The vagus nerve and its role in feeding

What caresses the nose, hugs the heart
April 11, 2017

By Dr Melodie de Jager

The vagus nerve is called a wandering nerve because it is the longest cranial nerve and ‘wanders’ to the pharynx, heart, lungs and entire digestive tract. This is important information for a new mom and dad, as a baby’s emotional state can affect the functioning of the vagus nerve, and the way a baby feeds and sleeps.

The vagus nerve is one of 12 cranial nerves and is also known as cranial nerve X. The vagus forms part of the involuntary nervous system and commands unconscious body procedures, such as keeping the heart rate constant and controlling food digestion. (www.healthline.com/human-body-maps/vagus-nerve)

HOW DOES IT WORK?

The vagus sends nerve energy via four branches to:

  • The pharynx – the soft part at the top of the throat that connects the mouth and nose to the esophagus (the tube that takes food to the stomach) and the larynx (the part of your throat between the nose and lungs that contains the vocal cords). (Cambridge Advanced Learner’s Dictionary & Thesaurus © Cambridge University Press). This helps a baby to latch and suckle well.
  • The heart to beat rhythmically
  • The lungs to breathe rhythmically
  • The digestive tract to metabolise food effectively.

When a baby’s mouth feeds rhythmically and the heart and breathing rates are steady this suck-swallow-breathe trio works in perfect harmony and Baby feeds, metabolises and sleeps with ease. But when Baby feels overwhelmed, or stressed the heart and breathing rates increase, and the vagus nerve reads the increase in rate as an emergency. It then redirects the nerve energy away from the pharynx to support the heart and that is why the mouth goes dry when you are stressed. The vagus nerve also redirects the nerve energy away from the digestive tract to support the lungs and that is why you ‘have butterflies in your tummy’ when you are anxious or nervous.

In a baby this means latching can become more difficult and the suck-swallow-breathe- trio gets disturbed. These are the perfect conditions to gulp air with milk, and to develop colic and reflux. The worst of it all is – a baby who battles to feed, battles to sleep.

WHAT CAN YOU DO?

Be mindful that a baby needs time to get used to living outside the womb where clothes, a variety of scents, loud sounds, light and space, frightens Baby. A frightened baby’s heart beats fast and lungs breathe shallowly, which disturbs feeding and sleeping.

In the first few weeks, mimic in-utero conditions as much is possible –limit contact with people other than mom and dad and bright light.

It would also be wise to be mindful of sharp smells, such as cleaning materials and mosquito spray, as the membranes in Baby’s nose are still fragile. Vary kangaroo care with tummy and back time on a flat surface so baby gets used to space and feeling his body move, while exploring space.

If Baby is upset, use two fingers to gently and slowly tap Baby’s breast bone. It works like a pace-maker and has a calming effect to restore the suck-swallow-breathe rhythm for easy feeding and sleeping.

Gently rub the hollow under the clavicle (collar bone), in line with the left eye, right next to the breastbone. This stimulation seems to have a positive effect on the vagus nerve and helps Baby to relax. When the vagus nerve energy flows to the pharynx and digestive track, and not only to the heart and lungs for survival, Baby feels calm and nurtured. Baby can now feed rhythmically and sleep peacefully.

A content baby feeds and sleeps with ease.

HOW OFTEN CAN YOU STIMULATE THE VAGUS NERVE?

Stimulate the vagus nerve when Baby is upset or niggly. Always mimic in-utero conditions first before you do vagus stimulation – a bright room or noisy mall may keep Baby in survival. Read your baby, he or she will use movement and a variety of cries to talk to you. Trust your instinct. You are a good mommy!

‘NERVY FACTS’

Jordan Rosenfeld shares what he calls ‘nervy-facts’ about the vagus nerve:

  1. The vagus nerve prevents inflammation

With a vast network of fibers stationed like spies around all your organs, when the vagus nerve gets wind of inflammation, it alerts the brain and elicits anti-inflammatory neurotransmitters via the cholinergic anti-inflammatory pathway. A certain amount of inflammation after injury or illness is normal. But an overabundance is linked to many diseases and conditions, from sepsis to the autoimmune condition rheumatoid arthritis. 

  1. It helps you make memories

A University of Virginia study showed success in strengthening memory in rats by stimulating the vagus nerve, which releases the neurotransmitter norepinephrine into the amygdala, consolidating memories. Related studies were done on humans, opening promising treatments for conditions like Alzheimer’s disease.

  1. It helps you breathe

The neurotransmitter acetylcholine, elicited by the vagus nerve, literally gives you the breath of life by telling your lungs to breathe.

  1. Its intimately involved with your heart

The vagus nerve is responsible for controlling the heart rate via electrical impulses to the sinoatrial node of the heart, where acetylcholine release slows the pulse. The way doctors determine the “tone” or “strength” of your vagus nerve (and your cardiac health) is by measuring the time between your individual heart beats, and then plotting this on a chart over time. This is your “heart rate variability.”

  1. It initiates your body’s relaxation response

When your ever-vigilant sympathetic nervous system revs up the fight or flight responses—pouring the stress hormone cortisol and adrenaline into your body—the vagus nerve tells your body to chill out by releasing acetylcholine. Its tendrils extend to many organs, acting like fiber optic cables that send instructions to release enzymes and proteins like prolactin, vasopressin, and oxytocin, which calm you down. People with a stronger vagus response may be more likely to recover more quickly after stress, injury, or illness.

  1. It translates between your gut and your brain.

Your gut uses the vagus nerve like a walkie-talkie to tell your brain how you’re feeling via electric impulses called “action potentials”. Your gut feelings are very real.

  1. Overstimulation of the vagus nerve is the most common cause of fainting.

If you tremble or get queasy at the sight of blood or while getting a flu shot, you’re not weak; you’re experiencing “vagal syncope.” Your body, responding to stress, overstimulates the vagus nerve, causing your blood pressure and heart rate to drop. During extreme syncope, blood flow is restricted to your brain, and you lose consciousness. But most of the time you just have to sit or lie down for the symptoms to subside.

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