The primary role of the immune system is to protect the body against pathogens: viruses, bacteria, parasites… With several lines of defence (physical barriers, white cells, antibodies …), it works to block access to these microorganisms, and to neutralise and/or eliminate them (1-2).
In practice then, an effective immune system will mean a lower tendency to infections, rapid recovery, normal wound-healing and good general health. In contrast, suffering from recurrent urinary or fungal infections, repeatedly catching winter colds, and feeling constantly tired (even after a good night’s sleep) are very often signs of weakened immunity (3).
Certain population groups have naturally weaker defences:
Certain foods disrupt immune system function, either because they release inflammatory or pro-oxidant molecules, or because they upset the balance of the microbiota (which we now know is linked to immunity).
Culprits include sugar, alcohol, fatty meats and charcuterie (and more generally, an excess of meat products), burnt foods and ultra-processed products (9), see our article on foods bad for immunity.
Sleep is thought to play a key role in immunological memory. One study suggests that sleeping at night facilitates the redistribution of T lymphocytes to lymph nodes and may increase production of interleukin-12 (IL-12), involved in, amongst others, immune surveillance against tumours (10).
Conversely, a prolonged lack of sleep may stimulate production of non-specific pro-inflammatory cytokines, which are responsible for chronic low-grade inflammation and immunodeficiency. Getting enough sleep (7-9 hours a night) would therefore seem to be essential for optimising the immune response.
The impact of sports activity on immunity varies significantly depending on the duration and intensity of the activity. Exercising at a moderate level for up to 60 minutes may improve immunosurveillance, with increased recirculation of immunoglobulins, neutrophils, NK (natural killer) cells and cytotoxic T lymphocytes (11).
This effect may be reversed, however, in the case of prolonged, intense exercise. Several epidemiological studies suggest an increased risk of upper respiratory tract infections in marathon-runners during training or following a competition (12), though certain factors specific to high-level sports activity (mental stress, sleep deprivation) may skew the interpretation of results.
Chronic stress is associated with raised levels of cortisol and corticosteroids. While these ordinarily keep the immune response in check, chronic elevations can induce a form of ‘resistance’, resulting in over-production of inflammatory cytokines, blurred communication between immune cells, and even reactivation of dormant viruses (13).
So try to minimise any nervous tension by engaging in sport, yoga or meditation, for example.
To boost your immunity, it’s important to eat a balanced diet, with plenty of micronutrients and antioxidants.
This means prioritising highly-coloured fruits and vegetables (containing good levels of vitamin C and polyphenols), forms of fibre that benefit the gut flora (present in pulses and whole grains) and natural probiotics (from fermented products) (14). Remember too to include seafood (a source of zinc) and oily fish (rich in omega-3) (15).
Several vitamins are excellent for immunity.
The star nutrient in orange juice, vitamin C is also concentrated in parsley and peppers. It plays a direct role in maintaining normal immune function, acting at different levels: strengthening the epithelial barrier, accumulating in neutrophil white cells, enhancing lymphocyte differentiation (16) … For those who eat few fruits and vegetables, supplementing with vitamin C (for example, the super-potent Triple C which combines three synergistic forms of vitamin C) is a sensible measure.
Vitamin D, primarily synthesised by exposure to the sun, also helps to maintain normal immune function (both innate and acquired). Vitamin D receptors are also expressed by B lymphocytes, T lymphocytes and antigen-presenting cells (17).
In particular, it’s been shown that a lack of zinc increases the risk of infection, yet more than a fifth of the global population is thought to have inadequate zinc status, with vegetarians and the elderly most affected (18). Such groups would therefore benefit from taking a supplement (such as the convenient, suckable Advanced Zinc Lozenges).
You can also support your immune system using plants.
Reishi (Ganoderma lucidum) for example, more than merits its ‘mushroom of immortality’ moniker! Documented in the Chinese pharmacopoeia as far back as the first century BC, this species of fungus helps to support immunity through its unique combination of polysaccharides, peptidoglycans and triterpenes (which can be found in Organic MycoComplex, a super-synergy of 7 organic, medicinal mushrooms) (19).
One of the most popular beehive products, propolis is unusually nutrient-rich, with over 300 exceptional compounds (flavonoids, phenolic acids, vitamins A and B, minerals…) (20). Bees cover the inside of their hive with this precious coating – a mixture of plant resins, wax and saliva - to seal it against intruders. Green propolis from Brazil (the ingredient in the supplement Green Propolis) is notable for its content of artepillin C which is attracting huge scientific interest (21).
An exceptional booster, ginseng root is known to help support vitality and maintain strong immune function. It is an adaptogen plant, which means it is able to improve the body’s resistance and response to various stressors. Scientists have been studying, in particular, the effects of the plant’s ginsenosides on macrophage phagocytosis, the process in which pathogens are engulfed (hence the standardisation to 30% ginsenosides of the supplement Ginseng 30%) (22).
The glycoprotein lactoferrin is part of the beta-globulin family. Abundant in colostrum, the first form of breast milk, it is also found in many organs and secretory fluids (saliva, tears, sperm, bronchial secretions ...) that interface with the outside world. Its ability to bind to iron, to which pathogens are particularly drawn, may account for its benefits (the supplement Lactoferrin, which is purified and free from synthetic excipients) is obtained directly from whey protein) (23).
Can you name 5 plants that help support the body’s defences? If the answer is no, get up to speed now with our list of plants known to benefit the immune system.
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