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Anxiety and the Autonomic Nervous System

by Jurriaan Plesman BA(Psych), Post Grad Dip Clin Nutr

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When studying anxiety attacks and phobias we should make a distinction between real fear and irrational fear.

I would like to elaborate on this using knowledge of biology as to what happens when we experience fear.

When we are faced with a tiger, or we encounter any kind of trauma, grief, rejection of a loved one and so forth, the body floods the system with adrenaline, the hormone of strenuous action and fear or fight. This hormone helps us to deal with the ‘danger’.

Adrenaline activates the Sympathetic Nervous System (SNS) which is a sub-branch of the Autonomic Nervous System.

It controls specific bodily organs to prepare us for fight or flight. These reactions are beyond the control of our consciousness and can be responsible for weird physiological symptoms.
The SNS dilates pupils of our eyes, shuts down the digestive organs, increases heart palpitations, relaxes the smooth muscles of bronchi and bronchioles, leading to “breathing problems”. The smooth muscles of the digestive tract is inhibited, so peristalsis stops, sphincter of the bladder also contracts and the bladder wall relaxes. This may lead to involuntary defecation, also known as encopresis. Blood vessels supply to the skeletal muscles are dilated. An overactive SNS is likely to open up blood vessels and flood your face, neck and ears in blushing. Other possible symptoms are: dizziness, shaking, trembling, (as when giving a talk in front of people), digestive disorders, swallowing problems, nausea, vomiting, or fear of vomiting or diarrhea, arrhythmia (irregular heart beats), ticks and restless legs, excessive sweating, depersonalization, incontinence, impotence, repetitive thoughts, ruminations, Anhedonia. It is obvious that these mental and bodily reactions helps to prepare the body for strenuous and quick actions in the face of environmental danger. The SNS diverts energy away from the vegetative to the muscular system.

Please note that in anxieties we see many symptoms – such as heart palpitations, stomach upsets and digestive disorders and so forth – that are the works of the SNS. Actions on the digestive system is often referred to as the Enteric Nervous System.

The Parasympathetic Nervous System (PSNS) – the other branch of the Autonomic Nervous System – on the other hand reverses the SNS and counteracts the SNS. This system is triggered by the neurotransmitter acetylcholine, which may be a important piece of information to people suffering from Bipolar Disorder. See: Bipolar patients. See notes below. The Autonomic Nervous System and its effects on organs see image here.

Thus this fear reaction is an important survival mechanism in the face of real danger.

The question is how is this related to anxiety attacks or the irrational fears that can wreck people’s lives.

The clue is adrenaline. The question is why should the body produce excess adrenaline out of the blue, without any trigger in the environment, causing us to have unexplainable anxiety attacks, phobias and heart palpitation? Hypoglycemia can cause to dump magnesium into urine, upsetting the delicate magnesium-calcium balance. This can trigger excess adrenaline secretion and contribute to hypertension (high blood pressure) and heart palpitations, anxiety and mood swings. (Hemat RAS 2003, page 38 and here). When magnesium is deficient, calcium can leak in soft tissue and cause damage – that is calcification. Mark Mayer p15

The function of adrenaline is to convert sugar stores in our body in the form of glycogen into glucose.(See image)

The reason for this is that brain is very sensitive to glucose levels. Although the brain represents only 2 per cent of the body by weight it requires about 60-70 per cent of available glucose in the body to energize the biochemical machinery of brain cells. (Stryer 634).

Glucose is the forerunner of Biological Energy called (ATP), which is essential in the manufacture of the relaxing and feel good neurotransmitters, such as serotonin.

Thus when the brain (in fact the HPA axis) senses a low blood sugar level it will send an hormonal message to the adrenal glands to pour adrenaline into the system. This raises blood sugar level and will feed the brain again, but it also causes us to feel fearful without an external object of fear. The fear is irrational.

Adrenaline not only activates the SNS, but is also a focusing hormone, forcing us to focus on any possible “danger” at the expense of anything else. It causes us to “ruminate”. Thus excess adrenaline production also lies at the root of Obsessive Compulsive Disorder (OCD) and Post Traumatic Stress Disorder (PTSD).

Thus now the question is why is the brain starved of energy causing it to trigger stress hormones??

There are many reasons for this, because there are many medical conditions that interfere with the proper absorption of glucose, such as the various digestive disorders, heavy metal intoxication replacing zinc substrates, coeliac disease, Crohn’s Disease and Ulcerative Colitis, hypothyroidism and hyperthyroidism. The list is unending.

However the majority cases of of energy starvation in the brain is due to Insulin Resistance, which blocks the transfer of glucose (and other nutrients) across cell membranes. This can lead to the hypoglycemic syndrome, with its multitude of psychological and physical symptoms.

This condition can be tested with the four hour Medical Test for Hypoglycemia. It can also be tested with the Nutrition Behavior Inventory Test (NBI) and the Hypoglycemia Questionnaire. If you score high you are likely to be hypoglycemic.

The non-drug treatment of this condition is going on a Hypoglycemic Diet.

This goes to show that the various forms of mental illnesses (really brain diseases) are due to a Nutritional Disorder.


Stryer, Lubert (1988), BIOCHEMISTRY, WH Freeman and Co, NY

Treatment of Bipolar Disorder
Bipolar disorder may be viewed as an imbalance between the sympathetic (energizing) and parasympathetic (relaxing) nervous system.
Acetylcholine is the major hormone that activates the Parasympathetic Nervous System, promoting states of rest and relaxation. It is formed from phosphatidylcholine with the help of vitamin B5 (pantothenic acid). Lecithin contains about 10-12% of phosphatidylcholine. People suffering from Bipolar Disorder may benefit from taking lecithin in the manic phase of the illness to counteract manic behaviour. 3 PubMed Studies, and PubMed Articles.  BUT this remedy should not be taken in the depressive stage of the illness. It has been suggested that the cycle of mania and depression in Bipolar Disorder can be moderated by controlling the manic phase, which over time may cause adrenal exhaustion leading to the inevitable depressive phase. By going on a hypoglycemic diet with megadoses of omega-3 fatty acids (fishoil) and supplementing the diet with choline (or lecithin) during the manic phase it is hypothesized that the depressive phase can be avoided. For Inositol depletion hypothesis, especially important in Bipolar Disorder and administration of lithium see EJ Nestler et als., 360. See 6 studies in support of omega-3 fatty acids for Depression and Bipolar Disorder. See also: here. See also: Research on Lithium and Bipolar Disorder.

In the depressive stage of Bipolar Disorder it may be worthwhile considering supplementing with L-phenylalanine (or Tyrosine) plus vitamin B6 (pyridoxine) which is decarboxylated to phenylethylamine (PEA) which has been shown to have an anti-depressive action in the brain. However, such supplementation or treatment should be under the strict supervision of a doctor or health care worker. Two Pubmed Studies. W Birkmayer et als.(1983), HC Sabelli, JI Javaid 1995, H Sabelli et als. 1996. See also M.R.Werbach summary of Bipolar Disorder here. For more nutritional therapies see: Alternative Mental Health.

See also at: Research Evidence for Hypoglycemia

Blushing – One source suggests: “The simplest method for enabling your para-sympathetic nervous system to lower anxiety is to use 7-11 breathing. This means you breathe in for a count of 7, hold briefly, and breathe out gently for a count of 11. No matter if you stick with the 7-11 count or some other combination, make sure the out-breath is longer than the in-breath. Practice the breathing technique in a quiet place, and then use it to calm a racing heart and cool a reddening face when you need it. Source

However, it should be realized that this is a Management Technique not likely to “cure” the underlying biochemical abnormality responsible for the symptoms.

It is also worthwhile to try out the Hypoglycemic Diet.

Please discuss this article with your health care worker, doctor or nutritional doctor or therapist.



Also try out taking LECITHIN to activate the Parasympathetic Nervous System as described above.


Arrhythmia or irregular heart beats should always be checked out with a doctor and can often be treated with supplementation with magnesium.

Also read:

Index to Specific Topics and Research

References to Mood Disorders and Nutrition

What is Hypoglycemia?

The Serotonin Connection.
Beating Anxiety and Phobias
Post Traumatic Stress Disorder and Hypoglycemia
Depression: a Nutritional Disorder
Depression: a Disease of Energy Production

36 Responses

  1. Lully says:


    Could a low carb diet lead to these issues? I have been dealing with this for a year now – anxiety, sleep issues, dizziness, etc. I’ve been on Lorazepam for a couple of months now but it doesnt seem to fix the issue, just mask it. I was on a low carb diet the year prior and I noticed that is when my sleep issues started, leading to anxiety, and all the symptoms of overactive nervous system when I go to bed. Please if you can, is it possible the low carb diet is the root of my problem?

  2. Mommy says:

    You don’t know how much this article meanss; I’m NOT bipolar, but almost everything else was written for me. I really need help but can’t get it.
    Thank you for your article.

  3. Gary Martin says:

    When the vagus nerve is stimulated during a bowel movement and the parasympathetic nervous system becomes dominant causing extreme tiredness, dizziness and brain fog, what drug etc. can be taken to prevent this from happening?

  4. Zarko says:

    I can appreciate the hope of fresh perspective on issues of anxiety and phobias, but sadly cannot see any assertions in this article other than that phobias and anxieties are possibly digestive problems?
    Are you serious?

    You are a scientist, for crying out loud, and here is an article that blatantly ignores that correlation does not imply causation.

    This sort of article is extremely dangerous for people trying to come to terms and accept that they might have a real psychological issue – not an illness but emotional issue that wrecking havoc in their lives.

    This line: “The question is how is this related to anxiety attacks or the irrational fears that can wreck people’s lives.” it seems is something you must have asked yourself after you have written the article.

    • Jurriaan Plesman says:

      The idea that anxiety is due to “real psychological issues” has been around for a long time. This may be the reason why conventional treatment of anxiety and phobias have been so unsuccessful. Many scientists and nutritional therapists now agree that there is a connection between anxiety attacks and nutrition. See: http://www.hypoglycemia.asn.au/2011/research-evidence-for-hypoglycemia/#ANXIETY
      Psychonutritional treatment approach to mood disorders is an evidence-based science and is here to stay. It does not deny the benefits of psychotherapy, but states that the nutritional/biochemical aspects of these mood disorders need to be treated first before considering psychological factors.

  5. Paolina says:

    Fascinating! .. and it gives hope for the future. I suffer from anxiety, blushing and thyroid related problems. From what I have experienced, my sometimes extreme emotional reactions to simple events can’t have a psychological cause only; it feels as if something inside is not balanced (and goes beyond rational thinking). I remember once, after a conversation during wich I started blushing and sweating for no reason, a nice man came to me saying he was sorry if he had said something that upset me so much …I told him “don’t worry, you didn’t say anything wrong, it’s my nervous system that plays tricks on me”. I live in Italy, what specialist should I search for to have help? Nutriitionist? Endocrinologist? Thank you in advance!

  6. Lynette says:

    Thank you immensely for this article. This is the first research I have located that links autonomic nervous system issues to anxiety, adrenal fatigue and hypoglycemia. In addition to having these symptoms, I also have FMS/CFS. (Incidentally, it seems that the underlying cause for FMS/CFS seems to be a nervous system malfunction as well. I read recently that patients that had their nerves cut due to excessive sweating developed FMS/CFS symptoms. This makes sense, given that these issues are also a Gulf-War syndrome, which correlates with the use of nerve agents.) I will reference this article on my blogsite, along with upcoming commentary on the connection between all of these conditions (symptoms) and potential treatments for the overarching cause (autonomic). I plan to start treating my nervous system as a whole in order to achieve recovery in all these areas. I have already begun dietary treatment and counseling with Dr. Youngberg Lifestyle Medicine.

  7. Jurriaan Plesman says:

    Thanks Lynette, This is good to hear. You can also contribute to

  8. SG says:

    This article was so helpful for me suffering BP Type II and as a med scientist.
    Do you have any further articles on diet for BP II?

  9. Linda Sinnett says:

    Need info on autonomic dysfuction

  10. Bobbie says:

    My husband has been treated for parasympathetic disorder by his cardiologist for 8 years. His doc says his parasympathetic system is not communicating with his sympathetic nervous system. Over time, the treatment with medication he has received does not seem to be working…at all. My husband moved from Philadelphia where is doctor is to New Orleans, and he should see someone in New Orleans. His physical and mental condition appears to be worsening. He is type 2 diabetes but won’t take meds, post mitral valve surgery 3 years ago, irradiated as a baby for enlarged thymus and had most of his thyroid removed, later submaxillary glad removed on the right, chronic bronchitis, now depression. I don’t know who could treat this disorder. What specialist can help him? I am watching him degenerate before my eyes. So sad and scary.

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