Psychoneuroimmunology examines the connection between the psyche, the nervous system and the immune system. A truly fascinating field. There has been a great deal of research on this since the 1960s. There are now thousands of studies on the topic of how and why our psyche/nervous system can influence the immune system. First, a brief explanation to avoid misunderstandings. When we speak of a "strong" or "weak" immune system, that does not necessarily mean it is "very active" or "not very active". Here, we use the term "strong" immune system to mean one that works very well, correctly and effectively. A poor, "weak" immune system can also be very (over-)active. Just think of autoimmune diseases. In those cases, certain unfavourable areas are hyperactive. The immune system is highly complex, with regulation, counter-regulation, activators and suppressors, information transfer via interleukins, cytokines and other signalling molecules, and a multitude of differently functioning cells. Only the perfect interplay of all these components leads to optimal function.
Why high activity does not necessarily equate to good function can be illustrated with the example of a combustion engine: if 7 cylinders fail in an 8-cylinder engine, then the last remaining cylinder works all the harder, overactive, yet the engine is still weaker and will break down more quickly in the long run. Overactivity therefore does not always mean better performance. So please bear in mind: for the sake of simplicity, a "strong" immune system in this text refers to a "correctly functioning" immune system, and a "weak" immune system refers to a faulty or partially defective immune system with suboptimal functions.
There have recently been some misunderstandings in the media because the distinction between a strong, i.e. well-functioning, and a (hyper-)active immune system was not made. Journalists without immunological training got things mixed up. This has consequences, as not only in autoimmune diseases but also in viral infections, a misactivated immune system — one that is hyperactive in the wrong places — can lead to a worsening of the illness, to a stronger inflammatory response, such that the misdirected immune system causes increased damage without effectively eliminating the virus. Therefore: a good immune system can eliminate the virus without much collateral damage, whereas a "weak" immune system cannot manage this, yet causes collateral damage to our body through hyperactivity in the wrong places. One must not erroneously conclude from this rather linguistic misunderstanding that a weak immune system might be more advantageous in one viral infection or another. We need a "strong" immune system, meaning one that functions properly and optimally.
A second brief foreword on psychological influencing factors. I know from everyday clinical practice that most people still have an incorrect understanding of psychosomatics. That bodily (dys)functions can have psychological causes is something many still find genuinely unbelievable. And then they typically say: "I'm not just imagining it".
Self-Tests on Psychosomatics
That genuinely measurable changes in the body can occur through psychological factors is something you can easily try for yourself with two examples:
Imagine standing very close to a tiger cage at the zoo, looking the tiger directly in the eyes. Now imagine the bars were gone. Your pulse will definitely rise. Measurably. So one can verify the neuronal input, the information travelling along our nerve pathways to the brain, relatively quickly with a simple heart rate monitor. In other words, pure information leads to a measurable physical change.
If that is not enough, here is a 2nd example: Place your left hand flat on a table. Take a hammer in your right hand and strike your left index finger. The cause of the bruised, swollen and bleeding finger is in this case psychosomatic. Your own psyche led you to lift the hand holding the hammer and strike your finger. So even an objectively visible, bleeding wound that everyone can see can have a psychological cause. But please don't try this at home — just imagine it 😉
And so the psyche and the nervous system control a great many functions of our body. Not just the right hand swinging the hammer, or the pulse during a beginning flight response triggered by nearby danger, or blood pressure when the printer or PC plays up again 😉
Avoiding Stress
Stress — the classic when it comes to the influence of the psyche on the body. Studies have shown that positive and, above all, short-term stress activates our immune system. This was also a sensible development in evolutionary terms. When the sight of a sabre-toothed tiger triggers acute stress in a human being. They flee, injuring themselves multiple times on stones, roots and branches. By then, the immune system is already running at full capacity so that these wounds heal quickly and without complications. As is always the case in our body, whether metabolism, immune system, nervous system or other systems, these systems work with regulation and counter-regulation. In other words, acute stress activates the immune system (regulation), whilst chronic stress, i.e. constant activation, leads in the long run to a weakening of the immune system (counter-regulation).
Acute stress: strengthening of the immune system; chronic stress: weakening of the immune system. Somewhat simplified and generalised, but this is usually the case — naturally there are exceptions, as always.
Sleep deprivation weakens the immune system considerably. After just 2 nights of sleep deprivation in healthy men, some immune functions in this study did not normalise even after 3 nights of normal sleep. Many people know this: if you have pulled one or two all-nighters, the scratchy throat almost inevitably follows. Stress, depression and relationship problems in particular weaken the immune system . One frequently observes in life that when a beloved spouse dies, the other follows shortly after. This is no coincidence. A severely weakened immune system is one of the fastest ways to shorten one's life. Similarly after, for example, difficult divorces. Severe illnesses, not infrequently including cancer, often follow for the partners, along with a poorer course of serious cancers.
Positive effects of acute stress through exercise: an acute physical exertion such as sport leads to an increased number of Natural Killer cells (NK cells). Regular strength training can also increase the number of NK cells . In a study, 394 volunteers were given nasal drops containing various viruses that cause respiratory infections (rhinovirus type 2, 9 and 14, respiratory syncytial virus or coronavirus type 229E). The psychological stress factor was determined for these individuals, and it was subsequently observed which subjects became infected, which developed cold symptoms, and how many remained symptom-free. The result showed a clear correlation: the higher the stress index, the more likely illness occurred.
As we can see, the risk of infection — that is, of contracting the virus at all — was higher the higher the Psychological Stress Index was. The result regarding symptom development is similar: the higher the psychological stress level, the more likely an established infection also led to illness symptoms (from 27 % in the lowest stress index to 47 % in the highest). A low stress level not only protects against infection but also against the onset of illness following an established infection.
Social factors, problems in relationships, loneliness and social isolation are a particularly negative stress factor and detrimental to the immune system . Studies have shown that such factors lead to a deficiency in, among other things, the hormone oxytocin. This belongs to the field of psychoendocrinology, which naturally also affects the immune system. Positive social contacts and physical closeness in particular increase oxytocin release and thereby improve the immune system . So: don't forget to give hugs!
When one speaks about psychoneuroimmunology, one thing must not be omitted: the placebo effect. Just as with the topic of psychosomatics, many still believe the placebo effect is merely "imagination". The objectively observable healing rates under placebo are enormous. Greater than most people think. It is no coincidence that new medications must first prove themselves against a placebo in order to be approved. In some cases, healing rates through placebo are 50 % and higher. If the medication then heals 55 % compared to 50 % for the placebo, the medication is attributed an additional effect and is approved. So for perhaps just 5 % more effect, but 100 % more side effects, a medication is brought to market.
As we have learnt so far, the psyche has a considerable influence on our immune system, on our hormones and metabolism, and thus on our health. Psychoneuroimmunology can also explain the placebo effect quite well. The placebo effect is based on the principle of suggestion. Suggestion means: the care, the positive encouragement from the therapist, and the expectation that the medication/placebo will bring healing, relief, and a solution to the problem, leads to psychoneuronal, immunological and endocrinological changes in the body that promote healing. Many now say, "placebo doesn't work on me". Of course, one can actively resist any suggestion. Then it naturally does not work. We know suggestion from autogenic training. Autosuggestion. One can of course harness these positive effects — or one resists and simply does not use them. Those who do not wish to need not practise autogenic training. But those who do can certainly make use of the positive effects.
Naturally, the placebo effect is particularly effective when one does not reject it from the outset. But if one knows it is merely a sugar pill, then the rejection is logically already pre-programmed and no one would expect an effect. In other words, if you tell the subjects that the measure is ineffective, you are suggesting precisely that: no effect. And that is exactly what happens. There is a famous example of the opposite of the placebo effect: the nocebo effect. The nocebo effect means: the suggestion that something is particularly harmful to health also leads to a negative effect on the body and on health. In the famous example , there was a young man who had participated in a study. It was a double-blind study on antidepressants. The young man was given pills and was to take them regularly to test their effect. During the course of the study, he had suffered considerable heartbreak in his private life and wanted to take his own life. So he swallowed all the pills he had (29 of them) to end his life. He was taken to hospital with severe symptoms of poisoning. His circulation was on the verge of failing. The doctors did not know how to save him, as they did not know what medication the pills contained. So enquiries were quickly made, the study leadership was contacted and asked what medication the young man had been given. The records showed that the man belonged to the placebo arm — meaning he had received inactive sugar pills. Which he did not know. Only when he was told this did his circulation stabilise and the life-threatening situation could be immediately resolved. In other words, the young man thought he had taken serious, potent medication in an overdose and would die from it.
One can see here the extreme power of placebo — in this case, the negative power of placebo (nocebo). Suggestion alone had very nearly cost this man his life. This effect exists equally for placebos and nocebos. But the negative effect from this story is surely even more striking. One can see from the nocebo effect what extremely harmful consequences the suggestion of negative things can have. One reason why pessimism, fear-mongering and panic can genuinely damage health. Almost every clinically practising doctor knows this. That is why it is an inherent medical duty to radiate and convey appropriate optimism (not unrealistic, of course) and confidence, likewise to allay fears and to avoid any kind of exaggerated panic or catastrophist atmosphere. For this too is part of health. Unfortunately, many (frequently purely mechanistically thinking, non-clinically active, e.g. laboratory) doctors very often do not know this. For me, this constitutes a key difference between a purely technically thinking medical professional and a physician. For thousands of years, good doctors have harnessed all these positive effects of psychoneuroimmunology to help their patients. In earlier times certainly purely intuitively, nowadays also on the basis of established, robust research findings.
Summary
Our psyche has a considerable influence on our health and specifically on our immune system. This field of research is called psychoneuroimmunology. The effect is enormous. Therefore, the expression that arguably serves as the heading for this branch of research fits particularly well:
„Laughter is the best medicine"
These Tips for a Better Immune System
😴 Healthy Sleep
Regular and healthy sleep is exceptionally important for the immune system.
🧘 Low Stress Levels
A low stress level makes us more resistant to illness. Particularly against viruses (that cause respiratory infections). Less stress means fewer infections and less frequent illness following infections.
🤗 Social Connections
Social contacts, strong social bonds and physical closeness have a considerable influence on the immune system. So: don't forget to give hugs!
😊 Positive Expectations
A positive expectation can bring us greater health, not infrequently even healing (placebo). So think positively (autosuggestion: "I am healthy", "I am fit"). Accept positive encouragement too.
📵 Avoid Nocebos
Nocebos can markedly harm our health. Therefore the news (as it is almost always negative) can significantly damage our health. Negative news can thus make you ill through the nocebo effect. So: try more often to simply not read, listen to or watch the news.
🧠 Mindfulness & Exercise
Learn (mindfulness) meditation. Free the mind from negative external and internal influences. This also works very well through sport and exercise. And of course, join in the mental training!
How Does Proper Nutrition Strengthen the Immune System?
Immunonutrition – Nutrition for the Immune System
Immunonutrition is a complicated word. But actually it is quite simple. It comes from immun(e system) and nutrition. So nutrition for strengthening the immune system. Food strengthens the immune system. Certain nutritional components do so particularly well. From this insight, the term immunonutrition was established in clinical medicine. It has been a topic in hospitals for a long time. Because a patient's nutritional status is a decisive factor in their subsequent course of recovery.
Large multicentre studies have clearly demonstrated the positive effects of specialised nutrition. Complication rates after operations are significantly reduced as a result. Infection rates in particular, but also the length of hospital stays , .
Particular nutritional components simply get patients back on their feet faster, strengthen the immune system, so that infections occur less frequently. So which components are used in immunonutrition? Primarily the essential nutritional components. There are approximately 47 of them. Namely the amino acids (proteins), vitamins, minerals and trace elements. The following nutritional components have proven to be particularly important for the immune system:
Vitamin C – High concentration in neutrophil granulocytes (immune cells), improves their function. Activates natural killer cells (NK cells) and thereby the immune system , , , . Important for wound healing. Vitamin C is responsible for the formation of collagen. This enables the production of new tissue .
Vitamin D – Stimulation of the immune system
Vitamin E – Stimulation of the immune system, T-cell activation
Zinc – Essential for the immune system
Glutamine, Arginine, Omega-3 Fatty Acids
and many more.
There are now many ready-made immunonutrition formulations available. These are also used clinically. They contain the aforementioned micronutrients as well as further essential vitamins, minerals, trace elements and amino acids. Simply the essential substances that the body needs for health. Clinical studies on patients have clearly demonstrated that this also works in practice. The complication rate after operations is lower: fewer infections, better and faster wound healing . Yet hospitals still serve only cheap "junk food" from outsourced suppliers (daily cost per patient for 3 meals: 3 euros). Believe me, I had to witness this for 18 years in the clinic. I always asked myself: how is a wound supposed to heal when no building material is coming in? The soggy bread roll, ultimately just sugar, certainly cannot be converted by the body into collagen and fibroblasts to heal a wound. Especially patients who receive such food for extended periods. Colleagues would often stand bewildered at the bedside, marvelling at why the wound simply would not heal. Well. Not even thinking beyond the obvious.
Not only after operations, but in general: the body regenerates itself every day. And for that it simply needs these necessary nutrients. Without them, there is no regeneration. Then there is only degeneration — rapid ageing and wear and tear. Premature age-related diseases. Therefore, give your body what it needs and it will repay you by continually regenerating, staying young and healthy.
Why am I able to write all of this as established knowledge? Because the studies are listed below. Because it has been proven. And because I have personally researched this topic and my doctoral thesis is about it (at last I get to cite myself ;-) ).
Does Vitamin C Help with the Common Cold?
The common cold is an umbrella term for acute viral infections of the upper respiratory tract (cough/runny nose/hoarseness). What many people experience regularly every winter. Under the common cold, infections of the upper respiratory tract are grouped together (URTI = upper respiratory tract infection). These are caused by viruses in 70–80 % of cases, such as rhinovirus, coronavirus, adenovirus, influenza and parainfluenza virus, respiratory syncytial virus and coxsackievirus. The remaining 20–30 % are bacterial .
The question of whether vitamin C helps against this, or protects against it, has been investigated in many studies. Some of these studies (the high-quality ones) have been compiled in meta-analyses. I would like to present 2 meta-analyses on the topic here.
The Cochrane meta-analysis comprises a total of 11,306 patients. No studies were included that examined a dose of less than 0.2 g of vitamin C per day, and no studies without placebo control. A distinction was made between whether participants took vitamin C regularly or only therapeutically, i.e. only began taking it when symptoms appeared. Only the group that had taken vitamin C regularly showed positive effects. The other group (i.e. those who only took vitamin C briefly during the cold) showed no effects whatsoever, neither positive nor negative. What do we learn from the study? Simply taking vitamin C briefly when you are already ill does little. It is better to take vitamin C regularly. Here are the effects:
8%
Reduction in illness duration in adults
14%
Reduction in illness duration in children
18%
Reduction in children taking 1–2g vitamin C/day
The study clearly states that the 14 % figure for children is a poorer result, as it came from studies with lower doses. This means that if children only showed better results with a higher dose of 1–2 grams per day, then I would venture to say that for adults one probably needs to think more along the lines of 2–3 grams of vitamin C per day (that is certainly how I handle it personally).
In a further meta-analysis of 9 randomised controlled trials, it was shown that vitamin C could shorten the duration of common colds, as the Cochrane analysis had already demonstrated. However, it was also shown here that the severity of symptoms could be reduced. Fever, chest pain, muscle and joint pain could be significantly reduced. It was also demonstrated that regular intake (e.g. 1 gram of vitamin C daily) followed by an additional higher dose when symptoms appear (approximately 3–4 grams of vitamin C) shows a more positive effect and accelerates recovery. By contrast, the therapeutic dose alone (i.e. only when symptoms occur) could not achieve any difference compared to placebo. This means only the regular intake of vitamin C is beneficial; one can then also take an additional higher dose at the onset of illness.
The authors ultimately recommend a daily intake of approximately 1 gram of vitamin C, and during illness 3–4 grams of vitamin C per day.
Many simply claim that vitamins are of no use. Very few will know these studies. Anyone who makes this claim must first scientifically refute these studies. With a Cochrane analysis, that could prove rather difficult. We only recommend things that we can substantiate, for which there are scientific/biochemical, logical connections or clinical data. These two aforementioned studies are, for me, very good evidence and the reason I personally take vitamin C regularly. One does not have to, of course. It is obviously a matter of personal choice. But if others (including and especially many colleagues) simply claim that vitamins are of no use, they would first need to refute these studies scientifically and statistically correctly (citing a "rubbish study" with 0.2 grams or less of vitamin C, which naturally cannot show any effects, is insufficient for this purpose).
Of course, the effects of a single micronutrient with, say, an 18 % reduction in illness duration are not extreme. But there are also many other important micronutrients that are highly relevant for the immune system. Only the combination and complete, optimal supply can logically bring the optimal effects.
Strengthening the Immune System with Vitamin D
In an article about "strengthening the immune system", vitamin D must not be omitted. There are entire books about vitamin D; one could write about it for days on end. However, as we have been experiencing for some time — and particularly at present — that a great deal is said and written (especially by the press and other media) without genuine foundations, without real scientific data, and very often even (negligently) without references, we wish to present only actual scientific data here. Unfortunately, claims are made with increasing frequency, even by experts, that do not withstand rigorous scientific scrutiny. We therefore wish to focus entirely on scientific studies on the topic of "strengthening the immune system". We want to know: what truly helps the immune system and protects against infections (respiratory infections in particular are of great interest to us at present), and what is actually scientifically confirmed.
A placebo-controlled, prospective, randomised double-blind study (i.e. the gold standard of studies) on the duration of upper respiratory tract infections, even with the (very low) dose of 10 µg vitamin D (400 IU) per day over 16 weeks compared to placebo, achieved a reduction in illness duration of 23 % (from an average of 13 days to 10 days) .
It is not only the relatively harmless "upper respiratory tract infections" as described in that interest us, but particularly the rate of pneumonia (lung infections). Also in , everyone was simply given 400 IU of vitamin D regardless of their blood level. The intriguing question, however, is how blood levels of vitamin D relate to this. On this point, there is a fascinating study: the correlation between vitamin D levels and the rate of pneumonia in elderly patients was determined. Result: of the patients with pneumonia, 71.4 % had a vitamin D deficiency, compared to 19.3 % vitamin D deficiency in those without pneumonia.
As with elderly patients in , the same has also been described for children. Children with a vitamin D deficiency have an increased risk of developing pneumonia . A further study shows the same result for neonates/premature babies .
In this laboratory study , it was demonstrated to what extent vitamin D alleviates the severity of inflammation in interstitial pneumonia and protects lung tissue. I mention this because when we speak colloquially of "strengthening the immune system", it is important to know that at a molecular biological level it is not simply always a matter of activation (one might then also think "overactivation"), but rather of optimised function, a regulation of the immune system. For vitamin D in particular is also helpful against autoimmune diseases. I would therefore ask you to accept "strengthening" as a linguistic simplification. For those with a scientific interest: we see in the studies an optimisation and controlled regulation of the immune system. The immune system is highly complex; individual factors are upregulated, others downregulated, and in the best case this leads to optimisation (which we then simply refer to as "strengthening" for ease of expression).
So far, all just smaller studies and pieces of research. One might now ask: where is the proof? Very well, here it is: a large meta-analysis from 2019 covering 8 studies with 20,966 people on vitamin D levels and the risk of pneumonia .
64%
Higher pneumonia risk with vitamin D deficiency
20,966
Subjects in the meta-analysis
23%
Shorter illness duration with vitamin D
Result: a vitamin D deficiency increased the risk of pneumonia (community-acquired pneumonia/CAP) to 1.64 times (odds ratio), or put differently: vitamin D deficiency means a 64 % higher risk of pneumonia. If you now think, well, it is only a bit of pneumonia: in the USA there are approximately 5.6 million cases of pneumonia per year, of which around 1.1 million require hospitalisation. Of these hospitalised patients, the mortality rate within 30 days is 20 % and within one year 30 %. That means approximately 330,000 deaths from pneumonia (note: that is regularly around 900 deaths every day, all year round). Calculated without vitamin D deficiency, we would arrive at 201,000 deaths. That means 129,000 fewer deaths from pneumonia alone, in the USA alone, from vitamin D alone. Data from a large meta-analysis. But vitamins are of no use, according to the mass media.
Only one large study from 2019 under point 5? No, we do not wish to rely on just a few scientists, so here is another analysis: a group from Harvard Medical School conducted a similar investigation in 2013: an analysis of 1,975 people. Result: those with a vitamin D level below 30 ng/ml had a 56 % higher risk of developing pneumonia .
Finally, something other than pneumonia. Hospital-acquired infections. A very recent prospective study published in March 2020: the comparison of vitamin D levels and the rate of nosocomial infections following liver surgery. Result: a higher vitamin D level lowers the risk of a hospital-acquired infection (a so-called nosocomial infection). What is particularly interesting is that the higher the vitamin D level, the lower the risk. The study calculated that for every increase in vitamin D level of 26.2 nmol/l, there was a 34 % reduction in infection rate.
7 studies, some of them meta-analyses with thousands of subjects, demonstrating the effect of vitamin D against infections. Including respiratory infections, and pneumonia in particular, which is of especial interest to us at present. There are many further publications on this. If I wanted to present them all, this article would not appear for at least a year. But I believe the fundamental message is clear: that vitamin D supports, maintains and "strengthens" our immune system is clearly demonstrated in many scientific publications. We see in the studies that those which took vitamin D blood levels into account are the better and more meaningful ones. So with vitamin D, the laboratory value is particularly important. Normal range: 30–100 ng/ml. Target value: 70 ng/ml (60–80).
And these extreme effects from the studies from vitamin D "alone". As we have seen, vitamin C "alone" and zinc "alone" also have considerable effects. What if one combined all 3? What if one supplied ALL 47 essential nutrients in sufficient quantities for optimal immune system function?
Quellen
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