Your immune system is your body’s frontline defence against bacterial, viral, and parasitic infections, plus other health challenges. However, it’s far more than a pathogen-fighting army – it also plays a crucial role in patrolling the body for abnormal cells – including cancer cells, and eliminating them before they can cause harm. Lifestyle choices, particularly diet, sleep, stress management, and exercise, are pivotal in maintaining optimal immune function.
1. Nutrition: Building Blocks of Immunity
A nutrient-rich diet ensures your immune cells function efficiently. It is key to eat good quality organic protein and good fats plus the following micronutrients:
- Vitamin D – regulates immune responses and supports T cell activity.
- Vitamin C – a powerful antioxidant that supports white blood cell function.
- Zinc – crucial for immune cell development, function, and wound healing.
- Selenium – protects immune cells from oxidative damage and supports T and NK cell activity.
- Probiotics – promote a healthy gut microbiome, closely linked to immune health.
- Vitamin A – maintains mucosal barriers and supports adaptive immunity.
- Vitamin E – a fat-soluble antioxidant that protects immune cells from oxidative stress.
- Iron – essential for immune cell proliferation, but both deficiency and excess can impair immunity.
Targeted Supplementation to fill the gaps: Even with a healthy diet, supplementation may be helpful when dietary intake is insufficient, especially vitamin D – where production is severely reduced due to a lack of sun exposure.
- Vitamin D – particularly in winter or low sun exposure
- Vitamin C – during periods of high physical stress or illness
- Zinc – short-term supplementation may reduce duration of colds
- Selenium – supports antioxidant defense in immune cells
- Probiotics – especially after antibiotics or gut disturbances
Ethical, Organic, & High-Quality Brands: My preferred brands are Wild Nutrition, Viridian, Ancient & Brave, and Ancient Nutrition. Check out my HEALF Affilate Shop for 10% discount on these brands and other brands you might prefer (please ensure you click on the discount pop-up and enter at checkout) which will appear as you start browsing – note, there is an ‘immune system‘ category within the HEALF HomePage where I have listed some of my favourite products.
Natural Compounds, Strong Defenses: The Immune Benefits of Phytonutrients: Phytonutrients found in whole foods play a powerful role in strengthening the immune system. Compounds like sulforaphane, abundant in broccoli sprouts and other cruciferous vegetables, help activate the body’s natural detoxification pathways and enhance immune surveillance against abnormal cells. Medicinal mushrooms such as shiitake, maitake, and reishi are rich in beta-glucans, which prime immune cells to respond more effectively to threats. Together, these plant-based compounds offer a natural, holistic way to keep the immune system resilient and balanced.
Nutrient RDAs (Adults, UK)
| Nutrient | RDA / Daily Requirement | Notes |
| Vitamin D | 10 µg (400 IU) | More may be needed in winter or low sun exposure – research suggests a dose of 2-4,000 iu per day is ideal for adults and 400-1,000 iu for children |
| Vitamin C | 40 mg | Smokers may require higher intake |
| Zinc | 9.5 mg (men), 7 mg (women) | Excess can impair copper absorption |
| Selenium | 75 µg | Avoid exceeding 400 µg/day |
| Vitamin A | 700 µg (women), 900 µg (men) | Excess preformed vitamin A can be toxic |
| Vitamin E | 4 mg | Supports antioxidant defense |
| Iron | 8.7 mg (men), 14.8 mg (women) | Deficiency impairs immunity |
| Probiotics | General maintenance: 5–10 billion CFU/day After antibiotics: 30 billion CFU/day for the first few months | Supports gut-associated immune function |
2. The Gut Microbiome & Probiotics
The gut microbiome is central to immune system regulation. A healthy gut ensures:
- Balanced immune responses
- Reduced systemic inflammation
- Gut-brain communication for overall wellness
Antibiotic History: If you’ve taken antibiotics in the last 10 years, your gut microbiome may be compromised (dysbiosis). Antibiotics can wipe out good bacteria, leaving mutated or harmful bacteria to thrive. This can lead to:
- Chronic inflammation
- Leaky gut
- Dysregulated immune function
Probiotic Guidance:
- General maintenance: 5–10 billion CFU/day
- After antibiotics: 30 billion CFU/day for the first few months
Probiotics not only support immune health but also gut and brain function. See my blog post: The Microbiome Explained: Your Hidden Health Superpower
3. Sleep: The Immune Reset
Sleep is immune restorative. During deep sleep:
- Cytokines (immune signalling proteins) are produced
- T cells and natural killer (NK) cells are activated
Sleep deprivation can suppress immune responses and increase susceptibility to infections. Adults should aim for 7–9 hours per night, with consistent sleep timing. See my blog post for more information on Sleep.
4. Stress: The Immune Suppressor
Chronic stress elevates cortisol, which:
- Suppresses T cell function and antibody production
- Increases inflammation, paradoxically weakening immunity
- Impairs sleep, creating a vicious cycle of immune suppression
Management strategies: mindfulness, meditation, deep breathing, yoga, or daily walks can reduce stress levels and support immune function.
5. Exercise: Boost, Not Burnout
Regular moderate exercise strengthens immunity by:
- Increasing circulation of immune cells (T cells, NK cells, antibodies)
- Reducing chronic inflammation
- Supporting healthy stress response and sleep quality
Caution: Excessive high-intensity exercise without recovery can temporarily suppress immunity. Aim for 150 minutes of moderate exercise weekly, including strength and aerobic activities.
Summary: Lifestyle Checklist for Immune Optimisation
✅ Nutrient-rich diet: Vitamins D, C, A, E, zinc, selenium, iron, probiotics
✅ Adequate sleep: 7–9 hours/night
✅ Stress management: meditation, mindfulness, breathwork
✅ Regular moderate exercise: 150 minutes weekly
✅ Targeted supplementation where diet is insufficient
✅ Healthy gut microbiome: especially after antibiotics, with high-dose probiotics initially
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