As a mental health therapist, I spend my days talking with people who are struggling with depression or anxiety or going through a tough time. Medication can be an important, sometimes lifesaving part of care. What I would love to see more often is an equally careful look at the whole picture of factors that shape mental health.
Diet, exercise, sleep, relationships, hormones, grief, stress, purpose, substance use (caffeine, alcohol, cannabis and nicotine are common ones), past trauma and gut health all play a part, yet they are rarely explored in a typical appointment. Making changes in these areas is easier said than done, especially without support. Still, I have never met anyone who regretted investing time in them. And if you are not ready to overhaul your lifestyle, gut health is one simple, research-supported and inexpensive place to start.
How does your gut affect your mood?
Anyone who has had a "stress tummy" knows the mind can affect the gut. In recent years researchers have shown that the connection runs both ways, through what is called the gut-brain axis, a complex, bidirectional communication system between the digestive tract and the brain.
Serotonin is one example. The digestive tract contains much of the body's serotonin, and gut bacteria help regulate how much is made there. That gut serotonin works mainly in the gut and bloodstream rather than in the brain, so it is not as simple as "unhealthy gut equals unhealthy mind." But researchers think microbial influence on tryptophan metabolism and the serotonin system may be one of several ways gut bacteria affect the brain.
Can probiotics really improve your mood?
The research is promising, if still early. Probiotics are live bacteria that support the gut, and a growing number of trials have tested them for mood:
- A 2016 meta-analysis of randomized trials found probiotics significantly lowered depression scale scores, in both healthy people and people with major depressive disorder.
- A larger 2019 meta-analysis of 34 trials found small but significant effects on depression and anxiety, with bigger effects in clinical groups than in the general population.
- In a 2023 pilot trial, adults with depression who were not fully responding to antidepressants and added a multi-strain probiotic for eight weeks showed greater improvement in depression and anxiety ratings than those given a placebo.
In other words, probiotics look like a useful addition for some people, not a replacement for therapy or medication.
Why diet matters for your gut bacteria
Mental health conditions are common: more than one in five US adults lives with a mental illness. At the same time, many of us eat a diet high in sugar and ultra-processed foods. In a mouse study, high-fat and high-sugar diets changed the gut microbiome, and the high-sugar diet impaired memory and mental flexibility. Mice are not people, but it is another reason to look at what is on your plate.
When your gut bacteria are in balance, they help digest food and support your immune system. Our article on chronic stress and gut health explains how stress can push that balance the wrong way.
How to add probiotics to your routine
Personally, I notice when my gut is "off," so I take a probiotic every day. If supplements are not your thing, start with probiotic foods:
- Yogurt and kefir, if you tolerate dairy. Check that live cultures are listed by name (for example, Lactobacillus acidophilus or Bifidobacterium).
- Unpasteurized fermented vegetables such as sauerkraut and kimchi.
- Miso, tempeh and kombucha.
If you prefer a supplement, Trust Your Gut Probiotic + Prebiotic Daily Essential contains 16 billion CFU from 6 strains that have been researched for their potential to support digestion, the immune system and mood balance, plus organic prebiotics. Our guide on how and when to take your probiotic covers timing.
When to reach out for support
Creating good mental health is no small feat. For most of us it can be overwhelming, frustrating and at times defeating. Know that it is not your fault, you are not alone, and there are changes you can make toward a calmer, more joyful life. If it is within your means, I strongly encourage working with a therapist who can help you understand the more complex causes of low mood. If you take medication for depression or anxiety, keep taking it as prescribed and talk to your doctor before making changes. Probiotics might be one helpful piece of the puzzle.
Megan Bruneau, M.A., RCC, is a mental health therapist, writer and wellness coach.
