both two weeks and four weeks. The only measurable difference was a slightly better reduction in large-diameter stools in one group. No side effects were observed in either arm of the study.¹

This is a single trial, and it was conducted in children rather than adults. Researchers have not yet replicated it in a larger population or across different age groups. Still, PEG is the gold-standard osmotic laxative in most clinical guidelines, so matching it in a controlled setting is a meaningful result. It suggests that molasses is doing something pharmacologically real, not just producing a placebo effect.

How Molasses Likely Relieves Constipation

The most probable mechanism is osmotic. When you consume a concentrated sugar solution, the unabsorbed sugars and minerals draw water into the intestinal lumen. The extra fluid softens stool and speeds transit through the colon. This is essentially the same principle behind PEG, lactulose, and magnesium citrate, all established osmotic laxatives.

Blackstrap molasses is exceptionally mineral-dense. Analysis of the molasses used in the clinical trial showed potassium at roughly 12,430 micrograms per milliliter, calcium at about 3,320 micrograms per milliliter, and iron at around 80 micrograms per milliliter, along with polyphenols at about 960 micrograms per milliliter.¹ That mineral load, especially the magnesium and potassium that molasses is known for, contributes to the osmotic pull. Magnesium in particular is a well-recognized natural laxative, which is why milk of magnesia works.

The polyphenol content may also play a supporting role. Polyphenols can influence gut motility and have been associated with changes in the gut microbiome in other contexts. But the osmotic effect is the primary driver here, and the mineral profile of blackstrap molasses makes it unusually well-suited for this purpose compared to plain sugar or lighter syrups.

Why Blackstrap Matters More Than Other Types

Not all molasses is created equal when it comes to constipation relief. Molasses is produced during the sugar refining process, and each successive boiling concentrates different compounds while removing more sucrose. Light molasses comes from the first boiling and is mostly sugar with relatively modest mineral content. Dark molasses comes from the second boiling and is somewhat richer. Blackstrap molasses, the product of the third and final boiling, has the lowest sugar content and the highest concentration of minerals, polyphenols, and other non-sugar compounds.

This distinction matters because the laxative effect depends largely on osmotically active substances that are not fully absorbed in the small intestine. Refined sugar gets absorbed quickly and efficiently, so it does very little for your bowels. The minerals and complex sugars in blackstrap molasses are what make it to the colon, where they can pull in water. If you grab a bottle of light or “mild” molasses off the shelf, you are essentially getting flavored sugar with a fraction of the active compounds. The clinical trial specifically used blackstrap molasses, and the results should not be assumed to extend to lighter varieties.¹

Sulfured vs. unsulfured is another label you will encounter. Sulfured molasses has sulfur dioxide added as a preservative during processing. Some people report that sulfured varieties cause more bloating and gas, which makes intuitive sense: sulfur compounds can be metabolized by gut bacteria into hydrogen sulfide, one of the gases responsible for that distinctive smell. If digestive comfort matters to you, unsulfured blackstrap is the safer bet.

Dosing and Practical Advice

The clinical trial used 1 mL of blackstrap molasses per kilogram of body weight per day, prepared as a 40% syrup. For a child weighing about 20 kilograms (roughly 44 pounds), that works out to 20 mL per day, or about 4 teaspoons.¹ In popular practice, the traditional adult dose that gets passed around is one to two tablespoons of straight blackstrap molasses, taken once daily or mixed into warm water, tea, or oatmeal. There is no rigorous adult dosing study to confirm this, but it is roughly consistent with scaling up the pediatric data.

Taste is an honest obstacle. Blackstrap molasses is intensely bittersweet with a strong, almost metallic bite. Mixing it into coffee or a smoothie helps. Stirring it into warm water with a squeeze of lemon is another common approach. Some people drizzle it over yogurt or baked sweet potatoes, which masks the intensity. Taking it on an empty stomach may produce faster results but can also cause more cramping, so starting with food is reasonable if you are new to it.

Give it a few days. The trial measured outcomes at two and four weeks, and improvements were already visible at the two-week mark. If you have been constipated for more than a week or two, a tablespoon of molasses is not going to produce overnight results. Consistency matters more than a single large dose, and overdoing it on day one is a reliable way to end up with diarrhea and cramps.

The Common Misconception About Fiber

A persistent myth online is that molasses relieves constipation because of its fiber content. This is wrong. Molasses contains essentially no dietary fiber. It is a concentrated liquid byproduct of sugar refining, and fiber, which comes from plant cell walls, does not survive that process. The laxative effect comes from its osmotic properties and mineral content, as described above, not from bulking up stool the way bran or psyllium would.

This misconception matters because it leads people to misunderstand what molasses is doing in their body. If you are already eating a high-fiber diet and still constipated, adding molasses is not redundant the way adding another fiber source might be. It works through a completely different mechanism. Conversely, if you need more fiber, molasses is not going to supply it.

Milk and Molasses Enemas

Separate from the oral remedy, there is a longstanding medical tradition of using milk and molasses as an enema. This is not a folk practice confined to home remedies; milk and molasses enemas have been used in hospital settings, including pediatric emergency departments, to treat fecal impaction.² The mixture works through the same osmotic principle: the sugars draw water into the rectum, softening impacted stool and stimulating the urge to evacuate.

At least one study compared milk and molasses enemas against sodium phosphate enemas (the standard option) in a pediatric emergency department setting to evaluate safety and efficacy.³ However, milk and molasses enemas are not without risk. Reports of cardiopulmonary complications in children have raised concerns about their use, particularly when large volumes are administered or when the child has underlying health conditions.² This is firmly in the category of procedures that should be supervised by a healthcare provider, not attempted at home with instructions from the internet.

Side Effects and When to Be Cautious

For most adults, a tablespoon or two of blackstrap molasses per day is unlikely to cause problems beyond some initial bloating or gas. The clinical trial in children reported no side effects at all over a full month.¹ But there are a few situations where caution is warranted.

Blood sugar: Blackstrap molasses is lower in sugar than light molasses, but it is still a concentrated sweetener. A tablespoon contains roughly 15 grams of carbohydrate. If you have diabetes or are monitoring blood sugar closely, account for it.
Iron overload: The iron content that makes blackstrap molasses appealing as a supplement can be a problem for people with hemochromatosis or other iron-storage disorders. Ironically, iron supplements themselves are notorious for causing constipation, but the form and dose of iron in molasses, combined with its other osmotic components, seems to avoid that effect in practice.
Potassium levels: The high potassium content could be relevant if you have kidney disease or are taking potassium-sparing medications. A tablespoon of blackstrap molasses delivers a meaningful amount of potassium, and people with impaired kidney function do not clear excess potassium efficiently.
Diarrhea from overconsumption: Because the mechanism is osmotic, taking too much produces diarrhea. This is the same risk profile as taking too much MiraLAX or magnesium citrate. Start with a small amount and increase gradually.

For children, always consult a pediatrician before using molasses as a laxative. The trial used carefully controlled dosing and excluded children with organic causes of constipation. A child who is persistently constipated may have an underlying condition that needs evaluation, not just a home remedy.

Roots in Traditional Medicine

The use of molasses for constipation is not a recent internet trend. In Persian traditional medicine, several sugarcane-derived formulations, including preparations specifically identified as blackstrap molasses, have been used for centuries to treat constipation in children.⁴ The clinical trial was explicitly motivated by this ethnopharmacological tradition, aiming to test whether a remedy with a long history of folk use could hold up under modern scientific scrutiny.

Similar traditions exist in other cultures. In the American South, blackstrap molasses was a widely used home remedy for constipation well into the 20th century, often given to children and elderly family members. Caribbean and Latin American folk medicine traditions also reference molasses or cane syrup for digestive complaints. The fact that these traditions developed independently across different cultures suggests that people noticed a genuine physiological effect and passed the knowledge along, even without understanding the osmotic mechanism behind it.

What Animal Research Adds

While the human evidence is limited to a single trial plus the enema literature, animal studies provide some additional context for how molasses affects the gut. Research in cattle has shown that molasses-based supplements can increase the production of butyrate in the rumen. Butyrate is a short-chain fatty acid that serves as the primary fuel source for cells lining the colon and plays a role in maintaining the gut barrier. In one study of stressed feedlot cattle, a molasses-based supplement increased butyrate levels, improved gut barrier function, and reduced markers of inflammation compared to a dry supplement.⁵

You cannot directly translate cattle digestive physiology to humans. Ruminants have a fundamentally different digestive system with multiple stomach compartments that ferment feed differently than our single stomach does. But the butyrate connection is interesting because human gut bacteria also produce butyrate when they ferment certain sugars and fibers, and butyrate has been linked to improved colonic motility and mucosal health in human studies. It is plausible that the undigested sugars in blackstrap molasses serve as a substrate for butyrate-producing bacteria in the human colon, adding a prebiotic-like benefit on top of the direct osmotic effect. This remains speculative for now, but it is a reasonable hypothesis waiting for a human trial to confirm it.

Animal nutrition research has also highlighted that overconsumption of molasses can disrupt microbial balance and cause electrolyte issues, at least in livestock. Reviews of molasses in ruminant diets typically recommend keeping it to a moderate fraction of the diet and introducing it gradually to avoid digestive upset.⁶ The parallel to human use is obvious: moderation and gradual introduction apply regardless of species.

Where Molasses Fits Among Your Options

If you are dealing with occasional constipation and prefer to try something from the pantry before heading to the pharmacy, blackstrap molasses is a reasonable first step. It has a real mechanism of action, a long track record in folk medicine, and at least one controlled trial showing it matches a standard laxative. It also happens to deliver meaningful amounts of iron, potassium, and calcium, which is a side benefit you do not get from MiraLAX.

Where molasses falls short is in the depth of its evidence base. PEG has been tested in dozens of trials across age groups and clinical settings. Blackstrap molasses has one pediatric trial. If your constipation is chronic, severe, or accompanied by other symptoms like blood in your stool, unexplained weight loss, or alternating diarrhea, those are situations where a conversation with a doctor matters more than any home remedy. Molasses is most sensible as a low-risk option for mild to moderate, uncomplicated constipation, used alongside adequate water intake and physical activity, and replaced with something better-studied if it does not help within a couple of weeks.