Calm, cheerful, well-rested—that’s serotonin quietly at work. Often nicknamed the “happy hormone,” this powerful neurotransmitter does far more than lift your spirits: it helps regulate mood, digestion, sleep, and even pain perception. When serotonin slips out of balance, anxiety, low mood, poor sleep, and gut discomfort can follow. So what exactly does serotonin do—and how can you naturally support healthy levels for a better mind–body balance?

More Than Just a Mood Booster: What Serotonin Really Does

Serotonin’s two jobs. It pulls double duty as a neurotransmitter and a hormone, relaying signals between nerve cells.

Where it’s made. Although famous for its role in the brain, about 90% of the body’s serotonin is produced in the gut. A portion enters the bloodstream and circulates to other tissues, where it acts hormonally and participates in intracellular signaling.

When serotonin runs low?

Low levels can impact mind and body. Common signs include:

• Depressed mood or sadness
  
  
• Anxiety or irritability
  
  
• Trouble falling or staying asleep
  
  
• Digestive issues (bloating, constipation)
  
  
• Heightened pain sensitivity
  
  

Low serotonin activity is associated with depression, anxiety disorders, and autism spectrum disorder (ASD). In ASD, disruptions in serotonin pathways may affect emotional regulation and social engagement.

How to Naturally Support Serotonin Levels

Although medications like SSRIs are commonly used to affect serotonin activity, there are several science-backed, natural ways to support your serotonin system:

1. Get More Sunlight

Exposure to natural light—especially in the morning—can stimulate serotonin production, improve mood, and help reset your sleep cycle.

2. Eat Tryptophan-Rich Foods

Tryptophan is an amino acid your body uses to make serotonin. Foods high in tryptophan include soy, dairy, nuts, seeds, and turkey. Pairing these with healthy carbs helps them reach the brain more effectively.

3. Exercise Regularly

Moderate physical activity like walking, yoga, or cycling can naturally boost serotonin levels and improve mood.

4. Support a Healthy Gut Microbiome

Because most serotonin is produced in the gut, keeping your microbiome balanced plays a key role. This is where a new kind of supplement—psychobiotics—enters the picture.

Psychobiotic PS128: Boosting Serotonin Naturally

Psychobiotics are a unique class of probiotics that impact not only gut health but also brain function—primarily through the gut-brain axis. 

Among these, Lactobacillus plantarum PS128 has gained attention for its neuromodulatory effects, particularly its ability to influence serotonin, a key neurotransmitter involved in mood regulation, stress response, and gastrointestinal function. 

In germ-free mouse models, PS128 altered serotonin levels in specific brain regions, providing early evidence of its direct role in modulating brain chemistry. Additionally, in rat models mimicking irritable bowel syndrome (IBS), PS128 was shown to restore serotonin balance in the hypothalamus and reduce visceral pain, suggesting dual benefits for mental and gut health. These findings support PS128’s growing reputation as a promising psychobiotic for mood support and gut-brain wellness

PS128: A Gut-Based Approach to Emotional Balance

Psychobiotics are a special type of probiotic strain that support mental health through the gut-brain axis. Among them, Lactobacillus plantarum PS128 is one of the most studied and promising:

• Promotes balance in serotonin and dopamine levels
  
  
• Helps reduce stress and anxiety
  
  
• Supports focus, calmness, and sleep quality

Preclinical studies suggest that Lactobacillus plantarum PS128 may naturally support serotonin balance in the brain and gut. In animal models, PS128 supplementation was linked to:

• Reduced anxiety- and depression-like behaviors, especially in mice exposed to early life stress.
  
  
• Increased serotonin levels in specific brain regions—even in germ-free mice, indicating direct gut-brain effects.
  
  
• Improved serotonin regulation in rats with irritable bowel syndrome, pointing to both mental and digestive benefits.
  
  

Preclinical research points to PS128 as a promising psychobiotic. By enhancing healthy serotonin signaling through the gut–brain axis, it may naturally support steadier mood, lower stress, and clearer emotions.

Start with your gut

Your emotional health is rooted in biology. Serotonin sits at the center of brain–gut communication—and PS128 may help reinforce that pathway. Looking for a science-supported first step toward feeling more balanced, focused, and emotionally resilient? Consider Neuralli MP. Powered by PS128, it offers a gentle, natural way to support serotonin signaling and overall mental well-being.