Sadness, or normal depression, is a universal human response to adverse situations. Normal depression is commonly experienced, and is transient. It occurs in reaction to significant life circumstances such as separation, loss or catastrophes, but does not necessarily lead to clinical depression. In those who have a predisposition to mood disorders, their sadness is overly intense and prolonged, and may occur without any apparent life stress.  Post natal depression is also becoming more common which can greatly impact family life.  

I have heard clients describe clinical depression as something like a dark, murky fog in the brain that blocks and distorts the brains functioning, smothering joy and peace. The textbook definition of clinical depression is having at least 2 of the following for more than 2 weeks:

  • Depressed mood

  • Anhedonia - the inability to experience pleasure from activities usually found enjoyable

  • Reduced energy

There are usually a range of other symptoms accompanying depression including sleep disorders and change in appetite.  There are usually feelings such as overwhelm, irritability, miserable and it is difficult to make decisions or to get on with the regular things in your life.  Many people mask depression with seeking excitement, over-using alcohol, drugs or comfort food.

Depression is the number one disability in the western world and The World Health Organisation (WHO) has predicted that by 2020, clinical depression will be the second biggest health problem world-wide, behind heart disease.

What causes clinical depression?

There are many theories as to why some people experience clinical depression and other mood disorders, but it is not yet known exactly why. It is thought that a dysfunction in neurotransmitters such as serotonin, dopamine, GABA and noradrenalin is responsible for mood disorders including clinical depression. However little is known about why these chemicals are dysfunctional.

Clinical depression is classed as a brain disorder. Dysfunction within the chemistry of the brain alters mood and gives rise to negative thoughts and sensations. From another perspective, personality and thought patterns are believed to alter the chemical functioning of the brain leading to mood disorders. How we think influences which neurotransmitters and hormones are produced or not produced.

  • Genetics: Is seen as a strong predisposing factor in mood disorders, however the precise mode of inheritance is not known and it is now widely accepted that genes require certain environmental conditions for expression. You may have a genetic predisposition to depression or mental illness, but it is still environmental factors which trigger and promote the disease

  • Nutrition: Nutritionists view brain chemical imbalances as a result of nutrient deficiencies and/or toxic influences. In order for neurotransmitters, such as serotonin, to be produced correctly certain essential nutrients are required. Essential nutrients are termed such because the body cannot produce them and will be compromised without them. Heavy metals and environmental chemical exposure are known to impact our health. A prominent sign of lead and mercury toxicity is depression

  • Inflammation: Inflammation is the body's response to harmful stimuli, such as pathogens, damaged cells, or irritants. There is mounting research strongly suggesting that chronic inflammation is a factor in disrupting neurotransmitter function which in turn leads to depression. Certain chemicals (pro-inflammatory cytokines) have a direct and indirect effect on the brain. They have been shown to lower the availability and alter the metabolism of neurotransmitters such as serotonin. Researchers have found elevations in 2 inflammatory cytokines (IL1B and TNF-a) are associated with severe depression

  • Psychology: Various aspects of personality appear to be a large contributing factor in the occurrence and persistence of depression. In dealing with life's challenges a person's style of coping may influence resistance to depression. Low self-esteem and self-defeating or distorted thinking are related to clinical depression. Depressed persons who are able to reflect upon and challenge their thinking patterns often show improved mood and self-esteem

  • Lifestyle: Is known to have an impact on all diseases including mental health disorders. Sleep, exercise and stress management are very important to consider in relation to depression

  • Gut: Traditional medicine recognises that all diseases begin in the gut. Modern research is beginning to unravel the puzzle of how our gut and its inhabitants (microbiota) influence the brain and how they have a crucial role to play in the development of brain disorders including depression

Depression and the Gut

All the bodys organs are nourished by blood, nourishment which is supplied by the digestive system. Food is fed into the digestive system which is fed into the blood stream to feed the body including the brain. What is in the digestive system may enter the blood stream, cross the blood brain barrier and have an effect on the brain.

Research has shown that our digestive system and its inhabitants, or microbiota, are strongly linked to how we feel and how the brain develops and functions. Clinical experience has shown me that correcting digestion and its microbiota can significantly normalise the brain's functioning and relieve depression and anxiety.

Our beneficial microbiota have many important roles to play in the gut and are seen as the housekeepers of the gut. Microbiota help in the development of the digestive system and over our life time maintain the integrity of the gut wall. They are involved in the digestion of our food by producing many digestive enzymes, they protect us against other pathogenic/disease promoting organisms by producing a host of antimicrobial substances including natural antibiotic and antiviral substances.

How does all this relate to the brain and depression? There is a definite link between the gut flora and the gut and how we feel. It is not commonly known that the majority of our feel good mood regulating hormones and neurotransmitters, including serotonin, are produced in the gut. One of the most exciting studies in this area was released last year stating

"The intestinal microbiota influences brain chemistry and behavior independently of the autonomic nervous system, gastrointestinal-specific neurotransmitters, or inflammation."

2011 Aug;141(2):599-609, 609.e1-3. Epub 2011 Apr 30: The intestinal microbiota affect central levels of brain-derived neurotropic factor and behavior in mice.

The following are specific factors related to gut function that affect the brains ability to function:

  • Alcohol: Alcohol and its by-product acetaldehyde are depressant substances. These are formed in the gut by pathogenic flora from the metabolism of sugar and starches

  • Neurotransmitter production: organisms in the gut contribute greatly to the production of neurotransmitters including serotonin and dopamine.  We should have a constant 'well-spring' of feel good chemicals coming from the gut.  When there is an imbalance of microbes in the gut there may not be enough good bugs to produce enough of the feel good neurotransmitters

  • Nutritional Deficiencies:

    • Zinc: Gut flora help us absorb minerals including zinc.  Long term zinc deficiency leads to a more permeable gut wall and blood brain barrier. When permeable, these barriers let substances through which disrupt brain function.  Zinc is needed for many processes including the manufacture of healthy neurotransmitters.

    • EFAs: Poor gut function reduces the body's ability to utilise essential fatty acids (EFA's). Deficiency leads to reduced effectiveness of neurotransmitters including serotonin (EFA's make up 20% of the nerve cell membranes and 60% of synapses). Since EFA's regulate inflammation there is more susceptibility to inflammation when they are lacking. Both contribute to depression

    • B vitamins: The B group vitamins are produced in the gut by beneficial microbiota, which is hindered by poor gut function. The brain requires a tiny but steady and constant supply of B vitamins to function at optimum. Any deficiency will hinder the production of neurotransmitters. Deficiency also effects the balancing of blood sugar levels, sleep and energy levels. All of these contribute to depression

    • Other vitamins and minerals: Serotonin requires nutrients such as B1, B2, B6, B9 and B12 and tryptophan, cholesterol, vitamin D, and the minerals selenium, calcium, magnesium and iron. Poor gut function can lead to deficiency which in turn can impair the production of serotonin and other neurotransmitters contributing to depression

  • Maldigestion: Substances called casomorphins and gluteomorphins are produced when gluten and dairy are not digested properly. These are known to contribute to neurological disorders including depression and anxiety

  • Inflammation: Poorly digested food and toxins from the gut stimulate inflammation within the body. Inflammation is a factor in disrupting neurotransmitter function which in turn leads to depression.  There are certain pathogenic microbes that live in the gut which stimulate inflammation - these are higher in depressed patients

  • Poor detoxification: Detoxification is essential and a normal part of our physiology. Part of detoxification involves deactivation and removal of old, used neurotransmitters and hormones. Detoxification relies on many steps to complete the process. Our beneficial microbiota is involved in steps of detoxification and without adequate good microbes our detox capacity is compromised leading to the re-circulation of dysfunctional hormones and neurotransmitters which disrupt brain function.  There are many known toxins and heavy metals which contribute symptoms of depression. 


Beyond Blue website

Science page