Lactulose may ease constipation due to Parkinson’s, study finds

Significant improvements seen with daily use of stool softener in syrup form

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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A woman is shown sitting on a toilet, struggling with a bowel movement.

Lactulose — a synthetic (lab-made) sugar used to soften stools — may ease symptoms of constipation in people with Parkinson’s disease, lowering a need for rescue laxatives, a pilot study found.

While these findings come from a small number of patients, they offer grounds for further research into lactulose’s safety and how well it works in managing the bowel problems that are frequent nonmotor symptoms of Parkinson’s.

The study, “The effects of lactulose on constipation in patients with Parkinson’s disease: An exploratory pilot study,” was published in the eNeurologicalSci journal by researchers in Japan.

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Parkinson’s can affect the autonomic nervous system, the network of nerves that directs involuntary bodily functions, including digestion. Constipation refers to bowel movements that are slow and often uncomfortable, and it can be evident before disease motor symptoms are manifest.

Lactulose is a synthetic sugar widely used as a laxative to treat chronic (long-lasting) constipation. It works by drawing water from the body into the bowel to slowly soften stools, making them easier to pass.

“However, despite its widespread use, the use of lactulose for the treatment of constipation in patients with [Parkinson’s] has not been evaluated in clinical trials,” the researchers wrote, leading them to look at how well a lactulose syrup works.

Their study enrolled 29 Parkinson’s patients, and 25 of them — 13 women and 12 men with a mean age 75.4 — completed it. The four who dropped out did so for various reasons: one found the syrup too sweet, another couldn’t keep a stool diary, and two others reported a worsening in “stool characteristics” that were considered adverse events.

All had been living with Parkinson’s for an average 6.9 years, and their average Hoehn and Yahr scale score was 2.7, indicating physical independence despite mild to moderate disability affecting both sides of the body.

During the three-week treatment period, they consumed an average 12.6 grams of lactulose syrup a day.

Patients’ average number of spontaneous bowel movements over those weeks rose significantly compared with the study’s three-week pretreatment period, increasing from 3.08 to 3.79 a week. The number of rescue laxatives used also fell significantly.

Stool consistency on the Bristol Stool Form Scale also improved significantly, from an average 3.22 to 3.66 points, the study reported. The Bristol Stool Form Scale describes stool consistency on a scale from one (hard lumps) to seven (watery).

Lactulose use was generally well tolerated, with no serious side effects reported.

Despite its small number of patients, study findings suggest that the use of “lactulose may increase the number of [spontaneous bowel movements]” as well as “improve stool consistency and reduce the use of rescue laxatives,” the researchers wrote.

“Further randomized controlled trials are needed to confirm the effects of lactulose on constipation in patients with [Parkinson’s],” they concluded.