Serotonin is a powerful neurotransmitter often referred to as the body’s “happy chemical.” It plays a central role in regulating mood, emotions, and overall wellbeing. While it is commonly associated with the brain, up to 90% of serotonin is actually produced and stored in the gut.

This strong gut–brain connection helps explain why digestive health has such a profound impact on mental health. When gut function is compromised—through poor diet, stress, or imbalances in gut bacteria—serotonin production can be affected, influencing mood and emotional stability.

The Gut–Brain Axis

Modern diets high in processed foods and low in fibre can contribute to gut imbalances such as dysbiosis, increased intestinal permeability (“leaky gut”), and overgrowth of unfavourable microbes. These conditions may disrupt serotonin production and signalling.

From both traditional and modern naturopathic perspectives, digestive health is foundational. A well-functioning gut supports not only nutrient absorption but also the production of key neurotransmitters like serotonin.

Key Functions of Serotonin

Serotonin influences multiple systems in the body:

Regulates mood and emotional stability
Supports memory and cognitive function
Influences appetite and satiety
Regulates sexual desire
Promotes restful sleep
Modulates pain perception
Supports healthy blood flow (vasodilation)
Assists in hormone signalling via the pituitary gland

Serotonin and Hormonal Health

Hormones and neurotransmitters are deeply interconnected. Oestrogen and progesterone both influence serotonin activity in the brain.

Oestrogen enhances serotonin production and increases receptor sensitivity, supporting mood and mental clarity.
Progesterone has a calming effect on the nervous system, indirectly supporting emotional balance.

During perimenopause and menopause, declining oestrogen levels can reduce serotonin activity. This may contribute to common symptoms such as mood swings, anxiety, irritability, and depression.

Mood Changes in Menopause

Emotional symptoms such as anxiety, low mood, and nervousness are frequently experienced during hormonal transitions. These changes are not only due to fluctuating hormones but are also linked to shifts in neurotransmitters like serotonin.

Supporting serotonin production—especially through improving gut health—can significantly enhance mood, resilience, and overall outlook.

Hormonal Neuro-Activity: How Hormones Shape the Mind

Hormones act as chemical messengers, influencing both physical processes and emotional states. They interact closely with neurotransmitters such as serotonin and dopamine, shaping how we feel, think, and respond to the world.

Here’s how key hormones affect the nervous system:

Oestrogen

Energising and mood-enhancing
Low levels: fatigue, low mood, poor concentration
High levels: anxiety, irritability, emotional sensitivity

Progesterone

Calming and soothing
Low levels: insomnia, restlessness, mood swings
High levels: sedation, low mood

Testosterone

Supports energy and libido
Low levels: fatigue, low motivation, reduced sexual desire
High levels: irritability, impulsivity

Serotonin

Regulates mood, appetite, and focus
Low levels: anxiety, depression, negativity, poor concentration
High levels: agitation, restlessness, headaches

Dopamine

Drives motivation, pleasure, and mental alertness
Low levels: low motivation, fatigue, social withdrawal
High levels: heightened energy, reduced need for sleep, overstimulation

Naturopathic Approaches to Supporting Serotonin

Both traditional healing systems and modern naturopathy recognise that mental wellbeing begins in the body—especially the gut.

Traditional wisdom focuses on:

Eating whole, seasonal foods
Supporting digestion with bitter herbs
Maintaining balance between rest and activity

Modern naturopathic strategies include:

Supporting gut health with fibre-rich foods and probiotics
Reducing processed foods and excess sugar
Ensuring adequate protein intake (for amino acids like tryptophan, a serotonin precursor)
Supporting nutrient levels such as magnesium, vitamin B6, and zinc
Managing stress through mindfulness, movement, and sleep hygiene
Encouraging sunlight exposure to naturally support serotonin levels

Herbal and nutritional therapies may also be used to support the nervous system and improve resilience, depending on individual needs. Serotonin is far more than a “happy hormone”—it is a vital link between the gut, brain, and endocrine system. Its relationship with oestrogen and progesterone highlights the importance of viewing health holistically.

By nurturing gut health, supporting hormonal balance, and adopting a whole-body approach, it is possible to enhance both mood and long-term wellbeing.

“When the gut is nourished and the mind is supported, balance becomes the body’s natural state.”

Serotonin & Hormonal Balance: The Gut–Brain Connection to Mood and Wellbeing