What does stress do to the body?

How is the body designed to deal with stress?

Recently, we did a blog post on sleep where we essentially covered ‘rest and digest’. This post is about the other mode the body can be in, which is ‘fight or flight’. When our brains perceive that we are in a ‘life-threatening’ situation, we activate our stress response which results in an activation of the sympathetic nervous system. In Palaeolithic times this fight or flight response would be useful to run from a sabre-tooth tiger and survive in the wild. In those situations the body temporarily stops prioritising the digestive system, or the functionality of the reproductive system. At these life or death stress situations, your body needs to focus all its energy on getting you out of that situation (whether by fighting or running away) and not in digesting food (if anything, you’re more likely to quickly dump the contents of your bladder/bowel!). Today though, our stressors are more often those that last much longer, such as work or social distresses, and we don’t exert the potential the body creates to get us out of that stressed event.

Types of Stress

Stress can be anything negative from physical to psychological trauma. Two categories of stress fall under acute stress (eustress) which is an alarm reaction to which recovery quickly follows. Eustress can also be enjoyable, like those who can be characterised as ‘adrenaline junkies’. It can be positive and motivating too. This kind of stress can also be lifesaving.

Chronic stress (distress) that is constant and repeated impairs the immune system, cascading into being detrimental for overall health. As the body cycles through prolonged or repeated alarm reactions, receptors in the hippocampus become desensitised and damaged.

There are many, many cascading signs and symptoms of Adrenal Stress:

  • Anxiety
  • Cognitive dysfunction
  • Confusion
  • Dark circles under eyes
  • Decreased ability to handle stress
  • Decreased memory recall
  • Decreased libido
  • Decreased productivity
  • Depressed mood
  • Difficulty concentrating
  • Difficulty waking up in the morning
  • Fatigue not relieved by stress
  • Feeling better after eating (blood sugar)
  • Insomnia
  • Lethargy

The HPA Axis

The stress response is managed by the HPA axis. This stands for Hypothalamus, Pituitary and Adrenal. These are three glands (hypothalamus and pituitary in the brain and adrenals on top of the kidneys) that release hormones and communicate with each other. The HPA axis connects the nervous system with the endocrine system. The process works like this:

The hypothalamus releases a hormone called CRH (sometimes written CRF) which binds to receptors in the pituitary, the pituitary releases ACTH which binds to receptors on the adrenal glands and stimulates the release of cortisol. Cortisol will continually be produced for a while, or at least until a concentration has reached a high enough level in the blood. When this happens CRH will stop being produced in the hypothalamus and blood levels will return to normal. With sustained stress, this process becomes dysfunctional and breaks down. This can be characterised as HPA dysfunction (commonly called Adrenal fatigue).

The Science

Chronic amounts of stress will result in a hyperactive (overactive) HPA axis and then lead to a hypoactive (underactive) HPA axis, and prolonged release of glucocorticoid hormones. The primary stress hormones that are released by the adrenals are glucocorticoids aldosterone and cortisol. These increase oxidative stress damage to neurons, in part by increasing glutamate and calcium (from the bones) and decreasing antioxidant enzymes.

Aldosterone is a hormone which increases water retention to increase blood pressure. Often when a stressful situation arises, our blood pressures spikes and aldosterone is part of that mechanism.

Cortisol is a stress hormone released by the adrenal glands and is mostly associated with stress. Cortisol increases glucose production (boosting blood sugar), protein catabolism and vessel sensitivity. It stimulates fat breakdown and inhibits glucose uptake in the muscles, which of course is useful for the fight or flight mode. Cortisol in high amounts can also break down bone matrix leading to low bone density. This can lead to osteoporosis when the bones become porous. Cortisol suppresses the immune system, and one of the ways it does so is by decreasing the inflammatory response. At first glance this would seem like a good thing, and often it can be. However inflammation is also a normal and vital part of the immune system in appropriate amounts. Inflammation only becomes a problem when it is prolonged and does not shut off causing long term damage. Small instances of inflammation can instruct the body to heal.


Elevated levels of circulating cortisol inhibit the thyroid axis, reproduction and growth hormone. Oestrogen is maintained not only by the ovaries, but also the adrenals, so it’s no wonder that PMS is a common disorder associated with high levels of stress. Cortisol release is increased with physical trauma, infection, anxiety, extreme temperatures and exercise to the point of exhaustion.

DHEA is a hormone and precursor to other hormones such as oestrogen. It counterbalances the effects of cortisol because DHEA possesses significant anti-glucocorticoid (cortisol and aldosterone) activity. Higher DHEA to cortisol ratios are much more optimal for toleration of stress. Low levels of DHEA indicate depression, impaired learning and memory, osteoporosis, low libido, inflammation and more. It is also suggested that DHEA might slow the ageing process.

HPA dysfunction (adrenal fatigue) occurs in phases. First comes the acute phase where the initial trauma/shock occurs. Then, the resistance phases where the body begins to adapt and get used to the ongoing stress but gradually gets tired. Then there is the exhaustion phase and you are no longer able to cope due to the length of the ongoing stress.

Alarm, Resistance and Exhaustion

Stages of cortisol and DHEA in HPA Dysfunction / Adrenal fatigue:

StageCortisol LevelDHEA Level
Resistance 1HighNormal
Resistance 2HighLow
Resistance 3NormalLow

This chart can be useful to see which nutrients can be used to support you. Cortisol certainly comes off as the ‘badie’ but as you can see that in the exhaustion phase cortisol is low, and we need the levels to be in a normal range. The further down the chart you go, the more chronic the stress response becomes over time. Nutrients used are sodium, magnesium, selenium, copper, vitamin C, D, E, Bs and amino acids.

The Alarm stage is very inflammatory and so the resistance phases attempt to bring down that inflammation. This is the phase that reduces the priority of certain bodily systems that are immediately required for the stressor (e.g. digestive system). During the alarm phase, you might experience increase blood pressure, suppressed appetite and increased cognitive arousal. Nutrients that get used up in this phase are amino acids, vitamins C, D, E and B vitamins.

The resistance stage is where the body attempts to resolve the stressor and transition into adaptation. Nutrients used here are potassium, iron, zinc, magnesium, vitamin A, C, Bs and amino acids. If resistance persists, the long-term demand for nutrients becomes a strain.

The exhaustion phase has also been named ‘adrenal burnout’ and can feel like a complete depletion of energy. This is where the glands in the body are unable to keep up with the demand of hormones required to maintain energy levels. Your adrenals should not be the primary energy supply, but the stress response makes them becomes just that, which can’t be sustained. This if often when people get their energy supply from blood sugar which is not ideal and can lead to insulin resistance.

This depletion of nutrients which are needed throughout the body will take its toll. When other bodily functions such as the digestive system are no longer a priority you can’t be surprised as to why stress can be a cause of so much ‘dis-ease’ in the body. Especially considering many health experts say that all illness begins in the gut, and 80% of the immune system is in the gastrointestinal system.

Stress hormones inhibit the function of immune cells such as neutrophils, macrophages, T and B lymphocytes, pro-inflammatory cytokines and adaptive immune responses. This of course will exacerbates and allow viral and bacterial pathogenesis, slow wound healing and alters autoimmune disease.

Stress effects the thyroid as CHR reduces thyroid stimulating hormone and cortisol inhibits conversion of other thyroid hormones. Activation of the HPA axis results in increased CRH and cortisol which is associated with decreased production of thyroid stimulating hormone. Glucocorticoids (cortisol and aldosterone) inhibit the activity of the enzyme 5-deiodinase which converts the relatively inactive thyroxine to the biological active T3.

Stress can lead to premature ageing because stress causes oxidative stress and lower telomerase activity and shorter telomere length, which are known determinants of cell ageing and longevity. Oxidative stress results in damaged cells which cause them to age quicker both inside and of the skin.

Nutrition Tips

One of the worst things you can do when in periods of stress is to miss a meal, which can be very easy to do as appetite is generally suppressed, and often in stressful situations food isn’t the first thing on your mind. But missing meals, or even just snacking on high carbohydrate foods can create a hypoglycaemic state which induces the stress mechanism further and releases cortisol.

Caffeine should be avoided when chronically stressed and when trying to avoid adrenal fatigue as caffeine itself increases cortisol, and so will have an additive effect to already high levels.

As blood pressure is a major factor in stressful situations, be sure to reduce sodium and increase potassium to level your BP. Prolonged high blood pressure can cause damage to your arteries.

Stress depletes the body of nutrients, so as always, eat a variety of nutritious foods to replenish your body’s supplies.

Priorities slow release foods such as complex carbohydrates to release energy gradually and avoid the negatives of blood sugar dysregulations. Complex carbohydrates also boost serotonin in the brain which is a ‘feel-good’ hormone which can alleviate stress and anxiety. Complex carbs also tend to have a good fibre content which is good for blood sugar balance, digestive function and wasted hormone clearance.

Proteins contain amino acids which are depleted through the alarm and resistance phases of stress. Amino acids are the building blocks to hormones and neurotransmitters that are needed in the requirement to keep the HPA axis running.


Magnesium is already a very widely deficient mineral, but it is drastically depleted when the body is stressed. Magnesium reduces the activity of the HPA axis due to its NMDA and GABA antagonistic properties. You can try magnesium topically too in sprays, or in magnesium flake baths as one of the best way to absorb magnesium is through the skin.

Vitamin B5 is an important part of coenzyme A, which is essential for the formation of cortisol in the adrenal cortex. It has been effective in treating fatigue and anxiety. B5 is necessary for fatty acid synthesis and degradation, steroid synthesis and metabolism of carbohydrates and protein. Deficiency in B5 is associated with adrenal atrophy, and is likely the most important B vitamin for stress.

Vitamin B6 deficiency has been identified as a significant predictor of increased overall psychological stress. Being a regulator of hormones, B6 is often a good choice to support through stress.

Vitamin B12 is required in mechanisms that affect mood and is one of the key B vitamins for the nervous system which, if compromised can lead to anxiety and depression which of course is connected to stress. B12 is necessary for methylation reactions necessary for the body to overcome genetic susceptibility to stress (read more about methylation here).

Vitamin E has been shown to protect the adrenal cortex from free radical damage and reduce cortisol production.

Herbal adaptogens such as Rhodiola, Liquorice and Ashwaganda for the first signs of adrenal fatigue. Adaptogens are natural herbs that have non-specific, normalising effects on physiology; they influence normal body functions only enough to encourage non-specific resistance to stressors. Other adaptogens include Siberian ginseng, withania somnifera, shisandra chinesis, cordyceps and gingko biloba. Be cautious if you have typically low blood pressure as liquorice can lower your BP further.

Rhodiola, is a great example of an adaptogen that works on the hypothalamus to increase resistance to toxins and stress. It improves the oxygen carrying capacity of the blood, helps stimulate endurance and mood elevation.

Potassium is a good nutrient to have to look after your adrenal glands so be sure to consume foods like bananas that are high in this mineral.

Vitamin C is necessary for the conversion of cholesterol into pregnenolone, one of the initial steps in cortisol production. It also helps in the production of sex hormones and DHEA. So it gets used up very quickly in stress, but is in high demand to combat all the oxidative damage that occurs due to stress. The requirement for vitamin C increases in result to stressors as it quickly depletes. Vitamin C can help individuals bounce back from stress much quicker and easier.

If you are concerned about your stress levels and think you might have HPA dysfunction, you can ask your practitioner to order you a salivary test which measures your cortisol and DHEA levels throughout the day.


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