When you encounter multiple and recurrent symptoms from the following list, you are most likely depressed:
- Low mood.
- Low energy.
- Low concentration.
- Low self-esteem.
- Feelings of guilt.
- Less appetite or voracity.
- Sleep disorder.
- Suicidal thoughts.
- Loss of interest or pleasure.
In the last 50 years, the frequency and prevalence of depression have risen sharply. Every year, approximately 10% of people in the industrialized Western world suffer from a major depressive episode. Men have a 25% risk of being severely depressed during their lifetime, while women have a 35% chance.
On research articles on the subject of depression, predisposition, mental flexibility, stress, biological elements, and the detrimental effects of medical treatment were all reviewed on many occasions.
Regarding depression’s biology. Deficits or excesses of certain neurotransmitters  in the brain are often related to depression. A lack of the protein Brain-Derived Neurotrophic Factor  (BDNF), causing the hippocampus  and other limbic  structures to deteriorate, has also been related to depression.
The standard treatment for depression focuses on influencing the productions of neurotransmitters, BDNF-protein, and other complex (and sometimes poorly understood) processes in the brain. This is often achieved by medicine and psychological therapy, the outcomes of which are debatable.
Focusing on diet and exercise first, in my opinion, is a smart idea.
Inflammation in the brain is commonly accepted as a cause of depression. In this area, supporting information includes:
- IL-6 , TNF , and other inflammation biomarkers are elevated in depressed individuals.
- Inflammation decreases the production of norepinephrine  and serotonin, the feel-good neurotransmitter.
- Inflammation disrupts glutamate regulation, which contributes to depression .
- Antidepressants also target inflammation suppression.
- Inflammation tends to lower neuroplasticity in the brain , and with that a flexible brain function.
Depression can be countered by avoiding the following nutritional causes of inflammation:
- Insulin resistance, weakened blood vessels, high blood pressure, overweight, and obesity are all signs of eating too much sugar and starch. All of these things allow pro-inflammatory molecules to be released. It’s worth noting that depression is fairly common in people who are overweight or have Type 2 Diabetes, and vice versa.
- Too many polyunsaturated fatty acids, especially omega-6 (see this post), load us up with signaling molecules that cause inflammation.
- Grains and legumes, as well as nightshades, dairy, nuts, and eggs, can cause a leaky gut (see this post) and a lot of unwanted inflammation.
 Neurotransmitters are chemicals that nerve cells (neurons) use to send signals to other cells in the nervous system. Depression is often related to the neurotransmitters norepinephrine, dopamine, and serotonin.
 BDNF influences certain central nervous system and peripheral nervous system neurons.
 The hippocampus is a major component in human and other mammalian brains. It’s a part of the limbic system that’s involved in long-term memory and spatial navigation.
 The limbic system is a set of brain structures that includes the hippocampus, amygdala, anterior thalamic nuclei, septum, and limbic cortex which seems to support a variety of functions such as emotion, actions, long-term memory, and olfaction.
 Interleukin-6 (IL-6) is a secreted protein/signaling molecule that has both pro- and anti-inflammatory properties.
 TNF (tumor necrosis factor) is a small cell-signaling protein that plays a role in systemic inflammation.
 Norepinephrine is a neurotransmitter; for more detail, see .
 Glutamate is a neurotransmitter that is important for learning and memory and plays a key role in long-term potentiation.
 Neuroplasticity is the brain’s capacity to adapt in response to one’s experiences. Learning by adding or removing connections or adding cells is referred to as “plasticity.”