How to Keep your Immune System Healthy


Since the lockdown initiated there has been a renewed interest in ‘wellness’ especially when it comes to maintaining a healthy immune system. The NHS and health services have never been this stressed in recent memory and we can play our part by staying as healthy as possible in order to lighten the load on the health system. Aside from avoiding non-emergency services one of the key things we can all do is stay in good mental and physical shape where possible. A cornerstone of this, is a strong immune system. The human immune system is a complex system comprised of key organs, cell types and signalling molecules all of which are designed to combat against internal threats including parasites, viral infections and bacterial infections. It is also very important in tissue repair following injury. Think of the immune system as a tiny army constantly circulating thorough your body that distinguishes ‘friend’ i.e. your own tissues from ‘foe’ i.e. any foreign bodies or pathogens. If a ‘foe’ is detected a range of responses are triggered, depending on the foe, that are designed to eliminate the threat as quickly as possible. Many of the symptoms we associate with being ill like fevers and runny noses are not strictly caused by the pathogen but are actually your bodies attempt to destroy them.

Typically, the immune response to a pathogen falls into two categories.

  • Innate Immune Response

This is a basic, all-purpose response to pathogens that all plants and animals possess. This response is mainly driven by a white blood cell type called leukocytes. The main issue with the innate response is that it is non-specific i.e. it is a sort of blanket response and isn’t designed to home in on any one particular pathogen. Many pathogens can evade this type of response.


  • Adaptive Immune Response

A targeted response that involves immune memory i.e. your immune cells ‘remember’ the pathogen that triggers this response so you can effectively fight it next time it is encountered. This is the basis by which vaccinations work. This type of response takes longer to occur and typically involves antigens, B cells and T cells.

Thinking of your immune system as an army helps to understand why it must be properly nourished. A poorly nourished army fights badly and that should be avoided. Your immune system gains nourishment from a range of things including good sleep, balanced diet, light exercise, avoiding excessive vices and supplementation.



Unsurprisingly, sleep and rest affect the functioning of the immune system (1). A lack of sleep also known as sleep deprivation is detrimental to immune function (2). It is thought that some immune system signalling pathways and their components (immune factors like cytokines) may play a role in the regulation of non-rapid eye movement (REM) sleep, hence why issues with immune system function might impact sleep regulation thus creating a cycle (3).

Bad sleep à Decreased immune function à Worse sleep à Weakened immune system

The medical community has known for years the negative impact that poor sleep or disruptions to our natural day/night cycle can have on health. It is no coincidence that shift workers and those working at night show increased risk of developing chronic conditions such as heart disease and asthma (4). It has been shown that sleep deprived individuals mount a less-than-normal response to active immunisations i.e. they do not produce as many antibodies in response to a threat as rested people do. Additionally, key proteins which are linked to both the sleep cycle and immune functions can be adversely affected by disturbances to natural light and dark cycles.

This is a very complex area of science when the intertwining of two systems are concerned and we do not have all the answers. However, what we do know is that poor sleep is associated with worsened immune function. Therefore, the first port of call in defence of this is to ensure your sleep is of decent quality. Not everyone needs 8 hours a night and anywhere from 4-9 hours is within the normal range. The quality of the sleep matters.


  • Try turning off electronic devices an hour before bed.


  • Read a good old-fashioned book prior to sleep instead of a kindle or phone.


  • Invest in good quality blinds or curtains that really darken your room


  • Avoid alcohol or stimulants like caffeine for at least 3 hours prior to hitting the hay.




Exercise is any physical activity that enhances or maintains physical health and wellness. We often encourage our readers to exercise as even short, light exercise is better than none. While exercise has a vast range of health benefits beyond the scope of this blog, what about exercise specifically in relation to immune system health?

Large sets of epidemiological data suggest that moderate exercise has a beneficial effect on the human immune system as a whole. Moderate exercise has been associated with a 29% decreased incidence of upper respiratory tract infections (URTI) (5). Interestingly, extreme exercise can actually suppress the immune system by decreasing the concentration of lymphocytes (6). However, we are espousing the virtues of light to moderate exercise!

Biomarkers of inflammation such as C-reactive protein, which are associated with chronic diseases, are reduced in active individuals when compared to sedentary individuals who do not exercise, and the positive effects of exercise are probably due to its anti-inflammatory effects. For example, in individuals with heart disease, exercise lowers blood levels of fibrinogen and C-reactive protein, an important cardiovascular risk marker (7).



Everyone likes a vice but despite the shocking statistics, millions of us continue to smoke and drink far too much. During lockdown, the sale of cigarettes and alcohol have skyrocketed. Most people like a drink, us included, but alcohol being legal doesn’t make it safe. Alcoholism and alcohol-related injuries cost the NHS 10’s of millions of pounds a year and that is not including the increased disease rates that stem from overindulgence. Alcohol, for example, is the 5th leading cause of cancer and smoking (first and second hand smoke) causes 15% of preventable deaths worldwide (8).

Doctors, clinicians and surgeons have long observed an association between excessive alcohol consumption and adverse immune-related health effects such as susceptibility to pneumonia. In recent decades, this association has been expanded to a greater likelihood of acute respiratory stress syndromes (ARDS), sepsis, alcoholic liver disease (ALD), and certain cancers with the list continuing to expand (9); a higher incidence of postoperative complications; and slower and less complete recovery from infection and physical trauma, including poor wound healing. Smoking too, has a serious impact on wound/surgery recovery and general immune system function (10).

We’re not in the business of ordering people around but the evidence is clear. Alcohol consumption should be moderated and if possible, you should think about quitting smoking. No other recreational human activity has been directly linked to death as much as smoking has. It’s very bad for multiple aspects of your health – no two ways about it. This is especially relevant with COVID-19 which primarily destroys the lungs. Your prognosis will be worse if you are a frequent smoker.



Good diet and nutrition are not only critical in maintaining a strong immune system but are also critical in the initial development of the immune system into a heathy one. Diseases that typically, but not always, stem from ‘overnutrition’ like Obesity and Type 2 Diabetes are typified by low-grade inflammation and adverse effects on immune function. Specific malnutrition including a lack of certain key minerals and vitamins can also compromise the immune response (11). Conversely, a diet rich in fatty acids may help support a healthy immune system (12). To hammer home the point of nutrition’s involvement in immune system health, undernourishment during human development can lead to permanent issues with the immune system (13).

A balanced diet, rich in vegetables, proteins and carbohydrates is a good for numerous aspects of health including the immune system. Fatty acids, which can be obtained from numerous foods including nuts and oily fish may be of particular benefit.



There are numerous supplementation options which evidence suggests can aid immune system functioning especially in those with deficient diets. Some of these options provide compounds and molecules that the immune system desperately needs in order to function properly, other supplements appear to interact with the immune system in a unique way, potentially boosting performance. Other supplements still may be able to indirectly support the immune system by aiding processes which we know are good for immune system health i.e. sleep support supplements.


CBD (Cannabidiol)

CBD may be useful in immune system maintenance in two important ways. The first relates to emerging evidence in rodent trials (and small-scale human studies) that suggest CBD and other cannabinoids may modulate sleep patterns. In rodent trials in particular, CBD increases total time spent asleep as well as sleep latency (14). We know from previous discussion that sleep is important in immune system maintenance. Despite what many CBD businesses and marketers will parrot, we are only just beginning to understand the complex interplay between cannabinoids like CBD and sleep regulation. While cannabinoids do have demonstrable effects on sleep, we need larger studies to determine how this happens and make definitive conclusions.

CBD also appears to have direct effects on the immune system that stems largely from the compounds anti-inflammatory properties. In support of previous rodent studies, experiments using human cell lines showed that CBD can have significant effects on the production of inflammatory cytokines meaning it could be useful in addressing aberrant inflammation (15). Many studies in rodents, cell lines and small human trials have shown that cannabidiol may have utility in treating diseases which stem from inappropriate immune system activation (inflammation and oxidative stress). This would include but is not limited to Diabetes Mellitus (Type 1 and 2), Inflammatory Bowel Disease such as Crohn’s as well as Depression and General Neuropathic Pain (16).

It seems then, that cannabidiol’s main effect is suppression of inflammation and suppression of the immune system but as always, things aren’t quite that simple. There is also evidence that CBD can somewhat ‘strengthen’ the immune system or at least direct it towards certain outcomes that can be perceived as ‘strong. For example, various in vitro (cell line) experiments have shown that cannabinoids like CBD induce apoptosis (controlled cell death) in cancerous cells (breast and prostate) (17). It is worth bearing in mind the CBD can also produce proliferation of immune cells as well and whether CBD induces growth or induces death in cells could be down to a number of factors including dose and experimental timing. Nevertheless, the story with CBD grows every more complex but ever more exciting.



Vitamins are in-organic molecules that are essential nutrients required for the normal functioning of metabolism. In short, no vitamins mean no life. Most vitamins are not single molecules but are instead a group of molecules called vitamers. There are 13 vitamins required for normal human metabolism and while many are ultimately involved in some aspect of immune system function, two in particular stand out as perhaps being the most well know.

Vitamin D is a very important vitamin that has hormone-like functions without being a hormone. It is very important in immune system function especially when it comes to the functioning of T-cells, a critical white blood cell. Only after binding with a version of vitamin D known as ‘calcidiol’ can the T-cell work as intended (18)(19). It has been suggested that the observed progressive decline in general hormone levels with age is partially responsible for weakened immune systems in older individuals (20). The age-related decline in immune function is also related to decreasing vitamin D levels and this is for two reasons. As people age, they stay indoors more due to decreased activity levels which means that they get less sun and therefore produce less cholecalciferol (active vitamin D) via sunlight. Second, as a person ages the skin becomes less adept at producing vitamin D (21) . As such, vitamin D supplementation may be a good idea for older individuals or for individuals who have limited exposure to the sun either for geographical reasons or specific reasons like night-shift work.

Vitamin C is another important, well researched vitamin that is necessary in order to mount an effective immune response. However, due to the work of Linus Pauling, who whether rightly or wrong, is a two-time Nobel Prize winner, confidently claims that ‘mega-dosing’ with vitamin C can not only prevent the common cold but also resolve serious diseases like cancer and heart disease. There is no good quality evidence supporting his claims and this is all the more egregious due to his previous accolades. Vitamin C remains important in immune functioning and as an anti-oxidant (22)(23). Human cannot synthesis vitamin C so the best ways to obtain this vitamin are through foods and supplementation. The one area of research where vitamin C supplementation may have a direct effect is in regard to the common cold. While supplementation does not reduce the chance of developing a cold it can reduce the duration of colds in the general population (24).



While some aspects of your lifestyle are closely linked to your immune system health such as diet and sleep others appear less so but remain very good for your overall health such as exercise. Supplementation, while not a quick route to health, may be a useful avenue for many individuals looking to gain an edge; even more so if you couple frequent supplementation with a focus on good diet, sleep and light exercise as well. This blog has been written to give a brief outline of what can and does affect the health of your immune system and while having a strong immune system is a huge benefit, COVID-19 appears to infect many regardless of immune system health so this blog is not a ‘defence against COVID-19’ guide. The suggestions in this piece are simply good, timeless advice, for staying physically fit inside and out.

As always if you would like any further information or need advice or support please reach out to us over the phone, email, webchat or social media.

Staying at home tips!  – lots of very good quick advice here that expands on our piece and adds new ideas as well.

Explaining COVID-19 to Children – useful article about how to explain our current situation to your kids without frightening them.

Claiming Support and Salaries – an updated webpage letting benefits claimants, employees and businesses know what they should do to gain advice and financial support.

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