The neurotransmitter serotonin plays a key role in psychological well-being. What many don't know is that this so-called "happiness hormone" is primarily produced in the gut. This site of synthesis explains the close connection between the brain and the digestive tract.
serotalin®: What role does serotonin play as a neurotransmitter in the interplay between gut health and psychological well-being?
D. Riehle: For a long time, it was assumed that the "happiness hormone" serotonin, a neurotransmitter that influences mental health, was produced in the brain. However, it has now become clear that 90% of its production takes place in the gut. More than 20 hormones originate there and are then transported to different parts of the body. Although the hormone is utilized in the synaptic cleft of the brain, and its duration of action can be significantly influenced by SSRI/SNRI drugs, the amount of the neurohormone released is largely determined by the function of the gut.
Therefore, in my view, it makes sense to also assess gut flora and gut function when diagnosing mental illnesses. Obsessive-compulsive disorder, depression, ADHD, dementia, and autism, in particular, are increasingly associated with impaired gut health; however, concrete scientific evidence is still lacking.
serotalin®: In your consulting practice, do you observe any connections between digestive problems and emotional well-being – and how do you explain possible interactions?
D. Riehle: Many people report how closely our gastrointestinal system is connected to our psyche. We now know about the close links between the digestive organs and the mind. Nevertheless, the phenomenon of comorbidity—the occurrence of multiple disorders affecting different organ systems—seems to be overlooked in medical practice and in the search for causes. In my experience, psychological complaints can have a significant origin in our gut. Conversely, the diagnosis of a comprehensive digestive problem often fails because no one considers the significant influence of our emotional state on the stomach and intestines.
Neurons covering up to 500 square meters in the gastrointestinal tract form the "enteric nervous system"—a highly developed network that "checks" incoming food and determines its composition—and thus has an enormous influence. The data gathered is then relayed accordingly, determining which nutrients are usable and which can be excreted.
Nevertheless, a principle of "coexistence" initially prevails in the gut, allowing bacteria, viruses, and germs ingested through food to coexist, even if some of them are harmful and could trigger inflammation. From my perspective, this makes it all the more important for everyone to proactively contribute to the composition of their gut flora. This allows for the support of a symbiosis of microorganisms, despite the influence of nerve cells that affect the gut's immune system. In my experience, these microorganisms are particularly necessary when their activity can demonstrably influence emotions, increase stress resistance, and strengthen concentration.
serotalin®: What role do you attribute to nutrition in relation to well-being, digestion and psychological balance – also with regard to possible influences on neurotransmitters such as serotonin?
D. Riehle: In my view, nutrition plays a crucial preventive role when it comes to mental health issues. While a healthy lifestyle cannot completely prevent them, a diet often described as "balanced" is a guarantee for creating the best physiological foundations, thus reducing the risk of developing mental illness – at least that's my assessment. It's generally recommended to consume plenty of fruits and vegetables, nuts, legumes, and especially omega-3-rich foods like fish or flaxseeds as a preventative measure.
If you're already caught in the vicious cycle of decompensation, overeating, and signs of metabolic syndrome, then in my experience, a drastic reduction in fat and short-chain carbohydrates is essential. I wholeheartedly recommend this for diabetes associated with mental stress and other metabolic disorders as well. Instead, the goal is to switch to fiber-rich, satiating foods – even if this presents a mental challenge for us creatures of habit. Whether it's eggs, Greek yogurt, beans, oatmeal, avocados, whole-grain bread, quinoa, figs, or lentils: these are often unfamiliar flavor experiences that also require creativity and innovation in preparation. The adjustment can be made easier, for example, through nutritional counseling or a cooking class.
The connections between the psyche, nutrition, and internal diseases are not yet fully understood. Nevertheless, it seems logical to me that endocrine disorders and gastroenterological-hepatological diseases, due to a disturbed metabolism, can act as a catalyst for the development of a manifest mental illness under certain predispositions and exogenous factors such as crises, losses, and traumatic events.
Although there are only selected overlaps between brain metabolism and the rest of the organism's circulatory system, biochemical imbalances in the brain and an imbalance in the levels of neurotransmitters such as serotonin can, in my opinion, be a source of the development and persistence of mental illnesses.
serotalin®: Many people associate serotonin with stress management or sleep. What experiences or insights do you bring to this topic from your consultations – completely independent of laboratory diagnoses?
D. Riehle: Especially in cases of irritable bowel syndrome and irritable stomach syndrome, it is considered clear that the psyche is the main factor in triggering and perpetuating digestive problems. The reciprocal influence between the gastrointestinal tract and the brain has been extensively documented.
Numerous stressors affect the gastrointestinal tract. In particular, bloating, heartburn, or a persistent alternation between constipation and diarrhea—or vomiting and nausea—can indicate that psychological factors are involved. Anyone who has ever struggled with such symptoms knows how much they negatively impact sleep quality.
Whether it's exam anxiety, stress in the office, bullying, "burnout" or various adjustment and stress disorders, depression and phobias: In situations with major challenges, the overload of the psyche can be passed on to the digestive tract.
serotalin®: From your perspective, are there certain phases of life – for example, in men from the age of 30 or 40 – in which topics such as energy, mood, or resilience are more frequently the focus?
D. Riehle: Almost every phase of life is characterized by challenges, as our existence is almost constantly in flux. Even if we are often unaware of it, we tend to suppress signs of exhaustion and lack of motivation in order to function. Consider, for example, starting a career in one's 20s to early 30s: high pressure from career building, financial insecurity, and the search for stability are commonplace. Or consider the classic period of starting a family in one's 30s to 40s, with its combination of professional development, intensive childcare, and partnership. This phase often leads to a lack of time and feeling overwhelmed.
The so-called midlife crisis, occurring between the 40s and 50s, is characterized by reflection on biographical goals, potential career stagnation, and physical changes (the "menopause" of both sexes). In the 50s and 60s, we are often preoccupied with the responsibility of caring for aging parents or sick relatives (the caregiving phase). Our own health issues also arise, affecting almost everyone at some point. And in the transition to retirement from the 60s onward, we must adapt to new structures and potentially deal with moving, a loss of social contacts, loneliness, or existential crises.
serotalin®: In your opinion, what are proven, practical measures for promoting balance and well-being – independent of medication?
D. Riehle: So-called "low-threshold" services such as psychosocial counseling, self-help groups, or complementary therapies should always be considered. These may include dietary changes, increased physical activity, improved sleep hygiene, or light therapy. Supplementation with vital nutrients tailored to individual needs can also be an option. In addition, relaxation training and stress management exercises are just as helpful as working on one's own beliefs, expectations, and demands.
Ultimately, it is often deeply ingrained personality patterns that contribute to maintaining a psychodynamic process. If we are also open to allowing insight into our subconscious in psychotherapy and engaging with the emotional "compost heap" that accumulates in each of us over a lifetime, there is a chance not only to plow through the surface but to penetrate to the depths. For simply addressing symptoms is usually insufficient to combat the underlying causes and eradicate the root of the problem.
serotalin®: Are you experiencing a demand for dietary supplements in your practice – and how do you address such questions in your daily consultations?
D. Riehle: I'm actually experiencing what the overall trend reflects. Demand for dietary supplements in Germany remains high and shows stable growth, despite economic challenges such as inflation. This can likely be explained primarily by increased health awareness, the aging population, and the desire to boost the immune system (especially since the COVID-19 pandemic). Consumers prefer multifunctional, natural, and bioavailable products. The younger generation, in particular, pays close attention to the quality, trendiness, and function of the individual active ingredients.
Clients usually come to me already well-informed. Driven in no small part by a lot of advertising, the focus is particularly on vitamins C, D, B12, magnesium, and calcium. I am very open to this topic, especially given my qualifications and further training, as I have personally experienced how supplementation can bring about the desired change—or even a new boost—in some cases.
There are many micronutrients that should not be taken haphazardly and should never be overdosed. Therefore, it should be standard practice to consult a doctor, assess any symptoms, receive nutritional advice, and have a blood test performed before randomly choosing a combination of various trace elements, amino acids, or minerals. This applies even though multivitamin preparations are now readily available in every pharmacy.
I believe it's essential to develop an individualized plan for each patient, one that includes comprehensive explanations of why certain components are needed – and why they can impact functional areas within a broader system that aren't immediately associated with them. In my opinion, an understanding of the rationale behind orthomolecular support, its far-reaching implications, and its complex interrelationships is crucial, as should be the case with any measure affecting our health.
serotalin®: What typical misunderstandings or myths do you encounter in connection with serotonin and dietary supplements?
D. Riehle: Most clients believe there are no connections between a neurotransmitter and a dietary supplement because, in their view, they are two completely different categories. I then always provide examples that prove otherwise. For instance, serotonin is synthesized in the body from the amino acid L-tryptophan. Dietary supplements containing L-tryptophan can support serotonin production because they increase the availability of this precursor. Studies show that L-tryptophan supplements can help with sleep disorders or mild depressive symptoms.
The minerals magnesium and zinc play a role in regulating neurotransmitters, including serotonin. A deficiency can impair serotonin function, which is why supplements can be beneficial in certain cases. Vitamin B6 is a cofactor in the conversion of L-tryptophan to serotonin. A deficiency could therefore impair serotonin production, making supplementation relevant in this context. Finally, there is growing evidence that omega-3 fatty acids can improve serotonin receptor function, which would indirectly have a positive effect on mood.
However, the following always applies: do not experiment, but seek advice from doctors, nutrition experts, pharmacists or alternative practitioners regarding selection, dosage and intake!
About the author: Dennis Riehle , born in 1985, from Konstanz on Lake Constance, is a psychological social, health and nutritional consultant, journalist and author. He was active as a volunteer self-help group leader for over two decades, continues to support clients in their daily lives and, based on his professional practice as well as his own personal experience, possesses a wealth of knowledge regarding mental imbalances and their complex, multifaceted connections.
