New study: Synbiotic2000 reduces proinflammatory markers in children taking ADHD medication

A new clinical study from Karolinska Institutet shows that Synbiotic2000 significantly reduces proinflammatory markers in children who are receiving medication for ADHD, as well as increasing levels of short-chain fatty acids.

Catharina Lavebratt, a lecturer in medical genetics at the Institute for Molecular Medicine and Surgery at Karolinska Institutet, is one of the researchers who led this new study. She is pictured here with Professor Stig Bengmark, one of the creators behind Synbiotic2000. Photo: Niklas Nyman

ADHD and the gut flora

Attention Deficit Hyperactivity Disorder (ADHD) is a neuropsychiatric condition affecting roughly 5% of children and 3% of adults. Symptoms usually include hyperactivity, impulsivity and an inability to focus. Around 75-80% of people with ADHD also display other psychiatric comorbidities, such as affective disorders or autism spectrum disorders.

Previous research has shown that there may be differences in the intestinal flora of people with ADHD compared to people without ADHD. Studies on mice have also shown that both their behaviour and their brains are affected when researchers transfer faecal microbiota from ADHD patients to these mice. There are therefore indications of a potential connection between the intestinal flora and symptoms of ADHD. No specific ADHD-related intestinal bacteria have ever been confirmed, however.

Gut-brain axis

The connection between the intestines and the brain, the so-called gut-brain axis, is an area of research that has garnered increasing interest in recent years. The gut-brain axis is made up of the communication pathways that connect the gut to the brain. The most direct link is the vagus nerve which runs all the way from the brain stem down into the intestinal wall. Other communication pathways between the intestines and brain include the blood, the immune system or the nervous system. In order to find new diagnostics and treatment methods, researchers are investigating the role of the gut-brain axis in various psychological phenomena, as well as how it affects neuropsychiatric conditions such as ADHD and autism.

Synbiotic2000 reduces symptoms of autism in children with ADHD

A previous study at Karolinska Institutet investigated the effects of Synbiotic2000 (3 strains of lactic acid bacteria combined with dietary fibre) on people with ADHD (with no autism diagnosis). This study showed that, compared to a placebo, Synbiotic2000 had positive effects on autism symptoms in children with ADHD. In addition, the study indicated a reduction in difficulties with managing emotions in adults with ADHD. The study also observed that roughly half of the participants had some type of inflammation at the start of the study. In light of this, a follow-up study was carried out to investigate the mechanisms behind these changes.

New study shows reduced inflammation in children receiving medication for ADHD

The aim of the follow-up study was to investigate the effects of Synbiotic2000 on immune markers and short-chain fatty acids (SCFAs) in adults and children with ADHD. A total of 320 people took part in the study at Karolinska Institutet, of which 248 people had an ADHD diagnosis and 72 people had no diagnosis. The test subjects were randomly divided into two groups, one of which was given Synbiotic2000 and the other a placebo. 189 people with an ADHD diagnosis and 57 people with no diagnosis completed the full course of treatment, which lasted for 9 weeks.

The study showed that at the beginning of the treatment, people with ADHD, especially children receiving medication for ADHD, had significantly higher levels of proinflammatory markers (sICAM-1 and sVCAM-1) and lower levels of short-chain fatty acids than people without ADHD. Children with ADHD also had significantly higher levels of several proinflammatory markers (e.g. IL-12/IL-23p40 and IL-2Rα) than the adults with ADHD, and even lower levels of short-chain fatty acids.

Following treatment with Synbiotic2000, proinflammatory markers (IL-12/IL-23p40) were significantly reduced in children receiving medication for ADHD compared to the placebo group. It was also observed that proinflammatory markers (IL-12/IL-23p40, sICAM-1 and IL-2Rα) decreased in children with ADHD (regardless of medication), and that levels of propionic acid (a short-chain fatty acid) increased after treatment with Synbiotic2000 compared to the placebo group, albeit without any statistical significance.

These findings pave the way for future studies on how Synbiotic2000 can benefit people with neuropsychiatric conditions. Regarding their findings, the researchers write in their article:

”This suggests that Synbiotic 2000, in children with ADHD, reduces markers of intestinal and vascular inflammation, the latter in part through increasing SCFA levels. The findings warrant further studies to determine if persons with ADHD would benefit inflammation-wise from dietary intake of Synbiotic 2000 or a similar synbiotic.”



Skott E, Yang LL, Stiernborg M, Söderström Å, Rȕegg J, Schalling M, Forsell Y, Giacobini M, Lavebratt C. Effects of a synbiotic on symptoms, and daily functioning in attention deficit hyperactivity disorder – A double-blind randomized controlled trial. Brain Behav Immun. 2020 Oct.

Yang LL, Stiernborg M, Skott E, Xu J, Wu Y, Landberg R, Arefin S, Kublickiene K, Millischer V, Nilsson IAK, Schalling M, Giacobini M, Lavebratt C. Effects of a Synbiotic on Plasma Immune Activity Markers and Short-Chain Fatty Acids in Children and Adults with ADHD—A Randomized Controlled Trial. Nutrients. 2023 Mar.


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