"You are as old as your immune system" is how an immunologist friend put it. The strength of your immune system is a big determinant of your biological age and how long you will stay healthy.
Unfortunately, as we age our immune function normally becomes weaker. This shows up as a decreased ability to fight viral and bacterial infections, diminished response to vaccination, increase risk of pneumonia and slower recovery times.
Absorption of nutrients by the intestines that support immunity also declines. And the immune system's ability to identify abnormalities and mutated cells and trigger their disposal also decreases. Which can manifest as an increased incidence of cancer.1
Researchers call all this immune-senescence.2
Finally, this decline in immune function triggers processes that accelerate aging. So, slow the decline in immune function and you slow ageing – and extend your health span.
To see how you can help resist this decline, it helps to understand that evolution has equipped you with two, interconnected, immune systems: the innate and the adaptive immune systems.
The Innate Immune System: your body's first line of defence
The innate immune system evolved first, and it provides an immediate response to foreign threats that it hasn't encountered before. You are confronted by a pathogen – say a virus – and your innate immune system is rapidly activated, often within minutes or hours of the invasion.
Innate immune cells called macrophages and neutrophils recognise, engulf and destroy invaders. Then Natural Killer (NK) cells complete the job by recognizing and killing any cells that have been infected with viruses or have become cancerous.
The innate immune cells are called T cells because they are created in the Thymus.
The Adaptive Immune System: Retains a memory of previous threats
The adaptive - (also called acquired) - immune system is your second line of defence. It remembers the specific shape of the surface of any virus or bacteria it has previously encountered. It then creates unique antibodies to attack and clear them – or marks them for destruction by NK cells.
The adaptive or acquired immune cells are white blood cells called B cells – because they are produced in the Bone marrow.
Following an infection, these cells become long-lived memory cells, which patrol the body, ready to mount a rapid defence if they encounter the same infection again.
In contrast to the innate immune cells reaction time of minutes or hours, the adaptive immune cells may take days or even weeks to fully mobilize a response after an encounter with a threat.
So, it was the generalised innate immune cells that helped initially to fight off the Covid virus and the very specific Adaptive immune cells that were stimulated and created by the Covid vaccines.
The collaboration between the two systems works like this. The innate system releases signalling molecules (called cytokines) during the initial inflammatory response. These cytokines instruct the now activated adaptive immune cells on the nature of the threat and direct its precisely customised response.
Very often an immune response will create inflammation as immune cells rush to the site of infection. But it is important that this inflammation is damped down after the threat has been dealt with – otherwise the inflammation can persist, leading to chronic, low-level inflammation.
This persistent inflammation is a contributor to many later life illnesses – including ageing itself – which is why researchers call it 'inflammageing'.
It is also why the anti-inflammatory nutrients in fruits and vegetables are so important.
For women, hormonal fluctuations during menstruation, and then later during and after the menopause, can affect your immunity. These hormonal changes disrupt immune balance and make women more susceptible to both immune related illness and auto-immune disease.
Oestrogen generally enhances immune responses, but post-menopause when oestrogen levels drop significantly, immune function may decline, making dietary and lifestyle immune support even more important.
Having got this biology lesson out of the way (!) – let's see how you can support your immune system.
Four proven ways to support your Immune System
First increase your intake of fruits, vegetables and herbs, which contain nutrients called polyphenols. These help reduce excess inflammation – which otherwise damages immune cells and reduces their effectiveness.
You'll have seen above that nutrient absorption in the gut declines as you get older – which is another reason why additional plant nutrients can help maintain immune function.
Medical News Today recommends the Mediterranean diet as the best way to ensure adequate levels of immune supporting plant nutrients.8
Second, fruits and vegetables contain many of the micro-nutrients that the immune system needs to stay strong – notably vitamins A, C, E, D, zinc, iron, copper and selenium. Protein is also essential for the enzymes that drive immune response.
Some plant foods have above average ability to enhance immune function. The list includes garlic, which is known to stimulate T-cells and has proven antiviral properties.
Broccoli should be high on your list along with leafy greens, such as spinach and kale, which (perhaps surprisingly) contain beta carotene - which converts to vitamin A, a vitamin that helps antibodies fight viruses.
Berry fruits like elderberry and blueberries contain phyto-nutrients like resveratrol which have antiviral and anti-inflammatory effects and help enhance immune system function.5
A recent paper in the Journal of Complementary and Integrated Medicine confirms that "phytonutrients play a positive role by maintaining and modulating immune function".6
Nuts like cashew, almonds and peanuts and seeds are rich in vitamin E, zinc and selenium and B6, which support immune system function and protect against oxidative stress. Which is why we recommend a handful a day.
Mushrooms, too, should feature in your menu at least twice a week – as research confirms they have: "antioxidative, antitumor, antiviral, antimicrobial, and immunomodulatory" compounds.7 All mushrooms have immune health benefits with shitake, turkey tail and reishi appearing especially beneficial.
Plant nutrients – including colour nutrients – further support stronger immunity via the gut. The gut is the site of an estimated 70% of immune activity, and this is strongly influenced by diet. A plant-rich diet with plenty of colourful fruits, vegetables and legumes, and plant nutrients, supports the growth and maintenance of beneficial microbes.
So, plant nutrients – like the 161 colour nutrients in DailyColours® - are vital in supporting and strengthening your immune system as you get older.
Whilst the occasional glass of (ideally red) wine is a pleasure for many of us - you should note that alcohol can damage immune cells in the blood and disrupt communication between immune system cells. So stay to the limits.
Finally, don't forget that regular exercise,9 keeping at a healthy-weight, at least 7 hours sleep and reducing stress are also important ways to support your immune system.
Moderate-intensity aerobic exercise stimulates the circulation of key immune cells, including T cells, B cells, natural killer (NK) cells, and macrophages, throughout your body. This increased circulation allows these immune cells to detect and respond to infections more efficiently. It also lowers stress levels and promotes better sleep.
Chronic stress suppresses immune function, so calming practices such as deep breathing, and yoga are also beneficial.
The book "The Power of Plant Colours to Slow Ageing" contains a lot more advice on increasing your health span and is free to download here.
References
- Aging and the immune system: An overview - PubMed (nih.gov)
- Innate and adaptive immunosenescence - PubMed (nih.gov)
- Causes, consequences, and reversal of immune system aging (nih.gov)
- Choose Foods that Boost Your Immunity and Fight Infection
- Foods to deliver immune-supporting nutrients - ScienceDirect
- Phytonutrients as therapeutic agents
- Frontiers | Immune regulatory functions of biologically active proteins from edible fungi
- Bioactive proteins from mushrooms - ScienceDirect
- Can physical activity ameliorate immunosenescence and thereby reduce age-related multi-morbidity? | Nature Reviews Immunology
- What diet is best for older adults?