TLDR: You need a healthy gut filled with the right kinds of bacteria to access the nutrients essential for mental health. Brains with ADHD and people who take stimulants seeking balance and recovery need specific nutrients, such as the ones found in Recoop, as well as a healthy brain-body connection regulated by your gut microbiome and enhanced by specific strains of bacteria. There's a body of scientific research that supports probiotics specifically for people with ADHD to support mood and fill the nutritional gaps that can affect sleep and mood.

But first, what is your "gut microbiome" really? What does it do and how is it connected to your brain? And why could specific bacteria, delivered in the form of probiotics, support people with ADHD to balance mood and support recovery when using stimulants?

Your body is made up of trillions of bacteria, viruses, and fungi, which are collectively labeled your microbiome. While some bacteria are connected to disease, others are actually very important for your immune system, heart, weight, and many other aspects of physical and mental health.

In fact, there are more bacterial cells in your body than human cells: 40 trillion bacterial cells in your body versus 30 trillion human cells. There are up to 1,000 species of bacteria in the human gut microbiome and these microbes may weigh as much as 2–5 pounds (1–2 kg), which is roughly the weight of your brain. Together, they function as an extra organ in your body and play a huge role in your health, which is why the gut microbiome is sometimes referred to as your "second brain".

A healthy gut microbiome dictates gut health by communicating with the intestinal cells, digesting certain foods, and preventing disease-causing bacteria from sticking to the intestinal walls. While the benefits of gut health are more often discussed in the context of physical health and disease, such as digestion and Irritable Bowel Syndrome, there's evidence that supports the role of gut health and bacteria in brain health and overall mental health.

Two facts about the gut microbiome explain how bacteria could possibly impact the brain and mental health.

First, certain species of bacteria can help make chemicals in the brain called neurotransmitters. For example, serotonin is an antidepressant neurotransmitter that’s mostly produced in the gut. Second, the gut is physically linked to the brain through millions of nerves. The conclusion from these two facts is that the gut microbiome can affect brain health by helping control the messages that are sent to the brain through these nerves.

A number of studies have shown that people with various psychological disorders have different species of bacteria in their guts, compared to healthy people. A small number of studies have also shown that certain probiotics can improve symptoms of depression and other mental health disorders, including ADHD.

In one study, scientists compared the gut microbiomes of people with ADHD and those of neurotypical patients, in what's called a double-blind study. They concluded, "The genus Bifidobacterium was correlated with a significant increase in the enzyme cyclohexadienyl dehydratase (CDT), which involved the synthesis of a dopaminergic precursor (phenylalanine)" In other words, scientists found a specific strain of bacteria that caused a significant increase in an enzyme that eventually creates dopamine in the brain.

One of the theories as to how people develop ADHD is that their brains fail to produce enough dopamine, the chemical known as the emotional "reward" for completing tasks and emotional regulation. If probiotics can help to support the brain's natural production of dopamine, probiotics can help a brain with ADHD balance mood.

The authors went on to say, "the differential microbiome composition found between patients with ADHD and controls in their study may account for altered reward anticipation responses, which is the neural hallmark of ADHD". This study was both novel and promising yet caution is still needed due to the relatively small sample size, controls for ADHD medications, and diet.

Other studies have connected the role of regulating the gut microbiome to children in infancy and even to the mothers of children from before they were born. In one study, giving infants less than 6 months old a strand of probiotics reduced ADHD and Autism when studied 13 years later. In a double-blind study of 75 patients, "At the age of 13 years, ADHD or Autism was diagnosed in 6/35 (17.1%) children in the placebo and none in the probiotic group (P = 0.008)." Other studies have pointed to the mother passing critical bacteria to the child through the birth canal. Other ways that infants and children can get a healthy mix of bacteria and fungus include exposure to dust and allergens in their homes.

In summary, the evidence in humans is preliminary but shows that chronic intake of probiotics is associated in healthy adults with altered brain connectivity during affective and attentive tasks, which support people with ADHD.