In recent years, a slew of studies have suggested that the trillions of bacteria and other microbes parked inside your intestinal tract have a strong influence on your mental health, and may even play a significant role in the development of neuropsychiatric conditions, such as attention deficit hyperactivity disorder (ADHD) .
Those microbes in your belly — which scientists refer to as the gut microbiome — influence your mental health via the gut-brain axis, a communication network connecting the gut, brain, and nervous system, according to a review published in January 2021 in Nutrients.
If ongoing studies confirm the association between gut bacteria and ADHD, new treatments that alter, eliminate, or prevent the development of certain microbes in the gut could become available for people with ADHD, which affects nearly 7.2 percent of children and 3.4 percent of adults around the world, per Children and Adults With Attention-Deficit/Hyperactivity Disorder (CHADD).
Currently, the standard treatments for ADHD include medication and therapy, says Aya Osman, PhD, a postdoctoral fellow at Icahn School of Medicine at Mount Sinai in New York City, who studies the link between the gut microbiome and neuropsychiatric disorders.
Although the research has a long way to go, experts have already made some key discoveries about this relationship.
ADHD and Gut Microbes: What Researchers Know So Far
Studies show that people with ADHD have a different composition of bacteria and other microorganisms in their gut than people who don’t have the condition.
“Some of the most compelling evidence comes from studies where the gut microbiome of humans with ADHD is transferred to mice, with those mice then exhibiting behavior and brain changes compared with mice who received gut microbiome from [people without ADHD],” says Andrea E. Cassidy-Bushrow, PhD, a senior scientist at Henry Ford Health in Detroit, who has studied the relationship between the gut microbiome and ADHD.
One such study, published in April 2020 in Microbiome, in which microorganisms from the intestinal tracts of people with or without ADHD were transplanted into mice, found that the mice who received microbiota from people with ADHD experienced changes to areas of the brain “previously reported to be altered in several neurodevelopmental disorders,” the researchers wrote.
In another study, published in April 2022 in Pediatric Research, Dr. Cassidy-Bushrow and her colleagues studied the gut microbiota of 314 infants using stool samples collected when the infants were 1 month old and 6 months old. After 59 of the children had been diagnosed with ADHD by age 10, their stool samples were examined again. The researchers found that distinct differences in the gut microbiome of the children with ADHD were evident when they were infants compared with children without ADHD.
“Our study showed that these gut microbiome differences may start in infancy, with children at age 10 with and without an ADHD diagnosis having different gut microbiomes in the first 6 months of life,” says Cassidy-Bushrow.
What Questions Still Need Answers?
“Larger studies are needed … to suggest hypotheses for if — and perhaps how — the gut microbiome impacts disease development,” says Sarkis Mazmanian, PhD, a medical microbiologist at the California Institute of Technology in Pasadena and an adviser to Seed Health, a company that manufactures live biotherapeutic products.
Future research is also needed to shed light on whether interventions that alter the gut microbiome — such as probiotics , supplements, and some foods, like yogurt, that contain live beneficial bacteria and other microorganisms — can help people with ADHD manage their symptoms. Currently, we don't have enough information, says Cassidy-Bushrow.
“When we understand that better, we will be better able to potentially design probiotics that can influence the gut microbiome to have a healthier composition and thus function,” she explains.
4 Ways People With ADHD Can Better Their Gut Health
Even though more evidence of a gut microbiome–ADHD connection is needed, it is possible to improve the health of your gut microbiome now, which will in turn boost your overall mental and physical health. After checking with your doctor, take the following steps.
1. Eat a Plant-Rich Diet
Although no diet can change the course of ADHD, certain eating patterns may make managing your symptoms easier.
For example, a study of nearly 15,000 preschool-age children in China, published in the November 2018 issue of the European Journal of Clinical Nutrition, linked a primarily vegetarian diet with a lower risk of ADHD symptoms, whereas processed foods, such as ready-made meals, many breakfast cereals, and hot dogs, were linked to an increased risk of ADHD symptoms.
Similarly, a review published in the March 2022 issue of Food Science and Human Wellness revealed that vegetarian diets promote a healthier gut microbiome than diets containing meat.
Don’t want to become a vegetarian? According to Dr. Mazmanian, you don’t have to. Simply fitting more plant foods into your daily diet will improve your gut health. “Just as there is no one universally healthy microbiome, there is no one-size-fits-all, ‘perfect’ diet,” he explains.
Key nutrients to include:
- Diverse sources of plant fibers and polyphenols (aka good-for-you compounds in plants), such as colorful vegetables, walnuts, pomegranates, berries, and green tea
- Fiber and microbiome-friendly carbohydrates, like those in broccoli, Brussels sprouts, beans, and sweet potatoes
- Omega-3 and monounsaturated fatty acids from foods, such as salmon, sardines, avocados, and olive oil
- In general, minimally processed foods low in sugar, saturated fats , preservatives, and food additives
2. Prioritize Your Sleep
It’s probably no surprise that adequate z’s keep ADHD symptoms in check — a lack of sleep can worsen ADHD symptoms like hyperactivity and impulsivity, according to CHADD. But did you know that sleep may be crucial for gut health, too? Good sleep is associated with more diverse healthy bacteria and other microorganisms in your gut, according to research published in October 2019 in PLoS One.
The trouble is, people with ADHD tend not to get enough sleep. CHADD estimates that about three out of every four kids and teens and four out of five adults with ADHD have a sleep disorder.
To enjoy better sleep each night :
- Aim to go to sleep and wake up at the same times every day.
- Avoid caffeine late in the afternoon or evening.
- Turn off your phone and other electronics before bedtime.
- Try to keep your bedroom’s temperature between 60 and 67 degrees Fahrenheit, which many doctors recommend as the ideal temperature for a comfortable sleep, per the Sleep Foundation.
If you’re still having trouble sleeping, be sure to let your doctor know. Sleep disorders are treatable health conditions.
3. Get Enough Exercise
Moderate to intense aerobic exercise can alleviate ADHD symptoms in kids and teens, according to a review of 30 studies published in the October 2017 issue of Complementary Therapies in Medicine. It also has positive effects on the composition of the gut microbiome, per a review published in the April 2019 issue of Exercise and Sport Sciences Reviews.
How much exercise is enough to make a difference? As little as 20 to 30 minutes a day, say CHADD experts. Types of aerobic exercise you could try, with your doctor’s approval, include:
4. Spend Time in the Great Outdoors
Being in nature is beneficial to both mental health and the gut microbiome, says Mazmanian. “Some scientific theories posit that greater contact with environmental microbes can supplement our own protective microbiota, supporting healthy immune function and helping to build adaptive immunity [the ability of the immune system to fight off harmful bacteria, viruses, and other pathogens],” he explains.
A study published in December 2020 in Scientific Reports found that exposure to bacteria in nature improved both gut health and behavior among preschool-age children. Another study, published in Applied Psychology: Health and Well-Being, found that regular time in nature and green spaces reduced symptom severity among kids with ADHD.