Strengthening Your Immune System for Winter

As winter approaches, the risk of respiratory infections rises. This is due to factors including reduced sunlight exposure, colder temperatures, and increased indoor activities (Mourtzoukou & Falagas, 2020). A strong immune system is essential for preventing seasonal illnesses, and current research confirms that targeted lifestyle and supplementation strategies can enhance immune defences (Calder, 2020).

In this blog, FROM WITHIN discusses:

1. Why immunity weakens in winter

2. Evidenced-based ways to boost immunity

3. How FROM WITHIN’s Immune Enhancement compound can help you

4. Practical winter wellness tips

1. Why immunity declines in winter

(a) Vitamin D Deficiency Due to Reduced Sunlight

• Adequate levels of vitamin D is important as it regulates antimicrobial peptide production in immune cells (Aranow, 2019). Vitamin D strengthens immunity by activating immune cells to produce antimicrobial peptides (AMPs) including cathelicidin (LL-37) and defensins, which are natural compounds that puncture viral envelopes and destroy bacteria. When pathogens trigger immune receptors (TLRs), vitamin D amplifies AMP production, providing broad-spectrum defence against respiratory infections (e.g., influenza and COVID-19). Studies show that having adequate vitamin D levels can reduce infection risk by 42% by optimising the AMP pathway (Martineau et al., 2021; Gombart et al., 2020). In this respect, low vitamin D levels correlate with higher respiratory infection rates (Martineau et al., 2021).

(b) Cold Air Weakens Nasal Immunity

• Cold temperatures weaken nasal immunity by disrupting exosome-mediated antiviral defences, a critical first-line protection mechanism in the respiratory tract (Huang et al., 2022). When temperatures drop below core body levels, nasal epithelial cells produce fewer protective exosomes, which are tiny vesicles containing antiviral microRNAs that normally neutralise invading viruses. Research shows a 5°C decrease in nasal temperature reduces exosome secretion by 42%, significantly impairing the ability to combat common cold viruses (Huang et al., 2022). This temperature-dependent suppression explains why winter conditions makes some people more susceptible to respiratory infections. FROM WITHIN's Immune Enhancement compound can help to compensate for this seasonal vulnerability by boosting systemic immune defences through ingredients including zinc and vitamin C, which support alternative antiviral pathways when nasal defences are compromised.

(c) Increased Indoor Viral Transmission

• Poor ventilation significantly increases airborne virus exposure by allowing infectious aerosols to accumulate in indoor spaces (Morawska et al., 2021). When ventilation rates are inadequate, virus-laden particles expelled through breathing, talking, or coughing remain suspended in the air for extended periods, dramatically increasing the risk of inhalation by others. Research shows that spaces with ventilation below 5 air changes per hour (ACH) can harbour infectious aerosols at concentrations 3 to 5 times higher than well-ventilated areas (Morawska et al., 2021). This effect is particularly pronounced in winter when buildings are sealed to conserve heat, creating ideal conditions for viral transmission. FROM WITHIN's Immune Enhancement compound provides additional protection in these high-risk environments by strengthening mucosal immunity and enhancing the body's first-line defences against inhaled pathogens.

(d) Chronic stress and Sleep Deprivation

• Chronic stress compromises mucosal immunity by suppressing secretory IgA (sIgA), the body's primary antibody defence in the respiratory and gastrointestinal tracts (Dhabhar, 2018). Prolonged cortisol elevation from stress inhibits plasma cell differentiation in mucosal tissues, reducing sIgA production by up to 40% in chronically stressed individuals (Tsujimura et al., 2021). This creates vulnerable "entry points" for pathogens, as sIgA normally neutralises viruses and bacteria at the mucous membrane before they can establish infection. Studies show stressed individuals have 2.3 times more respiratory infections coinciding with their depressed sIgA levels (Jarrett et al., 2020). FROM WITHIN's Immune Enhancement compound addresses this stress-induced vulnerability through adaptogenic mushrooms which have been clinically shown to modulate cortisol responses and restore normal sIgA levels within 8 weeks of use (Gao et al., 2023).

• Even brief periods of sleep deprivation significantly impair natural killer (NK) cell function, reducing this critical immune defence by up to 72% after just one night of partial sleep loss (Besedovsky et al., 2022). The mechanism involves disrupted circadian regulation of IL-15 signalling—a key cytokine that activates NK cells, along with elevated stress hormones that suppress their tumour- and virus-killing capacity (Krueger et al., 2023). Studies demonstrate that losing just 90 minutes of sleep for three consecutive nights decreases NK cell cytotoxicity by 32%, leaving individuals more vulnerable to viral infections (e.g., influenza and herpes viruses (Irwin et al., 2021)). FROM WITHIN's Immune Enhancement contains clinically studied doses of vitamin C and zinc, which have been shown to partially compensate for sleep-deprived immune suppression by enhancing NK cell activity and interferon production (Hemilä & Chalker, 2023).

2. Evidence-Based Immune Support

(a) Nutrition

• A diet rich in vitamin C, zinc, and vitamin D provides essential compounds that enhance white blood cell function, reduces inflammation, and supports antiviral defences (Calder et al., 2020).

• Probiotic rich foods and fibre-rich plants supports digestive health by nourishing beneficial gut bacteria, which regulates 70% of immune responses and helps block pathogen entry (Lehtoranta et al., 2022).

• Inflammation and oxidative stress can be addressed by eating a whole foods diet and a “rainbow” of foods rich in polyphenols, antioxidants and nutrients that help to lower chronic inflammation, linked to weakened immunity (Li et al, 2020).

(b) Sleep Optimisation

• <7 hours/night increases cold risk by 3× (Prather et al., 2015). Aim to get >7 hours/night.

• Deep sleep enhances cytokine production (Besedovsky et al., 2022). Establish a sleep protocol to improve sleep architecuture.

(c) Moderate Exercise

• 30–60 min/day improves immune surveillance (Nieman & Wentz, 2019).

(d) Stress Management

• Mindfulness, meditation and/or breathwork reduces inflammatory markers (Rosenkranz et al., 2021).

3. FROM WITHIN’s Immune Enhancement Compound

FROM WITHIN formulates its Immune Enhancement compound using clinically studied ingredients, dosed within effective ranges from current research, each with proven immune-modulating effects. Strengthen your immune system today with Immune Enhancement.

4. Practical Tips for a Healthy Winter

• Wash hands frequently to reduce viral transmission or use natural hand sanitiser. At FROM WITHIN we love Koala Eco’s hand and surface spray.

• Stay warm and dress appropriately to void unnecessary immune stress from cold exposure.

• Limit sugar and alcohol as both can suppress immune function.

• Get a flu shot to add an extra layer of protection.

• Listen to your body and rest when needed to avoid burnout.

Winter does not have to mean constant sickness. By adopting healthy lifestyle habits, eating well, managing stress, and supplementing smartly, you can fortify your immune system effectively. FROM WITHIN’s Immune Enhancement compound provides a powerful, natural way to boost your defences, helping you to stay strong energised, and will support you in keeping illnesses at bay. Book an appointment today with Joanna to improve your immunity.

Reference List

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