Digestive Symptoms

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by the death of motor neurons — the nerve cells that control muscle movement. The primary symptoms of ALS include muscle weakness, tremors, and cramps. However, patients may experience other symptoms — including digestive problems that may contribute to disease progression — which they may be unaware are associated with their disease.

Possible digestive symptoms

ALS patients may experience cramping, constipation, and bladder urgency. These problems may be so mild that patients may be unaware that the symptoms are connected to their ALS.

study published in Amyotrophic Lateral Sclerosis and Other Motor Neuron Disorders showed that ALS patients had delayed gastric emptying, which the researchers linked to autonomic nerve dysfunction. (Autonomic nerves are those that control autonomic functions such as digestion, breathing, and heartbeat).

The gut microbiome’s role in ALS

ALS may also change the composition of the harmless microorganisms that inhabit the digestive system and assist with food digestion — the so-called gut microbiome. Changes in the gut microbiome have been linked to a number of health conditions.

A study published in Biological Research for Nursing reviewed the current ALS research related to the gut microbiome. The authors found three publications, which indicated that microbiome profiles (the types and numbers of microorganisms present in the gut) were altered in ALS, including a decrease in bacteria that produce a small fatty acid molecule called butyrate.

Butyrate is produced by bacteria in the gut and is taken up as nourishment by the gut epithelium — the cells that line the gastrointestinal tract. The fatty acid is essential for maintaining the integrity of the gut lining. Using a mouse model of ALS, researchers showed that supplementing the diet of the animals with butyrate relieved symptoms and increased survival time. A small study in ALS patients and healthy volunteers also showed decreases in butyrate-producing bacteria. The authors concluded that the gut microbiome could not be discounted when considering ALS symptoms and disease progression.

Probiotic treatment

Mouse models of ALS have demonstrated that treatment with probiotic butyrate increased survival, reduced lesion severity, and restored normal gut bacteria. (A probiotic is any therapy that increases or improves the health of gut bacteria).

An exploratory clinical trial (NCT03324399) assessing the effect of probiotic use is currently ongoing. The trial includes 15 participants who were divided into two groups at the beginning of the trial according to the level of fatty acids present in their blood after a meal. The patients in each group receive probiotic treatment, and the researchers evaluate levels of fatty acids in their blood at intervals during the six-month study, along with changes in the gut microbiome. The trial is expected to conclude in July 2019.


ALS News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.