There are many ways that physical health can affect mental health.

For instance, certain diseases, such as diabetes and lupus, are closely linked to depression. Gut health and systemic inflammation can also affect behavior and mood.

The gut is the manufacturing site of many neurotransmitters. We are finding that the gut and dysbiosis in the gut can worsen mental illnesses, including depression, psychosis, and schizophrenia.1 This is a quickly evolving area of medicine, and new discoveries are being made every day. Ninety-five percent of serotonin is found in the gut.1 Probiotics can affect behavior, brain chemistry, and mood. Several probiotics are being marketed to alleviate anxiety and promote a sense of calm. Databases that catalog the probiotic products available on the market and the level of evidence for improved mental mood include AEProbio, Consumer Labs, Medline Plus, and Natural Database. 

One supplement that can positively affect the brain and mood is turmeric.2 The exact mechanisms are not completely understood, but it contains curcumin, which has anti-inflammatory and antioxidant property.

Fish oil also has anti-inflammatory properties and double as a source of essential fatty acids, which are necessary building blocks for brain matter and neurons. 

A balanced diet rich in omega-3 fatty acids is thought to help prevent cognitive deterioration, mood disorders, and neurological diseases.3

For a healthy mind, all the neurochemicals must be in balance. For example, too much dopamine is associated with behavior, such as compulsive shopping, excessive gambling, hypersexuality, and impulsive decisions. These behaviors are common adverse effects of drugs that increase dopamine levels in the brain. Low levels of dopamine are also associated with depression, restless leg syndrome, and weight gain.

Too much serotonin is associated with a serotonergic reaction, which can include anxiety, fever, a frequent “startle effect,” and insomnia. Low levels of serotonin are associated with anxiety, apathy, depression, fatigue, insomnia, and lethargy. 

It is best to give our bodies what they need nutritionally to maintain the ideal levels of neurochemicals, which are mainly made from amino acids and B vitamins.4,5 These neurotransmitters control mood and to a certain extent behavior (see Table). We should be getting our nutrients from food, but when that is not enough, vitamin supplements are an option.

Table. Neurotransmitters and the Roles They Play
Neurotransmitter Role Major Building Block
Serotonin (5-hydroxytryptamine or 5-HT) Happiness, optimism L-tryptophan>serotonin>
melatonin
 
Gamma-aminobutyric acid (GABA) Calming: GABA-a receptors have a valium-like effect, while GABA-b has a muscle relaxer-like effect. Glycine, which resembles GABA in its action
Acetylcholine Autonomic nervous system, associated with learning and memory; low levels are associated with dementia. Choline and acetyl coenzyme
Dopamine This is a feel-good chemical and is associated with weight loss, as well as impulsive destructive behaviors, such as compulsive shopping, gambling, and hypersexuality. Tyrosine, which is found in aged cheese and red wine
Norepinephrine A fight-or-flight naturally occurring chemical Tyrosine is converted to dopamine, which is hydroxylated to norepinephrine.
Serotonin and other endorphins Feel-good chemicals B vitamins and magnesium
 
L-tryptophan is an amino acid that is converted to 5-HTP, and that is then converted to melatonin and serotonin. Serotonin is the neurochemical that most anti-depressant drugs increase to produce positive effects. Sometimes depression sets in because brain chemicals dry up. Anxiety, depression, and insomnia are closely related to serotonin levels. Consuming this amino acid directly translates to better mood.6 Consuming other amino acids (tyrosine) that are needed to make other neurotransmitters (catecholamines and dopamine) have a more subtle effect on behavior and mood.

Meanwhile, B-vitamins are building blocks for many biochemicals in the brain and elsewhere in the body.

Folic acid and vitamin B12 are involved in the synthesis of serotonin and other neurotransmitters. Vitamin B12 deficiency has been found in many patients who have depression or decreased attention, concentration, and memory.7,8

The same occurs with low folic acid levels, which has also been associated with abulia, apathy, confusion, fatigue, and irritability.7,8

In both folic acid and vitamin B12 deficiency, the intensity of the deficiency has been associated with the severity of the symptoms of depression and with the cognitive deficit associated with dementia.7,8

Observations are that many patients with folic acid deficiency may present a lower response to psychopharmacological treatment than those with normal levels.7,8

Vitamin B6, also known as pyridoxine, has special importance as a precursor of serotonin and tryptophan and can also play a role in behavior and mood.8

Magnesium is essential for many biochemical reactions in the body and brain. Magnesium is well known for its relaxation properties. It is often used in water baths in the form of Epson salt. 

A healthy mind and pleasant mood are more than just having positive thoughts. A healthy mind is the result of a 3-way connection among our environment, physical health, and thought. It is no wonder that the Covid-19 virus and social distancing have affected our collective mental health.


REFERENCES
  1. Cheung SG, Goldenthal AR, Uhlemann AC, Mann JJ, Miller JM, Sublette ME. Systematic review of gut microbiota and major depression. Front Psychiatry. 2019;10:34. doi:10.3389/fpsyt.2019.00034
  2. Ng QX, Koh SSH, Chan HW, Ho CYX. Clinical use of curcumin in depression: a meta-analysis. J Am Med Dir Assoc. 2017;18(6):503-508. doi: 10.1016/j.jamda.2016.12.071
  3. Burhani MD, Rasenick MM. Fish oil and depression: the skinny on fats. J Integr Neurosci. 2017;16(s1):S115‐S124. doi:10.3233/JIN-170072
  4. Briguglio M, Dell'Osso B, Panzica G, et al. Dietary neurotransmitters: a narrative review on current knowledge. Nutrients. 2018;10(5):591. doi:10.3390/nu10050591
  5. Glenn JM, Madero EN, Bott NT. Dietary protein and amino acid intake: links to the maintenance of cognitive health. Nutrients. 2019;11(6):1315. doi:10.3390/nu11061315
  6. Lindseth G, Helland B, Caspers J. The effects of dietary tryptophan on affective disorders. Arch Psychiatr Nurs. 2015;29(2):102‐107. doi:10.1016/j.apnu.2014.11.008
  7. Kennedy DO. B Vitamins and the brain: mechanisms, dose and efficacy--a review. Nutrients. 2016;8(2):68. doi:10.3390/nu8020068
  8. Fernández-Rodríguez M1, Rodríguez-Legorburu I2, López-Ibor Alcocer MI3. Nutritional supplements in anxiety disorder. Actas Esp Psiquiatr. 2017;45(Supplement):1-7.